Age-Related Changes in FSH- and in LH-Sensitive Ovarian Adenyl Cyclase from Prepubertal Rats[*]

Abstract

FSH and LH stimulate adenyl cyclase (AC) activity in ovarian homogenates from 14 to 31-day-old rats. In presence of maximally active concentrations of LH, AC activity is maximal at 16-19 days of life and then decreases. In presence of maximally active concentrations of FSH, AC activity is relatively low in 14 to 16-day-old rats and then rises until a maximal value observed in 19 to 23-day-old rats. At this age the stimulation of the basal AC activity is higher with FSH (6 ×) than with LH (3 ×). Almost total additivity of the maximal actions of FSH and LH is observed in 16 to 18-day-old rats; in older animals, when FSH is highly active, there is only a partial or no additivity. Concentrations of pure hormones giving half maximal stimulation are smaller for FSH than for LH.

These results suggest that FSH, like LH, exerts at least some of its physiological effects by the intermediary of 3'5' cyclic AMP. They indicate that physiological changes at the level of receptor-adenyl cyclase systems can be important in regulating the response of target glands to stimulating hormones.

Key words

Adenyl Cyclase - Age - Development - Gonadotropins - FSH - LH - Ovary

1 Aided in part by a grant (72-7-0044) from DGRST (France).

1 Aided in part by a grant (72-7-0044) from DGRST (France).