Blockade of Ovulation in Rats by Forced Immobilization for Surgical Treatment

抄録

By using 4-day cycling rats, the influence of forced immobilization and a simplesurgical operation of cervical region, applied on the day of proestrus upon the expected ovulation on the following morning, were studied. When these treatments were given so as to cover the “critical period”, the ovulation was effectively blocked and the complete blockade was established by the 4hr of forced immobilization alone, or the 2hr of that with the surgical operation, where the ovulation was delayed by one day and the vaginal diestrus lasted for 3days after the vaginal estrus of one day.
Administration of rat hypothalamic extract or LH normalized the precipitation of the periodical ovulation in the rat, treated with the 2-hr immobilization and the surgical operation. The stimuli derived from these stressful treatments seemed to exert an inhibitory effect on LH-RF releasing mechanism to block the pre-ovulatory surge of LH and resulting in the delay in ovulation. Although a similar delay in ovulation was observed in pentobarbital anesthesia, its subsequence of the vaginal cytology was evidently different from that obtained in the stressful treatment. Different mechanisms would function in CNS, between the blockade response of the anesthesia and that of the forced immobilization with a surgical operation performed under arousal state.
Only the ether inhalation among anesthetics used in unrestrained rats at the critical period had no effect on the periodical ovulation. It is noteworthy that the blockade of ovulation by the forced immobilization with a surgical operation can be prevented by the simultaneous application of ether anesthesia.