Monoamine depletion does not alter angiotensin II binding sites in the rat brain.
6-Hydroxydopamine (6-OHDA) or 5,7-dihydroxytryptamine (5,7-DHT) was administered in the lateral cerebral ventricles of rats. These respective treatments caused reductions in norepinephrine (NE) and 5-hydroxytryptamine (5-HT) levels in the hypothalamus-thalamus-septum-midbrain (HTSM; 62% and 44%) and brainstem (57% and 26%), respectively. Catecholamine depletion in 6-OHDA-treated rats resulted in a 55% decrease in the pressor response to ICV Ang II which was not associated with any significant change in the binding of 125I-sarcosine1, isoleucine8 Ang II to Ang II binding sites in the HTSM or brainstem. The radioligand binding was not significantly affected by the 5,7-DHT treatment. These results indicate that brain Ang II binding sites are not predominantly localized on NE- or 5-HT-containing nerve terminals. They do not, however, preclude the existence of a small proportion of Ang II binding sites on these neuronal populations.
Walters
D E
DE
Department of VCAPP, Washington State University, Pullman 99164-6520.
Speth
R C
RC
D015116:5,7-Dihydroxytryptamine; D000320:Adrenergic Fibers / Q000187:drug effects / Q000378:metabolism*; D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D006892:Hydroxydopamines; D008297:Male; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D011945:Receptors, Angiotensin / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*
D015306:Biogenic Monoamines; D006892:Hydroxydopamines; D011945:Receptors, Angiotensin; D000804:Angiotensin II; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D016627:Oxidopamine