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Activation by Systemic Angiotensin II of Neurochemically Identified Neurons in Rat Hypothalamic Paraventricular Nucleus
Author(s) -
Dawson Corrine A.,
Jhamandas Jack H.,
Krukoff Teresa L.
Publication year - 1998
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1046/j.1365-2826.1998.00225.x
Subject(s) - medicine , endocrinology , angiotensin ii , hypothalamus , angiotensin ii receptor type 1 , supraoptic nucleus , chemistry , neuron , vasopressin , receptor , renin–angiotensin system , nicotinamide adenine dinucleotide phosphate , biology , neuroscience , blood pressure , biochemistry , oxidase test , enzyme
Using the immunohistochemical localization of the protein product of the immediate early gene, c‐ fos , to localize activated neurons in the paraventricular nucleus of the hypothalamus (PVN), we studied the chemical phenotypes of neurons activated by circulating angiotensin II (AII). We determined the proportions of activated PVN neurons that expressed AII type I receptor‐like immunoreactivity (AT 1 ‐L) or the neurohormones vasopressin (VP) and oxytocin (OXY). In addition, we identified activated PVN neurons that putatively produce nitric oxide (NO) on the basis of histochemical staining for nicotinamide adenine dinucleotide phosphate diaphorase (NADPH‐d). Conscious rats received intravenous AII infusions at a rate sufficient to elevate mean arterial pressure by 40–60 mmHg for 90 min; control rats received infusions of vehicle. Brains were prepared for double immunohistochemistry [Fos‐like immunoreactivity (FLI)/AT 1 ‐L, FLI/VP or FLI/OXY] or FLI/NADPH‐d histochemistry. Systemic AII infusions led to activation of 149±14 PVN neurons per section. In contrast, control animals showed activation of 21±6 PVN neurons per section. AII infusions elicited the activation of the following numbers of chemically identified PVN neurons per section: AT 1 ‐L, 24±5; VP, 26±5; OXY, 11±2; NADPH‐d, 22±4. Control animals had few activated PVN neurons per section. For each of the chemically identified populations of PVN neurons, the following proportions were activated: AT 1 ‐L, 12.5%; VP, 15.2%; OXY, 7.2%; NADPH‐d, 17.3%. The results suggest that PVN neurons producing the AT 1 receptor, VP, OXY, and NO, participate in the mediation of the central responses to circulating AII.