DIFFERENTIAL-EFFECTS OF OVARIAN LOCAL-ANESTHESIA DURING PRO-ESTRUS ONOVULATION BY THE RIGHT OR LEFT OVARY IN NORMAL AND HEMI-OVARIECTOMIZED ADULT RATS

The effects on spontaneous ovulation in normal and hemi-ovariectomized cyclic rats of an injection of saline or a local anaesthetic (2-dieth ylamine-2',6'-acetoxilidide hydrochloride with adrenaline, Xylocaine; administered at 13:00 h) into the bursa ovarica, were studied to inves tigate the participation of ovarian innervation in the regulation of t he response of ovarian follicles to endogenous gonadotrophins on the d ay of pro-oestrus. The injection of saline or Xylocaine into both ovar ies did not affect ovulation by the right ovary. Bilateral injection o f Xylocaine did not affect ovulation by the left ovary. However, when saline was injected into the right ovary and Xylocaine into the left o vary, the number of ova shed by the left ovary decreased significantly (0.9 +/- 0.7 versus 4.4 +/- 0.2, P < 0.01; Mann-Whitney U test). In h emi-ovariectomized animals, when the right ovary was anaesthetized, ov ulation was similar to that in saline-treated animals, and when the ri ght ovary was anaesthetized, ovulation was blocked tone of six animals ovulated). The injection of hCG at 14:00 h to hemi-ovariectomized rat s did not restore ovulation, whereas all the rats ovulated when anaest hesia occurred at 18:00 h. The present results suggest that on the aft ernoon of the day of pro-oestrus, before the LH peak, a neural signal modulates the response of the left ovary to gonadotrophins.