Augmentation of corticosterone release by means of a caffeine-ethanol interaction in rats

We examined whether the acute treatment with caffeine delivered before an e thanol injection would augment plasma corticosterone (CORT) levels. The eff ect of caffeine on blood ethanol levels was also assessed. After 10 days of acclimatization to the colony room conditions, male Wistar rats were injec ted with either caffeine (5 mg/kg, ip) or saline 30 min before the delivery of ethanol (0.8 g/kg, ip) or saline, respectively. Trunk blood was then co llected at 15 and 30 min after the ethanol injection for determination of p lasma CORT and blood ethanol levels. CORT was measured with the use of radi oimmunoassay, and blood ethanol levels were determined with the use of gas chromatography. The results showed that although caffeine and ethanol deliv ered singly failed to augment plasma CORT levels, the combination of both d rugs produced elevations in plasma CORT levels at 15 and 30 min. These find ings were found to be unrelated to changes in ethanol metabolism as caffein e failed to alter blood ethanol levels within the period tested. It was arg ued that the present elevations in plasma CORT levels observed in animals a dministered caffeine and ethanol may play a role in the caffeine-induced el evations in ethanol drinking observed elsewhere. (C) 2000 Elsevier Science Inc. All rights reserved.