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Inhibition of Medial Preoptic Area Improves Physical Performance in Trained Rats
Author(s) -
MüllerRibeiro Flávia Camargos,
Wanner Samuel Penna,
Drummond Lucas,
Campos Helton Oliveira,
Coimbra Candido Celso
Publication year - 2018
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.2018.32.1_supplement.lb268
Subject(s) - muscimol , treadmill , microinjection , endocrinology , medicine , chemistry , vo2 max , aerobic exercise , zoology , anesthesia , agonist , heart rate , biology , blood pressure , receptor
The medial preoptic area (MPO) plays a key role in the regulation of autonomic thermoeffectors and this area seems to be more activated after physical training, as evidenced by greater number of exercise‐induced c‐Fos immunoreactive neurons in trained rats. This observation raised the question as to whether inhibition of MPO can affect physical performance and thermoregulatory responses in trained rats. Following 2 weeks of high‐intensity interval training (HIIT), Wistar rats were submitted to an incremental‐speed exercise on a motor‐driven treadmill until fatigue after bilateral microinjection of muscimol (80 pmol/100 nl) to evaluate their aerobic capacity and thermoregulatory responses. The core body temperature (T c ) and the maximal oxygen uptake (VO 2 max) were recorded continuously during exercise. Physical training increased the time to fatigue (43 ± 2 min vs. 64 ± 2 min; p =0.0009; n=6); the maximum speed attained during the incremental exercise (24 ± 1 m/min vs. 31 ± 1 m/min; p =0.0013), the distance traveled (675 ± 36 m vs. 1261 ± 68 m; p =0.0008); and resulted in a higher oxygen uptake (38 ± 1 ml/min/kg vs. 42 ± 1 ml/min/kg; p =0.01). Interestingly, at fatigue, no difference in the absolute T c was found between the groups (38.28 ± 0.2 °C vs. 38.78 ± 0.1 °C; p =0.1). Bilateral blockade of MPO using muscimol improved physical performance, as observed by the increased time to fatigue (71 ± 6 min muscimol vs. 58 ± 2 min ‐ control, p =0.004; n=3); distance traveled (1528 ± 188 m muscimol vs. 1094 ± 84 m control; p =0.05); and maximum oxygen uptake (49 ± 1 ml/min/kg muscimol vs. 44 ± 2 ml/min/kg control; p =0.04). Regarding the thermoregulatory adjustments, MPO inhibition tended to increase T c at fatigue (40.37 ± 0.5 °C muscimol vs. 39.35 ± 0.2 °C ‐ control; p =0.08). There was an increase in the T c of the control animals during exercise but this temperature remained lower than that of the muscimol group ( p <0.001). Our findings show that neurons in the MPO are involved in the control of the aerobic capacity of trained rats, however, the improved physical performance of these animals caused by MPO inhibition did not result from changes in thermoregulatory adjustments. Support or Funding Information Conselho Nacional de Desenvolvimento Científico e Tecnlógico ‐ CNPq; grant 434646/2016‐4 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .