In the pubertal rat, the regulation of ovarian function involves the synergic participation of the sensory and sympathetic innervations that arrive at the gonad

BACKGROUND The present study investigates sectioning the superior ovarian nerve (SON) in rats with functional sensorial denervation induced by capsaicin administration at birth and the effects on the establishment of puberty, ovulation, serum progesterone, and estradiol concentrations. METHODS The animals were allotted randomly to one of the following experimental groups. Groups of 8-10 rats were injected at birth with capsaicin or vehicle, and on day 20 or 28 of life, they were submitted to a sham operation (SO). Other groups of 8-10 rats were injected at birth with capsaicin or vehicle, and on day 20 or 28 of life, they were submitted to the uni-or bilateral SON sectioning. The animals were killed at the first estrus. Serum concentration of progesterone (ng/ml) and estradiol (pg/ml) were measured using a radioimmunoassay. RESULTS Animals treated with capsaicin and subjected at 20 days of life to the left or bilateral section of SON had a delayed age of vaginal opening. Furthermore, animals with a lack of sensory information and subjected to a SO at 28 days of life had the same delay in the age of vaginal opening. Animals with sensorial innervation intact, subjected to unilateral section of the SON at 20 or 28 days of age, showed diminished ovulation rate and number of ova shed by the denervated ovary. In animals with sensorial denervation, the uni-or bilateral sectioning of the SON did not result in changes in ovulation. Progesterone and estradiol levels were different depending on the age of the animal in which the SON section was performed. CONCLUSIONS Based on the present results, we suggest that sympathetic innervation regulates ovulation and the secretion of steroid hormones and that the sensory fibers modulate the sympathetic innervation action on ovarian functions.