ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract Previous evidence has suggested that brain catecholamine levels are important in the regulation of central angiotensin II receptors. In the present study, the effects of norepinephrine and 3,4-dihydroxyphenylethylamine (dopamine) on angiotensin II receptor regulation in neuronal cultures from rat hypothalamus and brainstem have been examined. Both catecholamines elicit significant decreases in [125I]angiotensin II-specific binding to neuronal cultures prepared from normotensive rats, effects that are dose dependent and that are maximal within 4–8 h of preincubation. Saturation and Scatchard analyses revealed that the norepinephrine-induced decrease in the binding is due to a decrease in the number of angiotensin II receptors in neuronal cultures, with little effect on the receptor affinity. Norepinephrine has no significant actions on [125I]angiotensin II binding in cultures prepared from spontaneously hyper tensive rats. The downregulation of angiotensin II receptors by norepinephrine or dopamine is blocked by α1-adrenergic and not by other adrenergic antagonists, a result suggesting that this effect is initiated at the cell surface involving α1-adrenergic receptors. This is further supported by our data indicating a parallel downregulation of specific α1-adrenergic receptors elicited by norepinephrine. In summary, these results show that norepinephrine and dopamine are able to alter the regulation of neuronal angiotensin II receptors by acting at α1-adrenergic receptors, which is a novel finding.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1986.tb00729.x
