Fig. 5.

NPY-triggered hunger signaling activates GABAergic IRt/PCRt neurons innervating the rMR. a In vivo extracellular unit recording of action potentials of a rat IRt/PCRt neuron, which was confirmed to project to the rMR with a collision test [69]. An intracerebroventricular (ICV) NPY injection increased the firing rate of this neuron (unit) and reversed BAT SNA and T _BAT that had been increased by moderate body cooling. T _rec, rectal temperature. b Histochemical identification of a recorded IRt/PCRt neuron innervating the rMR with juxtacellular labeling (green, arrow). In situ hybridization revealed that this neuron expressed Gad1 mRNA (red), a marker of GABAergic neurons. Scale bar, 30 μm. c Location of rMR-projecting IRt/PCRt neurons successfully identified with juxtacellular labeling. Among them, all neurons activated by NPY injection expressed Gad1 (filled circles), whereas the Gad1-negative one did not respond to NPY injection (open circle). Modified from Nakamura et al. [69] with permission