CORRELATIONS BETWEEN THE HYPOTHALAMIC DENSITY OF H-3 CLONIDINE-BINDING SITES AND PLASMA TESTOSTERONE LEVELS IN MICE

Correlations between the specific binding of radiolabelled adrenoligan ds in frontal cortex and hypothalamus, and plasma testosterone levels were investigated in inbred mouse strains. Binding values were structu re and genotype dependent. There were significant negative intrastrain and interstrain correlations between hypothalamic binding of H-3-clon idine, an imidazoline with alpha(2)-adrenoceptor agonist specificity, and resting testosterone levels. Neither binding of the alpha(1)-adren oceptor antagonist H-3-prazosin nor of the beta-adrenoceptor antagonis t H-3-dihydroalprenolol (DHA) correlated significantly with hormone co ncentrations. The inverse correlation between hypothalamic H-3-clohidi ne-binding and plasma testosterone levels suggests a possible role of alpha(2)-adrenoceptors in the negative regulation of testosterone plas ma levels.