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D R Compton

Publications and source records attributed to D R Compton.

At least 19 recordsLinked to original sources
PubMed1999

Cannabinoid-induced mesenteric vasodilation through an endothelial site distinct from CB1 or CB2 receptors.

Cannabinoids, including the endogenous ligand arachidonyl ethanolamide (anandamide), elicit not only neurobehavioral but also cardiovascular effects. Two cannabinoid receptors, CB1 and CB2, have been cloned, and studies with the selective CB1 receptor antagonist SR141716A have implicated peripherally located CB1 receptors in the hypotensive action of cannabinoids. In rat mesenteric arteries, anandamide-induced vasodilation is inhibited by SR141716A, but other potent CB1 receptor agonists, such as HU-210, do not cause vasodilation, which implicates an as-yet-unidentified receptor in this effect. Here we show that "abnormal cannabidiol" (Abn-cbd) is a neurobehaviorally inactive cannabinoid that does not bind to CB1 receptors, yet causes SR141716A-sensitive hypotension and mesenteric vasodilation in wild-type mice and in mice lacking CB1 receptors or both CB1 and CB2 receptors. Hypotension by Abn-cbd is also inhibited by cannabidiol (20 microgram/g), which does not influence anandamide- or HU-210-induced hypotension. In the rat mesenteric arterial bed, Abn-cbd-induced vasodilation is unaffected by blockade of endothelial NO synthase, cyclooxygenase, or capsaicin receptors, but it is abolished by endothelial denudation. Mesenteric vasodilation by Abn-cbd, but not by acetylcholine, sodium nitroprusside, or capsaicine, is blocked by SR141716A (1 microM) or by cannabidiol (10 microM). Abn-cbd-induced vasodilation is also blocked in the presence of charybdotoxin (100 nM) plus apamin (100 nM), a combination of K(+)-channel toxins reported to block the release of an endothelium-derived hyperpolarizing factor (EDHF). These findings suggest that Abn-cbd and cannabidiol are a selective agonist and antagonist, respectively, of an as-yet-unidentified endothelial receptor for anandamide, activation of which elicits NO-independent mesenteric vasodilation, possibly by means of the release of EDHF.

Animals↗
PubMed1998

Ontogeny of mu opioid agonist anti-nociception in postnatal rats.

Mu opiate agonists morphine, fentanyl and meperidine are administered short-term to pediatric patients, from the neonatal period through adolescence. However, there has been no assessment of the effect of age on the analgesic efficacy or the concentration-response relationship for these opioids in human pediatric patients. Few studies in animals have correlated opioid anti-nociception and tissue levels of these opioids commonly administered to pediatric patients. The present study was conducted to examined the role of age on opioid anti-nociceptive potency and efficacy and brain and plasma opioid levels to provide predictive information on the effect of opioids in developing humans. Administration of trace amounts of tritiated drug with anti-nociceptive doses of unlabeled drug was used for the assessment of anti-nociception in the tail-flick test and for the measurement of brain and plasma drug equivalent levels in postnatal rats (PND 3-21). Morphine and fentanyl were completely efficacious in all postnatal ages examined, although age-related differences in drug potency, as well as, differences in brain and plasma levels were observed. There was a good correlation between morphine (r = 0.96) and fentanyl (r = 0.89) ED(50) values and their respective brain and plasma EC(50) equivalent levels. Meperidine had limited efficacy in young rats (PND 3-9) but was completely efficacious in older rats (PND 14-17). However, PND 21 rats experienced tonic-clonic seizures which limited its efficacy to 70% anti-nociception. Our data suggest that pharmacokinetics, the development of the blood-brain barrier and ontogeny of opioid receptor function may play important roles in the sensitivity of postnatal rats to mu receptor agonists.

Analgesics, Opioid↗
PubMed1998

Assessment of anandamide interaction with the cannabinoid brain receptor: SR 141716A antagonism studies in mice and autoradiographic analysis of receptor binding in rat brain.

