[Show abstract][Hide abstract] ABSTRACT: Cannabis is the most widely used illicit substance in the United States. Women report greater positive subjective effects of cannabis, and greater cannabis withdrawal compared to men. Female rodents are more sensitive than males to some acute effects of Δ⁹-tetrahydrocannabinol (THC), and females also develop greater tolerance to THC in some assays. The purpose of this study was to determine whether gonadal hormones modulate THC dependence in rats. Adult rats were gonadectomized (GDX) or sham-GDX, and hormone was replaced in half of the GDX rats of each sex (testosterone in males; estradiol and/or progesterone in females). THC (30 mg/kg) or vehicle was administered twice daily for 6.5 days, followed on the seventh day by vehicle or rimonabant challenge and assessment for withdrawal-related behaviors. Sham-GDX females developed greater tolerance than males to THC-induced hypothermia, and GDX females given progesterone showed greater tolerance to THC-induced locomotor suppression. Rimonabant precipitated withdrawal, as evidenced by increased somatic signs (forepaw tremors, licking) and increased startle amplitude. Testosterone in GDX males decreased withdrawal-induced licking. Estradiol and progesterone in GDX females increased withdrawal-induced chewing, and progesterone increased withdrawal-induced sniffing. These results suggest that estradiol and progesterone may promote the development of dependence, whereas testosterone may protect against dependence. While the present study indicates that testosterone and estradiol produce opposite effects on THC-induced behavior, estradiol appears to play a broader role than testosterone in modulating THC's behavioral effects. (PsycINFO Database Record
(c) 2015 APA, all rights reserved).
Full-text · Article · Aug 2015 · Experimental and Clinical Psychopharmacology
[Show abstract][Hide abstract] ABSTRACT: Diversion of synthetic cannabinoids for abuse began in the early 2000s. Despite legislation banning compounds currently on the drug market, illicit manufacturers continue to release new compounds for recreational use. This study examined new synthetic cannabinoids AB-CHMINACA, AB-PINACA, and FUBIMINA, with the hypothesis that these compounds, like those before them, would be highly susceptible to abuse. Cannabinoids were examined in vitro for binding and activation of CB1 receptors, and in vivo for pharmacological effects in mice and in Δ(9)-THC discrimination. AB-CHMINACA, AB-PINACA and FUBIMINA bound to and activated CB1 and CB2 receptors, and produced locomotor suppression, antinociception, hypothermia, and catalepsy. Further, these compounds, along with JWH-018, CP47,497, and WIN55,212-2, substituted for Δ(9)-THC in Δ(9)-THC discrimination. Rank order of potency correlated with CB1 receptor binding affinity, and all three compounds were full agonists in [(35)S]GTPγS binding, as compared to the partial agonist Δ(9)-THC. Indeed, AB-CHMINACA and AB-PINACA exhibited higher efficacy than most known full agonists of the CB1 receptor. Preliminary analysis of urinary metabolites of the compounds revealed the expected hydroxylation. AB-PINACA and AB-CHMINACA are of potential interest as research tools due to their unique chemical structures and high CB1 receptor efficacies. Further studies on these chemicals is likely to include research on understanding cannabinoid receptors and other components of the endocannabinoid system that underlie the abuse of synthetic cannabinoids.
The American Society for Pharmacology and Experimental Therapeutics.
