The effect of insulin in the central nervous system on fat oxidation during exercise

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K07544
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Applied anthropology
• Research Institution: Osaka City University
• Principal Investigator: Yokoyama Hisayo 大阪市立大学, 都市健康・スポーツ研究センター, 准教授 (10647829)
• Co-Investigator(Kenkyū-buntansha): 岡崎 和伸 大阪市立大学, 都市健康・スポーツ研究センター, 教授 (70447754) ; 今井 大喜 大阪市立大学, 都市健康・スポーツ研究センター, 講師 (40614483)
• Project Period (FY): 2016-10-21 – 2019-03-31
• Keywords: 鼻腔内インスリン投与 / 中枢神経系 / 脂肪酸化 / 漸増運動負荷 / 過体重 / 脂肪分解

Outline of Final Research Achievements

The effects of the intranasal administration (AD) of insulin (INS) on the maximum fat oxidation rate (maxFOR) during exercise were tested in 15 young normal-weight (N group) and 8 young overweight (O group) persons. On two separate days, either INS or placebo (PL) was randomly administered intranasally before a graded exercise test. Indirect calorimetry was used to assess maxFOR and FATmax during exercise. Blood INS and glucose levels did not change after INS AD. In the N group, maxFOR was reduced by INS AD. MaxFOR was significantly smaller in the O group than in the N group and was not influenced by INS AD. Exercise-induced elevation in blood epinephrine levels tended to be reduced by INS AD only in the N group.
Intranasal INS AD reduces fat oxidation during exercise without any peripheral effects, possibly by suppressing sympathetic nerve activity. This inhibitory effect is diminished in the O-group, suggesting that cerebral insulin effects are attenuated in this population.

Free Research Field

代謝内分泌学、運動療法

Academic Significance and Societal Importance of the Research Achievements

本研究は鼻腔内インスリン投与が血中インスリン濃度を上昇させることなく、運動時の脂肪酸化を抑制することを初めて明らかにした。一方、鼻腔内インスリン投与による運動中の脂肪酸化抑制効果が過体重で消失したことから、過体重では脳内インスリン作用が減弱しているものと考えられた。肥満の改善により脳のインスリン感受性が可逆的に向上するかどうかは臨床上重要な課題であり、今後の検討が必要である。