Effects of acute and chronic fluoxetine treatment on CRH-induced anxiety

THE effects of acute and chronic fluoxetine treatment on anxiogenic effect of corticotropin-releasing hormone (CRH) were studied in the social interac tion test in male Sprague-Dawley rats. Injection of CRH (100 ng, i.c.v.), f luoxetine (5 mg/kg, i.p.) or their combination had significant anxiogenic e ffects (decrease in total interaction time and increase in self-grooming) i n the social interaction test. The effects of CRH and fluoxetine in combina tion were not additive. Fluoxetine, but not CRH significantly inhibited loc omotor activity. After chronic fluoxetine treatment (5 mg/kg/day, 21 days) the acute anxiogenic effects of either CRH or fluoxetine were abolished. Ou r studies provide evidence for a 5-HT/CRH interaction in the regulation of anxiety. (C) 1999 Lippincott Williams & Wilkins.