No preview · Article · Jun 2015 · Journal of Pharmacology and Experimental Therapeutics
[Show abstract][Hide abstract] ABSTRACT: The CB1 receptor represents a promising target for the treatment of several disorders including pain-related disease states. However, therapeutic applications of Δ(9)-tetrahydrocannabinol (THC) and other CB1 orthosteric receptor agonists remain limited because of psychoactive side effects. Positive allosteric modulators (PAMs) offer an alternative approach to enhance CB1 receptor function for therapeutic gain with the promise of reduced side effects. Here we describe the development of the novel synthetic CB1 PAM, 6-methyl-3-(2-nitro-1-(thiophen-2-yl)ethyl)-2-phenyl-1H-indole (ZCZ011), which augments the in vitro and in vivo pharmacological actions of the CB1 orthosteric agonists CP55,940 and N-arachidonoylethanolamine (AEA). ZCZ011 potentiated binding of [(3)H]CP55,940 to the CB1 receptor as well as enhancing AEA-stimulated [(35)S]GTPγS binding in mouse brain membranes and β-arrestin recruitment and ERK phosphorylation in hCB1 cells. In the whole animal, ZCZ011 is brain penetrant, increased the potency of these orthosteric agonists in mouse behavioral assays indicative of cannabimimetic activity, including antinociception, hypothermia, catalepsy, locomotor activity and in the drug discrimination paradigm. Administration of ZCZ011 alone was devoid of activity in these assays and did not produce a conditioned place preference or aversion, but elicited CB1 receptor mediated antinociceptive effects in the chronic constriction nerve injury (CCI) model of neuropathic pain and carrageenan model of inflammatory pain. These data suggest that ZCZ011 acts as a CB1 PAM and provide the first proof of principle that CB1 PAMs offer a promising strategy to treat neuropathic and inflammatory pain with minimal or no cannabimimetic side effects.Neuropsychopharmacology accepted article preview online, 08 June 2015. doi:10.1038/npp.2015.148.
No preview · Article · Jun 2015 · Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology
[Show abstract][Hide abstract] ABSTRACT: The endogenous cannabinoid 2-arachidonoylglycerol (2-AG) plays an important role in a variety of physiological processes, but its rapid breakdown by monoacylglycerol lipase (MAGL) results in short-lived actions. Initial MAGL inhibitors were limited by poor selectivity and low potency. Here, we tested JZL184 and MJN110, MAGL inhibitor that possesses increased selectivity and potency, in mouse behavioral assays of neuropathic pain (chronic constrictive injury of the sciatic nerve; CCI), interoceptive cannabimimetic effects (drug discrimination paradigm), and locomotor activity in an open field test. MJN110 (1.25 and 2.5 mg/kg) and JZL184 (16 and 40 mg/kg) significantly elevated 2-AG and decreased arachidonic acid, but did not affect anandamide (AEA) in whole brain. Both MAGL inhibitors significantly reduced CCI-induced mechanical allodynia with the following potencies [ED50 (95% CL) values in mg/kg: MJN110 (0.43 (0.30-0.63) > JZL184 (17.8 (11.6-27.4))], and also substituted for the potent cannabinoid receptor agonist CP55,940 in the drug discrimination paradigm [ED50 (95% CL) values in mg/kg: MJN110 (0.84 (0.69-1.02)) > JZL184 (24.9 (14.6-42.5))]. However, these compounds elicited differential effects on locomotor behavior. Similar to CB1 receptor agonists, JZL184 produced hypomotility, while MJN110 increased locomotor behavior and did not produce catalepsy or hypothermia. Although these results suggest that MAGL inhibitors hold promise for the treatment of neuropathic pain, their substitution for CP55,940 in the drug discrimination assay may not be desirable for a therapeutic drug. Nonetheless, in contrast to CB1 receptor agonists, each MAGL inhibitor tested elicited few or no pharmacological effects in other standard assays used to infer cannabimimetic activity.
The American Society for Pharmacology and Experimental Therapeutics.
No preview · Article · Mar 2015 · Journal of Pharmacology and Experimental Therapeutics
[Show abstract][Hide abstract] ABSTRACT: A growing body of evidence implicates endogenous cannabinoids as modulators of the mesolimbic dopamine system and motivated behavior. Paradoxically, the reinforcing effects of Δ9-tetrahydrocannabinol (THC), the primary psychoactive constituent of cannabis, have been difficult to detect in preclinical rodent models. In this study, we investigated the impact of THC and inhibitors of the endocannabinoid hydrolytic enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) on operant responding for electrical stimulation of the medial forebrain bundle (intracranial self-stimulation, ICSS), which is known to activate the mesolimbic dopamine system. These drugs were also tested in assays of operant responding for food reinforcement and spontaneous locomotor activity. THC and the MAGL inhibitor JZL184 attenuated operant responding for ICSS and food, and also reduced spontaneous locomotor activity. In contrast, the FAAH inhibitor PF-3845 was largely without effect in these assays. Consistent with previous studies showing that combined inhibition of FAAH and MAGL produces a substantially greater cannabimimetic profile than single enzyme inhibition, the dual FAAH-MAGL inhibitor SA-57 produced a similar magnitude of ICSS depression as that produced by THC. ICSS attenuation by JZL184 was associated with increased brain levels of 2-arachidonoylglycerol (2-AG), while peak effects of SA-57 were associated with increased levels of both N-arachidonoylethanolamine (anandamide; AEA) and 2-AG. The CB1 receptor antagonist rimonabant, but not the CB2 receptor antagonist SR144528, blocked the attenuating effects of THC, JZL184, and SA-57 on ICSS. Thus, THC, MAGL inhibition, and dual FAAH-MAGL inhibition not only reduce ICSS, but also decrease other reinforced and non-reinforced behaviors.
