Suppression of food intake by intracerebroventricular injection of alpha-MSH varies with age in rats (Short communication)

Pétervári, E. and Balaskó, M. and Garami, András and Soós, Sz. and Székely, M. (2009) Suppression of food intake by intracerebroventricular injection of alpha-MSH varies with age in rats (Short communication). Acta Physiologica Hungarica, 96 (4). pp. 483-487. ISSN 0231-424X

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Abstract

During the aging process of mammals first a phase of obesity and increased adiposity is observed in middle-aged subjects, then anorexia and loss of body weight (sarcopenia) at old age. A possible agedependence of the anorexigenic alpha-melanocyte-stimulating-hormone (alpha-MSH) in these regulatory changes was studied. Male Wistar rats aged 6–8 weeks (juvenile), 3–4 months (young adult), 6 and 12 months (middle-aged), and 24–26 months (old) were equipped with chronic cannula to the lateral cerebral ventricle. The effect of 5 μg alpha-MSH injected through the cannula was analyzed on food intake evoked by 24-h food deprivation. Juvenile rats seemed almost resistant to alpha-MSH (21.9% suppression). In young adults alpha-MSH suppressed food intake by 68.7%. However, the alpha-MSH-induced anorexia was significantly less pronounced in middle-aged (55.7% or 26.4% in rats aged 6 or 12 months, respectively), and much more pronounced (73.3%) in old rats. The adiposity (judged by the relative amount of perirenal fat) increased until middle-age, but did not change between middle-age and old-age. It is concluded that changes in alpha-MSH responsiveness possibly contribute to both the age-related obesity in middle-aged rats and to the anorexia of old ones: first the adiposity then the age may be the important factor.

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