Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
J Endocrinol. 2010 Apr;205(1):37-47. doi: 10.1677/JOE-09-0405. Epub 2010 Jan 22.
Brain-derived neurotropic factor (BDNF) mediates many aspects of neuronal function, and plays a chief role in the central regulation of energy balance. In the periphery, it is expressed in organs involved in energy, lipid, and glucose homeostasis, including the liver, but its role there remains unclear. Here, we describe studies examining the effect of selectively depleting hepatic BDNF. Liver-specific mutant mice exhibited normal food intake and body weights when fed standard chow or high-fat diets (HFDs). However, whereas HFD intake induced mild hyperglycemia and hyperinsulinemia in wild-types (WTs), liver-specific BDNF mutants were protected from these effects. Serum levels of cholesterol and triglycerides were also elevated in HFD-fed WTs, but they were normal or slightly increased in BDNF mutants. Furthermore, whereas WTs fed HFD exhibited elevated levels of circulating alanine aminotransferase and aspartate aminotransferase, BDNF mutant males fed a similar diet had a normal content of both enzymes. Molecular analysis indicated that the livers of BDNF mutants fed HFD contained elevated levels of peroxisome proliferator-activated receptor alpha (Pparalpha or Ppara as listed in the MGI Database) and fibroblast growth factor 21 (Fgf21) transcripts compared with WTs. This is a notable finding as this pathway has anti-diabetic and lipid clearance effects. Accordingly, genes involved in lipid and glucose handling and targets of PPARalpha and FGF21 were upregulated in the BDNF mutant livers. The collective data indicate that hepatic BDNF might facilitate the emergence of insulin resistance, dyslipidemia, and liver disease following HFD challenge by suppressing PPARalpha and FGF21.
脑源性神经营养因子(BDNF)介导神经元功能的许多方面,并在能量平衡的中枢调节中发挥主要作用。在外周组织中,BDNF 表达于参与能量、脂质和葡萄糖稳态的器官中,包括肝脏,但它在肝脏中的作用尚不清楚。在这里,我们描述了研究选择性耗尽肝源性 BDNF 的影响。肝特异性突变小鼠在喂食标准饲料或高脂肪饮食(HFD)时表现出正常的食物摄入和体重。然而,尽管 HFD 摄入诱导野生型(WTs)的轻度高血糖和高胰岛素血症,但肝特异性 BDNF 突变体对此类影响具有保护作用。HFD 喂养的 WT 血清胆固醇和甘油三酯水平也升高,但 BDNF 突变体的水平正常或略有升高。此外,尽管 HFD 喂养的 WT 表现出循环丙氨酸转氨酶和天冬氨酸转氨酶水平升高,但类似饮食喂养的 BDNF 突变体雄性的两种酶含量正常。分子分析表明,与 WT 相比,HFD 喂养的 BDNF 突变体的肝脏中过氧化物酶体增殖物激活受体α(PPARα或 MGI 数据库中列出的 Ppara)和成纤维细胞生长因子 21(Fgf21)转录本水平升高。这是一个值得注意的发现,因为该途径具有抗糖尿病和脂质清除作用。因此,参与脂质和葡萄糖处理的基因以及 PPARα 和 FGF21 的靶基因在 BDNF 突变体肝脏中上调。这些数据表明,肝源性 BDNF 可能通过抑制 PPARα 和 FGF21 来促进 HFD 挑战后胰岛素抵抗、血脂异常和肝脏疾病的发生。