No preview · Article · Nov 2014 · Journal of Pharmacology and Experimental Therapeutics
[Show abstract][Hide abstract] ABSTRACT: The abuse of synthetic psychoactive substances known as "designer drugs," or "new psychoactive substances" (NPS), is increasing at an alarming rate. NPS are purchased as alternatives to traditional illicit drugs of abuse and are manufactured to circumvent laws regulating the sale and use of controlled substances. Synthetic cathinones (i.e., "bath salts") and synthetic cannabinoids (i.e., "spice") are two types of NPS that have received substantial media attention. Although low recreational doses of bath salts or spice compounds can produce desirable effects, high doses or chronic exposure often leads to dangerous medical consequences, including psychosis, violent behaviors, tachycardia, hyperthermia, and even death. Despite the popularity of NPS, there is a paucity of scientific data about these drugs. Here we provide a brief up-to-date review describing the mechanisms of action and neurobiological effects of synthetic cathinones and cannabinoids.
Full-text · Article · Nov 2014 · The Journal of Neuroscience : The Official Journal of the Society for Neuroscience
[Show abstract][Hide abstract] ABSTRACT: Introduction: While nicotine has been established as the primary addictive drug that promotes tobacco use, recent peer-reviewed studies
suggest that tobacco smoke contains additional chemical constituents that may have addictive potential. Additional research
is necessary to determine the addictive potential of these tobacco constituents individually and in combination with tobacco
smoke condensate; however, the behaviorally effective constituent doses necessary to conduct such studies are unclear. The
primary objective of this study was to conduct behavioral studies in adult rats to determine the relevant behaviorally effective
doses of the tobacco constituents, cotinine, myosmine, and anatabine to be used in future studies assessing the addictive
potential of these compounds.
No preview · Article · Sep 2014 · Nicotine & Tobacco Research
[Show abstract][Hide abstract] ABSTRACT: Synthetic indole-derived cannabinoids, originally developed to probe cannabinoid CB1 and CB2 receptors, have become widely abused for their marijuana-like intoxicating properties. The present study examined the effects of indole-derived cannabinoids in rats trained to discriminate Δ9-tetrahydrocannabinol (Δ9-THC) from vehicle. In addition, the effects of Δ9-THC in rats trained to discriminate JWH-018 from vehicle were assessed. Adult male Sprague–Dawley rats were trained to discriminate 3 mg/kg Δ9-THC or 0.3 mg/kg JWH-018 from vehicle. JWH-018, JWH-073, and JWH-210 fully substituted in Δ9-THC-trained rats and Δ9-THC substituted in JWH-018-trained rats. In contrast, JWH-320, an indole-derived cannabinoid without affinity for CB1 receptors, failed to substitute for Δ9-THC. Pre-treatment with 1 mg/kg rimonabant significantly reduced responding on the JWH-018-associated lever in JWH-018-trained rats. These results support the conclusion that the interoceptive effects of Δ9-THC and synthetic indole-derived cannabinoids show a large degree of overlap, which is predictive of their use for their marijuana-like intoxicating properties. Characterization of the extent of pharmacological differences among structural classes of cannabinoids, and determination of their mechanisms remain important goals.
