Recording of calcium responses in vagal neurons expressing GCaMP6s while stimulating mice with cytokines intraperitoneally. The heatmaps depict z -score-normalized fluorescence traces from two non-overlapping populations of neurons: responders to pro-inflammatory (Pro) cytokines (top panels) and responders to anti-inflammatory (Anti) cytokines (middle panels). Each row represents the activity of a single cell over 5 min. Stimulus was given at 60 s (dashed line). n = 5 mice, TNF (3 mice), IL-1 (2 mice) and IL-10 (5 mice); 21 of 423 imaged neurons responded to pro-inflammatory stimuli (13 to TNF and 8 to IL-1), and 11 of 423 responded to IL-10. As positive controls, we used intestinal stimulation with glucose (Glu; 10 s); this activates the gutbrain axis 5 , 6 , but stimulates different vagal neurons (lower panels). These imaging experiments used cytokine concentrations that were lower or comparable with that measured during LPS-induced inflammation (see Extended Data Fig. 10b ). The overall percent of responding neurons is similar to what is observed for vagal neurons dedicated to other bodybrain signalling pathways 2 , 6 . i.p., intraperitoneal.
