Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Department of Nutrition, Tenshi College, Sapporo, Japan.
Front Endocrinol (Lausanne). 2020 Apr 21;11:222. doi: 10.3389/fendo.2020.00222. eCollection 2020.
Since the recent rediscovery of brown adipose tissue (BAT) in adult humans, this thermogenic tissue has been attracting increasing interest. The inverse relationship between BAT activity and body fatness suggests that BAT, because of its energy dissipating activity, is protective against body fat accumulation. Cold exposure activates and recruits BAT, resulting in increased energy expenditure and decreased body fatness. The stimulatory effects of cold exposure are mediated through transient receptor potential (TRP) channels and the sympathetic nervous system (SNS). Most TRP members also function as chemesthetic receptors for various food ingredients, and indeed, agonists of TRP vanilloid 1 such as capsaicin and its analog capsinoids mimic the effects of cold exposure to decrease body fatness through the activation and recruitment of BAT. The antiobesity effect of other food ingredients including tea catechins may be attributable, at least in part, to the activation of the TRP-SNS-BAT axis. BAT is also involved in the facultative thermogenesis induced by meal intake, referred to as diet-induced thermogenesis (DIT), which is a significant component of the total energy expenditure in our daily lives. Emerging evidence suggests a crucial role for the SNS in BAT-associated DIT, particularly during the early phase, but several gut-derived humoral factors may also participate in meal-induced BAT activation. One intriguing factor is bile acids, which activate BAT directly through Takeda G-protein receptor 5 (TGR5) in brown adipocytes. Given the apparent beneficial effects of some TRP agonists and bile acids on whole-body substrate and energy metabolism, the TRP/TGR5-BAT axis represents a promising target for combating obesity and related metabolic disorders in humans.
自最近在成年人体内重新发现棕色脂肪组织 (BAT) 以来，这种产热组织引起了越来越多的关注。BAT 活性与体脂含量呈负相关，这表明 BAT 由于其能量消耗活性，对体脂积累具有保护作用。冷暴露激活并募集 BAT，导致能量消耗增加和体脂减少。冷暴露的刺激作用是通过瞬时受体电位 (TRP) 通道和交感神经系统 (SNS) 介导的。大多数 TRP 成员也作为各种食物成分的化学感觉受体发挥作用，事实上，TRP 香草素 1 的激动剂，如辣椒素及其类似物辣椒素，通过激活和募集 BAT，模拟冷暴露的作用，减少体脂。包括茶儿茶素在内的其他食物成分的抗肥胖作用可能至少部分归因于 TRP-SNS-BAT 轴的激活。BAT 还参与由进食引起的适应性产热，称为饮食诱导产热 (DIT)，这是我们日常生活中总能量消耗的重要组成部分。新出现的证据表明 SNS 在与 BAT 相关的 DIT 中起着关键作用，特别是在早期阶段，但一些肠道来源的体液因子也可能参与进食诱导的 BAT 激活。一个有趣的因素是胆汁酸，它通过棕色脂肪细胞中的 Takeda G 蛋白受体 5 (TGR5) 直接激活 BAT。鉴于一些 TRP 激动剂和胆汁酸对全身底物和能量代谢的明显有益作用，TRP/TGR5-BAT 轴代表了对抗肥胖和相关代谢紊乱的有前途的靶点。
