[Effects of gonadotropin releasing hormone analogues on chemotherapy-induced ovarian function damage in rats].
OBJECTIVE
To investigate the effects of gonadotropin releasing hormone agonist (GnRH-a) and antagonist (GnRH-ant) on cyclophosphamide (CTX)-induced ovarian damage in rats.


METHODS
Seventy-two Sprague-Dawley female rats were divided randomly into six groups, which received normal saline (NS), CTX, GnRH-a + NS, GnRH-a + CTX, GnRH-ant + NS, and GnRH-ant + CTX respectively. Levels of serum follicle-stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E(2)) were measured successively by the enzyme-linked immunosorbent assay method, and half of the rats were killed in the first week and between the fourth and the fifth week after stop of medication, respectively to compare the weight of the ovaries and the number of the primordial follicles and the growth follicles.


RESULTS
(1) Throughout experiment, the serum levels of FSH, LH and E(2) of the control group fluctuated slightly, while those in the CTX group kept rising. During medication treatment, compared with the control group [(118 +/- 16) microg/L, (350 +/- 35) microg/L] and the CTX group [(113 +/- 15) microg/L, (289 +/- 42) microg/L], the concentrations of LH [(42 +/- 8) - (47 +/- 7) microg/L, (31 +/- 5) - (36 +/- 7) microg/L] and FSH [(124 +/- 45) - (136 +/- 32) microg/L, (178 +/- 54) - (198 +/- 27) microg/L] in the GnRH-a groups and the GnRH-ant groups were maintained at low levels significantly and the levels of LH in the GnRH-ant groups were significantly lower than that in the GnRH-a groups, but the levels of FSH in the GnRH-ant groups were significantly higher than that in the GnRH-a groups (P < 0.05); and extremely different from the GnRH-a groups [(0.98 +/- 0.18) - (1.46 +/- 0.22) ng/L], the level of E(2) of the GnRH-ant groups [(3.58 +/- 0.43) - (3.98 +/- 0.74) ng/L] did not significantly decrease (P < 0.01). After stop of therapy, the concentrations of LH, FSH and E(2) in the GnRH-a groups and the GnRH-ant + NS group rose gradually and were similar to the levels of the control group (P > 0.05), but the levels of FSH, LH and E(2) of the GnRH-ant + CTX group rose obviously and were similar to the levels of the CTX group, especially the FSH , and the levels of LH and FSH of the GnRH-ant + CTX group [(156 +/- 12) microg/L, (520 +/- 44) microg/L] and the CTX group [(178 +/- 18) microg/L, (546 +/- 36) microg/L] were significantly higher than that of the other four groups [(121 +/- 15) - (132 +/- 13) microg/L, (335 +/- 35) - (359 +/- 26) microg/L] at the 4(th) - 5(th) week after stop of treatment (P < 0.05). (2) At the 1(st) week after stopping therapy, the GnRH-a + NS group [(12 +/- 5) mg/100 g]and the GnRH-a + CTX group [(18 +/- 8) mg/100 g] had the lowest weight of ovaries which was significantly different from the other groups [(30 +/- 9) - (37 +/- 8) mg/100 g, P < 0.05]. At the 4(th) - 5(th) week after stopping therapy, the GnRH-ant + CTX group [(22 +/- 6) mg/100 g] and the CTX group [(20 +/- 4) mg/100 g] had the lowest weight of ovaries which were significantly different from the other groups [(29 +/- 5) - (31 +/- 9) mg/100 g, P < 0.05]. (3) At the 1(st) week after stopping therapy, there were the largest number of primordial follicles [(824 +/- 45), (689 +/- 39)] and the lowest number of growth follicles [(15 +/- 1), (21 +/- 3)] in the GnRH-a + NS group and the GnRH-a + CTX group, but there were the lowest number of primordial follicles [(255 +/- 24), (343 +/- 29)] and the largest number of growth follicles [(110 +/- 21), (87 +/- 17)] in the GnRH-ant + CTX group and the CTX group. At the 4(th) - 5(th) week after stopping therapy, the number of growth follicles in the GnRH-a + NS group (58 +/- 11) and the GnRH-a + CTX group (56 +/- 16) recovered to almost the level of the control group (57 +/- 9, P > 0.05), but the number of all kinds of follicles declined significantly in the GnRH-ant + CTX group [(195 +/- 15), (36 +/- 12)] and the CTX group [(212 +/- 11), (36 +/- 9)] compared to the other four groups [(302 +/- 15) - (690 +/- 43), (44 +/- 12) - (58 +/- 11), P < 0.05].


CONCLUSIONS
In rat model, GnRH-a prevents the ovarian function damage induced by CTX, but GnRH-ant does not show similar protective effect.
Peng
Ping
P
Department of Obstetrics and Gynecology, Second Affiliated Hospital, SUN Yat-sen University, Guangzhou 510120, China.
Yang
Dong-zi
DZ
Zheng
Cheng-yu
CY
Mo
Ya-qin
YQ
He
Ying-ming
YM
Zhang
Qing-xue
QX
D000818:Animals; D015415:Biomarkers / Q000097:blood*; D003520:Cyclophosphamide; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists* / Q000037:antagonists & inhibitors*; D007986:Luteinizing Hormone / Q000097:blood; D006080:Ovarian Follicle / Q000187:drug effects / Q000503:physiopathology; D010053:Ovary / Q000187:drug effects / Q000503:physiopathology*; D010902:Pituitary Gland / Q000187:drug effects / Q000503:physiopathology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D015415:Biomarkers; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D003520:Cyclophosphamide; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone