Zentrale Regulation der Nahrungsaufnahme

Zusammenfassung

Die zentrale Regulation der Nahrungsaufnahme beruht auf der Verarbeitung von peripheren Signalen in einem Netzwerk unterschiedlicher Hirnareale. Dabei werden die in Relation zur Nahrungsaufnahme eintreffenden Signale subjektiv bewertet und führen zu adäquaten Reaktionen auf der Basis von früheren Erfahrungen und unter Berücksichtigung der momentanen Situation. Hypothalamische Kerngebiete wie der Nucleus arcuatus (ARC), der Nucleus paraventricularis (PVN) und der laterale Hypothalamus (LHA), aber auch der Nucleus tractus solitarii (NTS), die Area postrema (AP) und der Nucleus parabrachialis im Hirnstamm sowie die Amygdala, der Nucleus accumbens und mehrere andere Hirnareale sind an der Informationsverarbeitung beteiligt. Die übergeordnete Steuerung aller Prozesse und die Einleitung der bewussten Verhaltensreaktionen erfolgen durch die Hirnrinde. Die Information gelangt in das zentrale Netzwerk zum Teil über autonome, afferente Nerven, die im NTS umgeschaltet werden. Humorale Signale mit Bezug zur Nahrungsaufnahme werden durch die Chemosensoren der AP und im hypothalamischen ARC registriert. Insbesondere die anabolen (Neuropeptid Y und Agouti-related peptide) und katabolen Neuropeptidsysteme (Pro-opio-melanocortin, Cocaine und amphetamine-regulated transcript), welche den ARC mit dem PVN und dem LHA verbinden, wurden in den letzen Jahren gut charakterisiert. Diese Neuropeptidsysteme vermitteln die Effekte des Fettgewebshormons Leptin auf Nahrungsaufnahme und Energieabgabe, sie reagieren aber auch auf andere Hormone, Metabolite und Monoamine wie Serotonin. Trotz beträchtlicher Fortschritte bei der Aufklärung der zentralen Steuerung der Nahrungsaufnahme bleiben noch viele wichtige Fragen offen.

Abstract

The central control of food intake rests on the integration of peripheral signals in a network of different brain areas. The food intake-related signals are evaluated and trigger an adequate response which is modulated by the individual's previous experience and the situational context. Hypothalamic areas such as the arcuate nucleus (ARC), the paraventricular nucleus (PVN) and the lateral hypothalamic area (LHA), but also the nucleus of the solitari tract (NTS), the area postrema (AP) and the parabrachial nucleus in the hindbrain as well as the amygdala, the nucleus accumbens and several other brain areas are involved in the central control of food intake. Cortical structures control the information processing in these areas and initiate the conscious behavioral responses. Peripheral signals enter the central network in part through afferent nerves, which synapse in the NTS. Circulating food intake-related signals are detected by the AP and the ARC. Several anabolic (neuropeptide Y, agouti-related peptide) and catabolic neuropeptide systems (pro-opio-melanocortin, cocaine, amphetamine-regulated transcript), which link the ARC and other hypothalamic areas, have recently been well characterized. These neuropeptide systems mediate the effects of the adipose tissue hormone leptin on food intake and energy expenditure, but they also react to other hormones, metabolites, and even monoamines such as serotonin. Despite substantial progress towards an understanding of the central control of food intake during the last few years, several important questions remain still unanswered.

Schlüsselwörter

Hypothalamus - Neuropeptide - Monoamine - anabol - katabol - Leptin

Key words

Hypothalamus - neuropeptides - monoamines - anabolic - catabolic - leptin

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