Intractable Breathlessness

A number of lung diseases (e.g. chronic bronchitis and emphysema) are capable of producing shortness of breath that is often extremely distressing to the patient. Many of these conditions are irreversible, so it becomes necessary to target the symptom itself. The sensation of breathlessness is a complicated phenomenon that seems to depend upon central processing through respiratory and non-respiratory mechanisms (Guz 1996). Ideally, a treatment would relieve the unpleasant sensa tion without...

Inhibitors of Endocannabinoid Biosynthesis

Partly owing to the fact that the NAPE-PLD for AEA and the two DAGLs for 2-AG have been cloned only very recently, no selective inhibitors of endocannabinoid biosynthesis have been developed to date. However, several non-specific inhibitors have been shown to prevent the formation of either AEA or 2-AG. For the former compound, Cadas et al. (1997) showed that several non-selective hydrolase inhibitors, and particularly the PLA2 inhibitor (BTNP), could block the activity of crude preparations of...

Synaptic Plasticity

The anecdotal reports of effects of smoking cannabis on cognitive processes has naturally prompted investigation into the effects of cannabinoids on synaptic plasticity, and in particular long-term potentiation (LTP). To summarise 17 years of effort, it has been easy to show that cannabinoids have effects on LTP, and most commonly suppress it, but far more difficult to define the mechanisms by which this occurs. Emerging themes are that the commonly reported inhibition of LTP by synthetic...

Pharmacokinetics of Cannabidiol

Cannabidiol (CBD) is a natural constituent of Cannabis sativa that is not psychoactive (Benowitz et al. 1980 Perez-Reyes et al. 1973b Pertwee 2004), but possesses pharmacological activity that is being explored for therapeutic applications (Pertwee 2004). CBD has been reported to be neuroprotective (Hampson et al. 1998), analgesic (Holdcroft 1984 Karst et al. 2003 Vaughan and Christie 1984), sedating (Holdcroft 1984 Melamede 1984 Plasse 1984 Vaughan and Christie 1984), antiemetic (Plasse 1984),...

Effects of Cannabinoids on Neurotransmission

1 Institut f r Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universit t, Albertstrasse 25, 79104 Freiburg, Germany szabo pharmakol.uni-freiburg.de 2Institut f r Pharmakologie und Toxikologie, Rheinische Friedrich-Wilhelms-Universit t, Reuterstrasse 2b, 53113 Bonn, Germany 328 2 Effects of Cannabinoids on Ion Channels 328 2.1 Effects of Cannabinoids on Voltage-Gated Ion Channels 329 2.2 Effects of Cannabinoids on Ligand-Gated Ion Channels 330 2.3 What Is the...

Summary and Implications

There is compelling evidence to indicate that endocannabinoids are involved in retrograde signalling within a number of brain regions, including those involved in memory, motor control and reward addiction. It is possible that retrograde endocannabinoid signalling occurs in other 'cannabinoid-sensitive' regions of the central nervous system and might prove to be a general phenomenon. Briefly, the events underlying retrograde endocannabinoid signalling can be described as follows (Fig. 4)....

The Phylogenyof Cannabinoid Receptors and Other Endocannabinoid Receptors

What our survey of the phylogenetic distribution of endocannabinoids and associated enzymes indicates is that the ability of cells to produce and inactivate the molecules that we classify as endocannabinoids in mammals is an evolutionarily ancient phenomenon. Moreover, some components of the endocannabinoid system may date back as far as the common ancestor of all eukaryotic organisms. However, the ability of cells to produce these molecules does not necessarily imply that they function as...

Hepatic Metabolism

Burstein et al. were the first to show that 11-OH-THC and THCCOOH were primary metabolites of THC in rabbits and rhesus monkeys (Ben-Zvi et al. 1976 Ben-Zvi and Burstein 1974 Burstein et al. 1972). They also documented that THC could be metabolized in the brain. Harvey et al. monitored the metabolism of THC, CBD, and CBN in mice, rats, and guinea pigs and found extensive metabolism, but with inter-species variation (Harvey et al. 1979). Phase I oxidation reactions include allylic and aliphatic...

General Structure and Distribution

Cb1 Structure

Two cannabinoid receptors have been identified to date the CB1 receptor is localized predominantly in the central nervous system (CNS), whereas the CB2 receptor is located primarily in the immune system. The CB1 receptor cDNA was isolated from a rat brain library by a homology screen for GPCRs and its identity confirmed by transfectingthe clone into CHO cells and demonstrating cannabinoid-mediated inhibition of adenylyl cyclase (Matsuda et al. 1990). Initial identification of the lig-and for...

Pharmacological Actions of Cannabinoids

School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, 2 Bioassays for Characterizing CBj and CB2 Receptor Ligands 6 2.1 In Vitro Binding 2.2 In Vitro Functional Bioassays 2.2.1 Assays Using Whole Cells or Cell 2.2.2 Isolated Nerve-Smooth Muscle Preparations 2.3 In Vivo Bioassays 2.4 Cannabinoid Receptor Knockout 3 CBi and CB2 Cannabinoid Receptor 3.1 Cannabinoid Receptor Agonists 3.2 Cannabinoid CBi and CB2 Receptor 3.2.1 Selective CB 1 Receptor Antagonists 3.2.2...

