Background: Numerous studies suggest that apelin plays a significant role in cardiovascular regulation and in the pathogenesis of hypertension. The purpose of the present study was to determine whether apelin-13 (AP-13) is involved in the regulation of cardiovascular responses to acute stress in spontaneous hypertension.
Methods: The effects of intracerebroventricular (ICV) administration of AP-13 on changes in mean arterial blood pressure (MABP) and heart rate evoked by an alarming stress (air jet stress) were compared in awake normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). The rats were divided into four groups: Groups 1 (WKY) and 3 (SHR) received ICV infusion of 0.9% sodium chloride (vehicle), whereas Groups 2 (WKY) and 4 (SHR) were ICV infused with AP-13. All animals were exposed to the alarming stress.
Results: During the ICV administration of the vehicle, the pressor response to stress was significantly greater in SHR than in WKY. The ICV infusion of AP-13 reduced the pressor response evoked by the application of the stressor in SHR but not in WKY. It also abolished the difference in stress-induced MABP increases between WKY and SHR.
Conclusions: The results show that centrally acting apelin may play an essential role in the regulation of blood pressure responses to an alarming stress in SHR rats.