THE EFFECT OF VITAMIN-B-6 ON SEXUAL-BEHAVIOR IN THE RAT, POSSIBLY THROUGH SEROTONERGIC MECHANISMS

Serotonin type 2 (5-HT2) receptor activity has been reported to inhibit male sexual behavior and facilitate female sexual behavior in the rat. Recent research has revealed that chronic pyridoxine (vitamin B-6) administration decreases the number of 5-HT2 receptors in the hypothalamus, an area implicated in sexual activity. Therefore, pyridoxine may act to facilitate male sexual behavior and inhibit female sexual behavior by inhibiting 5-HT2 receptor activity. In the present series of experiments we recorded the sexual activities of male (Experiment 1) and female (Experiment 2) rats during daily chronic pyridoxine (100 mu g/kg) and saline administration. Pyridoxine acted to significantly reduce post-ejaculatory intervals (p<.05) and increase the proportion of animals ejaculating (p<.05). However, pyridoxine administration had no significant effect on female sexual behavior. Overall, these findings are consistent with an inhibitory effect of 5-HT2 activity in the male. Since pyridoxine also elevates serotonin and dopamine levels, it is possible that its differential effects on male and female sexual behavior may partially be due to the differing impact of the release of these neurotransmitters on male and female sexual behavior.