Cannabinoid Antagonist Drug Discrimination in Nonhuman Primates.

Despite a growing acceptance that withdrawal symptoms can emerge following discontinuation of cannabis products, especially in high-intake chronic users, there are no Food and Drug Administration (FDA)-approved treatment options. Drug development has been hampered by difficulties studying cannabis withdrawal in laboratory animals. One preclinical approach that has been effective in studying withdrawal from drugs in several pharmacological classes is antagonist drug discrimination. The present studies were designed to examine this paradigm in squirrel monkeys treated daily with the long-acting CB1 agonist AM2389 (0.01 mg/kg) and trained to discriminate the CB1 inverse agonist/antagonist rimonabant (0.3 mg/kg) from saline. The discriminative-stimulus effects of rimonabant were both dose and time dependent and, importantly, could be reproduced by discontinuation of agonist treatment. Antagonist substitution tests with the CB1 neutral antagonists AM4113 (0.03-0.3 mg/kg), AM6527 (0.03-1.0 mg/kg), and AM6545 (0.03-1.0 mg/kg) confirmed that the rimonabant discriminative stimulus also could be reproduced by CB1 antagonists lacking inverse agonist action. Agonist substitution tests with the phytocannabinoid ∆9-tetrahydrocannabinol (0.1-1.0 mg/kg), synthetic CB1 agonists nabilone (0.01-0.1 mg/kg), AM4054 (0.01-0.03 mg/kg), K2/Spice compound JWH-018 (0.03-0.3 mg/kg), FAAH-selective inhibitors AM3506 (0.3-5.6 mg/kg), URB597 (3.0-5.6 mg/kg), and nonselective FAAH/MGL inhibitor AM4302 (3.0-10.0 mg/kg) revealed that only agonists with CB1 affinity were able to reduce the rimonabant-like discriminative stimulus effects of withholding daily agonist treatment. Although the present studies did not document physiologic disturbances associated with withdrawal, the results are consistent with the view that the cannabinoid antagonist drug discrimination paradigm provides a useful screening procedure for examining the ability of candidate medications to attenuate the interoceptive stimuli provoked by cannabis discontinuation. SIGNIFICANCE STATEMENT: Despite a growing acceptance that withdrawal symptoms can emerge following the discontinuation of cannabis products, especially in high-intake chronic users, there are no FDA-approved pharmacotherapies to assist those seeking treatment. The present studies systematically examined cannabinoid antagonist drug discrimination, a preclinical animal model that is designed to appraise the ability of candidate medications to attenuate the interoceptive effects that accompany abrupt cannabis abstinence.

The effect of cannabinoid receptor 1 blockade on adipokine and proinflammatory cytokine concentration in adipose and hepatic tissue in mice with nonalcoholic fatty liver disease.

In high-fat diet (HFD) induced nonalcoholic fatty liver disease (NAFLD), there is an increase in the endocannabinoid system activity, which significantly contributes to steatosis development. The aim of our study was to investigate the effects of cannabinoid receptor type 1 blockade on adipokine and proinflammatory cytokine content in adipose and hepatic tissue in mice with NAFLD. Male mice C57BL/6 were divided into a control group fed with a control diet for 20 weeks (C, n = 6) a group fed with a HFD for 20 weeks (HF, n = 6), a group fed with a control diet and treated with rimonabant after 18 weeks (R, n = 9), and a group fed with HFD and treated with rimonabant after 18 weeks (HFR, n = 10). Rimonabant significantly decreased leptin, resistin, apelin, visfatin, interleukin 6 (IL-6), and interferon-γ (IFN-γ) concentration in subcutaneous and visceral adipose tissue in the HFR group compared to the HF group (p < 0.01). Rimonabant reduced hepatic IL-6 and IFN-γ concentration as well as plasma glucose and insulin concentration and the homeostatic model assessment index in the HFR group compared to the HF group (p < 0.01). It can be concluded that the potential usefulness of CB1 blockade in the treatment of HFD-induced NAFLD is due to modulation of the adipokine profile and proinflammatory cytokines in both adipose tissues and liver as well as glucose metabolism.