Plasma Corticosterone Response to Chronic Ethanol Consumption and Exercise Stress

Abstract

Acute exposure to ethanol induces a stress response in mice that is manifested by increased plasma corticosterone (PC) concentration. However, during chronic intake of 7.5% w/v ethanol, diurnal fluctuation of PC is dampened. Whether chronic consumption of 20% w/v ethanol alters normal diurnal fluctuation of plasma glucocorticoids is not known. Investigating the PC response in 20% w/v ethanol-consuming mice is of interest because glucocorticoids are known suppressants of natural killer (NK) cell activity and increased concentration or altered diurnal fluctuation of PC may have a modulatory role on NK cells in these mice. Mice given 20% w/v ethanol for at least 7 days and for as long as 10 weeks have suppressed splenic NK cell cytolytic activity. Thus, the purpose of this study was to examine whether mice given 20% w/v ethanol exhibited normal concentrations and diurnal variation of PC. To further define the glucocorticoid response in chronic ethanol-consuming mice, PC concentration was evaluated in response to a secondary stress of physical exercise. After 1 week, ethanol-consuming mice exhibited abnormal diurnal PC periodicity that was progressively dampened during the remaining 9 weeks. Acute physical exercise during Week 1 induced a 2-fold increase in PC concentration compared with pre-exercise values, a response that was independent of ethanol intake. After 6 and 10 weeks, the postexercise PC concentration was attenuated in ethanol-consuming compared with water-drinking mice. It was concluded that suppressed NK cell activity typically observed with this model of chronic ethanol intake is not directly associated with dampened diurnal fluctuation in PC.

Chronic Alcohol Consumption in Rats Leads to Desynchrony in Diurnal Rhythms and Molecular Clocks

“…In alcoholics, normal, overall elevated, and sporadic diurnal rhythms of cortisol have all been reported (Bertello et al, 1982;Margraf et al, 1967;Stokes, 1973). In mice, blunted diurnal CORT rhythms along with dampened amplitude have been seen after chronic alcohol (Kakihana and Moore, 1976;Sipp et al, 1993), findings consistent with our results in rats. Moreover, we found that chronic alcohol in rats advanced the molecular clock (Per1) in the adrenal and pituitary glands, yet the SCN was unaffected.…”

Chronic ethanol ingestion modulates proanxiety factors expressed in rat central amygdala

“…However, there is conflicting evidence regarding the effects of chronic ethanol on resting levels of corticosterone (Guaza et al, 1983;Rasmussen et al, 2000). Despite these contrasting reports, chronic exposure can blunt both circadian cycling of corticosterone (Sipp et al, 1993) as well as the responsiveness of the HPA axis to external stressors (Ogilvie et al, 1998). These findings suggest that chronic ethanol's interaction with the HPA axis may be relatively subtle.…”

Effects of Ethanol Consumption on Enriched Natural Killer Cells from C57BL/6 Mice

“…Increased glucocorticoid levels can suppress NK a~t i v i t y~~,~~; however, in our model, plasma glucocorticoid levels were not elevated in ethanol-consuming mice relative to water-drinking mice. 31 Several substances have been implicated in the cytolysis mediated by NK cells, such as perforins, certain proteases (granzymes), and tumor necrosis factor.32 Nelson et a1. 33,34 reported that tumor necrosis factor secretion by rat alveolar.…”