The effect of denervation on compensatory ovarian hypertrophy

Hemiovariectomized rats were randomly assigned to 1 of 5 groups: controls, 6-hydroxydopamine (6-HD)-treated, abdominal vagotomy, 6-HD-treated plus abdominal vagotomy and pelvic parasympathectomy. 15 days later all animals were sacrificed and the amount of compensatory ovarian hypertrophy (COH) was calculated. Vagotomy and vagotomy plus 6-HD treatment interrupted estrous cycles and significantly decreased COH. Vagotomized rats with both ovaries intact had disrupted estrous cycles but ovarian weights were not affected. In a subsequent study, rats in estrus were sham-operated, unilaterally ovariectomized (ULO), vagotomized, or vagotomized + ULO, and serum levels of LH and FSH were determined at 5 and 24 h. ULO caused a significant (p less than 0.05) increase in LH and FSH at 5 h. Vagotomy significantly (p less than 0.05) depressed LH and FSH levels in hemiovariectomized animals at 5 h. By 24 h LH was significantly higher in ULO than in either sham-operated (p less than 0.05) or vagotomy (p less than 0.01) groups. Also, vagotomy significantly (p less than 0.01) depressed FSH levels at 24 h. These results suggest a functional role for the vagus nerve in normal cyclic activity, COH, and gonadotrophin (Gn) secretion.