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Comparison of the cardiovascular responses evoked by chemical activation of the left and right sides of dorsomedial hypothalamus
Author(s) -
Custódio Carlos Henrique Xavier,
CampagnoleSantos Maria José,
Fontes Marco Antônio Peliky
Publication year - 2008
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.22.1_supplement.1170.5
Subject(s) - microinjections , medicine , heart rate , endocrinology , hypothalamus , anesthesia , cardiology , central nervous system , blood pressure
Activation of dorsomedial hypothalamus (DMH) neurons by microinjections of the GABA A antagonist, bicuculline methiodide (BMI), evokes physiological cardiovascular changes typically seen in experimental emotional stress. We compared the heart rate (HR), renal sympathetic activity (RSNA) and renal blood flow (RBF) responses produced by chemical activation of right (R) and left (L) sides of DMH. Rats were anesthetized (urethane 1.4 g/Kg), prepared for recording of cardiovascular variables and for microinjections. In all animals, RSNA and RBF were recorded on the L side. In protocol 1 (n=5), BMI (40pmol/100nL) was injected first into LDMH and 40 min. later, into the RDMH. Inversely, in the protocol 2 (n=5) BMI was injected first into the RDMH and later into the LDMH. In both cases there were always greater increases in RSNA with reductions in RBF when BMI was injected into the LDMH, i.e., ipsilateral to the side where RSNA and RBF were recorded (average RSNA: L= +50% and R= +26.5%; average RBF: L= −14% and R= −6.5%). In both protocols RDMH activation caused greater tachycardia when compared to LDMH activation (ΔHR Protocol 1: L= 45±3 bpm vs. R= 74±4 bpm; Protocol 2: R= 78±5 bpm vs. L=55±6 bpm; P <0.05). These results indicate that the descending cardiovascular pathways from DMH are predominantly lateralized and suggesting that the right DMH might exert a prominent control on heart rate changes. Support: CNPq, FAPEMIG, CAPES.