Role of the Endocannabinergic System in Hemorrhagic Endotoxic and Cardiogenic Shock and Liver Cirrhosis

The profound and long-lasting, yet reversible, hypotension elicited by potent synthetic cannabinoids (Lake et al. 1997a) suggested that endocannabinoids maybe involved in pathological conditions associated with extreme hypotension such as various forms of shock. Observations over the last decade have provided evidence for a key role of endocannabinoids in the hypotension associated with hemor-rhagic (Wagner et al. 1997), endotoxic (Varga et al. 1998 Liu et al. 2003 Batkai et al. 2004a Wang et...

References

Abadji V, Lin S, Taha G, Griffin G, Stevenson LA, Pertwee RG, Makriyannis A (1994) (R)-Methanandamide a chiral novel anandamide possessing higher potency and metabolic stability. J Med Chem 37 1889-1893 Abood ME, Ditto KE, Noel MA, Showalter VM, Tao Q (1997) Isolation and expression of a mouse CB1 cannabinoid receptor gene. Comparison of binding properties with those of native CB1 receptors in mouse brain and N18TG2 neuroblastoma cells. Biochem Pharmacol 53 207-214 Adams IB, Ryan W, Singer M,...

Regulation of Endocannabinoid Levels Under Pathological Conditions

Although we now know that the effects of endocannabinoids and exogenously administered THC can be both qualitatively and quantitatively different, the fact that the symptoms of many ailments have been reported to be alleviated by THC and Cannabis provided the rationale to test whether pathological alterations of endocannabinoid signalling can be causative of pathological states, or of their signs. There is now increasing evidence that endocannabinoid levels undergo significant changes in...

Effects on the Immune System Using In Vitro Models 231

Early experiments involved the use of mixed cell populations, since these more closely replicated the in vivo condition of a complex mixture of distinctive cell types cross-talking through soluble mediators as well as interacting with each other through cell-contact-dependent modalities. Furthermore, the use of mixed cell populations lent itself to the application of depletion and reconstitution studies for the definition of specific cell subpopulations affected by cannabinoids. Lefkowitz et...

The Role of Receptor Regulation in the Development of Cannabinoid Tolerance

Cannabinoid tolerance develops in the absence of pharmacokinetic changes (Martin et al. 1976) therefore, biochemical and or cellular changes are responsible for this adaptation. The production of tolerance can be associated with a drug's abuse potential (O'Brien 1996) therefore receptor mechanisms contributing to cannabinoid tolerance are of significant interest. One hypothesis for tolerance development is that receptors lose function during chronic agonist treatment, leading to diminished...

Endocannabinoid Pharmacological Actions Some Major Differences from THC

The pharmacology of endocannabinoids overlaps with that of THC to a great extent. However, important qualitative and quantitative differences have been observed between the pharmacological actions in vivo of THC and, for example, AEA. Together with the high metabolic instability of endocannabinoids, the observation that some of these compounds can activate receptors different from CB1 and CB2 can certainly explain some of these differences. This is particularly true for the four behavioural...

Biosynthesis of AEA and Other WAcylethanolamines

AEA belongs to the family of the N-acylethanolamines (NAEs), which have been investigated since the 1960s. Work performed by H. Schmid and co-workers long before the discovery of AEA had shown that these compounds are biosynthesized via a phospholipid-dependent pathway (Fig. 2), i.e. the enzymatic hydrolysis of the corresponding N-acyl-phosphatidylethanolamines (NAPEs) (Schmid et al. 1990, 1996,2002a Hansen et al. 1998, for reviews). The enzyme catalysing this reaction is a phospholipase D...

RoleofCB1 Receptors in the Cardiovascular Effects of Cannabinoids

The discovery of anandamide, the first endocannabinoid (Devane et al. 1992), has raised the obvious question whether it possesses cardiovascular activity similar to THC. Upon its intravenous bolus injection into anesthetized rats and mice, anan-damide was found to elicit a triphasic blood pressure response and bradycardia (Varga et al. 1995 Pacher et al. 2004 Batkai et al. 2004b see Fig. 1) similar to that reported earlier for THC (Siqueira et al. 1979). The first phase of the response Fig. 1....

Interaction Between Cannabinoids and Ethanol

There is now considerable evidence to suggest a possible involvement of the cannabinoid CB1 receptor in the addiction-related effects of ethanol (Mechoulam and Parker 2003). Both, cannabinoids and ethanol produce some similar physiological and behavioural responses including euphoria, motor incoordination and hypothermia. CB1 ligands are able to modulate ethanol preference and self-administration (Arnone et al. 1997 Freedland et al. 2001 Mechoulam and Parker 2003). Furthermore, chronic ethanol...

Introduction Of Experimental Pharmacology

Currently, there is a growing interest in the biology, chemistry, pharmacology, and toxicology of cannabinoids and in the development of potential cannabinoid medications. It is clear that the endogenous cannabinoid system plays a critical role in physiological and behavioral processes. Endogenous cannabinoid neurotransmit-ters, receptors, and transporters, synthetic cannabinoid agonists and antagonists, and cannabis-based extracts are the subject of extensive research. It is hoped that these...

CB1 Cannabinoid Receptors and Emotional Behaviour

Different evidence suggests that the endocannabinoid system plays an important role in the regulation of emotional-like behaviour. Thus, the CB1 cannabinoid receptor is widely distributed in limbic and cortical areas involved in the control of emotion. The administration of cannabinoid ligands produces emotional-like responses in different behavioural paradigms. Furthermore, cannabinoids also exert a modulatory role on the activity of the hypothalamic-pituitary adrenal axis (HPA), and these...