Anandamide is the newly discovered endogenous cannabinoid ligand that binds to brain cannabinoid receptors and shares most, but not all, of the pharmacological properties of delta 9-THC. Therefore, this study was undertaken to determine whether its interaction with the CB1 receptor in brain was identical to that of delta 9-THC. Anandamide depressed spontaneous activity and produced hypothermia, antinociception and immobility in mice after i.v. administration. However, none of these effects was blocked by pretreatment with the selective CB1 antagonist, SR 141716A. However, the metabolically stable analog 2-methyl-2'-fluoroethylanandamide produced reductions in motor activity and antinociception in mice, effects that were blocked by the antagonist. To determine whether anandamide's receptor binding mimicked that of other cannabinoids, an autoradiographic comparison of anandamide, SR 141716A and CP 55,940 competition for [3H]CP55,940 binding was conducted throughout rat brain. The receptor affinities for all three compounds did not change according to brain area. As expected, Bmax values differed dramatically among differ brain areas. However, the Bmax values for each brain area were similar regardless of the compound used for displacement. These data suggest that anandamide, SR 141716A and CP 55,940 compete for the same cannabinoid receptor throughout brain despite SR 141716A's failure to block anandamide's pharmacological effects. Although there is no question that anandamide binds to the cannabinoid receptor, failure of SR 141716A to block its pharmacological effects in mice poses a dilemma. The results presented herein raise the possibility that anandamide may not be producing all of its effects by a direct interaction with the CB1 receptor.

Animals↗
PubMed1998

Structure-activity relationships of indole- and pyrrole-derived cannabinoids.

Early molecular modeling studies with Delta9-tetrahydrocannabinol (Delta9-THC) reported that three discrete regions which interact with brain cannabinoid (CB1) receptors corresponded to the C-9 position of the cyclohexene ring, the phenolic hydroxyl and the carbon side chain at the C3 position. Although the location of these attachment points for aminoalkylindoles is less clear, the naphthalene ring, the carbonyl group and the morpholinoethyl group have been suggested as probable sites. In this study, a series of indole- and pyrrole-derived cannabinoids was developed, in which the morpholinoethyl group was replaced with another cyclic structure or with a carbon chain that more directly corresponded to the side chain of Delta9-THC and were tested for CB1 binding affinity and in a battery of in vivo tests, including hypomobility, antinociception, hypothermia and catalepsy in mice and discriminative stimulus effects in rats. Receptor affinity and potency of these novel cannabinoids were related to the length of the carbon chain. Short side chains resulted in inactive compounds, whereas chains with 4 to 6 carbons produced optimal in vitro and in vivo activity. Pyrrole-derived cannabinoids were consistently less potent than were the corresponding indole derivatives and showed pronounced separation of activity, in that potencies for hypomobility and antinociception were severalfold higher than potencies for hypothermia and ring immobility. These results suggest that, whereas the site of the morpholinoethyl group in these cannabinoids seems crucial for attachment to CB1 receptors, the exact structural constraints on this part of the molecule are not as strict as previously thought.

Animals↗
PubMed1997

Synthesis and pharmacological comparison of dimethylheptyl and pentyl analogs of anandamide.

(Dimethylheptyl)anandamide [(16,16-dimethyldocosa-cis-5,8,11,14-tetraenoyl)ethanolamine ] (17a) and its amide analogs were synthesized by Wittig coupling of a ylide derived from a fragment of arachidonic acid. These amides were compared to the endogenous cannabinoid receptor ligand arachidonylethanolamide (anandamide, 2a) and its amide analogs in pharmacological assays for potential enhancement of cannabimimetic activities. The receptor affinity to rat brain membranes of the dimethylheptyl (DMH) analogs increased by an order of magnitude in most comparisons to the corresponding anandamides in displacement assays versus the cannabinoid agonist [3H]CP 55,940 or antagonist [3H]SR141716A, for which rank order differences in affinity were observed. An order of magnitude enhancement of potency with comparable or higher efficacy in behavioral assays in the mouse tetrad of tests of cannabinoid activity was observed in 17a versus 2a. In contrast, no enhancement in potency for the pentyl to DMH side chain exchange was seen in the mouse vas deferens assay. The data indicate a structural equivalence between classical plant cannabinoids and 2a as well as different receptor-ligand interactions that characterize multiple receptor sites or binding modes.

