engleski

VAGAL INFLUENCE ON COMPENSATORY OVARIAN HYPERTROPHY IS IMPORTANT ONLY BRIEFLY AFTER HEMICASTRATION

Background. Rat ovary is richly innervated. A part of the innervation is vagal in origin. Compensatory ovarian hypertrophy (COH)is induced by unilateral ovariectomy (hemicastration) and is based on increased follicular growth aimed to compensate for the loss of the endocrine and reproductive function. The involvement of vagi nerves has been long suggested. The results presented here suggest that vagal influence is important only during the first few hours after hemicastration and that it, apparently, includes neural input to the ovary. Materials and Methods. Mature Wistar female rats (2-3 consecutive estrus cycles) were used. Hemicastration was always performed on the day of estrus. In the first group of experiments: a) animals were vagotomized immediately after hemicastration ; b) animals were vagotomized 4.5 hours after hemicastration or c) the abdominal vagi were exposed to 2% lidocaine for 10 minutes and hemicastration followed after 30 minutes. COH was estimated on day 10 after hemicastration (or sham hemicastration). In the second group of experiments, ovarian cAMP concentrations after hemicastration were measured and the effects of vagotomy and local lidocain treatment were analyzed. Results. COH was inhibited by vagotomy performed immediately after hemicastration, but not by vagotomy delayed till 4.5 hours after hemicastration. The brief exposure of the vagi nerves to lidocaine also inhibited COH. At 15 minutes after hemicastration, elevated cAMP concentrations were found in the remnant ovary. This hemicastration-induced increase was inhibited by vagotomy done prior to hemicastration and partly by vagotomy delayed till 10 minutes after vagotomy and by lidocaine treatment of the vagi nerves. At 5 hours after vagotomy, the ovarian cAMP levels were not increased or affected by vagotomy. Conclusions. The results suggest that the vagal influence on COH is important only within a few first hours after hemicastration and that it, apparently, includes a neural input to the ovary.

vagus; ovary; compensatory growth; muscarinic receptors

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