Enalapril decreases angiotensin II receptors in subfornical organ of SHR.
We studied brain angiotensin II (ANG II) receptors by quantitative autoradiography in adult normotensive Wistar-Kyoto (WKY) rats and in spontaneously hypertensive rats (SHR) after treating the rats with the converting-enzyme inhibitor enalapril, 25 mg/kg, po daily for 14 days. Enalapril treatment decreased blood pressure in only SHR, inhibited plasma angiotensin-converting enzyme activity by 85%, and increased plasma ANG I concentration and renin activity in both WKY and SHR. In the untreated SHR animals, ANG II receptor concentrations were higher in the subfornical organ, the area postrema, the nucleus of the solitary tract, and the inferior olive when compared with the untreated WKY rats. Enalapril treatment produced a large decrease in only subfornical organ ANG II receptors of SHR. The selective reversal of the alteration in subfornical organ ANG II receptors in SHR may indicate a decreased central response to ANG II and may be related to the mode of action of angiotensin-converting enzyme inhibitors in this model.
Nazarali
A J
AJ
Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, Maryland 20892.
Gutkind
J S
JS
Correa
F M
FM
Saavedra
J M
JM
D000110:Acetylcholinesterase / Q000097:blood; D000803:Angiotensin I / Q000097:blood; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D004656:Enalapril / Q000494:pharmacology*; D008297:Male; D009490:Neurosecretory Systems / Q000378:metabolism*; D009928:Organ Specificity; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011945:Receptors, Angiotensin / Q000187:drug effects / Q000378:metabolism*; D012016:Reference Values; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000187:drug effects; D013045:Species Specificity; D013356:Subfornical Organ / Q000187:drug effects / Q000378:metabolism*
D011945:Receptors, Angiotensin; D000804:Angiotensin II; D004656:Enalapril; D000803:Angiotensin I; D000110:Acetylcholinesterase; D012083:Renin