Effect of food deprivation and streptozotocin-induced diabetes on hypothalamic neuropeptide Y release as measured by a radioimmunoassay-linked microdialysis procedure

Central administration of neuropeptide Y (NPY) produces a robust feeding response in the rat. It is still unclear how, and in response to what endogenous stimuli NPY is released. We have developed a radioimmunoassay-linked microdialysis procedure for measuring hypothalamic NPY release in both the anaesthetised and freely moving rat. We have used the procedure to show that anesthesia dramatically decreased NPY release, while a 48 h period of food deprivation significantly increased extracellular NPY concentrations. Streptozotocin-induced diabetic rats also showed increased hypothalamic NPY release compared to controls. These results provide more evidence that NPY may be involved in mediating the hyperphagia associated with starvation and diabetes mellitus. The development of a sensitive microdialysis procedure to measure NPY will allow further detailed investigation of the hypothalamic NPY system.