The dynamics of progesterone output in perifused granulosa layer of the Japanese quail (Coturnix coturnix japonica): response to adenosine 3',5'-cyclic monophosphate and aminoglutethimide.
A perifusion system has been developed in which the rates of progesterone output of quail granulosa layer in response to steroidogenic stimuli, can be measured under dynamic condition. In response to a continuous perifusion for 8 h with dibutyryl cyclic AMP (dbcAMP), there was a gradual increase in the rate of progesterone output, which reached a plateau at 4-5 h of perifusion. When progesterone output was inhibited by aminoglutethimide, a reversible inhibitor of the cholesterol side chain cleavage reaction, dbcAMP caused the accumulation of cholesterol in mitochondria. The rate of progesterone output after the release of inhibition was much faster when the tissue had been stimulated with dbcAMP during the inhibition. This indicates that dbcAMP stimulates progesterone production by increasing the steroidogenic cholesterol in mitochondria. However, the resumption of progesterone output after the release of inhibition was not observed unless the tissue was again stimulated with dbcAMP. This indicates that the mitochondrial cholesterol is not readily available for the cholesterol side chain cleavage enzyme, and there is another step of stimulation of dbcAMP for progesterone output of quail granulosa layer.