Animals↗
PubMed1997

Importance of the C-1 substituent in classical cannabinoids to CB2 receptor selectivity: synthesis and characterization of a series of O,2-propano-delta 8-tetrahydrocannabinol analogs.

The separation of the mood-altering effects of cannabinoids from their therapeutic effects has been long sought. Results reported here for a series of C-9 analogs of the cyclic ether O,2-propano-delta 8-tetrahydrocannabinol (O,2-propano-delta 8-THC) point to the C-1 position in classical cannabinoids as a position for which CB2 subtype selectivity occurs within the cannabinoid receptors. O,2-Propano-11-delta 8-THC, O,2-propano delta 9,11-THC, O,2-propano-9-oxo-11-nor-hexahydrocannabinol (O,2-propano-9-oxo-11-nor-HHC), and O,2-propano-9 alpha- and O,2-propano-9 beta-OH-11-nor-HHC were synthesized and evaluated in radioligand displacement assays for affinity at the CB1 and CB2 receptors and in the mouse vas deferens in vitro assay and the mouse tetrad in vivo assay for cannabinoid activity. Evaluation of binding affinity at the CB1 and CB2 receptors revealed that each compound possesses a modest increased affinity for the CB2 receptor. Analogs which contained an oxygen attached to C-9 (i.e., oxo and hydroxy derivatives) showed the highest affinity and selectivity for CB2 (for O,2-propano-9-oxo-11-nor-HHC, Ki(CB1) = 90 nM, Ki(CB2) = 23 nM, selectivity ratio 3.9; for O,2-propano-9 beta-OH-11-nor-HHC, Ki(CB1) = 26 nM, Ki(CB2) = 5.8 nM, selectivity ratio 4.5). Each compound was found to produce a dose-dependent inhibition of electrically-evoked contractions of the mouse isolated vas deferens when administered at submicromolar concentrations. This inhibition could readily be prevented by the selective CB1 cannabinoid receptor antagonist SR-141716A. The analogs exhibited unique in vivo profiles with O,2-propano-delta 9,11-THC exhibiting antinociception with reduced activity in three other in vivo measures and O,2-propano-9 beta-OH-HHC exhibiting lack of dose responsiveness in all measures. The CB2 selectivities in the O,2-propano analogs may be due to differences in solvation/desolvation that occur when the ligands enter the CB1 vs CB2 binding site. Alternatively, the CB2 selectivities may be a results of an amino acid change from a hydrogen bond-accepting residue in CB1 to a hydrogen bond-donating residue in CB2.

Animals↗
PubMed1997

Synthesis, pharmacology, and molecular modeling of novel 4-alkyloxy indole derivatives related to cannabimimetic aminoalkyl indoles (AAIs).

Several novel 4-alkyloxy-aminoalkyl indole derivatives 3 were synthesized from 4-benzyloxyindole (1). Alkylation of 1 with 4-(2-chloroethyl)morpholine (NaH/HMPA) formed 2. Deprotection using palladium hydroxide on carbon/hydrogen followed by alkylation with the appropriate alkyl bromide gave the target compounds 3b-3j. In the synthesis of 3i and 3j, the appropriate alkyl bromides 13 and 17 were prepared from the commercially available 1-naphthylethyl bromide 9 using the chain lengthening sequences as shown in Scheme 3. In receptor binding assay and in vivo testing, the long chain alkoxy compounds 3g and 3h (Ki = 127 nM) showed affinity for the CB1 receptor which was approximately 16-35-fold less than that of WIN 55,225. However, the pharmacological profile of 3h mimics that of WIN 55,212. An examination of the SAR of these analogues shows that translocating the napthyl group in AAIs from the C-3 position to C-4 via an oxygen (ether linkage) decreases activity which is in contrast to previous findings that a naphthylcarbonyl at C-4 retains activity. The present work points to the importance of the role of a keto group in the interaction with the receptor. Molecular modeling work suggests that, although reasonable superposition of key structural features between delta 9-THC and AAIs can be made, the overlay is not straightforward. The present study also illustrates the difficulty in accommodating AAIs into the cannabinoid pharmacophore and it seems likely that a unique pharmacophore will need to be developed. Only then will the similarities to and differences from the classical cannabinoid pharmacophore be clearly delineated.

