CYTOCHROME-P-450 LEVELS OF IMMATURE RAT OVARIES DURING EARLY FOLLICULAR DEVELOPMENT - QUANTIFICATION, CELLULAR AND SUBCELLULAR-DISTRIBUTION, ENZYMATIC-ACTIVITY AND RESPONSE TO FSH IN-VIVO AND IN-VITRO

Absolute values of cytochrome P-450 (cyt. P-450) content were determin ed by dual beam spectrophotometry in mitochondrial and microsomal frac tions of granulosa cells and stroma (theca and interstitial cells) obt ained from ovaries of immature rats treated with diethylstilbestrol (D ES) or with DES and FSH. Cholesterol side-chain cleavage activity and aromatase activity were also measured in relevant cell fractions. The cyt. P-450 content in the granulosa cell mitochondria was significantl y increased in FSH-treated animals (cyt.P-450 in nmols /mg protein, me an +/- SE: DES-treated 0.027+/- 0.00213, N=9; DES/FSH-treated 0.0668+/ -0.0120, N=13, P=0.014). The increased cyt. P-450 content was associat ed with an increase in cholesterol side-chain cleavage activity confir ming the functional relevance of the spectrophotometric measurements. The increase in cyt. P-450 content in stroma after FSH treatment was n ot statistically significant but there was a significant increase in c holesterol side-chain cleavage activity. The cholesterol side-chain cl eavage activity of intact granulosa cells from secondary follicles of DES-treated rats was significantly stimulated by in vitro exposure to FSH during 2 hr assay incubations. A significant cyt. P-450 content wa s detected in the microsomal fraction of granulosa cells from DES-trea ted rats which was not associated with aromatase activity. Granulosa c ell microsomal cyt. P-450 content was not significantly altered by in vivo FSH treatment despite a dramatic increase in aromatase activity o f such microsomal preparations.