食欲と内在性有機化合物

抄録

The regulation of food intake is conducted by the feeding and satiety centers in the hypothalamus, part of the brain. Blood born materials such as glucose, insulin, free fatty acids, and glucagon, which are related to metabolism, are known to be involved in the induction of hunger or satiety. Behavior and electrophysiological experiments have shown that these and other humoral factors act as hunger and satiety signals, through the chemosensitive neurons located in the two centers. To identify other blood factors that might affect body weight by controlling feeding, blood from rats in various stages of food deprivation was analyzed for its constituents. Two short chain sugar acids, 3, 4-dihydroxybutanoic acid (2-deoxytetronic acid, 2-DTA) and 2, 4, 5-trihydroxypentanoic acid (3-deoxypentonic acid, 3-DPA), were isolated by a gas chromatograph-mass spectrometer-computer system. Their effects on rat feeding behavior and on neuron activity were investigated. Injections of 2-DTA into the rat third cerebral ventricle suppressed food intake. The same amounts of 3-DPA elicited feeding. The activity of chemosensitive neurons was suppressed by 2-DTA in the feeding center and facilitated in the satiety center. The effect of 3-DPA was just opposite on the neurons in these two centers. High correlation between modulation of feeding behavior and changes in chemosensitive neuron activity suggested that 2-DTA may act as an endogenous satiety substance and 3-DPA as a hunger substance. The effect of 3-hydroxybutyric acid and other related substances were also verified and discussed.