Tsai-Morris C H, Ghosh M, Hirshfield A N, Wise P M, Brodie A M
Biol Reprod. 1983 Sep;29(2):342-6. doi: 10.1095/biolreprod29.2.342.
Ovarian aromatase activity was inhibited by prolactin treatment in both cycling rats and immature gonadotropin-primed animals. Cycling rats were injected s.c. with prolactin (4 mg/kg BW) beginning on diestrus 1. Aromatase activity in the largest follicles on diestrus 2 and on proestrus was reduced relative to controls. None of the prolactin-treated animals had ovulated when examined on the expected estrus morning. In other experiments, the immature pregnant mare's serum gonadotropin (PMSG)-primed rat was used as a model for the cycling rat. Microsomal aromatase activity but not the activity of the C17-21 lyase was reduced in ovaries of animals injected with prolactin [6 IU (200 micrograms)/rat] 48 h after PMSG administration and sacrificed 4 h later. Furthermore, aromatase activity was significantly increased when endogenous prolactin was inhibited by bromocryptine (CB-154). The effect of LH treatment, on the other hand, was to increase both aromatase and lyase activities. However, prolactin pretreatment did not consistently prevent the LH-induced increase in aromatase activity. The results suggest that inhibition of ovulation by prolactin is mediated, at least in part, by direct inhibition of aromatase activity.
在性周期大鼠和未成熟促性腺激素预处理动物中，催乳素处理均可抑制卵巢芳香化酶活性。从动情间期1开始，对性周期大鼠皮下注射催乳素（4 mg/kg体重）。与对照组相比，动情间期2和动情前期最大卵泡中的芳香化酶活性降低。在预期的发情日早晨检查时，接受催乳素处理的动物均未排卵。在其他实验中，将未成熟的孕马血清促性腺激素（PMSG）预处理大鼠用作性周期大鼠的模型。在给予PMSG 48小时后注射催乳素[6 IU（200微克）/只大鼠]并在4小时后处死的动物卵巢中，微粒体芳香化酶活性降低，但17 - 21碳链裂解酶活性未降低。此外，当用溴隐亭（CB - 154）抑制内源性催乳素时，芳香化酶活性显著增加。另一方面，促黄体生成素（LH）处理的作用是增加芳香化酶和碳链裂解酶的活性。然而，催乳素预处理并不能始终阻止LH诱导的芳香化酶活性增加。结果表明，催乳素对排卵的抑制作用至少部分是通过直接抑制芳香化酶活性介导的。
