OBJECTIVETo investigate the cardiovascular responses induced by activation of the paraventricular nucleus of hypothalamus (PVN) and the roles of the central nucleus of amygdala (CeA) on this effect.

METHODSThe PVN was activated by microinjection of L-glutamate or electrical stimulation. The CeA was injected with L-glutamate or Kainic acid (KA). The femoral arterial pressure, mean arterial pressure (MAP), electrocardiogram (ECG) and heart rate (HR) of the male SD rats were recorded when the PVN was electrically stimulated.

RESULTThe blood pressure increased when the PVN was activated either by electrical current or by L-glutamate. The blood pressure increased for (10.27+/-1.80)mmHg and the change of heart rate was -10.66 +/- 8.11 beat/min after L-Glu (100 nl) was injected into the ipsilateral CeA. The pressor response of PVN stimulation could still be evoked by electrical stimulation of (13.78 +/- 3.18)mmHg 10 min after kainic acid (100 nl) was injected into the ipsilateral CeA. But this pressor response decreased of 6.57 mmHg compared to that before injection of KA (P <0.05). The locations of the electrode tips and termination of the injector tracts were identified according to the atlas after the recording.

CONCLUSIONStimulating the PVN elicits pressor response in rats. The CeA mediates partly the pressor response elicited by activation of the PVN.