Age-related alterations in the central thermoregulatory responsiveness to alpha-MSH

• Published in: Journal of thermal biology 2015-04, Vol.49-50, p.9-15
• Main Authors: Rostás, I., Füredi, N., Tenk, J., Mikó, A., Solymár, M., Soós, S., Székely, M., Pétervári, E., Balaskó, M.
• Format: Article
• Language: English
• Subjects: Age Factors; Aging; Alpha-melanocyte-stimulating-hormone; alpha-MSH - administration & dosage; alpha-MSH - physiology; Animals; Body temperature; Body Temperature - drug effects; Body Temperature Regulation - drug effects; Eating - drug effects; Infusions, Intraventricular; Male; Oxygen consumption; Oxygen Consumption - drug effects; Rat; Rats; Rats, Wistar
• ISSN: 0306-4565; 1879-0992
• DOI: 10.1016/j.jtherbio.2015.01.004

Alpha-melanocyte-stimulating-hormone (alpha-MSH) is a neuropeptide that induces weight loss via its anorexigenic and hypermetabolic/hyperthermic effects. Two major public health problems of the human population involving energy balance (i.e. middle-aged obesity and aging cachexia) also appear in other mammals, therefore age-related regulatory alterations may also be assumed in the background. Previous studies demonstrated characteristic age-related shifts in the anorexigenic effects of centrally applied alpha-MSH with strong effects in young adult, diminished efficacy in middle-aged and very pronounced responsiveness in old rats. The present study aimed to investigate age-related changes in the acute central thermoregulatory responsiveness to an alpha-MSH injection in rats and to compare them with those of food intake-related responsiveness. Oxygen consumption (VO2), core (Tc) and tail skin temperatures (Ts, indicating heat loss) of male Wistar rats of different age groups (from 2 to 24 months of age), were recorded in an indirect calorimeter complemented by thermocouples upon intracerebroventricular alpha-MSH administration (0, 5µg) at a slightly subthermoneutral environment (25–26°C). Acute alpha-MSH-induced rises in VO2 and Tc were most pronounced in the young adult age-group. In these rats the hyperthemic effects were somewhat diminished by an activation of heat loss. Juvenile animals showed weaker hyperthermic responses, middle-aged rats none at all. Alpha-MSH-induced hyperthermia became significant again in old rats. Acute thermoregulatory (hypermetabolic/hyperthermic) responsiveness to alpha-MSH shows a distinct age-related pattern similar to that of acute anorexigenic responsiveness. Thus, our results may also contribute to the explanation of both middle-aged obesity and aging cachexia. •Acute central hyperthermic effects of alpha-MSH show characteristic shifts with aging.•Hyperthermic alpha-MSH effects decline in middle-aged and increase again in old rats.•These age-related changes may contribute to middle-aged obesity and aging sarcopenia.