An angiotensin system in the anterior hypothalamic area anterior is involved in the maintenance of hypertension in spontaneously hypertensive rats.
An overactive brain renin-angiotensin system is one of the factors contributing to the pathogenesis of hypertension in spontaneously hypertensive rats (SHR). We examined brain sites where enhanced activity of an angiotensin system is responsible for the pathogenesis of hypertension in SHR. The angiotensin receptor antagonist, losartan was injected into tissues around rostral parts of the third ventricle in conscious rats. Losartan (0.22 nmol) injected into the anterior hypothalamic area, anterior (AHA) produced a depressor response in SHR but not in Wistar Kyoto rats (WKY). Angiotensin II (0.091-0.91 pmol) injected into the AHA produced a pressor response in both WKY and SHR, and the pressor response to angiotensin II was greater in SHR than that of WKY. Carbachol (3 pmol) injected into the AHA also produced a pressor response in WKY and SHR, and the pressor response to carbachol was almost the same in both strains of rats. Release of angiotensin peptides in the AHA was greater in SHR than that of WKY. These findings suggest that an angiotensin system in the AHA is enhanced and this enhancement of angiotensin system is involved in the maintenance of hypertension in SHR. Both increased pressor reactivity to angiotensin II and increased release of angiotensin peptides in the AHA appear to be related to this enhancement of angiotensin system in SHR.
Kubo
T
T
Department of Pharmacology, Showa College of Pharmaceutical Sciences, Machida, Tokyo, Japan.
Yamaguchi
H
H
Tsujimura
M
M
Hagiwara
Y
Y
Fukumori
R
R
D000804:Angiotensin II / Q000008:administration & dosage; D000809:Angiotensins / Q000378:metabolism*; D000818:Animals; D007025:Anterior Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism*; D000959:Antihypertensive Agents / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects; D002217:Carbachol / Q000008:administration & dosage; D006973:Hypertension / Q000209:etiology / Q000378:metabolism*; D019808:Losartan / Q000008:administration & dosage; D008297:Male; D008845:Microinjections; D010477:Perfusion; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D000809:Angiotensins; D000959:Antihypertensive Agents; D000804:Angiotensin II; D002217:Carbachol; D019808:Losartan