Comportamento alimentar bases neuropsíquicas e endócrinas

Résumé 0

" Feeding behaviour is an anthropologicdeterminant of survival and evolution.From it depends the energetichomeostasis in which the formation ofenergetic pools in liver and fat massmaintained during long periods if thereis a negative energetic balance.The brain has a fundamental rolein this homeostasis through three physiologicalmechanisms:– Hunger/ saciety control;– Caloric waste;– Anabolic and catabolic regulationby autonomous nervous system andhormones.The hypothalamus is the main localof central nervous system in the energeticmetabolism coordination; it integratesa great variety of external andinternal signalling and generates neuroendocrineoutputs.Afferents limbs to cerebral centresand the respective efferent loop haveshort or long term effect. The peptidesinvolved in short term are the sacietyfactors produced during meal determiningits interruption. Between them CCKhas the more relevant role.Long term factors have a main rolein caloric homeostasis. Leptin is a relevantlipostatic factor controlling energeticequilibrium by a feedback mechanismoriginated in fat mass with coordinatingeffects in hypothalamus.Other agents are insulin,Neuropep-tide Y (NPY) and Cocaineand Amphetamine Regulated Transcript(CART). Insulin secretion is triggeredby glycemic increase and modulatedby fat mass excess. Insulin increasesglucose uptake in peripheral tissuesprovoking a deficit of glucose disposableto cerebral neurons. Theneuropeptide Y gene is expressed in asmall population of arcuate neurons,from where it is transported to otherhypothalamic sites. NPY central infusionenhances a net energetic gain andfat mass accumulation. CART is expressedin hypothalamic areas that inducesaciety by “downregulation” ofNPY related RNA in the arcuate.Redundancy and synaptic plasticityhave an important role in energetichomeostasis. Further studies will decideif these molecules represent multiple systemsor if they are hierarchyred."