Abstract:
Objectives To investigate the protective effect and mechanism of a gonadotropin-releasing hormone antagonist (GnRH-ant) against an ovarian function injury induced by pelvic radiotherapy in a rat model.
Method 1. Ten female Wistar rats were randomly assigned to gonadotropin-releasing hormone agonist (GnRH-a) and GnRH-ant groups using the random number table method. The rats were subcutaneously injected with goserelin (0.25 mg once) or cetrorelix (5 μg/day for 10 days). Changes in luteinizing hormone (LH) and estradiol (E2) in each group were dynamically observed. 2. Forty female Wistar rats were randomly divided into four groups (control, GnRH-ant, R, and GnRH-ant+R) and then given corresponding treatments. Ovarian wet weight, levels of serum LH, E2, and AMH, and the number of follicles at every stage were compared between groups through analysis of variance and independent sample t-test.
Results1. In the GnRH-a group, LH and E2 levels increased initially and then gradually decreased, reaching a low value in approximately 10 d. In the GnRH-ant group, LH and E2 levels decreased rapidly, reaching the minimum value in 4 d without flare-up effect. 2. After pelvic radiotherapy, the ovarian wet weight in the GnRH-ant+R group was significantly higher(58.3±9.1) mg vs. (37.8±7.1) mg, t=5.61, P=0.000 than that in group R. In the GnRH-ant+R group, the levels of E2(57.49±13.45) pg/mL vs. (16.64±6.54) pg/mL, t=8.64, P=0.000 and AMH(5.47±1.32) mIU/mL vs. (2.23±0.72) mIU/mL, t=6.81, P=0.000 were significantly higher than those in group R. The FSH level in GnRH-ant+R group was significantly lower(27.74±7.75) mIU/mL vs. (8.35±1.43) mIU/mL, t=7.75, P=0.000 than that in group R. The number of primordial and primary follicles in group GnRH-ant+R was significantly higher (46.2±12.3 vs. 27.6±5.1, t=4.42, P=0.000) than that in group R.
Conclusions GnRH-ant can rapidly induce ovarian inhibition without flare-up effect. Subcutaneous injection of GnRH-ant before pelvic radiotherapy can inhibit the ovary and stop the follicles in the primary and primordial follicle stages, thus reducing the damage induced by radiotherapy.