Interaction Between Cannabinoid Receptors and Other Addictive Drugs

Different evidence supports the possible existence of functional interactions between cannabinoids and other drugs of abuse including opioids, psychostimulants, ethanol and nicotine. Findings in support of a link between cannabinoids and other drugs of abuse include (1) the existence of common physiological and pharmacological properties (opioids, ethanol, nicotine) (2) the stimulation of dopamine release after their administration (psychostimulants, opioids, ethanol, nicotine) (3) the...

Role of Endocannabinergic System in Hypertension

As early as in the 1970s, the potential use of cannabinoid ligands as antihypertensive agents had been considered (Archer 1974 Crawford and Merritt 1979 Varma et al. 1975 Zaugg and Kyncl 1983), in the hope that their neurobehavioral and cardiovascular effects could be separated. Although an early study in normotensive rats indicated rapidly developing tolerance to the hypotensive and bradycardic effects of THC (Adams et al. 1976), a subsequent study in spontaneously hypertensive rats (SHR)...

Nonclassical Cannabinoids

A second class of cannabinergic ligands possessing close similarity with CCs was developed at Pfizer in an effort to simplify the CC structure, while maintaining or improving biological activity (Johnson and Melvin 1986 Little et al. 1988). This group of compounds, generally designated as non-classical cannabinoids (NCCs), includes AC-bicyclic (e.g., 25 and 26, Fig. 7) and ACD-tricyclic (e.g., 27, Fig. 7) ligands lacking the pyran B-ring of CCs. Of these the best known is CP- Fig. 7....

Measurement of Cannabinoid Receptor Density

CB1 Receptor Mapping Autoradiographic studies with high-affinity THC analogs both in rat brain tissue (Herkenham et al. 1990) and in postmortem human brain tissue (Thomas et al. 1992 Biegon and Kerman 2001) have demonstrated high concentrations of cannabinoid receptors in the basal ganglia and especially in its outflow nuclei, the globus pallidus, and substantia nigra. High concentrations are also found in hippocampus and cerebellum. The cerebral cortex, especially the cingulate gyrus, also has...

Sublingual and Dermal Administration

Due to the chemical complexity of cannabis plant material as compared to synthetic THC, cannabis extracts are being explored as therapeutic medications. One reproducible extract of the Cannabis sativa plant contains approximately equal amounts of THC and CBD (see Pharmacokinetics of Cannabidiol, Sect. 3). The efficacy of cannabis extracts has been evaluated in clinical trials for analgesia (Holdcroft 1984 Vaughan and Christie 1984), spasticity, and other indications in affected patients...

What Is the Functional Consequence of the Inhibition of Somadendritic Ion Channels

The majority of the experiments in which the effect of cannabinoids on somaden-dritic ion channels was studied were carried out on cell lines, on cells artificially expressing the CB1 receptor or on isolated neurons. It is not known whether the effects also occur under natural conditions. For example, cannabinoid receptor agonists did not influence voltage-dependent calcium channels in caudate-putamen medium spiny neurons (Szabo et al. 1998), although these neurons are known to synthesise CB1...

Other Metabolic Reactions

The hydrolysis products of both AEA and 2-AG, i.e. arachidonic acid and ethanol-amine or glycerol, are immediately recycled into membrane phospholipids to possibly re-enter the biosynthetic pathways of the two endocannabinoids at a later stage. However, 2-AG can be directly esterified into (phospho)glycerides prior to its hydrolysis, via phosphorylation and or acylation of its two free hy-droxyl groups (for a review see Sugiura et al. 2002). This pathway was suggested to occur in mouse N18TG2...

AEA Uptake Inhibitors

Many analogs of AEA have been tested as inhibitors of the AEA uptake process (Table 4). The reader is referred to comprehensive papers that include most of the structure-activity profiles of the first generation of inhibitors (Piomelli et al. 1999 Jarrahian et al. 2000 Di Marzo et al. 2002). Of these analogs, the best studied has been AM404 (N-(4-hydroxybenzyl)arachidonoylamine), which inhibits AEA uptake into neurons and other cell types with IC50 values in the low micromolar range and...

Ontogeny of the Endogenous Cannabinoid System

The existence of several components of the endogenous cannabinoid system has been demonstrated in the fetal and neonatal rat brain. The system is active in this period of life and shows significant differences in the expression and or activity of its components during the consecutive steps of early stages of development. Most of the studies carried out on the presence and or the activity of the components of this system during development have focused on the cannabinoid CBi receptor (Mailleux...

Inhibitors of Endocannabinoid Inactivation

Several selective FAAH inhibitors have been developed (for reviews see Bisogno et al. 2002 Deutsch et al. 2002), some of which have IC50 values in the low nanomolar or subnanomolar range of concentrations (Boger et al. 2000 Kathuria et al. 2003) (Fig. 4). The first FAAH inhibitors to be developed, such as the irreversible inhibitor methyl-arachidonoyl-fluoro-phosphonate (MAFP) (Deutsch et al. 1997b De Petrocellis et al. 1997), and the trifluoromethyl ketones, which are competitive inhibitors,...

Interaction Between Cannabinoids and Psychostimulants

The endogenous cannabinoid system has been reported to be involved in the addictive effects induced by other drugs of abuse, such as cocaine and other psychostimulants. Dopaminergic activity in the mesocorticolimbic system is considered a common feature mediating the primary reinforcing effects of most drugs of abuse (Di Chiara 1998). Psychostimulants facilitate this dopaminergic neurotransmission by different mechanisms, including the enhancement of extracellular dopamine concentrations,...

