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Exaggerated response to acute stress in the spontaneously hypertensive rat (SHR) is linked to dysregulation of the hypothalamic orexin system
Author(s) -
Hayward Linda F.,
Castellanos Mabelin
Publication year - 2013
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.27.1_supplement.699.9
Subject(s) - orexin , endocrinology , medicine , hypothalamus , orexin a , arousal , blood pressure , lateral hypothalamus , neuropeptide , biology , neuroscience , receptor
Heightened sensitivity to stress is a hallmark of of hypertension. Orexinergic neurons in the hypothalamus are critical for cardiorespiratory arousal and defense responses. This raises the possibility augmented responses to stress observed in hypertension may be linked to dysregulation of the orexin system. Thus, the present study tested the hypothesis that exaggerated cardiovascular responses to acute stress in the SHR are associated with heightened activation of the orexin system. Adult male SHR and Wistar rats (n=4/group) were either sacrificed immediately for mRNA extraction from the hypothalamus or chronically instrumented for blood pressure (BP) monitoring during novel air jet stress. Prepro‐ orexin mRNA was identified to be significantly reduced in the SHR (21±6% of Wistar). Alternatively, 20 min of air jet stress elicited both a heightened BP response in the SHR and a significant increase in the number of c‐fos positive neurons in the lateral hypothalamus (103±10 vs 27±3 neurons, SHR vs Wistar) and an increase in the number of orexin/c‐fos double labeled neurons (25±5 vs 3±1 neurons, SHR vs Wistar). These results demonstrate that the exaggerated autonomic response to acute stress in hypertension is linked to abnormalities in the orexin system, including abnormally low gene expression at baseline and elevated system recruitment in response to acute stress.