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Effect of bilateral lesions in the amygdala on the maximum running velocity and cardiovascular response in rats during treadmill running
Author(s) -
Tsukioka Kei,
Yamanaka Ko,
Waki Hidefumi
Publication year - 2020
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.2020.34.s1.02748
Subject(s) - habituation , amygdala , medicine , treadmill , intensity (physics) , stimulation , heart rate , cardiology , anesthesia , psychology , blood pressure , audiology , physics , quantum mechanics
The high intensity of exercise around/at maximum levels induces psychological distress. It is known that the amygdala in the limbic system is one of the regions of the brain controlling such emotion, as well as regulating the cardiovascular system. Therefore, we hypothesized that the amygdala could play an important role in limiting the high‐intensity exercise performance. To test this, we examined whether bilateral amygdala lesions increased maximal exercise performance with altered cardiovascular responses during exercise. The arterial pressure in rats was chronically measured using radio‐telemetry during treadmill running. The rats were subjected to forced running for 60 min per day (velocity ≤20 m/min) for 3 days to achieve treadmill habituation. Thereafter, an incremental exercise test was conducted until exhaustion (pre‐test). Exercise intensity was initiated at 10 m/min, and the velocity was increased by 2 m/min every 3 min. In the amygdala lesion group, the bilateral lesions in the amygdala were induced by electrical stimulation (direct current 1 mA for 5 s). In the sham group, the tip of the electrode was inserted into the amygdala and immediately removed without electrical stimulation. After surgery, re‐training was conducted similar to the habituation protocol, and the incremental exercise test was repeated (post‐test). In the sham group, there were no significant differences between pre‐ and post‐test in the mean maximum running velocities (pre‐test: 47.2 ± 1.8 m/min, post‐test: 44.0 ± 2.8 m/min) and running time (pre‐test: 56.5 ± 3.2 min; post‐test: 49.9 ± 4.7 min). However, the mean maximum running velocity was greater (pre‐test: 45.5 ± 2.3 m/min; post‐test: 54.0 ± 0.6 m/min; p < 0.05) and the running time was longer (pre‐test: 57.9 ± 3.4 min; post‐test: 70.0 ± 0.8 min; p < 0.05) in the post‐test as compared to the pre‐test of the lesion group. Moreover, we found that the mean arterial pressure in both groups of animals exhibited a gradual increase during submaximal exercise (low/moderate intensity) followed by a drastic increase during high/maximal‐intensity exercise. However, compared to the sham group, the mean arterial pressure response in the amygdala lesion group was significantly lower during submaximal exercise, whereas it was greater during high/maximal‐intensity exercise, suggesting that the amygdala could play a role in limiting the exercise performance by modulating the autonomic cardiovascular control. Support or Funding Information Grant‐in‐Aid for JSPS Fellows (19J22706)