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Human chorionic gonadotropin binding sites in the human endometrium
S Bhattacharya1, J Banerjee, S Sen
1School of Life Science, Department of Zoology, Visva-Bharati University, Santiniketan, West Bengal, India.
Acta Endocrinologica
|July 1, 1993
Summary
Human endometrium contains specific binding sites for human chorionic gonadotropin (hCG). Zinc ions significantly enhance hCG binding, suggesting ovarian function influences this interaction.
Area of Science:
- Reproductive Endocrinology
- Gynecology
- Molecular Endocrinology
Background:
- Specific binding sites for luteinizing hormone (LH)/human chorionic gonadotropin (hCG) have been previously identified in the uteri of various animal species.
- The presence and characteristics of these binding sites in human endometrium remain less understood.
Purpose of the Study:
- To identify and characterize human chorionic gonadotropin (hCG) binding sites within the human endometrium.
- To investigate the influence of ovarian functional state (ovulatory vs. anovulatory) on hCG binding in the endometrium.
- To explore the effect of divalent metal ions on hCG binding to human endometrial tissue.
Main Methods:
- Human endometrial tissues were obtained from ovulatory and anovulatory women aged 35-42 years.
- Radioligand binding assays using [125I]hCG were performed on endometrial tissue preparations.
- Scatchard plot analysis was employed to determine binding affinity (dissociation constant) and capacity.
- The impact of various divalent metal ions (Zn2+, Mg2+, Mn2+, Ca2+) on [125I]hCG binding was assessed.
Main Results:
- Specific, high-affinity, low-capacity hCG binding sites were identified in human endometrium from both ovulatory and anovulatory women.
- Dissociation constants were similar in ovulatory (3.5 x 10(-10) mol/l) and anovulatory (3.1 x 10(-10) mol/l) women.
- Maximum binding capacity differed significantly, being lower in ovulatory (3.85 nmol/kg protein) versus anovulatory (6.12 nmol/kg protein) endometrium.
- Zinc ions (Zn2+) significantly increased [125I]hCG binding (p < 0.005), while manganese ions (Mn2+) showed a marginal increase; other ions had no effect.
Conclusions:
- The human endometrium possesses specific binding sites for hCG with characteristics of high affinity and low capacity.
- The functional state of the ovary appears to influence the binding capacity of hCG in the endometrium.
- Zinc ions play a significant role in modulating hCG binding to the human endometrium.