Analgesics↗
PubMed1997

Cannabinoid-induced hypotension and bradycardia in rats mediated by CB1-like cannabinoid receptors.

Previous studies indicate that the CB1 cannabinoid receptor antagonist, N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-met hyl-1H-pyrazole-3-carboxamide HCl (SR141716A), inhibits the anandamide- and delta9-tetrahydrocannabinol- (THC) induced hypotension and bradycardia in anesthetized rats with a potency similar to that observed for SR141716A antagonism of THC-induced neurobehavioral effects. To further test the role of CB1 receptors in the cardiovascular effects of cannabinoids, we examined two additional criteria for receptor-specific interactions: the rank order of potency of agonists and stereoselectivity. A series of cannabinoid analogs including the enantiomeric pair (-)-11-OH-delta9-THC dimethylheptyl (+)-11-OH-delta9-THC dimethylheptyl were evaluated for their effects on arterial blood pressure and heart rate in urethane anesthetized rats. Six analogs elicited pronounced and long lasting hypotension and bradycardia that were blocked by 3 mg/kg of SR141716A. The rank order of potency was (-)-11-OH-delta9-THC dimethylheptyl > or = (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol > (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol > THC > anandamide > or = (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol, which correlated well with CB1 receptor affinity or analgesic potency (r = 0.96-0.99). There was no hypotension or bradycardia after palmitoylethanolamine or (+)-11-OH-delta9-THC dimethylheptyl. An initial pressor response was also observed with THC and anandamide, which was not antagonized by SR141716A. We conclude that the similar rank orders of potency, stereoselectivity and sensitivity to blockade by SR141716A indicate the involvement of CB1-like receptors in the hypotensive and bradycardic actions of cannabinoids, whereas the mechanism of the pressor effect of THC and anandamide remains unclear.

Animals↗
PubMed1997

The effect of the enzyme inhibitor phenylmethylsulfonyl fluoride on the pharmacological effect of anandamide in the mouse model of cannabimimetic activity.

Anandamide is an putative endogenous cannabinoid ligand that produces pharmacological effects similar to those of Delta9-tetrahydrocannabinol, the principle psychoactive constituent in marijuana. There is considerable evidence that the enzyme inhibitor phenylmethylsulfonyl fluoride (PMSF) is capable of altering the actions of anandamide in vitro by blocking its metabolism. Therefore, studies were conducted in mice to determine whether PMSF could produce cannabinoid effects by altering endogenous levels of anandamide as well as determining whether PMSF could potentiate the effects of exogenously administered anandamide. Mice receiving i.p. injections of PMSF exhibited cannabinoid effects that included antinociception, hypothermia and immobility with ED50 values of 86, 224 and 206 mg/kg, respectively. Spontaneous activity was reduced at doses greater than 100 mg/kg. However, none of these effects was blocked by the cannabinoid antagonist SR 141716A. On the other hand, pretreatment with an inactive dose of PMSF (30 mg/kg) potentiated the effects of anandamide on tail-flick response (antinociception), spontaneous activity and mobility by 5-, 10- and 8-fold, respectively. PMSF did not alter anandamide's hypothermic effects. Overall, these findings with PMSF underscore the importance of metabolism in the actions of anandamide. It still must be established whether metabolites of anandamide contribute to its pharmacological activity.

Analgesics↗
PubMed1996

Agonist-antagonist characterization of 6'-cyanohex-2'-yne-delta 8-tetrahydrocannabinol in two isolated tissue preparations.

