Ontogeny of responsiveness to gonadotrophins and prostaglandin E in the neonatal rat ovary

Abstract

Summary. The Ovaries of 4-day old rats cultured for 2-12 days in medium without hormonal supplementation produced small and decreasing amounts of steroids. The addition of LH did not alter progesterone production during the first 4 days of culture but significantly stimulated it during Days 4-8 of culture. FSH and testosterone (1 fL g/ml) had no effect on their own, but when FSH or testosterone were added together with LH, progesterone production during Days 4-10 of culture was greatly enhanced. The acquisition of responsiveness to LH did not depend on previous exposure to the hormone, since a full response in progesterone production to LH was obtained in the ovaries after 4-8 days of culture without LH addition.Production of oestradiol-17P was slightly enhanced by LH during Days 4-10 of culture.FSH had no effect on its own, but augmented the effect of LH. The addition of testosterone alone significantly stimulated oestradiol production even during the first 2 days. This effect of exogenous testosterone was greatly enhanced by FSH. It is concluded that the ability of the neonatal ovary to respond to LH by the eighth day post partum is acquired by an autonomous developmental process and is not dependent upon previous exposure to gonadotrophins and steroid hormones. However, once sensitivity to the gonadotrophin is attained, steroidogenesis is controlled by an interplay of gonadotrophins and steroid hormones. In contrast to LH, the ovaries are responsive to PGE z at birth.Introduction.

Development of Luteinizing Hormone Action in the Perinatal Rat Ovary1

“…Action of LH and production of testosterone start simultaneously in the testis on embryonic Day 15.5 [1,2]. In contrast, in the ovary the responsiveness to LH appears postnatally at the end of the first week of life [3][4][5][6][7] concomitantly with the onset of steroidogenesis [8][9][10]. Functional FSH receptors can be detected some days earlier in the perinatal rat ovary, at the age of 4-5 days [7,11].…”