CHANGES IN PHYSICAL STATE OF OVARIAN MEMBRANES DURING PSEUDOPREGNANCYIN THE RAT

The role of the physical state of ovarian membranes was studied in imm ature rats after PMSG- and hCG-induced pseudopregnancy. Parallel chang es in LH/hCG receptors, progesterone secretion and rigidity of membran e lipids were observed during pseudopregnancy. Possible structure-func tional properties of the LH/hCG receptor were analyzed by the thermal perturbation technique. Thermal stability of the receptor was higher 5 days after hCG ovulatory injection to rats compared to days 11 or 18 and to control rats. Pseudopregnancy modified the quenching of protein fluorescence. The Stern-Volmer constants for controls and for rats on days 5, 11 and 18 of pseudopregnancy were found to be 2.4 and 4.6, 5. 1 and 4.4, respectively, indicating that accessibility of fluorophores for the quencher was increased.