Analysis of the hypothalamic-pituitary-ovary axis in the neonatally-androgenized female rat.

The administration of testosterone propionate (TP) in the female rat at the neonatal age has been used for several yr as a model to study anovulation during adulthood. The present work was designed in order to see whether some neuroendocrine parameters vary with age in this animal model. Hypothalamic LHRH content and LH-FSH anterior pituitary (AP) content and plasma levels were evaluated in samples taken from both neonatally-androgenized and littermate control female rats at different ages (15 to 100 days old). Additionally, we have studied pulsatile LH-FSH released in plasma and in vivo AP response to LHRH in both neonatally-androgenized and control female rats during adulthood. The results indicate that the neonatal TP treatment did not induce any change in hypothalamic LHRH content over development. Neonatally androgenized rats have decreased both LH-FSH AP content and plasma levels at the infantile age (15-day old). LH-FSH AP content remained reduced in samples taken up to the 30th day of age. Plasma LH-FSH levels on the day 30 of age were similar in both groups. TP-treated rats studied on the 100th day of age had: a) an altered pulsatile rhythm of gonadotropin release in plasma due to the decreased LH-FSH trough and average mean values, and to the diminished FSH peak amplitude values, as well as an increased LH:FSH ratio; and b) an impaired in vivo LHRH-induced LH-FSH release.(ABSTRACT TRUNCATED AT 250 WORDS)