Central mechanisms involving in responses under stress : differences between spontaneously hypertensive rats and normotensive wistar kyoto rats.

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In the modern stressful society, it is required to clarify relationship between the hypertension and the stress to afford the medical method for caring the hypertension or to solve the stress for the better life. Under working hypothesis that the hypertension may be caused by the abnormality in the central neurons controlling circulation, we have investigated to accumulate various neurophysiological findings by using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY).Using the double-immunoreactive (IR) method, the topology and numbers of barosensitive neurons that contain glutamate (Glu), glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH), phenylethanolamine N-methyltransferase (PNMT) and choline acetyltransferase (ChAT) were compared between the two strains of SHR and WKY. In the test experiment, the numbers of FosB/ChAT-IR neurons in the nucleus tractus solitarii (NTS), dorsal motor nucleus of vagus nerve (DMX) and ambiguus nucleus (AMB) were si … More gnificantly smaller in SHR than in WKY. The numbers of c-Fos/TH-IR neurons in the caudal ventrolateral medulla (VLM) were significantly larger in SHR than in WKY. These results suggest that a smaller number of barosensitive cholinergic neurons in the DMX and AMB in SHR causes the weaker baroreceptor-cardiac vagal reflex in SHR, and that a larger number of barosensitive catecholaminergic neurons in the caudal VLM in SHR are involved in the stronger baroreceptor-vasopressin reflex in SHR. Details were described in the paper in #11 reference. On the other hand, a peptide "apelin" , which is localized in the vascular walls, adipocytes and gastric mucosa, is worthy of attention. Apelin 12, one of the apelin peptide derivatives was found to lower blood pressure. The decrease of blood pressure by intravenous injection of apelin 12 was significantly larger in SHR than in WKY. We are going to studying the neural mechanism of the physiological function of apelin 12 with regard to the hypertension and stress. Less