Regulation of LH/HCG receptors during the ovarian cycle in rats

The number of LH/HCG receptors varied during the ovarian cycle. Most 125I-HCG was bound in the diestrous II stage, least amounts of free binding sites were detectable in estrous. Bromocriptine, an inhibitor of prolactin secretion, suppressed the cyclic variations in free LH/HCG receptors. From this finding it is concluded that LH/HCG receptors of the corpus luteum of the cycle are occupied by LH just once and then degraded. The variations in the number of free LH/HCG receptors are probably due to the synthesis and degradation of only luteal receptors.