Cannabinoids in the Hypothalamus and Pituitary

The presence of endocannabinoids has been shown in the hypothalamus (Herken-ham 1995) and in the anterior pituitary (Gonzales 1999). The central cannabinoid receptor (CBi receptor) is also present is these structures. The hypothalamus contains fewer cannabinoid binding sites than other areas of the CNS. Nevertheless the effects caused by the activation of CB1 receptors in the hypothalamus are important, maybe because the receptors are more or less concentrated within specific hypothalamic...

Pharmacokinetics and Metabolism of the Plant Cannabinoids Tetrahydrocannabinol Cannabidiol and Cannabinol

Chemistry and Drug Metabolism, Intramural Research Program, 5500 Nathan Shock Drive, Baltimore MD, 21224, USA mhuestis intra.nida.nih.gov 2 Pharmacokinetics of 2.1 Absorption 2.1.1 Smoked 2.1.2 Oral 2.1.3 Rectal 2.1.4 Sublingual and Dermal Administration 2.3 Metabolism 2.3.1 Hepatic 2.3.2 Extrahepatic 2.4 Elimination 2.4.1 Terminal Elimination Half-Lives of 2.4.2 Percentage THC Dose Excreted as Urinary 2.4.3 Cannabinoid Glucuronide 2.4.4 Urinary Biomarkers of Recent Cannabis 3 Pharmacokinetics...

Endocannabinoids

In 1992 an arachidonic acid ethanolamide derivative (52, AEA, Fig. 13) isolated from porcine brain and characterized as an endogenous ligand for the cannabinoid receptors was named anandamide (Devane et al. 1992b). AEA is a highly lipophilic compound encompassing four non-conjugated cis double bonds and is sensitive to both oxidation and hydrolysis. It was shown to bind to the CB1 receptor with moderate affinity (K 61 nM), has low affinity for the CB2 receptor (K 1,930 nM), and behaves as a...

Effects of Cannabinoids on the Brain

To date, there is no evidence for gross morphological and structural changes in brain following short-term or long-term marijuana smoking. Although this has been investigated over many years, of particular interest here are studies that have utilised modern imaging techniques such as magnetic resonance imaging (MRI). There were no regional or global changes in brain tissue volume or composition in cannabis users (Block et al. 2000). More subtle changes can be determined through post-mortem...

Constitutive Activity

The CB2 receptor has also been shown to be constitutively active (Bouaboula et al. 1999a). Furthermore, CB2 receptors expressed in CHO cells also sequester Gi proteins the CB2 inverse agonist SR144528 inhibits basal G protein activity as well as switching off MAPK activation from receptor tyrosine kinases and the GPCR lysophosphatidic acid (LPA) receptor (Bouaboula et al. 1999a). CB2 receptors are constitutively phosphorylated and internalized (Bouaboula et al. 1999b). Autophosphorylation as...

Other Motor Disorders

To our knowledge, no data exist on the role(s) of cannabinoid receptors in other basal ganglia disorders in the human, such as tardive dyskinesia, Gilles de la Tourette's syndrome, dystonia, and others. Even so, cannabinoids might be of interest for the treatment of at least some of these diseases (for reviews see Consroe 1998 Fern ndez-Ruiz et al. 2002 Table 2 for more details). Thus, a relationship between cannabis use and the incidence of tardive dyskinesia has been described in psychiatric...

Effects of Cannabinoids on Neurotransmission in the Peripheral Nervous System

Effects of cannabinoids on the sympathetic nervous system have been studied in isolated tissues and in pithed animals (Table 4). Sympathetic neurons were usually activated by electrical stimulation. Activation of CB1 receptors led to inhibition of noradrenaline and or ATP release and, consequently, to inhibition of the effector responses in the heart, in mesenteric and renal blood vessels and in the vas deferens. Figure 5A shows that cannabinoids inhibit sympathetic neuroeffector transmission...

In Vitro and ExVivo Neuroimaging Using Autoradiography 211

In in vitro receptor autoradiography, frozen human or animal brains are processed to form thin (20 pm) sections fixed onto glass slides. The sections are incubated in receptor radioligand solution to allow labeling of receptor-rich areas and washed to remove unbound radioligand. Subsequent exposure of sections using film, imaging plates, or a beta imager yields maps of the receptor distribution. The images produced by autoradiography have spatial resolution of approximately 50 pm, although...

Mechanisms of FAAH Regulation

Expression of FAAH is up-regulated by progesterone and leptin and down-regulated by estrogen and glucocorticoids (Maccarrone et al. 2001a, 2003b Waleh et al. 2002). Changes in FAAH protein concentrations are paralleled by changes in mRNA levels, consistent with transcription regulation by these factors. Although steroid hormone-response elements have been described in the promoter region of the FAAH gene in rodents and human, the precise mechanisms by which progesterone, estrogen, and...

FAAH Inhibitors

The characterization of FAAH activity and its role in eCB signaling has been enabled by the development of effective FAAH inhibitors, with diverse structures and affinities for the enzyme (Table 1). Most of the inhibitors target the catalytic site of FAAH and thereby prevent the interaction of the enzyme and its substrates. The first identified inhibitor of FAAH was phenylmethylsulfonyl fluoride (PMSF) an agent widely used to inhibit serine proteases (Deutsch and Chin 1993). PMSF inhibits FAAH...

CB1 and CB2 Cannabinoid Receptor Ligands

In terms of chemical structure, established cannabinoid receptor agonists fall essentially into four main groups classical, nonclassical, aminoalkylindole and eicosanoid (reviewed in Howlett et al. 2002 Pertwee 1999a). - The classical group consists of dibenzopyran derivatives that are either cannabis-derived compounds (phytocannabinoids) or their synthetic analogues. Notable examples are the phytocannabinoids49-THC,48-THC and cannabinol (Fig. 1), and the synthetic cannabinoids,...

