트레드밀 운동이 고지방 식이 유도 비만 쥐의 골격근 인슐린 신호 경로에 미치는 영향
The Effects of Regular Treadmill Exercise on Skeletal Muscle Insulin Signaling Pathway in High Fat Diet Induced Obesity Rats
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이 연구는 고지방식이 유발 비만 쥐의 8주간 규칙적인 트레드밀 운동이 인슐린 신호 전달 경로인 IRS-1/PI3K/Akt 단백질 수준과 mTOR 경로인 mTOR/mTORC1/S6K1의 변화를 살펴보기 위하여 실시하였다. 실험동물은 4주령 sprague-dawley rat 수컷 24마리를 1주간의 적응기간을 둔 뒤, 15주간 고지방식이로 비만을 유도하였다. 실험 동물은 고지방식이군(OD, n=8), 고지방식이 훈련군(ODT, n=8), 정상식이군(ND, n=8)으로 분류하였다. 트레드밀 운동은 1~4주는 주 5회 40분간 실시하였으며, 5~8주는 주5회 60분간 실시하였다. 그 결과 IRS-1과 PI3K는 OD군이 ND와 ODT군에 비해 유의하게 낮게 나타났다(p＜0.05). 그리고 mTOR와 S6K1은 OD군이 ND와 ODT군에 비해 유의한 차이가 나타났다(p＜0.05). 따라서 고지방식이 비만 유발 쥐의 8주간 규칙적인 트레드밀 운동은 골격근의 인슐린 신호 경로인 IRS-1과 PI3K 단백질 수준 향상에 긍정적 영향을 주며, 또한 mTOR 경로에서 S6K1을 개선시키는 것으로 나타나, 인슐린 신호경로와 S6K1의 변화를 통해 인슐린 민감성의 향상을 가져온 것으로 사료된다.
Abstract
The purpose of the study is to investigate how regular treadmill exercise for 8 weeks affects on expression of insulin pathway (IRS-1/PI3K/Akt) which is crucial signaling pathway to modulate insulin homeostasis on skeletal muscle for obese rats induced by high fat diet for 14 weeks and what is the relation between insulin pathway and mTORC1-S6K1 (mTOR pathway) which controls insulin pathway. The subject of this study was 24 white male rats of Sprague-dawley and we induced them to be obesity by diet for 14 weeks with water after the environmental adaptation for a week. Animals were divided three groups which are obesity diet group (OD, n=8), obesity diet training (ODT, n=8) and normal diet group (ND, n=8). They performed treadmill exercise for 40 minute 5 times a week for 1 to 4 weeks. For 5 to 8 weeks, treadmill exercise was performed for 60 minute 5 times a week. As a result, IRS-1 and PI3K were significantly decreased in OD group compared with ND group and significantly increased in ODT group compared with OD group (p<0.05). Although p-Akt was not significantly change, it tended to support previous studies (p<0.05). Also, mTORC1 was not significantly changed among groups. But S6K1 was significantly decreased in OD group compared with ND group and increased in ODT group compared with OD group. Therefore, we concluded that regular treadmill exercise for 8 weeks increased IRS-1 and PI3K protein levels affected on positive insulin signaling pathway. Furthermore, not overexpression of mTORC1-S6K1 but leading the change of S6K1 caused differentiation of insulin signaling steps according to muscular fiber.
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