Concurrent LH and forskolin action on adenylate cyclase activation and progesterone synthesis in corpora lutea from pregnant ewes.

The present communication documents LH- and forskolin–-induced activation of adenylate cyclase (AC) system and progesterone synthesis in corpora lutea from pregnant ewes. The activation of AC in plasma membranes by LH or forskolin was amplified by Gpp(NH)p. These results suggest that regulatory nucleotide component (Ns) of the AC complex is required for full expression of the maximal response of ovine luteal AC to forskolin. Simultaneous addition of maximal concentrations of forskolin (10–4M), Gpp(NH)p (10–4M) and LH (10–7M) led to greater than additive (i.e. synergistic) responses: the experimental value was 4.71 ± 0.19 nmoles cAMP/mg of membrane protein, whereas the theoretical additive effect was 3.17 ± 0.10 nmoles/mg of membrane protein (p<0.001). These data reveal that more Ns or C component is being activated in these cells when combined treatments with these agents are applied.In intact cells maximum stimulatory concentrations of forskolin or LH caused similar increase in progesterone production wi...