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Modulatory effects of GABA in the Paraventricular Nucleus of conscious rats subjected to exercise training
Author(s) -
MartinsPinge Marli Cardoso,
Abreu Samantha Bagolan,
Lenhard Adriane,
Mehanna Aida,
Hasser Eileen M
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.1175.9
Subject(s) - microinjection , muscimol , medicine , endocrinology , hypothalamus , femoral artery , tonic (physiology) , mean arterial pressure , microinjections , anesthesia , agonist , blood pressure , heart rate , receptor
The paraventricular nucleus (PVN) of the hypothalamus is an important site for autonomic and neuroendocrine regulation, where gamma‐aminobutyric acid (GABA) system play an important role. The central mechanisms underlying modulatory effects of exercise training, have yet to be characterized. The aim of this study was analyze the cardiovascular effects of microinjection of bicuculine (BIC), muscimol (Musc), into the PVN of conscious rats submitted to swimming training (ST). After the ST protocol, adult male Wistar rats (250 to 300 g) were anesthetized for implantation of guide cannulas to PVN. After 5 days, a femoral artery and a femoral vein were catheterized for recording mean arterial pressure (MAP) and drugs injection. 24 hours later, unilateral microinjection of BIC (n=8) in the control rats (C) produced an increase in MAP (23±3 mmHg) and HR (93±12 bpm). After ST (n=9) the cardiovascular effects of BIC were attenuated for MAP and did not change for HR (DMAP= 15±2 mmHg; DHR= 88±19 bpm). A bilateral microinjection of Musc in C rats induced a decrease in MAP and HR (DMAP= −14±1 mmHg; DHR=−95±18 bpm). After ST Musc promoted a higher decrease in MAP and no alterations in HR (DMAP= −28±4 mmHg, DHR=−54±12 bpm). Our data showed that ET seems to enhance GABA tonic inhibition in the PVN and/or a blunted effect in the excitatory system to regulate cardiovascular function, which are in line with a decreased sympathetic activity.