The effect of acute and chronic restraint on the central expression of prepro-neuropeptide Y mRNA in normotensive and hypertensive rats

Neuropeptide Y (NPY), one of the most abundant neuropeptides found in the c entral nervous system (CNS), has been implicated in the regulation of many autonomic functions, including cardiovascular control and the central stres s response. The present study represents a detailed investigation of the ef fects of acute and chronic restraint stress on the expression of the mRNA e ncoding the NPY precursor, prepro-NPY, in the CNS of normotensive Wistar-Ky oto (WKY) rats and spontaneously hypertensive rats (SHR) using in situ hybr idization histochemistry, Basal (unstressed) levels of prepro-NPY mRNA expr ession were found to be significantly increased in the hypothalamic arcuate nucleus of SHR compared to WKY rats, with similar levels of prepro-NPY mRN A expression found in the remaining central nuclei. Following exposure to b oth acute and chronic restraint, significant changes in prepro-NPY mRNA exp ression were found in a variety of central regions in both strains, includi ng the arcuate nucleus and hippocampus (both strains), medial amygdala and cortex (WKY only), and dentate gyrus, nucleus of the solitary tract and ven trolateral medulla (SHR only). A comparison of the temporal response to res traint revealed that significant differences between strains existed in reg ions such as the arcuate nucleus, hippocampus and dentate gyrus, providing further evidence that hypertensive rats apparently have an impaired neural stress response. The present study demonstrates that exposure to restraint results in significant changes in prepro-NPY mRNA expression in specific nu clei of both WKY and SHR that are components of not only the central circui try regulating the stress response, but also the neural network modulating autonomic function.