Cannabinoids and Thermoregulation

One of the characteristic pharmacological properties of CB1 receptor agonists is an ability to induce hypothermia (Pertwee 1985). The changes of body temperature caused by cannabinoids are dose dependent. According to Pertwee, higher doses of THC cause hypothermia by lowering the thermoregulatory set point, while lower doses are hyperthermic. It has been postulated that differential Gs and Gi protein activation by CB1 receptors could explain these findings (Sulcova et al. 1998)....

Measurement of Cannabinoid Effects on Brain Metabolism

Acute Effects of 49-THC on Brain Glucose Metabolism Two papers have been published utilizing PET to assess the effects of cannabinoids on rCGM in human subjects. (Volkowetal. 1991,1996). The most consistent observation both in normal controls and habitual marijuana users was an increase in relative metabolic rate in the cerebellum after i.v. 49-THC. This increase was positively correlated both with concentrations of 49-THC in the plasma and with the intensity of self-reported ratings of...

Interaction Between Cannabinoids and Nicotine

The consumption of cannabis is highly associated with tobacco, which contains nicotine, an important psychoactive compound (Nemeth-Coslett et al. 1986 Mc-Cambridge and Strang 2004). The administration of THC and nicotine in rodents produces multiple common pharmacological responses including analgesia, hypothermia, impairment of locomotor activity and addiction (Hildebrand et al. 1997 Ameri 1999 Maldonado and Rodriguez de Fonseca 2002). Nicotine responses are mediated by the activation of...

Absorption 211

Stoned Woman Ten Years After

Route of drug administration and drug formulation determine the rate of drug absorption. Smoking, the principal route of cannabis administration, provides a rapid and efficient method of drug delivery from the lungs to the brain, contributing to its abuse potential. Intense pleasurable and strongly reinforcing effects may be produced due to almost immediate drug exposure to the central nervous system. Slightly lower peak THC concentrations are achieved after smoking compared to intravenous...

Epilepsy

Epilepsy afflicts around 1 of the world's population, and historically was an important target for medicinal cannabis (O'Shaugnessy 1843 Reynolds 1890). Modern anti-epileptic drugs fail to provide satisfactory control in up to 30 of patients, and all can produce disabling or even life-threatening unwanted effects. A confusing picture emerges when cannabinoids are evaluated in animal models of epilepsy (Karler and Turkanis 1981 Consroe and Snider 1986). CBD has anticonvulsant properties with a...

Urinary Biomarkers of Recent Cannabis

Significantly higher concentrations of THC and 11-OH-THC in urine are observed when Escherichia coli -glucuronidase is employed in the hydrolysis method compared to either Helix pomatia -glucuronidase or base (Kemp et al. 1995a,b). THC and 11-OH-THC are primarily excreted in urine as glucuronide conjugates that are resistant to cleavage by alkaline hydrolysis and by enzymatic hydrolysis procedures employing some types of -glucuronidase. Kemp et al. demonstrated that -glucuronidase from E. coli...

Measurement of Cannabinoid Effects on Blood Flow

A9-THC and its active metabolite 11-OH-THC both reduce rCBF, as measured using autoradiography with 14C iodoantipyrine (IAP) . Rats injected with A9- THC at doses ranging from 0.5 to 16 mg kg 30 min prior to sacrifice had variably decreased rCBF in 16brain areas, including the CA1 region of the hippocampus, the frontal and medial prefrontal cortex, the nucleus accumbens, and the claustrum. Other regions, such as the medial septum, caudate, cerebellum, and several other cortex regions, remained...

Oral Administration

There are fewer studies on the disposition of THC and metabolites after oral as compared to the smoked route of cannabis administration. THC is readily absorbed due to its high octanol water coefficient, estimated to be between 6,000 and over 9 million by different technologies (Harder and Rietbrock 1997). The advantages of cannabinoid smoking are offset by the harmful effects of cannabinoid smoke hence, smoking is generally not recommended for therapeutic applications. Synthetic THC...

Endocannabinoids Act via Presynaptic Cannabinoid CB1 Receptors to Inhibit Transmitter Release

THC and a number of synthetic non-selective cannabinoid receptor agonists (such as WIN 55,212-2 and HU-210) modulate neuronal excitability by presynaptic CBi-mediated short-term inhibition of glutamatergic and y-aminobutyric acid (GABA)ergic synaptic transmission (for more detailed reviews see Schlicker and Kathmann 2001 Alger 2002). Release studies have demonstrated that cannabinoids also modulate other neurotransmitter systems. In accordance with the electrophys-iological evidence, anatomical...

Virodhamine

O-Arachidonoylethanolamine was identified in rat brain and named virodhamine (Porter et al. 2002). This compound is similar to anandamide in being formed from arachidonic acid and ethanolamine, but virodhamine contains an ester linkage rather than anandamide's amide linkage. Like anandamide, it appears to act as a partial agonist. However, a microdialysis study suggested that while its tissue concentrations are similar to anandamide, it is released in much higher amounts. The existence of this...

