PLASMA-CORTICOSTERONE RESPONSE TO CHRONIC ETHANOL-CONSUMPTION AND EXERCISE STRESS

Acute exposure to ethanol induces a stress response in mice that is ma nifested by increased plasma corticosterone (PC) concentration. Howeve r, during chronic intake of 7.5% w/v ethanol, diurnal fluctuation of P C is dampened. Whether chronic consumption of 20% w/v ethanol alters n ormal diurnal fluctuation of plasma glucocorticoids is not known. Inve stigating the PC response in 20% w/v ethanol-consuming mice is of inte rest because glucocorticoids are known suppressants of natural killer (NK) cell activity and increased concentration or altered diurnal fluc tuation of PC may have a modulatory role on NK cells in these mice. Mi ce given 20% w/v ethanol for at least 7 days and for as long as 10 wee ks have suppressed splenic NK cell cytolytic activity. Thus, the purpo se of this study was to examine whether mice given 20% w/v ethanol exh ibited normal concentrations and diurnal variation of PC. To further d efine the glucocorticoid response in chronic ethanol-consuming mice, P C concentration was evaluated in response to a secondary stress of phy sical exercise. After 1 week, ethanol-consuming mice exhibited abnorma l diurnal PC periodicity that was progressively dampened during the re maining 9 weeks. Acute physical exercise during Week 1 induced a 2-fol d increase in PC concentration compared with pre-exercise values, a re sponse that was independent of ethanol intake. After 6 and 10 weeks, t he postexercise PC concentration was attenuated in ethanol-consuming c ompared with water drinking mice. It was concluded that suppressed NK cell activity typically observed with this model of chronic ethanol in take is not directly associated with dampened diurnal fluctuation in P C.