Combination of a GnRH agonist with an antagonist prevents flare-up effects and protects primordial ovarian follicles in the rat ovary from cisplatin-induced toxicity: a controlled experimental animal study.

BACKGROUND: With the continuous improvement of surgery and chemotherapeutic treatments, many tumour patients increasingly achieve long-term survival and can even be completely cured. However, platinum-containing drugs, which are widely used to treat a variety of types of cancer, cause menstrual disorders and ovarian failure, which in turn lead to infertility. Thus far, gonadotropin releasing hormone (GnRH) agonist (GnRHa) and antagonist (GnRHant) are reported to act as protective agents of the ovary in chemotherapy through the inhibition of the female gonadal axis. Nevertheless, they both have disadvantages that limit their use. GnRHa causes a flare-up effect during the first week after administration, and no long-acting GnRHant agent is available. GnRHa combined with GnRHant may prevent the flare-up effect of GnRHa and rapidly inhibit the female gonadal axis. Several clinical studies with small sample sizes have reported controversial conclusions. In this strictly controlled animal study, we investigated the advantages of combination treatment with GnRHa and GnRHant.

METHODS: Rats aged 12 weeks were divided into six groups: Control, cisplatin (CDDP), GnRHa, GnRHant, Combination (sht, short-term) and Combination (lng, long-term) of GnRHa and GnRHant. The last four groups received Triptorelin (1 mg/kg·d, for 14 days), Cetrorelix (0.5 mg/kg·d, for 10 days), a combination of Triptorelin (1 mg/kg·d, for 10 days) and Cetrorelix (0.5 mg/kg·d, for 10 days) in the long-term group and for 3 days in the short-term group. The Control and CDDP groups received saline (1 ml/kg·d, for 10 day). Then, all groups apart from the Control group received cisplatin (1 mg/kg·d, for 10 days), and the Control group received another 10 days of saline as described above. Blood samples were collected to detect the serum levels of E2, LH and FSH. Observation of oestrous cyclicity was also performed after drug administration. Finally, bilateral ovaries were collected for histological study and follicle counting.

RESULTS: We observed a flare-up effect in rats treated with GnRHa, but not in any of the combination groups. The percentage of normal cyclicity increased from 0% in the CDDP group to 25.0%, 33.3%, 66.7% and 41.7%, in the GnRHa, GnRHant, combination (lng) and combination (sht) groups, respectively. Pretreatment with GnRHa, GnRHant and combination (lng) significantly protected the primordial follicles from destruction by preserving 57.6%, 63.4%, 87.1% and 60.4% of the follicles, respectively.

CONCLUSIONS: The combination of a GnRH agonist with antagonist completely prevented the flare-up effect and enhanced the protective effect of the ovary from cisplatin-induced gonadotoxicity in rats.