CHEN, Yiru

CHEN, Yiru

A Humble learner

[Biomedical][course]Gut-brain glucose sensing

2 minute read

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God, another biomedical course summary!

Welcome to Chen’s learning blog! This is a space where I share my thoughts, experiences, and insights on mostly bioinformatics, many biomedical, some computor science! Whether you’re a fellow enthusiast or simply curious, I invite you to join me on this journey as we explore the captivating world of gene, protein, RNA… and codes.

So, sit back, grab a beverage, and let’s dive into the fascinating realm of Gut-brain glucose sensing together! But just introduction.

Three major glucose sensor sections

  • Gut glucose sensor
  • Portal vein
  • Brain glucose sensor

  • Pancreas glucose sensor

  • Definition of glucose sensor
    • need glucose transporters
      • GLUT
        • passive carrier
      • SGLT
        • a plasma membrane carrier requires energy to transport glucose against its concentration gradient
    • need G protein coupled receptors
      • GPCR: sweet taste receptor
        • T1R2 + T1R3
    • evokes complex neural and endocrine responses that control glucose metabolism

      Gut

      Glucose sensing in small intestine

  • Conducted by enteroendocrine cell (EECs)
    • Apical surface glucosensing
    • One pathway depends on GPCR, T1R2 and T1R3
    • One pathway depends on SGLT-1: more important one 300

      Incretin

  • Peptide secreted after nutrient intake and stimulate insulin secretion
  • Two incretins
    • GIP: gastric inhibitory polypeptide
    • GLP-1: glucagon-like peptide 1

400

  • how the GLP-1 regulate insulin secreted by the beta-cells
  • 刺激胰岛素合成:
    • GLP-1可以上调胰腺β细胞中胰岛素基因的转录,促进胰岛素的合成。
  • 促进胰岛素分泌:
    • GLP-1可以直接作用于胰腺β细胞,通过多种信号通路刺激胰岛素的分泌。
    • 这包括激活腺苷酸环化酶-cAMP通路,增加细胞内钙离子浓度等。
  • 促进β细胞增殖:
    • GLP-1可以通过激活MAPK和PI3K-Akt等信号通路,促进胰腺β细胞的增殖和新生。
    • 这有助于扩大β细胞量,增强胰岛功能。
  • 抑制β细胞凋亡:
    • GLP-1可以抑制胰腺β细胞的细胞凋亡过程,保护β细胞免受损伤。
    • 这也有助于维持β细胞的数量和功能
  • 抑制glucagon
  • GIP和GLP作用上的区别就是它促进glucagon的分泌生成

Oral glucose intake

  • Oral glucose tolerance test
    • 评估glucose代谢功能的检查方法
    • 测量集体在口服glucose之后的血糖变化情况，评估耐受能力
  • Impaired oral glucose tolerance
    • Decreased circulating GLP-1
    • Accelerated gastric emptying
    • normal food intake and body weight
  • Dipeptidyl peptidase-4(DPP4)
    • 可以讲活性形式的GLP-1，GIP转变为无活性的形式
    • 因此DPP4的活性的增高会导致对于glucose 的耐受能力下降

neuropod cell and vagal nerve

  • Using glutamate as neurotransmitter, form synapse with the neuron of the vagal nodose to transduce sense from gut to brain

Portal vein

  • Hepatic portal vein denervation (去神经)impairs oral glucose tolerance
  • Key roles in control
    • Liver
      • glycogen synthesis by the liver
    • Brain
      • send signals to the brain and elicits suppression of hepatic glucose production
    • skeletal muscle and adipose tissue
      • increase peripheral glucose utilisation in a number of tissues
    • Pancreas
      • Portal vein glucosensors may also target the pancreas to control the release of these two hormones
  • Portal vein is the most important glucose sensor section
    • more sensitive than brain sensors
    • the most suitable place in the body for sensing blood glucose
      • During the fasted to fed transition, the portal glucose concentration increases more than systemic blood glucose
      • Due to the high glucose consumption of the intestine, the portal glucose concentration drops below the systemic glucose concentration during post-absorptive period
      • Due to the intestinal gluconeogenesis

other sensing

  • Lipid sensing in small intestine
  • protein sensing in small intestine

    Impact of micrbiome on gut-brain signalling

  • main effect is producing short chain fatty acid

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