Chronic daily ethanol and withdrawal: 6. Effects on rat sympathoadrenal activity during "abstinence"

We have reported that repetitive daily ethanol consumption increased anxiety-like behavior in rats 4 weeks after ethanol consumption had ceased, consistent with the persistently increased anxiety exhibited by abstinent alcoholics. Increased anxiety is associated with sympathoadrenal activation, so we have now also investigated ethanol-induced persistent changes in basal and stress-induced plasma epinephrine (E) and norepinephrine (NE) levels. Male Sprague-Dawley rats received liquid diet containing ethanol versus pair-fed isocaloric control liquid diet for 9 weeks. After 5 weeks' subsequent "abstinence" (i.e., no ethanol in the diet), the control rats exhibited low basal plasma E and NE, which were both increased by 150-300% within 5 min after transfer to a novel cage in a novel room, returning toward basal levels within 15 min. "Abstinent" ethanol-treated rats exhibited elevated basal E levels (195% of controls, P<.05), which were not significantly altered by transfer to novel environment; basal NE levels tended (P<.07) to be elevated and likewise were not altered by novel environment. These results suggest that daily ethanol consumption can induce persistent increases in sympathoadrenal activation during subsequent "abstinence," which are relatively refractory to further stimulation.