Conversion of progesterone to 5 alpha-pregnane-3,20-dione and 3 alpha-hydroxy-5 alpha-pregnan-20-one by rat medical basal hypothalami and the effects of estradiol and stage of estrous cycle on the conversion.

Abstract

Tissue slices of rat medial basal hypothalami (MBH’s) from various stages of estrous cycle were incubated with 3H-progesterone. Regardless of the stage of the estrous cycle, most of the recovered tissue radioactivity was present in the 1000 × g pellet after subcellular fractionation. The radioactivity associated with the 1000 × g pelletafter subcellular fractionation. The radioactivity associated with the 1000 X g pellet was isolated and identified on the basis of reverse isotopic dilution techhniques by purification to a constant specific activity. With all incubations the 2 major metabolites identified were 5α-pregnane-3,20-dione and 3αhydroxy- 5α-pregnan-20-one. Other metabolites of progesterone, if any, appear to be present in very small amounts (2–3%). Although no qualitative changes in metabolism of progesterone were observed with respect to the stage of the estrous cycle, quantitative variations were evident. Higher accumulations of 3H-5αpregnane- 3,20-dione as compared to 3H-3α-hydroxy- 5α-pregnan...