Potential role of signal transducer and activator of transcription 3 in the amygdala in mitigating stress‐induced high blood pressure via exercise in rats

Abstract Aim Chronic stress elevates blood pressure, whereas regular exercise exerts antistress and antihypertensive effects. However, the mechanisms of stress‐induced hypertension and preventive effects through exercise remain unknown. Thus, we investigated the molecular basis involved in autonomic blood pressure regulation within the amygdala. Methods The effects of a 3‐week restraint stress and daily voluntary exercise against stress on cardiovascular parameters and gene expression profiles in the amygdala were examined using a microarray method. Candidate genes were selected from differentially expressed genes; the localization of their expression within the central nucleus of the amygdala and their roles in cardiovascular regulation were examined using small‐interfering RNA transfection and radiotelemetry. Results Chronic restraint stress caused an increase in blood pressure levels; however, with voluntary exercise, the blood pressure levels remained comparable to those of the controls. Compared with the controls, chronic restraint stress decreased signal transducer and activator of transcription 3 expression in the amygdala, whereas voluntary exercise improved its expression to normal levels. Immunohistochemical staining revealed the expression of signal transducer and activator of transcription 3 in neurons of the amygdala; inhibition of this expression using small‐interfering RNA increased the arterial pressure. However, spontaneous baroreflex gain and low‐ and high‐frequency components of heart rate variability remained unaffected by the inhibition of signal transducer and activator of transcription 3. Conclusion In the amygdala, signal transducer and activator of transcription 3 regulates the blood pressure levels and is possibly involved in blood pressure elevation in response to chronic stress and its improvement by voluntary exercise.