Superoxide anion is elevated in sympathetic neurons in DOCA-salt hypertension via activation of NADPH oxidase.
Superoxide anion (O2-*) production is elevated in sympathetic ganglion neurons and in the vasculature of hypertensive animals; however, it is not known what enzymatic pathway(s) are responsible for O2-* production. To determine the pathway(s) of O2-* production in sympathetic neurons, we examined the presence of mRNA of NADPH oxidase subunits in sympathetic ganglionic neurons and differentiated PC-12 cells. The mRNAs for NADPH oxidase subunits p47phox, p22phox, gp91phox, and NOX1 were present in sympathetic neurons and PC-12 cells, whereas the NOX4 homologue was present in sympathetic neurons but not PC-12 cells. Freshly dissociated celiac ganglion neurons from normal rats and PC-12 cells produced O2-* when treated with the PKC activator PMA; O2-* production increased by 317% and 254%, respectively. The PMA-evoked increases were reduced by pretreatment with the NADPH oxidase inhibitor apocynin. These findings indicate that NADPH oxidase is the primary source of O2-* in sympathetic ganglion neurons. When celiac ganglia from hypertensive rats were incubated with apocynin, O2-* levels were reduced to the same levels as normotensive animals, indicating that NADPH oxidase activity accounted for the elevated O2-* levels in hypertensive animals. To test this latter finding, we compared NADPH oxidase activity in extracts of prevertebral sympathetic ganglia of DOCA-salt hypertensive rats and sham-operated rats. NADPH oxidase activities were 49.9% and 78.6% higher in sympathetic ganglia of DOCA rats compared with normotensive controls when using beta-NADH and beta-NADPH as substrates, respectively. Thus elevated O2-* levels in hypertension may be a result of the increased activity of NADPH oxidase in postganglionic sympathetic neurons.
Dai
Xiaoling
X
Department of Physiology, 2201 Biomedical and Physical Sciences Bldg., Michigan State University, East Lansing, Michigan 48824, USA.
Cao
Xian
X
Kreulen
David L
DL
D000818:Animals; D003900:Desoxycorticosterone; D004789:Enzyme Activation; D005728:Ganglia, Sympathetic / Q000378:metabolism*; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism*; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000378:metabolism*
D013481:Superoxides; D003900:Desoxycorticosterone; D019255:NADPH Oxidases