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Angiotensin receptor binding in rostral ventrolateral medulla (RVLM) is reduced by destruction of the C1 neurons
Author(s) -
Bourassa Erick A.,
Stedenfeld Kristen A.,
Li Xia,
Speth Robert C.,
Sved Alan F.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1169.14
Subject(s) - rostral ventrolateral medulla , medicine , brainstem , chemistry , endocrinology , angiotensin ii , receptor , medulla oblongata , central nervous system , biology
The RVLM, a brainstem site critical in cardiovascular regulation, contains angiotensin Type 1 receptors (AT1R) and stimulation of these receptors increases arterial pressure. Elevated stimulation of these receptors may contribute to sympathoexcitation seen in some rat models of hypertension, as injection of AT1R antagonists into RVLM decreases arterial pressure in these hypertensive models. Within the RVLM, there are two groups of spinally‐projecting sympathoexcitatory neurons based on neurochemical phenotype: those that contain catecholamine biosynthetic enzymes, termed C1 cells, and those that do not. Although evidence supports the hypothesis that the C1 and the AT1R‐expressing populations of the RVLM overlap, this hypothesis has not been tested. Local injection of saporin toxin conjugated to a dopamine‐beta‐hydroxylase antibody(antiDBH‐Sap) selectively destroys C1 cells. Using this lesioning approach, we examined the effect of C1 cell depletion on density of AT1R binding sites in the RVLM. Autoradiographic localization of (125)‐I‐sarcosine(1), isoleucine(8) Ang II revealed high affinity AT1R binding in the RVLM. Selective unilateral lesions of C1 neurons in the RVLM reduced AT1R binding in the RVLM compared to the unlesioned side and the RVLM of rats injected with a control toxin. These data suggest that a large proportion of AT1R in the RVLM are located on C1 neurons. (NIH HL‐55687, HL‐76083)