This investigation was directed at characterizing some of the pharmacological properties of 6'-cyanohex-2'-yne-delta 8-tetrahydrocannabinol (O-823), a compound with high affinity for cannabinoid binding sites (Ki = 0.77 nM). In mouse vasa deferentia, O-823 behaved as a potent partial cannabinoid CB1 receptor agonist (EC50 = 0.015 nM). In the guinea-pig myenteric plexus preparation, it antagonized WIN 55.212-2 [(R)-(+)-[2,3-dihydro-5-methyl-3-[(4-morpholino)methyl]pyrrolo-[1,2,3-de ]-1, 4-benzoxazin-6-yl](1-naphthyl)methanone] and CP 55.940 [(-)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4-(3-hydroxypropyl ) cyclohexan-1-ol] with Kd values of 0.65 and 0.27 nM, respectively. After in vivo delta 9-tetrahydrocannabinol pretreatment. the sensitivity of vasa deferentia to O-823-induced inhibition of electrically evoked contractions was reduced by 127-fold. 3.162 nM O-823 was inhibitory in unpretreated vasa deferentia but antagonized CP 55,940 in pretreated tissues (Kd = 0.26 nM). O-823 is probably an antagonist in the myenteric plexus preparation and delta 9-tetrahydro-cannabinol pretreated vasa deferentia but a partial agonist in unpretreated vasa deferentia because the first two of these preparations contain fewer receptors than the third.

Analgesics↗
PubMed1996

Pharmacological characterization of BNMPA (alpha-benzyl-N-methylphenethylamine), an impurity of illicit methamphetamine synthesis.

alpha-Benzyl-N-methylphenethylamine (BNMPA), an impurity of illicit methamphetamine synthesis, has previously been reported to produce convulsions in mice without affecting spontaneous locomotor activity or altering methamphetamine-induced increases in spontaneous activity. In this study the in vitro effects of BNMPA on a variety of neuronal receptor types was determined to better characterize the pharmacological actions of this novel compound. BNMPA and N-demethyl-BNMPA fully displaced the dopamine transporter selective ligand [3H]CFT (2-beta-carbomethoxy-3-beta-(4-fluorophenyl)tropane) from rat striatal membranes with Ki values (mean +/- S.E.M) of 6.05 microM +/- 0.15 and 8.73 microM +/- 1.66, respectively. BNMPA also inhibited [3H]dopamine uptake into striatal synaptosomes with an IC50 value of 5.1 +/- 1.4 microM. The basal efflux of [3H]dopamine from striatal slices was slightly enhanced by BNMPA only at concentrations > or = 100 microM. BNMPA had no effect on [3H]norepinephrine efflux from hippocampal slices. BNMPA displaced tritiated paroxetine and prazosin binding from rat cortical membranes with Ki values of 14.5 microM and 11.7 microM respectively. In electrophysiological studies, BNMPA (100 microM) had no significant effects on either GABAA Cl- currents in cultured neurons or non-NMDA glutamate receptors expressed in oocytes. However, BNMPA significantly inhibited NMDA-stimulated currents in oocytes expressing the NR1/2A or NR1/2C receptor subunit combinations (IC50 values = 24.6 +/- 1.8 and 24.0 +/- 1.5 microM, respectively). This inhibition was rapid, reversible and voltage-dependent. These results indicate that BNMPA has multiple sites of action in the CNS that could be important in modulating a variety of behavioral effects upon exposure to this synthetic byproduct of illicit methamphetamine synthesis.

Analysis of Variance↗
PubMed1996

Evaluation of agonist-antagonist properties of nitrogen mustard and cyano derivatives of delta 8-tetrahydrocannabinol.

delta 8-Tetrahydrocannabinol (delta 8-THC) is a naturally occurring cannabinoid with a characteristic pharmacological profile of in vivo effects. Previous studies have shown that modification of the structure of delta 8-THC by inclusion of a nitrogen-containing functional group alters this profile and may alkylate the cannabinoid receptor, similar to the manner in which beta-funaltrexamine (beta-FNA) alkylates the micro-opioid receptor. Two novel analogs of delta 8-THC were synthesized: a nitrogen mustard analog with a dimethylheptyl side chain (NM-delta 8-THC) and a cyano analog with a dimethylpentyl side chain (CY-delta 8-THC). Both analogs showed high affinity for brain cannabinoid receptors and when administered acutely, produced characteristic delta 9-THC-like effects in mice, including locomotor suppression, hypothermia, antinociception and catalepsy. CY-delta 8-THC shared discriminative stimulus effects with CP 55,940; for NM-delta 8-THC, these effects also occurred, but were delayed. Although both compounds attenuated the effects of delta 9-THC in the mouse behavioral tests, evaluation of potential antagonist effects of these compounds was complicated by the fact that two injections of delta 9-THC produced similar results, suggesting that acute tolerance or desensitization might account for the observations. NM-delta 8-THC, but not CY-delta 8-THC, attenuated the discriminative stimulus effects of CP 55,940 in rats several days following injection. Hence, addition of a nitrogen-containing functional group to a traditional cannabinoid structure does not eliminate agonist effects and may produce delayed attenuation of cannabinoid-induced pharmacological effects.

