PGF2α-induced loss of corpus luteum gonadotrophin receptors |
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Authors: | Martin Hichens Daniel L. Grinwich Harold R. Behrman |
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Affiliation: | Department of Reproductive Biology Merck Institute for Therapeutic Research Rahway, New Jersey 07065 USA |
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Abstract: | In experiments and we have previously shown that PGF2α directly antagonized the action of gonadotrophins on the corpus luteum. To determine if this action of PGF2α may occur as a consequence of an induced loss of gonadotrophin receptors, binding of hCG to rat luteal tissue was measured following PGF2α treatment . In immature rats which were treated with exogenous gonadotrophin to luteinize the gonads, PGF2α produced a marked and highly significant decrease in circulating progesterone when administered 24 hours before sacrifice. Although the affinity constant (Ka; 1.2-2 × 1010 L/M) of the luteal receptor to hCG was not affected, PGF2α treatment produced a marked fall in the binding capacity of the luteal tissue to hCG. This response was absent, however, when PGF2α was incubated directly with luteal receptor or administered during early pseudopregnancy when corpora lutea are more resistant to luteolysis. Experiments are in progress to determine if the decrease in capacity of luteal receptors to bind hCG is the mechanism or a consequence of luteolysis produced by PGF2α. |
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