Demonstration and topographical distribution of LHRH receptors in the central nervous system in the normal and castrated male rat

The topographical distribution of [125I]-LHRH binding sites was studied on brain sections of adult male rat by quantitative autoradiography. High density of sites was observed in the hippocampus, amygdala and entorhinal cortex (4-7 fmol of LHRH bound/mg protein). Lower density of sites was observed in the septum and frontal cortex. The receptor density was not significantly modified at day 5 following castration. Under the same conditions the pituitary receptors were significantly increased. The presence of specific LHRH binding sites in the limbic system may explain the behavioural effect observed following intracerebroventricular injection of LHRH. However, their functions under physiological conditions remain to be elucidated.