hCG-induced loss of LH-hCG receptor and desensitization of adenylate cyclase.

hCG-induced loss of hCG (LH) receptors and desensitization of adenylate cyclase in the pseudopregnant rat ovary have been studied. At various time intervals after hCG treatment, the decrease in hCG-stimulated adenylate cyclase activity was closely related to the reduction in available hCG receptors. The hCG-induced desensitization of adenylate cyclase and a fall in hCG binding activity were also dose-dependent and directly correlated. There were no changes in the affinity of receptors binding and in the apparent Km for adenylate cyclase activation. These findings indicate that the loss of hCG receptors is associated with desensitization of adenylate cyclase following the hCG injection.