Fig. 5: Myenteric neuronal responses to luminal acetate in the jejunum of a live mouse.

a, Schematic (left; adapted from ref. ³⁰ (Wiley)) and imaging set-up (right) for Ca²⁺ imaging of enteric neuronal activity in response to luminal infusion of nutrient solution in a loop of mouse jejunum in vivo. The mouse was anaesthetized using isoflurane and its body temperature was maintained using an infrared lamp. Flexible tubing was inserted into a loop of jejunum proximal to the imaging site to infuse nutrient (acetate, 100 mM; n = 3 mice) or Krebs solution (control; n = 2 mice), and distal to the imaging site for the outflow of solution. The jejunal loop was stabilized using a custom-designed silicone mesh. b,c, Top, acetate (b) or Krebs solution (c) was applied, and examples of responding neurons are indicated (arrowheads). Frames from the live recording (green overlay, live) are mapped onto an image of the fixed MP (greyscale, fixed) using a semi-automated registration strategy. Middle, traces depict Ca²⁺ transients in the responding neurons (green arrowheads). The start of acetate or Krebs application is marked with white arrows. Bottom, with post hoc immunolabelling (immunohistochemistry; IHC) of imaged myenteric neurons (Hu⁺), acetate responders included calbindin⁺ and nNOS⁺ neurons (b), whereas Krebs infusion activated nNOS⁺ neurons (c). Scale bars, 50 µm.