Role of Vanilloid TRPV1 Receptors in the Cardiovascular Effects of Cannabinoids

Structural similarities between anandamide and vanilloid compounds such as capsaicin (Di Marzo et al. 1998) raised the possibility of an interplaybetween these two systems. Indeed, Zygmuntetal. (1999) demonstrated that in rat mesenteric arteries, the endothelium-independent vasodilator effect of anandamide is inhibited by the TRPV1 receptor antagonist capsazepine or by a CGRP receptor antagonist. They further demonstrated that anandamide binds to the cloned TRPV1 receptor with micromolar...

In Vivo Studies 321

Lower oesophageal sphincter (LOS) relaxation is the chief mechanism for gastro-oesophageal reflux, and thus represents a potential target in the treatment of gastro-oesophageal reflux disease. The principal anatomical components of LOS relaxation are afferent gastric pathways, brainstem integrative centre, and efferent inhibitory pathways to the lower oesophageal sphincter. Functional studies have shown that i.v. administration of the cannabinoid receptor agonists WIN 55,2122 and A9-THC...

Exogenous Cannabinoids

Smith et al. (1978) were among the first to note structure-activity relationships of natural and synthetic cannabinoids in suppression of humoral and cell-mediated immunity. They indicated that THC, 48-THC, 1-methyl 48-THC and abnormal 48-THC caused immunosuppression, based on reduction of the humoral immune response to SRBC as measured by spleen plaque-forming cells. Furthermore, this suppression was not related to CNS activity, since 1-methyl48-THC and abnormal 48-THChad minimal CNS activity....

CB2 Receptor Activation

As with the CB1 receptor, mutation of the highly conserved aspartate residue in the second TM domain of the CB2 receptor, D2.50(80) to glutamine or glutamate, disrupted G protein coupling without affecting high-affinity agonist binding (Tao and Abood 1998). The DRY motif has been shown to be important for activation of a number of GPCRs. This motif has been examined in two separate studies of the CB2 receptor, with different results (Feng and Song 2003 Rhee et al. 2000b). Both investigations...

Covalent Binding Probes

Makriyannis and co-workers have developed several novel cannabinoid receptor affinity ligands (for recent reviews see Khanolkar et al. 2000 Palmer et al. 2002) that encompass reactive groups at judiciously chosen positions within the classical cannabinoid structure and can be used as probes for obtaining information on the receptor binding domain. Two types of reactive groups were incorporated (1) electrophilic isothiocyanate group (NCS) that target nucleophilic amino acid residues such as...

T and YMaze Procedures

Rodents show spontaneous alternation behaviour when tested in simple T- or Y-shaped mazes. They can also be forced to alternate, i.e. when food reward is placed at the end of the goal arm of the T Y. As pointed out for the eight-arm radial maze, this paradigm uses food or drinking of juice as reward and is contra-indicated when using cannabinoids. Systemic administration of A9THC prior to daily testing decreased the alternation score (Nava et al. 2000). In control animals, in vivo brain...

Phenotypes of Dorsal Root Ganglion Cells Expressing CB1Rs and CB1R mRNA

To better understand the role of cannabinoids in sensory processing, phenotypes of dorsal root ganglion cells that synthesize CBIRs have been investigated by several laboratories (Ahluwalia et al. 2000, 2002 Bridges et al. 2003 Hohmann and Herkenham 1999b Price et al. 2003). Small-diameter cells in the dorsal root ganglia, in general, correspond to nociceptors and thermoreceptors, respond to high-threshold stimuli, and have unmyelinated or thinly myelinated axons. The small-diameter cells fall...

Effects on the Immune System Using In Vivo Models

Experimental animal models, using guinea pigs and mice, have been used for nearly a century to document effects of various toxic and infectious agents on host resistance. These in vivo models have offered unique advantages for assessment of effects of drugs on infection and immunity due to their well-defined immune systems. Furthermore, use ofanimal modelshasallowedforthe definitionoffactorsof host resistance that are targeted by drugs under stringently controlled conditions. As a result,...

The SR14428 Binding Site

The SR144528 binding site (Table 1) on CB2 has been analyzed by a combination of site-directed mutagenesis and molecular modeling (Gouldson et al. 2000). Mutation of C175 (in the third EC loop) to serine resulted in a receptor with normal affinity for 3H CP 55,940, but loss of recognition of SR144528. Consequently, SR144528 did not act as an antagonist at this mutant. An eightfold loss of affinity for WIN 55,212-2 was observed with the C175S mutant. Mutation of S4.53(161) and S4.57(165) to...

Cannabinoid Research Utilizing MRI

Anatomical Studies An early paper using the comparatively primitive technique air encephalography to evaluate neuroanatomical changes in chronic cannabis users reported cerebral atrophy (Campbell et al. 1971), and sparked a debate in the field. Other studies using more advanced techniques such as computerized axial tomography have not substantiated these results (Co et al. 1977 Kuehnle et al. 1977). Two more recent papers utilizing MRI to assess anatomical changes in marijuana using subjects...

Cannabinoid Receptors and Their Ligands Ligand Ligand and Ligand Receptor Modeling Approaches

Department of Chemistry and Biochemistry, University of North Carolina Greensboro, P.O. Box 26170, Greensboro NC, 27402, USA 1.1 Cannabinoid Receptor Agonists 1.2 Cannabinoid CB 1 Receptor Antagonists Inverse Agonists 251 1.3 CB2 2 CB Pharmacophore Development Ligand-Ligand and Ligand-Receptor 3 Classical Non-classical CB Pharmacophores CoMFA Pharmacophores for Classical Non-classical CBs 254 3.1.1 Side Chain SAR 3.2 Ligand-Receptor Studies for Classical Non-classical CB Binding to CBi 257 3.3...

