Production of oestradiol, camp and 125I-hcg binding by rat ovaries during the reproductive cycle.

Plasma concentration of oestradiol in female rats is dynamically altered in the reproductive cycle, depending on the biosynthesis and secretion of oestradiol secretion by the ovaries. The present study has followed oestradiol and cAMP concentration in the plasma and ovaries, and 125I-HCG binding during the pro-oestrus, oestrus and di-oestrus. Oestradiol concentration in plasma and its production by the ovaries were found to be highest in the pro-oestrus and lowest in the oestrus. These changes depend on the production and secretion of gonadotrophins. The mediator of gonadotropin action is cAMP whose ovarian concentration is lowest in the oestrus. LH stimulates the cAMP synthesis in the ovaries during the cyclic stages, without any significant difference being apparent between the various stages. 125I-HCG binding is highest in the di-oestrus stage, when concentration of endogenous gonadotrophins is low.