EFFECTS OF 3RD INTRACEREBROVENTRICULAR INJECTIONS OF CORTICOTROPIN-RELEASING FACTOR (CRF) ON ETHANOL DRINKING AND FOOD-INTAKE

Corticotropin releasing factor (CRF), a neuropeptide secreted by hypot halamic and extrahypothalamic neurons, is thought to mediate stress-re lated behaviors. The tension reduction hypothesis suggests that ethano l drinking reduces stress; that drinking is reinforced by this reduced stress; and that the probability of drinking therefore subsequently i ncreases. CRF also decrease food intake, and might: decrease ethanol d rinking similarly. We addressed these hypotheses directly by assessing the effects of intracerebroventricular (ICV) CRF upon ethanol drinkin g (1 h/day). Rats were provided drinking tubes containing ethanol solu tions that were gradually incremented in concentration (from 2% to 8% w/v, over 38 days). Ethanol intakes remained stable, ranging from 0.4 to 0.5 g/kg per hour on average, and a two-bottle choice test revealed that ethanol was preferred reliably to water. Third-ICV cannulae were surgically implanted and CRF or vehicle was acutely injected immediat ely prior to the sessions. CRF dose-dependently reduced ethanol intake by 31% (0.5 mu g) and 64% (5.0 mu g), and reduced 24-h food by 9% and 21%, respectively, but did not alter body weights. ICV CRF reduced et hanol drinking despite any acute stress-like effects that may have bee n present. Hence, these data are inconsistent with the tension reducti on hypothesis. On the other hand, our results support the concept that food intake and ethanol drinking may be mediated by similar mechanism s.