Repeated idazoxan increases brain imidazoline receptors in normotensive (WKY) but not in hypertensive (SHR) rats.
The specific binding of [3H]idazoxan in the presence of 10(-6) M (-)-adrenaline was used to evaluate the density of imidazoline receptors in the brain of spontaneously hypertensive (SHR) rats and sex- and age-matched normotensive Wistar-Kyoto (WKY) rats. In SHR rats the density of imidazoline receptors (cerebral cortex, hypothalamus, and medulla oblongata) was not different from that in normotensive (WKY) rats. However, repeated treatment with idazoxan consistently increased (23-80%) the density of imidazoline receptors in the various brain regions of WKY rats but not in SHR rats. In normotensive Sprague-Dawley rats, repeated treatment with the imidazoline drugs idazoxan and cirazoline also increased (33-37%) the density of imidazoline receptors in the cerebral cortex. The lack of regulation by idazoxan of the density of imidazoline receptors in the brain of SHR rats might reflect the existence of a relevant abnormality of these receptors in this genetic model of hypertension.
Department of Fundamental Biology and Health Sciences, University of the Balearic Islands, Palma de Mallorca, Spain.
G
G
Olmos
A
A
Miralles
F
F
Barturen
J A
JA
García-Sevilla
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D004146:Dioxanes / Q000378:metabolism / Q000494:pharmacology*; D007031:Hypothalamus / Q000378:metabolism; D019329:Idazoxan; D054755:Imidazoline Receptors; D007700:Kinetics; D008526:Medulla Oblongata / Q000378:metabolism; D009928:Organ Specificity; D051381:Rats; D011918:Rats, Inbred SHR; D011919:Rats, Inbred Strains; D011921:Rats, Inbred WKY; D011955:Receptors, Drug / Q000187:drug effects / Q000378:metabolism*; D013045:Species Specificity
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D054755:Imidazoline Receptors; D011955:Receptors, Drug; D019329:Idazoxan