The Antidepressants Fluoxetine and Bupropion Differentially Affect Proceptive Behavior in the Naturally Cycling Female Rat

Abstract

Fluoxetine, like other selective serotonin reuptake inhibitors, inhibits women's sexual desire and female rats' sexual behavior. Bupropion produces pro-sexual effects in women with and without depression, and yohimbine increases men's and male rats' sexual motivation, but their effects on female rats' proceptivity are unknown. To investigate the effects of fluoxetine, bupropion, and yohimbine on proceptivity and receptivity in the naturally cycling female rat. We studied the effect of chronic (minimum 14 days) fluoxetine (1.25 mg/kg, subcutaneous) and bupropion (5 mg/kg, intraperitoneal) and acute yohimbine (1 mg/kg, intraperitoneal) on sexual behavior of female rats selected in natural proestrus during an ejaculatory series. We also analyzed the effects of these treatments on locomotor activity. The main outcome measures were frequencies of hops/darts and ear wiggling, lordosis quotient and intensity, and locomotor activity. Fluoxetine inhibited ear wiggling and hopping/darting, while bupropion stimulated hopping/darting. These treatments did not modify the lordosis quotient and its intensity. Yohimbine did not change any aspect of female sexual behavior. At the doses and treatments used, fluoxetine and bupropion did not alter locomotor activity or disturb the length of the estrous cycle; however, yohimbine inhibited locomotor activity. The motivational components of female sexual behavior are more sensitive than the receptive components to the inhibitory actions of fluoxetine. Bupropion selectively stimulated hopping/darting, while yohimbine lacked an action on female sexual behavior.