Pharmacological modulation of repeated ethanol withdrawal-induced anxiety-like behavior differs in alcohol-preferring P and Sprague-Dawley rats.

Previous work with Sprague-Dawley (SD) rats indicated that subjecting these rats to multiple episodes of ethanol diet could provoke anxiety-like responses. Because alcohol-preferring P rats have been reported to have neurochemical alterations in many systems shown to modulate anxiety-like responses, P rats were compared to SD rats. Rats were subjected to one or three cycles of 5 days' exposure to 4.5% or 7% ethanol diet to assess anxiety-like behavior. The social interaction test was conducted 5 h after ethanol was removed. Other groups of P and SD rats were injected with flumazenil (5 mg/kg), a benzodiazepine (BZD) receptor antagonist, CP-154,526 (10 mg/kg), CRF1 receptor antagonist, SB243,213, a 5-HT2C receptor inverse agonist, or vehicle during the 1st and 2nd withdrawals but not the third. After a single 5-day cycle of ethanol exposure, SD rats did not exhibit a change in social interaction, but P rats exhibited a decrease after exposure to the 7% ethanol. Both strains of rats exhibited anxiety-like behavior following three cycles of exposure to ethanol and the concentration of ethanol in the diet did not influence the response. It was confirmed that flumazenil, CP-154,523, and SB243,213 had prophylactic effects on anxiety-like behavior in the SD rats. Neither flumazenil nor SB243,213 was as effective in the P rats, while the CRF1 receptor antagonist completely counteracted the reduced social interaction in repeatedly withdrawn P rats. A small study showed that buspirone, a 5-HT1A agonist, also had prophylactic effects in P rats. These findings show that alcohol-preferring P rats exhibit anxiety-like behavior more readily following exposure to ethanol-containing diets and that this behavior is counteracted more readily by pretreatment with a CRF1 receptor antagonist than with BZD or 5-HT2C receptor antagonists.