Study Of The Function In Anorexia Of Neuropeptide Y In Rat Hypothalamus Under The Condition Of Acute Hypoxia At Stimulated High Altitude

Hypothalamus is the center of neurosecretion and appeptite regulation, in which there is a complex "appeptite regulation network"(ARN).Through signal transfer of all kinds of appeptite regulation signals, the "appeptite regulation network" regulates the appeptite of animals synthetically. As an orexigenic signal in hypothalamus , NPY actives Y1 and Y5 receptor (Y1R and Y5R) to promote appeptite. As an anorexigenic signal in hypothalamus, GLP-1 actives receptor to inhibit appeptite and the orexigenic action of NPY. The ARN would be affected by the changes of the body itself or environment.And then the appeptite would be promoted or inhibited, resulting in increase or decrease of food intake. In order to investigate the function in anorexia of neuropeptide Y in rat hypothalamus under the condition of acute hypoxia at stimulated high altitude, in present study, we observed the change of food intake of rats under the condition of acute hypoxia. We also examined the expression of NPY, Y1R, Y5R and GLP-1 with the method of RT-PCR and immunochemistry, as well as the change of hypothalamus neuron by electron microscope.Results are summarized as follows:1. Under the condition of acute hypoxia at high altitude (3 000 m, 4 000 m, 5 000 m, 6 000 m) , food intake of rats in the test groups decreased;2. Under the condition of acute hypoxia at high altitude (3 000 m, 4 000 m, 5 000 m, 6 000 m) , the mRNA expression of NPY,Y1R and Y5R of the test groups decreased (P < 0.05, P < 0.01) .At the same altitude , the mRNA expression of NPY, Y1R and Y5R of the test groups decreased, with the increase of hypoxia time; At the same hypoxia time, the mRNA expression of NPY, Y1R and Y5R of the test groups decreased with the increase of altitude;3. Under the condition of acute hypoxia at high altitude (3 000 m, 4 000 m, 5 000 m, 6 000 m) , the mRNA expression of GLP-1 of the test groups increased (P < 0.05, P < 0.01). At the same altitude , the mRNA expression of GLP-1 of the test groups increased with theincrease of hypoxia time; at the same hypoxia time,the mRNA expression of GLP-1 of the test groups increased with the increase of altitude ;4. The expression of NPY of the test groups and the normal groups could be detected in ARC, PVN and DMN of the hypothalamus. Under the condition of acute hypoxia at high altitude (3 000 m, 4 000 m, 5 000 m, 6 000 m) , the number of NPY immunoreactive positive cells decreased (P < 0.05, P < 0.01) . At the same altitude, the number of NPY immunoreactive positive cells decreased with the increase of hypoxia time; at the same hypoxia time ,the number of NPY immunoreactive positive cells decreased with the increase of altitude;5. The structure of neuron in hypothalamus of rats was damaged for acute hypoxia. These findings above suggest that the appeptite of rats can be inhibited by acutehypoxia; The expression of NPY, Y1R and Y5R were decreased, but that of GLP-1 was increased, and the neuron in hypothalamus of rats was damaged, which maybe play an important role in the inhibition of appetite induced by acute hypoxia.