The effect of hypothalamic lesions on immuno‐reactive alpha‐melanocyte stimulating hormone secretion in the rat.

Publisher Website
Google Scholar
Abstract
The hypothesis that MSH [melanocyte stimulating hormone] secretion in the rat is under a tonic inhibitory control by the CNS. Electrothermic lesions were made in the medio-basal hypothalamus (m.b.h.) which destroyed the hypothalamo-hypophyseal connexions. Plasma and pituitary .alpha.-MSH were measured using a sensitive and specific radioimmunoassay technique. Pituitary .alpha.-MSH content decreased to 17% of control levels 24 h after the lesion and returned to normal by 7 days. Plasma .alpha.-MSH was maximally elevated 15 min after the lesion, and returned to normal by 2 h. No further change over control levels was found for the remainder of the experiment (98 days). The similarity of the plasma .alpha.-MSH response after m.b.h. lesions to that found previously after administration of long acting dopamine receptor blocking drugs suggests that these lesions may interrupt impulse flow in dopaminergic tubero hypophyseal neurons which are thought to be important in the inhibitory control of MSH secretion in the rat. The rat pituitary, unlike that of lower vertebrates, is evidently able to re-establish basal MSH secretion very quickly after disconnexion from central control.