Alcohol alters rat adrenomedullary function and stress response

Most alcohol researchers do not address the effects of intoxication on the sympatho-adrenomedullary system response to stressful situations. We previously determined that rats consuming nearly 9 g ethanol (EtOH) per kg body weight per day in liquid diet form for 1 week increased adrenal gene expression of enzymes for catecholamine synthesis that was further elevated by acute IMMO. We hypothesized that the response to chronic mild stressors would also be altered after consumption of lower concentrations of EtOH in drinking water. Two experiments were conducted: 10% w/v for 4 weeks or 6% w/v for 7 weeks +/- wire mesh restraint (WMR). These were compared with ad libitum (adlib) and pair-fed control rats. Adrenal gene expression of catecholamine synthesizing enzymes was assayed. Tyrosine hydroxylase gene expression was elevated 80% to 90% by alcohol consumption in both experiments (P0.001) compared with adlib control rats. Dopamine betab-hydroxylase and phenylethanolamine-N-methyl transferase gene expressions were unaffected by 10% alcohol (P0.05) but were increased by 6% alcohol (P0.01). WMR decreased already elevated gene expression of all three enzymes. Pair feeding to 6% EtOH drinkers also increased gene expression for the three enzymes but was decreased by WMR, although not to levels of adlib rats. Increased gene expression for adrenal synthesis of catecholamines in response to repeated alcohol consumption increases the likelihood that the subject can respond physiologically to acute or chronic stress. This may have life-saving consequences in humans and in animals known to consume fermented materials and may contribute to increased aggressive behavior.