No abstract

Bilateral lesions of the ventromedial nucleus(VMN) were performed in the 3rd cycle of a sequence of 4-day cycles in Wistar rats by means of stereotaxically-oriented platinum unipolar electrodes. Small (SVMN) or large (LVMN) lesions were produced by the passage of a cathodic current for 7 or 14 sec, respectively. Groups of intact 4-day cyclic and 5-day cyclic rats, and of dorsomedial nucleus (DMN) lesioned and VMN sham (SH) operated females served as controls. A modification of the duration of one or both of the 2 first post-operative cycles was found in 31 out of 60 SVMN and in 11 out of 12 LVMN lesioned females. Only 2 out of 16 DMN lesioned and none of the 17 SH operated rats exhibited a change of post-operative cycle length. No modification of the duration of the 4th and/or the 5th cycles occurred in control non-operated females after a sequence of three 4-day cycles. Further study of vaginal cycles in animals with modified cycle duration showed that estrous rhythm changed from 4- to 5-day or to alternate 4- and 5-day cycles following VMN lesions. Ovulation regularly occurred during the night following proestrus of either 4- or 5-day cycles in VMN lesioned animals. Neither frequency of ovulation nor mean number of corpora lutea/rat differed when compared with DMN lesioned or SH operated females. On the contrary, a significant diminution of sexual receptivity resulted from SVMN lesions in comparison with DMN and SH animals (4-day cycles) or with intact control animals (5-day cycles). LVMN lesions almost completely abolished mating receptivity.

The olfactory bulbs were removed in 2- to 3-month-old virgin Wistar rats; one month later, the animals were tested for precocious and oestrous mating activity during 5-day cycles. The mating frequencies observed in control and operated animals, respectively, were 35/87 and 4/50 during the night following day 3 (dioestrus 3), 36/42 and 31/38 during the night following day 4 (prooestrus), and 42/70 and 17/30 during the night following day 3, following injection of a single dose of 10 µg oestradiol. Precocious ovulation was triggered by coitus in unoperated as well as in operated oestradiol-primed animals. In operated animals, no disturbance of spontaneous ovulation frequencies was recorded, but a small decrease in the mean number of corpora lutea was observed.

No abstract

The effects of meprobamate on the ovary were studied in two different strains of virgin 4-day cyclic Wistar rats. Antiovulatory action of the drug was observed when administered on the morning of prooestrus between 9 and 12 a. m. This action was shown to be quantitative and depending on the time of the injection. A difference in the activity of meprobamate was evidenced between the two strains experimented. This action of the tranquillizer was supposed to be mediated by neural structures. Only weak antiovulatory effects of the meprobamate were observed when the drug was administered after 4.30 p. m. on the day of prooestrus. Furthermore the ovulatory action of exogenous gonadotrophin was not prevented by meprobamate.