Changes in alpha-melanocyte-stimulating hormone content in discrete hypothalamic areas of the male rat during a twenty-four-hour period.
Circadian variations in alpha-melanocyte-stimulating hormone (alpha-MSH) content of discrete hypothalamic areas of the male rat were observed either with radioimmunoassay or bioassay. In the medial basal hypothalamus and preoptic area the alpha-MSH content increased sharply between 02.00 and 06.00 h, showing the highest concentration at 06.00 h. In contrast, no significant changes in alpha-MSH content were detected in the lateral hypothalamus during a 24-hour period. Pituitary alpha-MSH also showed a diurnal variation which was different from that in the two hypothalamic areas. The finding that alpha-MSH values in the brain are maximal during the activity period of the rat is in agreement with results demonstrating a role of alpha-MSH in behaviour and locomotor activity.
Scimonelli
T
T
Instituto de Investigación Médica Mercedes y Martín Ferreyra, Cordoba, Argentina.
Celis
M E
ME
Eberle
A N
AN
D000818:Animals; D001681:Biological Assay; D002940:Circadian Rhythm; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D000521:alpha-MSH / Q000378:metabolism*
D000521:alpha-MSH