No preview · Article · Sep 2014 · Pharmacology Biochemistry and Behavior
[Show abstract][Hide abstract] ABSTRACT: The recent discovery of allosteric modulators of the CB1 receptor including PSNCBAM-1 (4) has generated significant interest in CB1 receptor allosteric modulation. Here in the first SAR study on 4, we have designed and synthesized a series of analogs focusing on modifications at two positions. Pharmacological evaluation in calcium mobilization and binding assays revealed the importance of alkyl substitution at the 2-aminopyridine moiety and electron deficient aromatic groups at the 4-chlorophenyl position for activity at the CB1 receptor, resulting in several analogs with comparable potency to 4. These compounds increased the specific binding of [(3)H]CP55,940 in agreement with previous reports. Importantly, 4 and two analogs dose-dependently reduced the Emax of the agonist curve in the CB1 calcium mobilization assays, confirming their negative allosteric modulator characteristics. Given the side effects associated with CB1 receptor orthosteric antagonists, negative allosteric modulators provide an alternate approach to modulate the pharmacologically important CB1 receptor.
Preview · Article · Aug 2014 · Journal of Medicinal Chemistry
[Show abstract][Hide abstract] ABSTRACT: Background:
Sex differences in cannabinoid effects have been reported in rodents, with adult females typically being more sensitive than adult males. The present study compared the development of antinociceptive tolerance to delta-9-tetrahydrocannabinol (THC) in adult, gonadally intact female vs. male rats.
Cumulative dose-effect curves were obtained for THC (1.0-18 mg/kg i.p.) on warm water tail withdrawal and paw pressure tests. Vehicle or the sex-specific ED80 dose for THC was administered twice daily for 9 days; THC dose-effect curves were then re-determined.
On the pre-chronic test day, THC was significantly more potent in females than males in producing antinociception on the tail withdrawal and paw pressure tests. After 9 days of twice-daily THC treatment (5.4 mg/kg/injection in females and 7.6 mg/kg/injection in males), THC potency on both tests decreased more in females than males. On the tail withdrawal test, chronic THC produced 4.2- vs. 2.8-fold increases in ED50 values in females vs. males, respectively. On the paw pressure test, chronic THC produced 4.4- vs. 2.9-fold increases in ED50 values in females vs. males, respectively. Chronic THC treatment did not significantly disrupt estrous cycling in females.
These results demonstrate that--even when sex differences in acute THC potency are controlled--females develop more antinociceptive tolerance to THC than males. Given the importance of drug tolerance in the development of drug dependence, these results suggest that females may be more vulnerable than males to developing dependence after chronic cannabinoid exposure.
Full-text · Article · Aug 2014 · Drug and Alcohol Dependence
[Show abstract][Hide abstract] ABSTRACT: Mechanisms that may underlie age and sex differences in the pharmacological effects of cannabinoids are relatively unexplored. The purpose of the present study was to determine whether sex differences in metabolism of Δ(9)-tetrahydrocannabinol (THC), similar to those observed previously in adult rats, also occurred in adolescent rats and might contribute to age and sex differences in its in vivo pharmacology. Male and female adolescent rats were exposed to THC acutely or repeatedly for 10 days. Subsequently, some of the rats were sacrificed and blood and brain levels of THC and one of its metabolites, 11-hydrox-Δ(9)-THC (11-OH-THC), were measured. Other rats were evaluated in a battery of in vivo tests that are sensitive to cannabinoids. Concentrations of 11-OH-THC in the brains of female adult and adolescent rats exceeded those observed in male conspecifics, particularly after repeated THC administration. In contrast, brain levels of THC did not differ between the sexes. In vivo, acute THC produced dose-related hypothermia, catalepsy and suppression of locomotion in adolescent rats of both sexes, with tolerance developing after repeated administration. With a minor exception, sex differences in THC's effects in the in vivo assays were not apparent. Together with previous findings, the present results suggest that sex differences in pharmacokinetics cannot fully explain the patterns of sex differences (and lack of sex differences) in cannabinoid effects across behaviors. Hormonal and/or pharmacodynamic factors are also likely to play a role.