Animals↗
PubMed1996

In vivo characterization of a specific cannabinoid receptor antagonist (SR141716A): inhibition of delta 9-tetrahydrocannabinol-induced responses and apparent agonist activity.

SR141716A has been described as a cannabinoid receptor antagonist. This study was conducted to determine whether SR141716A was capable of antagonizing the pharmacological effects of the prototypical cannabinoid agonist delta 9-THC. The AD50 (+/- 95% confidence limits) obtained after a 10 min i.v. pretreatment with SR141716A in measures of hypoactivity, hypothermia, and antinociception were: 0.12 (0.02-0.66), 0.087 (0.037-0.201), and 0.16 (0.03-1.01) mg/kg, respectively. The effect of SR141716A lasted up to 1 hr (antinociception, 10 mg/kg), 4 hr (locomotion, 1 and 3 mg/kg), or 24 hr (hypothermia, 3 mg/kg). Further evaluation revealed an AD50 value of 2.7 mg/kg (1.7-4.4) in the PPQ-stretch procedure. Additionally, the ED50 (+/- S.E.) of morphine in the tail-flick antinociception procedure was increased by SR141716A (30 mg/kg, i.v.) from 3.2 (+/- 0.3) to 5.3 (+/- 0.6) mg/kg. Finally, SR141716A produced direct effects on locomotor activity at doses greater than 3 mg/kg. Locomotion was stimulated to more than 200% of control (20 mg/kg), with an ED50 value of 4.7 (+/- 1.5) mg/kg. The ED50 value represents stimulation to levels approximately 150% of control. It is not clear whether this pharmacological activity represents an uncharacterized action of SR141716A, or an index of tonic activity of an endogenous cannabinergic system. SR141716A will be useful in establishing the biochemical events responsible for the in vivo effects of exogenous cannabinoids, as well as in establishing the existence of a putative endogenous cannabinergic system.

Analgesia↗
PubMed1996

Evaluation of binding in a transfected cell line expressing a peripheral cannabinoid receptor (CB2): identification of cannabinoid receptor subtype selective ligands.

Two cannabinoid receptors have been identified to date; one is located predominantly in the central nervous system (CB1), whereas the other is located exclusively in the periphery (CB2). The purposes of this study were to explore further the binding requirements of the CB2 receptor and to search for compounds displaying distinct affinities for either cannabinoid receptor. The binding affinities of a series of cannabinoids tested previously at the CB1 receptor were determined at cloned human CB1 and CB2 receptors using a filtration assay. In addition, possible allosteric regulation of the CB2 receptor was examined. Sodium and a GTP analog elicited a concentration-dependent decrease in specific binding to the CB2 receptor. The affinity of cannabinol for CB2 receptors (Ki = 96.3 +/- 14 nM) was confirmed to be in approximately the same range as that of delta 9-THC (Ki = 36.4 +/- 10 nM). Affinities at cloned CB1 and CB2 receptors were compared with affinities determined in the brain. Although most of the chosen compounds did not discriminate between CB1 and CB2, several ligands were identified that showed selectivity. Affinity ratios demonstrated that two 2'-fluoro analogs of anandamide were over 23-fold selective for the CB1 receptor and confirmed the CB1 selectivity of SR141716A {N- (piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4- methyl-1H-pyrazole-3-carboxamidehydrochloride}. In addition, WIN-55, 212-2 {(R)-(+)-[2, 3-dihydro-5-methyl-3-[(4-morpholinyl) methyl] pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl](1-naphthalenyl) methanone} and a closely related propyl indole analog were shown to be 6.75- and 27.5- fold selective, respectively, for the CB2 receptor. These ligands can now serve as a basis for the design of compounds with even greater selectivity.

