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Angiotensin II and the locus coeruleus
R C Speth1, K L Grove, B P Rowe
1Department of Veterinary and Comparative Anatomy, Washington State University, Pullman.
Progress in Brain Research
|January 1, 1991
Summary
Angiotensin II acts in the locus coeruleus (LC), a brain region rich in its receptors. The predominant receptor subtype in the LC is the AII beta receptor, which is elevated in hypertensive rats.
Area of Science:
- Neuroscience
- Pharmacology
- Cardiovascular Research
Background:
- The locus coeruleus (LC) is implicated as a key brain site for angiotensin II action.
- Angiotensin II-like material and numerous angiotensin II receptors are found in the LC.
- Evidence suggests these receptors are located on noradrenergic neurons within the LC.
Purpose of the Study:
- To characterize angiotensin II receptor subtypes in the rat LC.
- To investigate potential alterations in angiotensin II and its receptors in spontaneously hypertensive rats.
- To explore the functional role of angiotensin II in the LC.
Main Methods:
- Immunocytochemistry to detect angiotensin II-like material.
- Radioligand binding assays using selective agonists and antagonists for angiotensin II receptor subtypes.
- Neurotoxin studies to identify receptor-bearing cell types.
- Comparative analysis between spontaneously hypertensive rats and normotensive controls.
Main Results:
- The rat LC expresses both known angiotensin II receptor subtypes.
- The PD123177-sensitive AII beta receptor subtype is predominant in the LC.
- Angiotensin II and its receptors are upregulated in the LC of spontaneously hypertensive rats compared to normotensive controls.
Conclusions:
- The LC is a significant site for angiotensin II signaling, with a predominance of AII beta receptors.
- Hypertension is associated with elevated levels of angiotensin II and its receptors in the LC.
- The precise physiological function of angiotensin II within the LC remains to be fully elucidated.