Age related differences in dopamine-stimulated adenylate cyclase sensitivity to "in vivo" chronic ethanol treatment

Alcohol and the brain: setting the benefit/risk balance

This article reviews the literature and presents some unpublished data on the CNS effects of alcohol at doses not producing tolerance and dependence. The available evidence indicates that the effect of low doses of ethanol may qualitatively differ from those produced in animal models mimicking alcoholism. For example, rats exposed for two months to alcohol in drinking water at a concentration (3%) not inducing tolerance or dependence, as assessed by lack of withdrawal signs upon treatment suspension, appear to be less stressed in the two-way avoidance-learning tests. Accordingly, the treated rats perform better and learn faster than sucrose-fed controls, while this behavior is disrupted by high levels of ethanol intake. These initial observations suggest that discontinuity may exist between the effects of low and high doses of this substance and underscore the need to expand research on the effects of alcohol on the CNS to include the bottom end of the dose-response curve.

The influence of cholesterol on synaptic fluidity, dopamine D1 binding and dopamine-stimulated adenylate cyclase

The present study examined the influence of the synaptic cholesterol/phospholipid ratio on fluorescence polarization, the binding of SCH23390 to dopaminergic D1 binding sites and dopamine-stimulated adenylate cyclase activity. The cholesterol/phospholipid ratio of synaptic membranes from bovine caudate was modified by incubating the membranes with a lipid transfer protein and liposomes which were either loaded with or lacking cholesterol. The results of this study demonstrated that the number of binding sites (Bmax) for SCH23390 was insensitive to alterations in the synaptic cholesterol/phospholipid ratio and membrane order. However, when the cholesterol/phospholipid ratio was decreased by 30%, membrane order and binding affinity (Kd) were decreased. Despite the lack of change in the number of D1 binding sites, the activity of dopamine-stimulated adenylate cyclase was markedly inhibited by an elevated cholesterol/phospholipid ratio. The results of these studies are discussed in terms of their potential relevance to aging.

Chronic consumption of ethanol increases glucose oxidation in isolated cerebral tissue of rat

Tolerance to ethanol was induced in male Wistar rats by adding 15% ethanol to the drinking water for 3 and 9 months. The oxidation of [U-14C]glucose was measured in cerebral cortex prisms. 14CO2 production in prisms for ethanol-treated animals was markedly increased when compared to controls. Neither a single injection of a low dose of ethanol nor a comparable concentration of ethanol in vitro had this stimulatory effect.