The gonadotrophin-enhancing effect of RCF-2 (prepared from aqueous extracts of rat cerebral tissue) was evaluated in several species of laboratory animals. RCF-2 alone did not induce any discernible gonadal response. Superovulation in immature rats treated with pregnant mare serum (PMS) or a combination of PMS and human chorionic gonadotrophin (HCG) was significantly increased by RCF-2. Ovulation in intact PMS-treated rats was increased to 84–127% above the response of controls. Hypophysectomized or intact rats treated with PMS + HCG shed 34–53% more ova when they were treated with 0·2 mg. RCF-2.
An almost maximal uterine weight response was found in immature mice treated with RCF-2 in combination with subminimally effective doses of HCG. RCF-2 neither induced ovulation in post-partum rabbits nor in PMS-treated rats in which the release of luteinizing hormone was blocked. The results of these studies suggest that fraction RCF-2 does not act centrally to evoke a release of gonadotrophins but probably has a direct ovarian effect.