title: Age-related alterations in the central thermoregulatory responsiveness to alpha-MSH.
abstract: 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, 5 µg) 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.
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary.
authors.forename: I
authors.initials: I
authors.lastname: Rostás
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary.
authors.forename: N
authors.initials: N
authors.lastname: Füredi
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary.
authors.forename: J
authors.initials: J
authors.lastname: Tenk
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary.
authors.forename: A
authors.initials: A
authors.lastname: Mikó
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary.
authors.forename: M
authors.initials: M
authors.lastname: Solymár
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary.
authors.forename: S
authors.initials: S
authors.lastname: Soós
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary.
authors.forename: M
authors.initials: M
authors.lastname: Székely
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary.
authors.forename: E
authors.initials: E
authors.lastname: Pétervári
authors.affiliation: Department of Pathophysiology and Gerontology, Medical School, University of Pécs, 12 Szigeti Str., H-7624 Pécs, Hungary. Electronic address: marta.balasko@aok.pte.hu.
authors.forename: M
authors.initials: M
authors.lastname: Balaskó
mesh_terms: D000367:Age Factors; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D057967:Infusions, Intraventricular; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D000521:alpha-MSH / Q000008:administration & dosage / Q000502:physiology*
chemical_list: D000521:alpha-MSH
keywords: Aging; Alpha-melanocyte-stimulating-hormone; Body temperature; Oxygen consumption; Rat