Animals↗
PubMed1995

Identification of an endogenous 2-monoglyceride, present in canine gut, that binds to cannabinoid receptors.

In this study, we report the isolation from canine intestines of 2-arachidonyl glycerol (2-Ara-Gl). Its structure was determined by mass spectrometry and by direct comparison with a synthetic sample. 2-Ara-Gl bound to membranes from cells transiently transfected with expression plasmids carrying DNA of either CB1 or CB2--the two cannabinoid receptors identified thus far--with Ki values of 472 +/- 55 and 1400 +/- 172 nM, respectively. In the presence of forskolin, 2-Ara-Gl inhibited adenylate cyclase in isolated mouse spleen cells, at the potency level of delta 9-tetrahydrocannabinol (delta 9-THC). Upon intravenous administration to mice, 2-Ara-Gl caused the typical tetrad of effects produced by THC: antinociception, immobility, reduction of spontaneous activity, and lowering of the rectal temperature. 2-Ara-Gl also shares the ability of delta 9-THC to inhibit electrically evoked contractions of mouse isolated vasa deferentia; however, it was less potent than delta 9-THC.

Animals↗
PubMed1995

A novel class of potent tetrahydrocannabinols (THCS): 2'-yne-delta 8- and delta 9-THCS.

A series of 3-alkyl-2'-yne (side chain) acetylenic analogs of delta 9-THC were synthesized and evaluated for in vitro and in vivo activity. Analogs were evaluated for receptor affinity in a [3H]CP-55,940 displacement assay and for in vivo pharmacological activity in a mouse procedure utilizing a tetrad of measures. These compounds represent a preliminary exploration of the consequences of restricting the flexibility of the side chain regarding cannabimimetic activity. All analogs proved to have receptor affinities (4-11 nM) that were five to ten times greater than that observed for delta 9-THC. However, the in vivo activities of these compounds varied greatly. All analogs proved to possess the greatest potency for production of antinociception, with activity similar to or less than that observed for the production of hypomotility, hypothermia, and catalepsy. The most potent analog 11b exhibited an ED50 of 0.031 mg/kg in the tail-flick procedure, with values in other measures being between 0.5 and 1.0 mg/kg. The least active compound (11c), though still possessing a KI of 11 nM, exhibited ED50 values of 3.1 and 9.3 mg/kg for tail-flick and temperature procedures, as well as 41 and 48 mg/kg for ring-immobility and spontaneous locomotor activity, respectively. This profile (high receptor affinity but low in vivo potency) would normally be suggestive of a compound with antagonist properties (at least for immobility and activity measures). It is unclear why these acetylenic analogs were so potent in vitro, while only one (11b) exhibited the degree of in vivo potency anticipated based upon comparison to values for delta 9-THC. It is possible these side chain modifications do not interfere with receptor recognition, but limit receptor activation or second messenger signal transduction. Regardless, it is clear these novel analogs provide a basis for the further exploration of the cannabinoid receptor pharmacophore.

Analgesics↗
PubMed1995

Pharmacological and behavioral evaluation of alkylated anandamide analogs.

Anandamide (arachidonylethanolamide), isolated from porcine brain, has been shown to bind to the cannabinoid receptor and also to produce cannabimimetic activity in pharmacological assays. This study examined structure-activity relationships in alkylated anandamide analogs. The analogs were evaluated for their ability to displace [3H]CP-55,940 in a filtration binding assay using rat brain membranes in the presence and absence of the enzyme inhibitor phenylmethylsulfonyl fluoride (PMSF). Behavioral activity was assessed by the ability of the analogs to produce hypomotility and antinociception. Methylations at carbons 2 and 1 produced compounds stable in the absence of PMSF with similar affinities and behavioral activity as anandamide. Addition of larger alkyl groups at these positions or nitrogen methylation reduced receptor affinity and behavioral potency. These results indicate that methylations at specific carbons of anandamide confer stability in vitro.

Alkylation↗