Fig. 5.

Involvement of glucose transporters in d-glucose sensing by neurons that are deactivated by d-glucose (GI neurons). Metabolism-dependent mechanisms detected in rodents are depicted in which a decrease of the extracellular d-glucose concentration leads to reduced d-glucose uptake by the glucose transporters Glut1, Glut2, Glut3, and/or Glut4. Decreased intracellular d-glucose promotes changes in metabolism resulting in a decrease and increase of intracellular ATP and AMP, respectively. a A mechanism based on the decrease of intracellular ATP is shown. Due to decreased intracellular ATP, the activity of the Na⁺-K⁺ATPase is reduced. This leads to a depolarization of the plasma membrane. The depolarization activates VDCC leading to an increase of intracellular Ca²⁺ that promotes neurotransmitter release. b Two mechanisms that are promoted by the increase of intracellular AMP activating AMP-dependent kinase AMPK are shown. Activation of AMPK may lead to a depolarization of the plasma membrane by blocking the chloride channel CFTR or the two-pore-domain potassium channel K2P. Opening of VDCCs leads to an increase of intracellular Ca²⁺ that triggers neurotransmitter release