These experiments explored the effect of 70 mg atropine sulfate, and several doses of Gonadormone Byla, given at 1700 on diestrous I or at 1700 on diestrous II in the strains WI and WII rats derived in the authors' laboratory from Wistar rats. In Experiment 1 300 rats, 30 per group, received 2.5 or 5.0 mouse units of Gonadormone per 100 gm body weight at 1700 of diestrous I, with or without atropine, and were killed for serial ovarian sections at 1100 of proestrus. The 2.5 unit experime nt generated significant differences in frequency of luteinization between season of the year (p less than .001), between atropine and no atropine treatment (p less than .001), and season of atropine administration (p less than .05). Atropine decreased frequency of luteinization defined as proportion of a group having luteinized with or without retained ova. There were no differences in mean coefficients of ovulation, i.e., mean proportion of ovulated corpora lutea in each rat among all luteinized follicles, between rat strains or atropine treatments. The 5 unit dose of gonadotropin per 100 gm body weight increased luteinization 100% over the 2.5 unit dose. In the 2nd series of 180 rats, the frequency of luteinization induced by 1.25 units of gonadotropin was decreased by atropine (p less than .01), but the frequency of ovulation and response in the 2 rat strains did not differ. The results were interpreted as due in part to endogenous gonadotropin release, although atropine was thought to act directly on the ovary.

The question whether atropine inhibits follicular growth in rats induced by Gonadormone Byla was tested. 52 rats of strain WI, and 48 WII rats about 20 gm heavier, were injected at 1700 in diestrous I with 2.5 mouse units of gonadotropin per 100 gm body weight and 28 of each group also with 70 mg atropine sulfate sc, then serial ovarian sections were prepared at 1700 of proestrus. Atropine reduced the mean number of follicles 400 mcm in diameter or above (p less than .02), but did not affect their size distribution. A 2nd series of 48 rats were injected at 1700 of diestrous II with 1.5 units of gonadotropin per 100 gm body weight and half the rats with atropine. Again, atropine reduced the number of developing follicles (p less than .05) without affecting their mean diameter or size distribution.

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.