No preview · Article · Jun 2014 · Neuroscience Letters
[Show abstract][Hide abstract] ABSTRACT: The mechanism through which marijuana produces its psychoactive effects is Δ9- tetrahydrocannabinol (THC)-induced activation of cannabinoid CB1 receptors. These receptors are normally activated by endogenous lipids, including anandamide and 2-arachidonoyl glycerol (2-AG). A logical "first step" in determination of the role of these endocannabinoids in THC's psychoactive effects is to investigate the degree to which pharmacologically induced increases in anandamide and/or 2-AG concentrations through exogenous administration and/or systemic administration of inhibitors of their metabolism, fatty acid amide hydrolase (FAAH) or monoacylglycerol lipase (MAGL), respectively, share THC's discriminative stimulus effects. To this end, adult male mice and rats were trained to discriminate THC (5.6 and 3mg/kg, respectively). In Experiment 1, exogenous administration of anandamide or 2-AG did not substitute for THC in mice nor was substitution enhanced by co-administration of the FAAH or MAGL inhibitors, URB597 and N-arachidonyl maleimide (NAM), respectively. Significant decreases in responding may have prevented assessment of adequate endocannabinoid doses. In mice trained at higher baseline response rates (Experiment 2), the FAAH inhibitor PF3845 (10mg/kg) enhanced anandamide substitution for THC without producing effects of its own. The MAGL inhibitor JZL184 increased brain levels of 2-AG in vitro and in vivo, increased THC-like responding without co-administration of 2-AG. In rats, neither URB597 nor JZL184 engendered significant THC-appropriate responding, but co-administration of these two enzyme inhibitors approached full substitution. The present results highlight the complex interplay between anandamide and 2-AG and suggest that endogenous increases of both endocannabinoids are most effective in elicitation of THC-like discriminative stimulus effects
No preview · Article · May 2014 · European Journal of Pharmacology
[Show abstract][Hide abstract] ABSTRACT: Background
Chronic recreational marijuana users often report withdrawal symptoms when trying to quit, with some reports suggesting withdrawal may be more pronounced in women. In animal models, female rodents show enhanced sensitivity to acute Δ9-tetrahydrocannabinol (THC) administration, but chronic administration has been studied little.
Sex differences in THC dependence in rats were examined. Adult male and female Sprague-Dawley rats were administered 30 mg/kg THC or vehicle twice daily for 6.5 days. On day 7, rats were challenged with vehicle or rimonabant, counterbalanced across dosing groups, and were assessed for withdrawal-related behaviors.
During chronic THC dosing, disruption of estrous cycling and weight loss (both sexes) were observed. Whereas overt signs of withdrawal were minimal in THC-treated rats challenged with vehicle, rimonabant precipitated a pronounced withdrawal syndrome in THC-dependent rats that was characterized by changes in a number of domains, including somatic (paw tremors, head twitches, and retropulsion), early-stage cognition (lack of locomotor habituation, disrupted prepulse inhibition), and affective (increased startle reactivity). With the exception of increased retropulsion in female rats, sex differences were not noted. In vehicle-treated rats, rimonabant induced puritis.
This study represents the first examination of THC dependence in adult rats of both sexes, extends previous findings to females, and revealed some sex differences. The results suggest that the changes that occur during precipitated withdrawal from THC extend beyond somatic signs to more nuanced disruptions of cognitive and affective functioning. The breadth of withdrawal signs observed in rodents mirrors those that have been observed in humans.
Full-text · Article · Apr 2014 · Drug and alcohol dependence
[Show abstract][Hide abstract] ABSTRACT: Several allosteric modulators (AMs) of the CB1 receptor have been characterized in vitro, including Org27569, which enhances CB1-specific binding of [H]CP55,940, but behaves as an insurmountable CB1-receptor antagonist in several biochemical assays. Although a growing body of research has investigated the molecular actions of this unusual AM, it is unknown whether these actions translate to the whole animal. The purpose of the present study was to determine whether Org27569 would produce effects in well-established mouse behavioral assays sensitive to CB1 orthosteric agonists and antagonists. Similar to the orthosteric CB1 antagonist/inverse agonist rimonabant, Org27569 reduced food intake; however, this anorectic effect occurred independently of the CB1 receptor. Org27569 did not elicit CB1-mediated effects alone and lacked efficacy in altering antinociceptive, cataleptic, and hypothermic actions of the orthosteric agonists anandamide, CP55,940, and Δ-tetrahydrocannabinol. Moreover, it did not alter the discriminative stimulus effects of anandamide in FAAH-deficient mice or Δ-tetrahydrocannabinol in wild-type mice in the drug discrimination paradigm. These findings question the utility of Org27569 as a 'gold standard' CB1 AM and underscore the need for the development of CB1 AMs with pharmacology that translates from the molecular level to the whole animal.