Study on neuropeptide Y mRNA and its protein expression in the hypothalamus of streptozotocin-induced diabetic rats

Objective To study the changes of neuropeptide Y (NPY) mRNA and its protein expression in the hypothalamus of streptozotocin (STZ) induced diabetic rats and the effect of neuropeptide Y on the pathophysiological roles of diabetes mellitus. Methods The rats were divided into five groups, i.e. normal control, 3 and 24 week diabetes, 3 and 24 week diabetes treated with insulin. The NPY content and its mRNA in the hypothalamus were detected by immunocytochemistry and in situ hybridization respectively. Results The NPY contents in arcuate nucleus, paraventricular nucleus and paraventricular area were significantly increased in 3 and 24 week diabetic rat groups as compared with the normal control. The NPY mRNA was only increased in the arcuate nucleus. However, the content of NPY and its mRNA in 3 week STZ diabetic rats were higher than those in 24 week STZ diabetic rats. The NPY content and its mRNA were visibly reduced after insulin treatment. Conclusion The increase of NPY in hypothalamus may be responsible for the development of hyperphagia and polydipsia in diabetic rats. Insulin deficiency may contribute to the increase of hypothalamic NPY gene expression in diabetic rats.