Differential ovulatory responses of the right and left ovaries of the adult rat to unilateral lesion and anaesthesia of the cervico-vaginal plexus

Abstract

Differences were observed in the ovulation rates of the right and left ovaries in response to unilateral lesions of the cervico-vaginal plexus (CVP) followed by pseudopregnancy or by anaesthesia of the CVP induced with panthocaine plus adrenaline (right ovary 6.7 +/- 0.4 (S.E.M.) vs left ovary 4.6 +/- 0.9; P less than 0.05). Pseudopregnancy (days showing a dioestrous smear after copulation with a vasectomized male before an oestrous smear following a pro-oestrous one) lasted longer in rats with a lesion in the CVP than in a control pseudopregnant group (14.9 +/- 0.5 vs 11.2 +/- 0.5; P less than 0.01). Anaesthesia of the CVP performed on each day of the oestrous cycle did not modify the ovulation rate compared with laparotomized animals. Both laparotomy and anaesthesia of the CVP performed on oestrus or day 1 of dioestrus blocked ovulation but when they were performed on day 2 of dioestrus or pro-oestrus they failed to do so (laparotomy 9/18 vs 12/14, P less than 0.05; anaesthesia of CVP 3/11 vs 17/17, P less than 0.05). The number of ova shed by the left ovary in animals with anaesthetized CVP was lower than by the right ovary (4.5 +/- 0.6 vs 6.2 +/- 0.5; P less than 0.05). These results add further support to the idea that the CVP participates in the regulation of ovulation rate, and that the left ovary is less adaptable than the right when innervation is challenged.

A comparative analysis of the neuroendocrine mechanisms regulating ovulation, affected by a unilateral implant of atropine in the preoptic-anterior hypothalamic area, in intact and hemiovariectomized adult rats

“…In intact animals, ovulation did not occur after blockade of the cholinergic system by atropine implants in the right side of the POA-AHA on oestrus, and was nor¬ mal when the implant was in the left side ); opposite results were obtained from hemi¬ ovariectomized animals. These results agree with the hypothesis that there exists a direct neural connection between the gonads and the central nervous system which participates in the fine tuning of the effects of gonadotrophins on the gonads (Domínguez & Riboni, 1971;Burden, 1978;Gerendai, Rotszthjn, Marchetti & Scapagnini, 1979;Kawakami, Kubo, Uemura & Hayashi, 1981;Kawakami, Nishihara & Ohno, 1983;Nance, Bhargava & Myatt, 1984;Cook, 1987;Gerendai, 1988;Frankel, Chapman & Cook, 1989;Domínguez, 1990). When the animals were hemiovariectomized, the neural information arising from the extirpated ovary was missing, and the nervous centres adapted to the new situation.…”

“…There are several indications that ovarian innervation plays an important role in the mechanisms regulating compensatory ovarian hypertrophy (Burden, 1978;Gerendai, 1980;Gerendai & Halasz, 1981;Nance, White & Moger, 1983;Chavez et al 1987;Cruz et al 1990), since there are no permanent changes in gonado¬ trophin levels after hemiovariectomy (Flores, Ledesma, Ulloa-Aguirre & Domínguez, 1990). The present results indicated that compensatory ovarian hypertrophy depends on cholinergic neural information arising from the left side of the POA-AHA, though the sensitivity of the ovary to gonadotrophins, measured by the increase in the weight of the ovary and the weight of the uterus, was not affected.…”

Effects of unilateral or bilateral superior ovarian nerve section in infantile rats on follicular growth

“…Right and left ovaries respond in distinct ways to different experimental situations (Chávez et al 1987, Domínguez 1990, D'Albora et al 1992, Gerendai et al 1995, Cassina & Domínguez 1996, Gerendai & Halasz 1997, and these differences have been explained by differences in the ovarian innervation (Domínguez et al 1989). The differences in follicular growth and differentiation induced by sectioning of the right or left SON in innervated and denervated ovaries support such an interpretation.…”