Mendoza M E, Menjívar M, Garza-Flores J, Romano M C
Departamento de Fisiología, Biofisica y Neurociencias, Centro de Investigación y de Estudios Avanzados del I.P.N., México, D.F., Mexico.
J Steroid Biochem Mol Biol. 1993 Nov;46(5):579-83. doi: 10.1016/0960-0760(93)90185-y.
The short term effects of norethisterone (NET), progesterone (P), estradiol (E2) and dihydrotestosterone (DHT) on the gonadotropin secretion of pituitary cells, from both male and female rats, in primary culture primed with E2 were studied. In female cells, NET only increased the GnRH-induced secretion of LH, while P increased both LH and FSH. Male pituitary cells showed an increased response to GnRH after P pretreatment only if the E2 concentration was augmented. However with the same E2 conditions pretreatment with NET decreased the stimulated LH, but not FSH secretion. Pretreatment with E2 inhibited LH stimulated secretion from pituitary cells of male but not female rats. Furthermore DHT treatment diminished the GnRH response for both LH and FSH in pituitary cells from both sexes. Androgen pretreatment increased basal gonadotropin secretion in male but not in female cells. Basal FSH secretion was increased by NET pretreatment in male cells. This suggests that NET is metabolized by cultured pituitary cells to A-ring reduced compounds during the 4 h incubation period. The formation of NET metabolites, particularly the 3 beta, 5 alpha and 5 alpha-NET might be responsible for the estrogenic and androgenic effects observed when NET was administered to the cultured pituitary cells.
研究了炔诺酮（NET）、孕酮（P）、雌二醇（E2）和双氢睾酮（DHT）对原代培养的、用E2预处理的雄性和雌性大鼠垂体细胞促性腺激素分泌的短期影响。在雌性细胞中，NET仅增加GnRH诱导的LH分泌，而P增加LH和FSH分泌。仅当E2浓度增加时，雄性垂体细胞在P预处理后对GnRH的反应才增强。然而，在相同的E2条件下，NET预处理会降低刺激的LH分泌，但不会降低FSH分泌。E2预处理抑制了雄性而非雌性大鼠垂体细胞中LH刺激的分泌。此外，DHT处理降低了两性垂体细胞中LH和FSH对GnRH的反应。雄激素预处理增加了雄性而非雌性细胞中的基础促性腺激素分泌。NET预处理增加了雄性细胞中的基础FSH分泌。这表明在4小时的孵育期内，NET被培养的垂体细胞代谢为A环还原化合物。NET代谢产物的形成，特别是3β、5α和5α-NET，可能是将NET施用于培养的垂体细胞时观察到的雌激素和雄激素作用的原因。
