Molecular and Neuroendocrine Determinants of Seasonal Body Weight Regulation

This thesis deals with the characterisation of neuroendocrine pathways involved in seasonal body regulation revealed by the Siberian hamster (Phodopus sungorus). In the neuronal centre of body weight regulation, the hypothalamus, central signal transduction of the "adiposity signals" lepti...

Ausführliche Beschreibung

Gespeichert in:
1. Verfasser: Tups, Alexander
Beteiligte: Klingenspor, Martin (Dr.) (BetreuerIn (Doktorarbeit))
Format: Dissertation
Sprache:Deutsch
Veröffentlicht: Philipps-Universität Marburg 2005
Biologie
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Zusammenfassung:This thesis deals with the characterisation of neuroendocrine pathways involved in seasonal body regulation revealed by the Siberian hamster (Phodopus sungorus). In the neuronal centre of body weight regulation, the hypothalamus, central signal transduction of the "adiposity signals" leptin and insulin (both inhibit food intake) and of the food intake stimulating hormone ghrelin was investigated comprehensively. Another aim of this thesis was the identification of the molecular identity underlying the phenomenon of leptin resistance, a key event in the onset of obesity. Furthermore, possible convergence of central leptin- and insulin signalling pathways was investigated. The hypothalamic signal transduction of both hormones was strikingly seasonally regulated implying a central role of these humoral signals in mediating seasonal body weight changes. The molecular identity of seasonally induced leptin resistance could be unravelled: It is caused by modulation of the signal transduction cascade distal to the leptin receptor. Moreover, the results of this thesis contradict to the popular opinion of possible synergistic effects conveyed by the anorexigenic hormones leptin and insulin which are related to their hypothalamic signalling. Ghrelin and its central signalling by the ghrelin receptor is very likely responsible for the acute regulation of food intake whereas it does not act on chronic changes in energy homeostasis (seasonal body weight cycles).