Rev-erbα Knockout Reduces Ethanol Consumption and Preference in Male and Female Mice.

Alcohol use is a contributor in the premature deaths of approximately 3 million people annually. Among the risk factors for alcohol misuse is circadian rhythm disruption; however, this connection remains poorly understood. Inhibition of the circadian nuclear receptor REV-ERBα is known to disrupt molecular feedback loops integral to daily oscillations, and impact diurnal fluctuations in the expression of proteins required for reward-related neurotransmission. However, the role of REV-ERBα in alcohol and substance use-related phenotypes is unknown. Herein, we used a Rev-erbα knockout mouse line and ethanol two-bottle choice preference testing to show that disruption of Rev-erbα reduces ethanol preference in male and female mice. Rev-erbα null mice showed the lowest ethanol preference in a two-bottle choice test across all genotypes, whereas there were no ethanol preference differences between heterozygotes and wildtypes. In a separate experiment, alcohol-consuming wildtype C57Bl/6N mice were administered the REV-ERBα/ß inhibitor SR8278 (25 mg/kg or 50 mg/kg) for 7 days and alcohol preference was evaluated daily. No differences in alcohol preference were observed between the treatment and vehicle groups. Our data provides evidence that genetic variation in REV-ERBα may contribute to differences in alcohol drinking.

Intracerebroventricularly and systemically delivered inhibitor of brain CYP2B (C8-Xanthate), even following chlorpyrifos exposure, reduces chlorpyrifos activation and toxicity in male rats.

Chlorpyrifos is a pesticide that is metabolically activated to chlorpyrifos oxon (acetylcholinesterase inhibitor) primarily by the cytochrome P450 2B (CYP2B) enzyme subfamily in the liver and brain. We have previously shown that intracerebroventricular pretreatment with a CYP2B inhibitor, C8-Xanthate, can block chlorpyrifos toxicity. Here, we assessed whether delayed introduction of C8-Xanthate would still reduce toxicity and whether peripheral administration of C8-Xanthate could also inhibit chlorpyrifos activation in the brain and block toxicity. Male rats (N = 4-5/group) were either pretreated with C8-Xanthate (40 µg intracerebroventricular or 5 mg/kg intraperitoneal), or vehicle (ACSF or saline, respectively), 24 h before chlorpyrifos treatment (125 mg/kg subcutaneous) and then treated daily with inhibitor or vehicle until 7 days post-chlorpyrifos treatment. Additional groups received vehicle pretreatment, switching to C8-Xanthate 1, 2, 3, or 4 days after chlorpyrifos and then continuing with daily C8-Xanthate treatment until 7 days post-chlorpyrifos treatment. Neurotoxicity was assessed at baseline (before chlorpyrifos) and then daily after chlorpyrifos, using behavioral assessments (e.g., gait score). Neurochemical assays (e.g., serum and brain chlorpyrifos) were performed at the end of study. Pretreatment with C8-Xanthate completely prevented chlorpyrifos toxicity, and delayed introduction of C8-Xanthate reduced toxicity, even when started up to 4 days after chlorpyrifos treatment. Discontinuation of C8-Xanthate treatment 7 days post-chlorpyrifos treatment did not result in the reappearance of toxicity, tested through 10 days after chlorpyrifos treatment. These findings suggest that CYP2B inhibitor treatment, even days after chlorpyrifos exposure, and using a peripheral delivery route, may be useful as a therapeutic approach to reduce chlorpyrifos toxicity.