The influence of raphe nucleus lesions on fertility in the female rat

By lesioning brain raphe nuclei, the effect of decreasing the activity of the serotoninergic (5-HT) system on the fertility of the female rat was investigated. The females were mated on the 10th day after lesioning. On both the 15th and 21st day of pregnancy the numbers of live and resorbed foetuses and the weights of placentas in the lesioned groups did not differ statistically as compared with the control group. Interestingly, the lesioned group showed an increase in the number of ovulating cells on the one hand, and decrease in the number of implantations on the other. The data obtained strongly suggest that midbrain serotoninergic cell groups (B7, B8) inhibit ovulation and are not associated with initiation of labour in the female rat.