METYRAPONE-INDUCED SUPPRESSION OF CORTICOSTERONE SYNTHESIS REDUCES ETHANOL-CONSUMPTION IN HIGH-PREFERRING RATS

The fluid intake of male Wistar rats with simultaneous access to water and 6% ethanol was determined between 0900 and 1500 h. In high-prefer ring males (normally covering > 60% of their daily fluid consumption i n the form of ethanol), two injections with the corticosterone synthes is inhibitor metyrapone (50 mg/kg) at 0900 h and 1200 h for 4 consecut ive days significantly reduced ethanol preference such that they prefe rred water over alcohol. Treatment with corticosterone (0.6 mg/kg) 2 h before each metyrapone injection partially cancelled this effect of t he synthesis inhibitor. By contrast, there was no significant effect o f metyrapone treatment on the drinking of ethanol in low-preferring ra ts (normally covering <30% of their daily fluid consumption in the for m of ethanol). These results suggest that the adrenal secretion of cor ticosterone directly or indirectly modulates the intake of alcohol in high-preferring rats.