Characterization and comparison of testicular LH/hCG receptors of rhesus monkeys (Macaca mulatta) and green monkeys (Cercopithecus aethiops)

Testicular luteinizing hormone (LH/hCG) receptors were characterized in seven green monkeys and compared with those of four rhesus monkeys. Testicular tissue showed high binding affinity for ¹²⁵I-hCG, (0.9–2.5 × 10⁹ M^?1, and 0.7–1.64 × 10⁹ M^?1 respectively, for green and rhesus monkeys) and low binding capacity (0.343–0.682 fmol/mg and 0.198–0.355 fmol/mg testicular homogenate, respectively). There was no difference in binding affinity between the two groups. Testicular LH/hCG receptors in both species bound human LH (hLH) and hCG but did not cross react with ovine LH (oLH). Rat testicular tissue showed similar high binding affinity (6.4 × 10⁹ M^?1) and low binding capacity (1.04 fmol/mg tissue homogenate) for ¹²⁵I-hCG. Rat LH/hCG receptors bound hLH, hCG, and oLH to a similar degree.