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Serotonin (5‐HT) Innervation of the Nucleus Tractus Solitarius (NTS) Is Necessary for Sympathetic Recovery following Hypotensive Hemorrhage.
Author(s) -
Kung LingHsuan,
Scrogin Karie
Publication year - 2009
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.23.1_supplement.1011.7
Subject(s) - medicine , endocrinology , blood pressure , tyrosine hydroxylase , serotonin , lesion , sympathetic nervous system , rostral ventrolateral medulla , heart rate , anesthesia , raphe nuclei , chemistry , dopamine , receptor , serotonergic , surgery
We tested if 5‐HT projections to the NTS facilitate sympathetic and respiratory recovery from hypotensive hemorrhage (HH). Rats were subjected to selective (n=9) or sham (n=8) lesion of 5‐HT nerve terminals by injection of 5,7‐dihyroxytryptamine or ascorbic acid (0.01%) into cardio‐respiratory afferent terminal fields of the NTS. After 1 wk, blood pressure (BP), heart rate (HR), renal sympathetic‐ and diaphragmatic EMG activity were recorded during blood withdrawal (21 ml/kg/10 min) in unanesthetized rats. Lesion reduced the initial sympathoexcitation (‐12.3 ± 23.4 vs. +106.6 ± 38.3 % baseline, P<0.05), but not the subsequent sympathoinhibition to blood loss. Sympathetic and ventilatory recovery 35 min after HH were reduced (+6.2 ± 13.2 vs. +127.9 ± 48.7 %baseline, P<0.05 and ‐32.4 ± 4.6 vs. +45.7 ± 18.9 %baseline intergrated dEMG, P<0.05). BP and HR were not affected. Lesion reduced 5‐HT immunoreactivity (IR) in the NTS by 93% (P<0.01), but did not affect tryptophan hydroxylase IR in raphe nuclei or tyrosine hydroxylase IR in adrenergic nuclei. 5‐HT innervation of the NTS is necessary for normal sympathoexcitatory and ventilatory responses to blood loss. Supported by HLBI 72354 and AHA 0815529G.