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The Inhibition of Binding of Iodinated Human Chorionic Gonadotropin to Mouse Ovary in Vivo1

1972; Oxford University Press; Volume: 90; Issue: 2 Linguagem: Inglês

10.1210/endo-90-2-384

1945-7170

Sandra Kammerman, ROBERT E. ANFIELD,

Reproductive Physiology in Livestock

An in vivo system to study the uptake of human chorionic gonadotropin (HCG) by mouse ovaries has been developed. At various times following the injection of biologically active, radioiodinated HCG, the specific activity of various tissue specimens was measured and found to be significantly greater in ovaries than in blood, liver, or kidney. In contrast, 125I-albumin was not specifically concentrated by the ovary. The ovarian uptake of 125I-HCG has also been measured after the administration of 125I-HCG in combination with gonadotropin molecules or their derivatives. Increasing amounts of biologically active, unlabeled HCG injected with iodinated HCG progressively inhibited the uptake of 125I-HCG. Human luteinizing hormone (HLH) was also a potent competitor of 125I-HCG uptake. Asialo- HCG was less effective than native HCG in blocking the uptake of 125I-HCG. The beta subunit of HCG possessed some inhibitory effect on 125IHCG binding, but the alpha subunit had little if any effect. It is probable that some of these results with HLH and the HCG derivatives are secondary to variations in the plasma half-life of these molecules. (Endocrinology90: 384, 1972)