Effect of dietary NaCl on tyrosine hydroxylase in the superior cervical ganglia of Dahl rats.

To investigate the involvement of peripheral catecholamines in the development of Dahl-Iwai salt-sensitive (DIS/Eis) hypertension, we performed immunohistochemical staining of tyrosine hydroxylase (TH) in the superior cervical ganglia (SCG) of DIS/Eis rats and Dahl-Iwai salt-resistant (DIR/Eis) rats, and in situ hybridization histochemistry for demonstration of TH mRNA localization in the SCG of these rats. DIS/Eis and DIR/Eis rats were fed on a high (8%) salt diet or on a low (0.3%) salt diet for 4 weeks. Nerve cells in the SCG of DIS/Eis high salt rats exhibited more intense TH-immunoreactivity (P < 0.01) and hybridization signals (P < 0.01) than those of the other experimental groups. These findings suggest that activation of peripheral sympathetic nerves may account for hypertension in DIS/Eis rats on a high salt diet.