Catherine Lopez

Background: Histone deacetylase 6 (HDAC6) inhibition can alleviate depression‐ and anxiety‐like behaviors. Accordingly, HDAC6 may be a promising target to mitigate negative reinforcement in alcohol use disorder (AUD). We previously reported reduced α‐tubulin acetylation in mice withdrawn from chronic intermittent ethanol (CIE) vapor inhalation, suggesting potential HDAC6 hyperactivity in this mouse model of AUD. The present study aimed to probe the behavioral significance of this acetylation deficit by testing whether HDAC6 inhibition can reverse ethanol drinking escalation in CIE‐exposed mice. Methods: Male C57BL/6J mice were subjected to limited‐access ethanol drinking sessions (two‐bottle choice, 2BC) combined with CIE to escalate voluntary ethanol intake relative to air‐exposed counterparts (Air). Ethanol and saccharin intake during 2BC was measured after acute and subchronic administration of bavarostat, a brain‐penetrant HDAC6 inhibitor. Acetyl‐lysine and acetyl‐α‐tubulin levels were quantified via immunoblotting. Results: Acute administration of bavarostat at 100 mg/kg, but not lower doses, significantly reduced ethanol intake in both Air and CIE mice. Ethanol intake during subchronic administration of 100 mg/kg bavarostat was reduced on the first day in both Air and CIE mice compared to vehicle‐treated counterparts, but this effect was lost on subsequent days. CIE mice also consumed more saccharin than Air controls. Bavarostat did not impact saccharin intake in either group. When saccharin was offered along with ethanol, CIE mice consumed significantly more ethanol and less saccharin than Air counterparts, indicating intact taste discrimination. Bavarostat administered prior to brain collection significantly increased acetyl‐lysine and acetyl‐α‐tubulin levels in the frontal cortex, confirming reduced HDAC6 activity. These levels did not differ between Air and CIE mice. Conclusions: Systemic administration of bavarostat reduces voluntary ethanol drinking in mice. This effect is dose‐dependent, selective for ethanol, independent of ethanol dependence, and transient. These findings support HDAC6 as a viable target to acutely reduce the drive to consume ethanol.

BACKGROUND: Dyslipidemia increases cardiovascular disease risk, the leading cause of death worldwide. Under time-restricted feeding (TRF), wherein food intake is restricted to a consistent window of <12 hours, weight gain, glucose intolerance, inflammation, dyslipidemia, and hypercholesterolemia are all reduced in mice fed an obesogenic diet. LDLR (low-density lipoprotein receptor) mutations are a major cause of familial hypercholesterolemia and early-onset cardiovascular disease. METHODS: We subjected benchmark preclinical models, mice lacking LDLR-knockout or ApoE knockout to ad libitum feeding of an isocaloric atherogenic diet either ad libitum or 9 hours TRF for up to 13 weeks and assessed disease development, mechanism, and global changes in hepatic gene expression and plasma lipids. In a regression model, a subset of LDLR-knockout mice were ad libitum fed and then subject to TRF. RESULTS: TRF could significantly attenuate weight gain, hypercholesterolemia, and atherosclerosis in mice lacking the LDLR-knockout mice under experimental conditions of both prevention and regression. In LDLR-knockout mice, increased hepatic expression of genes mediating β-oxidation during fasting is associated with reduced VLDL (very-low-density lipoprotein) secretion and lipid accumulation. Additionally, increased sterol catabolism coupled with fecal loss of cholesterol and bile acids contributes to the atheroprotective effect of TRF. Finally, TRF alone or combined with a cholesterol-free diet can reduce atherosclerosis in LDLR-knockout mice. However, mice lacking ApoE, which is an important protein for hepatic lipoprotein reuptake do not respond to TRF. CONCLUSIONS: In a preclinical animal model, TRF is effective in both the prevention and regression of atherosclerosis in LDLR knockout mice. The results suggest TRF alone or in combination with a low-cholesterol diet can be a lifestyle intervention for reducing cardiovascular disease risk in humans.

Corticotropin-releasing factor (CRF, encoded by Crh ) signaling is thought to play a critical role in the development of excessive alcohol drinking and the emotional and physical pain associated with alcohol withdrawal. Here, we investigated the parasubthalamic nucleus (PSTN) as a potential source of CRF relevant to the control of alcohol consumption, affect, and nociception in mice. We identified PSTN Crh neurons as a neuronal subpopulation that exerts a potent and unique influence on behavior by promoting not only alcohol but also saccharin drinking, while PSTN neurons are otherwise known to suppress consummatory behaviors. Furthermore, PSTN Crh neurons are causally implicated in the escalation of alcohol and saccharin intake produced by chronic intermittent ethanol (CIE) vapor inhalation, a mouse model of alcohol use disorder. In contrast to our predictions, the ability of PSTN Crh neurons to increase alcohol drinking is not mediated by CRF ₁ signaling. Moreover, the pattern of behavioral disinhibition and reduced nociception driven by their activation does not support a role of negative reinforcement as a motivational basis for the concomitant increase in alcohol drinking. Finally, silencing Crh expression in the PSTN slowed down the escalation of alcohol intake in mice exposed to CIE and accelerated their recovery from withdrawal-induced mechanical hyperalgesia. Altogether, our results suggest that PSTN Crh neurons may represent an important node in the brain circuitry linking alcohol use disorder with sweet liking and novelty seeking.