Goto K, Kotsuji F, Tominaga T
Department of Obstetrics and Gynecology, Fukui Medical School, Japan.
J Endocrinol. 1995 Jun;145(3):501-11. doi: 10.1677/joe.0.1450501.
The effects of gonadotrophin-releasing hormone analogue (GnRHa; buserelin) on the pituitary function and morphology of food-restricted rats were compared with those of authentic GnRH. After adult female rats had been restricted to 10 g food/day for 60 days, various doses of GnRHa (10 ng, 100 ng and 1 microgram) or GnRH (10 micrograms) were administered either daily for 7 days or twice a week for 4 weeks from day 61 of the period of underfeeding. Underfeeding brought about a decrease in the pituitary gonadotrophin content, serum levels of gonadotrophins and oestradiol, and the number and size of both LH- and FSH-positive pituitary cells. Daily and/or twice-weekly administration of authentic GnRH to underfed rats produced an increase in pituitary and serum gonadotrophin levels and the number and size of both LH- and FSH-positive pituitary cells. The administration of GnRHa daily for 7 days increased serum gonadotrophin levels, while it produced a reduction in the pituitary gonadotrophin content and number and size of both LH- and FSH-positive pituitary cells in a dose-dependent manner. Twice-weekly administration of GnRHa also produced an elevation of serum gonadotrophin levels and reduction of pituitary gonadotrophin content, although it did not affect the numbers and areas of LH- and FSH-positive pituitary cells. A GnRH loading test performed after the GnRHa treatment showed that the GnRHa treatment performed in this study did not produce down-regulation of the GnRH receptor. Thus, it can be concluded that the gonadotrophin-synthesizing activity of GnRHa is weaker than that of authentic GnRH, or that GnRHa may preferentially exert gonadotrophin-releasing activity rather than gonadotrophin-synthesizing activity in the anterior pituitary of underfed rats.
将促性腺激素释放激素类似物（GnRHa；布舍瑞林）对限食大鼠垂体功能和形态的影响与天然促性腺激素释放激素（GnRH）的影响进行了比较。成年雌性大鼠在60天内每天限食至10克，从限食期的第61天起，每日给予不同剂量的GnRHa（10纳克、100纳克和1微克）或GnRH（10微克），持续7天，或每周两次，持续4周。限食导致垂体促性腺激素含量、血清促性腺激素和雌二醇水平降低，以及促黄体生成素（LH）和促卵泡生成素（FSH）阳性垂体细胞的数量和大小减少。对限食大鼠每日和/或每周两次给予天然GnRH，可使垂体和血清促性腺激素水平升高，以及LH和FSH阳性垂体细胞的数量和大小增加。每日给予GnRHa 7天可使血清促性腺激素水平升高，同时以剂量依赖的方式使垂体促性腺激素含量以及LH和FSH阳性垂体细胞的数量和大小减少。每周两次给予GnRHa也可使血清促性腺激素水平升高，垂体促性腺激素含量降低，尽管它不影响LH和FSH阳性垂体细胞的数量和面积。在GnRHa治疗后进行的GnRH负荷试验表明，本研究中进行的GnRHa治疗未导致GnRH受体下调。因此，可以得出结论，GnRHa的促性腺激素合成活性弱于天然GnRH，或者GnRHa可能在限食大鼠的垂体前叶中优先发挥促性腺激素释放活性而非促性腺激素合成活性。
