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In vivo MEMRI reveals persistent activation of the brain autonomic areas by an acute systemic angiotensin II injection
Author(s) -
Zubcevic Jasenka,
Perez Pablo D,
Jun Joo Yun,
Carvajal Jessica Marulanda,
Raizada Mohan K,
Febo Marcelo
Publication year - 2012
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.26.1_supplement.lb801
Subject(s) - brainstem , angiotensin ii , hypothalamus , rostral ventrolateral medulla , medicine , amygdala , endocrinology , central nervous system , premovement neuronal activity , neuroscience , medulla oblongata , biology , blood pressure
Angiotensin II (ANGII) acts centrally to activate the sympathetic nervous system in hypertension. Here, we show that even a single systemic ANGII injection causes long‐lasting neuronal activation in the autonomic brain areas. Methods In vivo mapping of basal and ANGII‐evoked neuronal activity was carried out in the Wistar‐Kyoto (WKY) rat using manganese‐enhanced MRI (MEMRI) at 4.7Tesla. Rats were treated with manganese chloride (MnCl2 30 mM solution, i.p.;16–20 hrs prior to the MRI), and T1‐weighted images were obtained 16–20 hrs after a single ANGII injection (0.32μg/kg i.p.). Coronal slice scans (positioned caudally from end of the cerebellum/medulla rostrally towards the hypothalamus) were manually segmented using itkSNAP, and data analyzed for differences in normalized signal intensity. Results Acute ANGII injection caused an immediate pressor response (ÄSBP=~20mmHg) which normalized 2 hours following the injection. Despite this, ANGII evoked persistent neuronal activation in the central amygdala, hypothalamus (PVN, preoptic and lateral hypothalamic areas), and brainstem (NTS and RVLM). Conclusion Even a single systemic ANGII injection results in a lasting effect on the brain autonomic areas. Thus, repeated pro‐hypertensive stimuli in these brain areas may lead to pre‐sympathetic neuronal plasticity, resulting in heightened sympathetic drive and hypertension.