Ligand Ligand Studies of the Aminoalkylindoles and Related Compounds

Eissenstat and co-workers were first to develop a pharmacophore for AAI binding at CB1. These investigators presented two pharmacophoric models developed using mouse vas deferens (MVD) data (Eissenstat et al. 1995). The first model was an independent pharmacophore with three key structural features (see compound 3 for numbering system) (1) the nitrogen atom in the amino alkyl side chain (2) the C-3-aroyl ring, represented by a dummy atom placed at its centroid and (3) a heterocyclic nucleus...

Aminoalkylindoles

The fourth chemical class of cannabinergic ligands, the aminoalkylindoles (AAIs) were initially developed at Sterling Winthrop as potential non-ulcerogenic analogs of non-steroidal anti-inflammatory drugs (NSAIDs) (Bell et al. 1991) and bear no structural relationship to the cannabinoids. These analogs also exhibited antinociceptive properties that eventually were attributed to their interactions with the cannabinoid receptors (D'Ambra et al. 1992 Eissenstat et al. 1995). The most widely...

Dorsal Column Visceral Pain Pathway

The dorsal column pathway maybe of major importance for visceral pain (Berkley and Hubscher 1995 Willis et al. 1995). This pathway originates from the visceral processing circuitry in the gray matter surrounding central canal of the spinal cord and ascends ipsilaterally in the dorsal columns, the white matter areas adjacent to the midline on the dorsal aspect of the spinal cord. The putative involvement of the dorsal column in visceral pain is noteworthy for two reasons, the first being that it...

The Phylogenetic Distribution and Evolutionary Origins of Endocannabinoid Signalling

School of Biological Sciences, Queen Mary, University of London, London E1 4NS, UK M.R.Elphick qmul.ac.uk 2.1 The Phylogenetic Distribution of Anandamide and Enzymes Involved in Anandamide 2.2 The Phylogenetic Distribution of Fatty Acid Amide Hydrolase 287 2.3 The Phylogenetic Distribution of 2-AG and Enzymes Involved in 2-AG Biosynthesis 2.4 The Phylogenetic Distribution of Monoglyceride Lipase 288 3 The Phylogeny of Cannabinoid Receptors and Other Endocannabinoid 3.1 Receptors Related to...

Introduction To Experimental Pharmacology

Marijuana is the most commonly used illicit drug among women of reproductive age. Its use during pregnancy in developed nations is estimated to be approximately 10 Park et al. 2004 . However, reports dealing with the effects of prenatal exposure to this substance of abuse on the length of gestation, fetal growth, and offspring behavior are still controversial Park et al. 2004 . In animal models, the consumption of marijuana or other Cannabis sativa derivatives during pregnancy and or lactation...

Normalization of Cannabinoid Urine Concentrations to Urine Creatinine Concentrations

Normalization of the cannabinoid drug concentration to the urine creatinine concentration aids in the differentiation of new vs prior cannabis use and reduces the variability of drug measurement due to urine dilution. Due to the long half-life of drug in the body, especially in chronic cannabis users, toxicologists and practitioners are frequently asked to determine if a positive urine test represents a new episode of drug use or represents continued excretion of residual drug. Random urine...

Fast Inhibitory Neurotransmission

CB1 receptor-mediated inhibition of GABAergic neurotransmission has been observed in many brain regions, belonging to different functional systems Table 2 . Thus, cannabinoids depress cerebral cortical GABAergic neurotransmission. Neurotransmission is also depressed in nuclei belonging to the extrapyramidal motor control system caudate-putamen, globus pallidus and substantia nigra pars reticulata Fig. 6 also shows cannabinoid effects on inhibitory neurotransmission in the extrapyramidal motor control system . GABAergic synaptic transmission in the cerebellum, a major brain region involved in motor control, is inhibited as well Fig. 7 also shows cannabinoid effects on inhibitory neurotransmission in the cerebellar cortex . Figure 2 shows inhibition of GABAergic neurotransmission in the cerebellar cortex, and Fig. 3 shows that the inhibition is due to the inhibition of GABA release from presynaptic axon terminals. In several nuclei belonging to the limbic system e.g. hippocampus and...

What Is the Functional Role of Presynaptic Cannabinoid Receptors

It is evident from Sects. 4 and 5 that presynaptic CB1 receptors are ubiquitous in the central and peripheral nervous system. Even within one functional system, several components of the neuronal circuitry are equipped with CB1 receptors. This will be illustrated in two functional systems the extrapyramidal motor control system Fig. 6 and the cerebellum Fig. 7 . Figure 6 shows the most important glutamatergic, GABAergic and dopaminergic neuronal connections within the extrapyramidal motor...

Identification of Amino Acids Which Discriminate CB1 and CB2 Receptor Subtypes

The CB1 and CB2 receptors Fig. 2 share only 44 overall amino acid identity, which rises to 68 in the TM domains Munro et al. 1993 . However, most cannabi-noid receptor agonists do not discriminate between the receptor subtypes Felder et al. 1995 Pertwee 1997 . There are several ligands which are CB1 - or CB2-selective 5- to 60-fold , and a few ligands with a greater separation of activity at each receptor 100- to 1,000-fold Griffin et al. 1999, 2000 Hanus et al. 1999 Huffman et al. 1996, 1999...

Bioassays for Characterizing CB1 and CB2 Receptor Ligands

Several cannabinoid receptor ligands have been radiolabelled with tritium, and these have been used both to determine the CB1 and CB2 receptor affinities of unla-belled cannabinoids in displacement assays and to establish the tissue distribution patterns of these receptors reviewed in Howlett et al. 2002 Pertwee 1999a . As indicated in Tables 1,2 and 3, some of these compounds bind more readily to CBi or to CB2 receptors, whilst the others bind more or less equally well to both these Table 1....

