Expression of c‐Fos protein in the nucleus of tractus solitary (NTS) and paraventricular nucleus of the hypothalamus (PVN) elicited by electrical stimulation of the aortic depressor nerve in conscious L‐NAME‐induced hypertensive rats

Abstract

To detect possible alterations of the baroreflex arch, we assessed the expression of c‐Fos in the NTS and PVN of L‐NAME‐induced hypertensive rats submitted to electrical stimulation of the aortic depressor nerve (ADN) in conscious state. Rats were treated for 14 days with L‐NAME (n=7), D‐NAME (n=5) or tap water (CONTROL; n=6). The animals were equipped with catheters in the femoral artery and vein, and a pair of electrodes for intermittent (5s on/10s off) electrical stimulation (1mA, 2ms and 60Hz) during 20 min. L‐NAME treated rats showed higher arterial pressure and heart rate than D‐NAME and CONTROL rats. The hypotensive response and bradycardia due to electrical stimulation did not differ among groups. The density of c‐Fos in the intermediate and commissural caudal NTS, and magnocelular and parvocelular portions of the PVN was higher in L‐NAME treated rats. In conclusion, electrical stimulation of the ADN activated more effectively neurons in the NTS and PVN of L‐NAME induced hypertensive rats. These findings suggest a greater buffering effect of the NTS upon the PVN in this hypertensive model.Supported by CAPES, CNPq and FAPESP.