Chemical lesion of the circumventricular organs with monosodium glutamate reduces the blood pressure of spontaneously hypertensive but not of one kidney-one clip hypertensive rats.
Subcutaneous injection of monosodium glutamate (MSG) on days 1, 5 and 9 of the experiment (5 g/kg per day) significantly reduced the blood pressure of a group of 10 spontaneously hypertensive rats (SHR) measured 7 and 14 days after treatment (200 +/- 7 mmHg vs 172 +/- 8 mmHg or 185 +/- 3 mmHg, respectively), without affecting that of 11 age-matched Wistar Kyoto (WKY) rats (127 +/- 7 mmHg vs 123 +/- 5 mmHg and 119 +/- 5 mmHg, respectively). Using autoradiographic methods and 125I-Sar1-angiotensin II, receptor binding was shown to be higher in the subfornical organ (SFO) of SHR (332 +/- 31 fmol/mg protein) when compared to WKY rats (240 +/- 30 fmol/mg protein) and similar (222 +/- 21 vs 170 +/- 14 fmol/mg protein) in the paraventricular nucleus (PVN). Binding to angiotensin-converting enzyme (ACE) was evaluated using the ACE inhibitor 125I-351A as ligand. Binding to ACE was lower in SHR in the PVN and the globus pallidus (GP) of SHR when compared to WKY rats (PVN: 111 +/- 9 vs 172 +/- 13 and GP: 163 +/- 2 vs 213 +/- 7 fmol/mg protein) and similar in the SFO, choroid plexus (ChP) and caudate nucleus (CD) of both strains (SFO: 779 +/- 107 vs 805 +/- 169; ChP: 2,780 +/- 210 vs 3,140 +/- 360 and CD: 461 +/- 42 vs 424 +/- 18 fmol/mg protein). No changes in angiotensin II (Ang II) receptor number or binding to ACE were detected in these brain areas after MSG treatment of SHR or WKY rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Corrêa
F M
FM
Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil.
Saavedra
J M
JM
D000818:Animals; D001345:Autoradiography; D001794:Blood Pressure / Q000187:drug effects*; D001923:Brain Chemistry / Q000187:drug effects; D002552:Cerebral Ventricles / Q000737:chemistry / Q000187:drug effects* / Q000503:physiopathology; D004195:Disease Models, Animal; D006977:Hypertension, Renal / Q000503:physiopathology*; D007703:Peptidyl-Dipeptidase A / Q000032:analysis / Q000187:drug effects; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017208:Rats, Wistar; D011945:Receptors, Angiotensin / Q000032:analysis / Q000187:drug effects; D012970:Sodium Glutamate / Q000494:pharmacology*; D013997:Time Factors
D011945:Receptors, Angiotensin; D007703:Peptidyl-Dipeptidase A; D012970:Sodium Glutamate