The Phylogenetic Distribution of 2AG and Enzymes Involved in 2AG Biosynthesis

2-AG was originally identified as a potential endogenous cannabinoid in mammals by Mechoulam et al. 1995 and Sugiura et al. 1995 and subsequent studies indicate that 2-AG is also present in several non-mammalian species, including the insect Drosophila melanogaster McPartland et al. 2001 and the annelid Hirudo medicinalis Matias et al. 2001 . These findings suggest that 2-AG may have a broad phylogenetic distribution. However, as with anandamide, the ability of organisms to generate 2-AG will...

Classification of Cannabinoid Receptor Ligands

Cannabinoide Ring Ring

Classical cannabinoids CCs are ABC-tricyclic terpenoid compounds bearing a benzopyran moiety Figs. 1-3,5, and 6 . This class includes the natural product - -49-THC 1, Fig. 1 , the more stable and almost equipotent isomer - -48-THC 2, Fig. 1 , and other pharmacologically active constituents of the plant Cannabis sativa. Many CC analogs have been synthesized and evaluated pharmacologically and biochemically for reviews see Goutopoulos and Makriyannis 2002 Khanolkar et al. 2000 Makriyannis and...

Regulation of MGL Activity

MGL activity in vitro is not affected by the addition of calcium to the incubation buffer Sakurada and Noma 1981 Balsinde et al. 1991 Konrad et al. 1994 . However, MGL activity could be inhibited by calcium, as two studies have reported an increase in activity following the addition of ethylene glycol-bis 3-aminoethyl ether N,N,N,N',-tetraacetic acid EGTA to the assay buffer Sakurada and Noma 1981 Witting et al. 2004 . Very high concentrations of sodium i.e., 1 M are inhibitory Sakurada and...

Introduction

Marijuana, or Cannabis sativa, has been valued for its medicinal as well as its psy-chotropic properties dating back to ancient times. However, reports from as early as the 1960s have indicated that marijuana and select components also could compromise human health, including the ability to resist infections. Included among these components is a class of compounds collectively known as cannabinoids. At least 60 have been identified. These include cannabidiol CBD , cannabinol CBN , cannabigerol...

Enantioselective Cannabinergic Ligands

Ligand enantioselectivity is often an important criterion in the characterization of drug receptors and in the development of biochemical and pharmacological assays. Thus, a highly enantioselective enantiomer can be a radioligand in a binding assay in which its much-less-potent enantiomer can be used to determine non-specific binding. Similarly, the less active enantiomer can serve as a control in in vitro or in vivo drug evaluations. The cannabinergic ligand library includes a number of key...

The Classical NonClassical Endogenous CB Binding Region

As stated above, the mutation studies of CB1 demonstrated greater than 1,000-fold loss in affinity and efficacy for HU-210, CP 55,940, and anandamide at K3.28 192 A Chin et al. 1998 Song and Bonner 1996 . This indicated that K3.28 192 is a primary interaction site for the phenolic hydroxyl of HU-210 and other classical cannabinoids, as well as the non-classical cannabinoids e.g., CP 55,940 in the CB1 receptor Huffman et al. 1996 . Modeling studies suggested that the alkyl side chain of CP...

Prediction Models for Estimation of Cannabis Exposure

Although there continues to be controversy in the interpretation of blood cannabinoid results, some general concepts have wide support. A dose-response relationship has been demonstrated for smoked THC and THC plasma concentrations Perez-Reyes et al. 1981,1982 . It is well established that plasma THC concentrations begin to decline prior to the time of peak effects, although it has been shown that THC effects appear rapidly after initiation of smoking Huestis et al. 1992d . Individual drug...

Endocannabinoid as Retrograde Neurotransmitter

Several recent studies have begun to elucidate the cellular and molecular mechanisms underlying the numerous and profound effects of cannabinoids on the brain. Indeed there is now compelling evidence that endocannabinoids act as activity-dependent retrograde inhibitors of synaptic transmission. In the hippocampus, CB1 receptors are localized presynaptically in GABA axon terminals, most of which originate from CCK-positive basket cells Katona et al. 1999 . Endocannabinoids are probably...

Imaging of the Brain Cannabinoid System

Gatley Center for Translational Neuroimaging, Brookhaven National Laboratory, 30 Bell Avenue, 1 Present address Harvard Medical School, Mclean Hospital, 115 Mill Street, ADARC Oaks 328, Belmont, MA 02478, USA 2 Overview Five Major Experimental Strategies 2.1 In Vitro and Ex Vivo Neuroimaging Using 2.1.1 Technique Overview 2.1.2 Autoradiographic Tracers and Their 2.2 Noninvasive Neuroimaging Techniques PET, SPECT, and MRI 429 2.2.1 Technique Overview 2.2.2...

Evidence for Additional Cannabinoid Receptor Subtypes

Not all of the effects of anandamide are mediated through the currently defined cannabinoid receptors. Anandamide inhibits gap-junction conductance and intercellular signaling in striatal astrocytes via a CB-receptor independent mechanism, since the cannabimimetic agents CP 55,940 and WIN 55,212-2 did not mimic the effect of anandamide, nor did the CB1 receptor antagonist SR141716A reverse anandamide's actions Venance et al. 1995 . Additional fatty acid ethanolamides have been isolated, as well...