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Evaluation of the heart rate changes evoked by air jet stress after inhibition of the right or left sides of dorsomedial hypothalamus
Author(s) -
Peliky Fontes Marco Antônio,
CampagnoleSantos Maria J,
Xavier Custódio Carlos Henrique
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.1170.4
Subject(s) - muscimol , tachycardia , medicine , heart rate , anesthesia , agonist , cardiology , endocrinology , receptor , blood pressure
Neurons in the dorsomedial hypothalamus (DMH) play a key role in mediating tachycardia resulting from stressful stimuli. We investigated a possible hemispheric difference in DMH neurons on tachycardia evoked by experimental stress. Changes in heart rate (HR) produced by air jet stress after right (R) or left (L) inhibition of the DMH were evaluated in two separated groups (G1, G2). Under tribromoethanol anesthesia (250 mg/Kg) rats received guide cannulas into DMH and a femoral artery catheter. Air jet stress (1.5 litres/min in a 10 min period) was repeated in 2 consecutive days in conscious rats. G1 (n=5) received injections of GABA A agonist, muscimol, (1nmol / 100nL) into LDMH at the 1 st day and into the RDMH at the second day. In the G2 (n=5) the sequence of muscimol injections into the DMH was inverse, i.e. R before L. Strikingly, in both groups the tachycardia evoked by air stress was greatly reduced after RDMH inhibition (G1: L=143±17 bpm, R=58±20 bpm; G2: R=56±13 bpm, L=124±12 bpm P <0.05). In additional control experiments we found that after vehicle (NaCl 0.9%) injections into DMH, the tachycardia evoked by air stress averaged 119±17 bpm (n=10). We conclude that activation of the right DMH is critical to the full cardiac response observed during stress. Support: CNPq, FAPEMIG, CAPES.