Cyclic AMP in sheep ovarian follicles: site of production and response to gonadotrophins.

This study was undertaken (i) to establish a relationship between cyclic AMP (cAMP) production and the degree of LH and FSH stimulation; (ii) to determine the effects of various gonadotrophins on follicular formation of cAMP; and (iii) to identify the precise intrafollicular site of cAMP formation. The formation of cAMP increased rapidly in follicles exposed to LH. Maximum concentrations were reached after 90 min and were maintained for 180 min. Extracellular release of cAMP increased steadily throughout the 180-min experimental period. Tissue levels of cAMP increased proportionally and significantly when LH concentrations in the medium were increased from 0 to 200 mi.u. ml-1. Tissue levels of cAMP were significantly increased by HCG, prostaglandin E-2 and noradrenaline, but not by prolactin, prostaglandin F-2alpha, serotonin or melatonin. Cyclic AMP formation occurred predominantly in the thecal compartment; the membrana granulosa contributed less than 3% of the total amount of cAMP formed after gonadotrophic stimulation. A significant amount of cAMP from the thecal cells was released into the extracellular compartment and appeared to pass into the granulosa cells.