Aim: To study the role of NO in the midbrain periaqueductal gray (PAG) in the development of stress-induced hypertension (SIH).
Methods: The model of stress-induced hypertension (SIH) rat was established by electric-foot in company with noise, NADPH-d histochemistry technique was used to investigate the change of nitric oxide synthase (NOS) positive neurons. Selecting and using microinjection and radioimmunoassay, we studied the effects of blood pressure and the content of Ach in rostral ventrolateral medulla (RVLM) after microinjection of L-NNA into PAG.
Results: (1) The blood pressure increased, the cell number decreased and the grey degree value increased for the NOS positive neurons of PAG dorsolateral subdivision in SIH rats, and the content of Ach increased in RVLM. (2) Following microinjection of 100 mmol/L 0.1 microl L-NNA into PAG, the mean arterial pressure (MAP) and the content of Ach in RVLM increased in control rats, whereas the change of MAP was significantly smaller in SIH rats than control.
Conclusion: The plastic change of NOS positive neurons of PAG in SIH rats may be involved in the development of SIH, which may be mediated by Ach in RVLM.