Some Biological Properties of Human Chorionic Follicle Stimulating Hormone

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Abstract
The biological properties of human chorionic follicle stimulating hormone (hCFSH) for rat ovaries were investigated. Highly purified hCFSH behaved in the ovarian augmentation test like bovine FSH and significantly enhanced 3H-thymidine uptake by granulosa and theca cells in the ovary of the hypophysectomized rat. In contrast, highly purified hCG (human chorionic gonadotropin) had little effect in the ovarian augmentation test and had no effect on 3H-thymidine uptake by the ovary. hCFSH may promote ovarian follicular growth resulting from granulosa cell proliferation and enlargement. Freshly harvested porcine granulosa cells were employed in an in vitro system to investigate specific binding of hCFSH to the ovarian receptor. 125-hCFSH and 125I-hCG were incubated with cell suspensions. Binding of these hormone preparations was proportional to the cell number and increased with the time of incubation through 120 min. The binding of 125I-hCFSH to the cells was greater than that of 125I-hCG. Increasing concentrations of unlabeled hCFSH in the incubation mixture progressively inhibited the uptake of 125I-hCFSH by granulosa cells. Unlabeled hCG was not able to compete with 125I-hCFSH binding. A similar inhibition of the binding of 125I-hCG to the cells was also seen in the presence of unlabeled hCG. The granulosa cell has at least 2 different types of receptor sites: one for hCFSH and the other for hCG.