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Central projections to medulla for autonomic adjustments to exercise in rats
Author(s) -
Koba Satoshi,
Kato Momone,
Hanai Eri,
Watanabe Tatsuo
Publication year - 2016
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.30.1_supplement.995.1
Subject(s) - rostral ventrolateral medulla , efferent , microinjection , medulla oblongata , neuroscience , medicine , brainstem , hypothalamus , endocrinology , chemistry , central nervous system , biology , afferent
While research efforts have been made on determination of central regions responsible for autonomic adjustments to exercise, neurocircuitries between the regions are little known. Rostral ventrolateral medulla (RVLM), which contains sympathetic premotor neurons, is reportedly activated by exercise. In this study, we attempted to identify central efferent pathways which project to the RVLM and play a role in cardiovascular regulation during exercise. In the first set of experiments, immunofluorescence staining was performed on coronal brain sections of treadmill‐exercised rats which had preliminarily received microinjection of cholera toxin B subunit (CTb, a monosynaptic retrograde tracer) into the RVLM. A significant number of RVLM‐CTb‐labelled cells with immunoreactivity of Fos, a marker of activated neuronal cells, was found in paraventricular hypothalamic nucleus (PVN) and caudal periaqueductal gray (cPAG) of the exercised rats. These data suggest that PVN neurons sending efferent projections to the RVLM (PVN‐RVLM neurons) as well as cPAG neurons projecting to the RVLM are activated by voluntary exercise. In the second set of experiments, effects of selective stimulation of PVN‐RVLM neurons on blood pressure in anesthetized rats were investigated. Adeno‐associated virus (AAV) vector encoding channelrhodopsin2 had been ejected into the PVN of rats. Photostimulation of the RVLM of the AAV‐ejected rats caused a pressor response (N=4). These data suggest that activation of PVN‐RVLM neurons causes sympathoexcitation. Taken together, PVN‐RVLM neurons are considered a pathway which plays a role in evoking sympathoexcitatory response to exercise in rats. Support or Funding Information Supported by JSPS KAKENHI Grant number 15H05367 (SK) and 26670112 (SK).