Fig. 3: Transient thalamic galanin expression complements Galr1 expression in glutamatergic neurons of the principal sensory trigeminal nucleus (Pr5).

a Schema of the somatosensory whisker pathway with its neuronal relay sites in the Pr5 and VB highlighted. b In situ hybridization revealed promiscuous Gal expression in the ventrobasal thalamus (VB) on postnatal day (P)7. Note that Galr1 expression could not be detected in Slc17a6⁺ glutamatergic neurons of the VB (arrowheads in ‘1’). Conversely, the Pr5 contained Slc17a6⁺ neurons that harbored Galr1 but not Gal expression (arrowheads, c). Open dashed rectangles in b, c denote the positions of the insets (‘1’). d Single-nucleus RNA-seq from the VB identified Gal⁺ neurons as glutamatergic (Slc17a6⁺; d₁) at P7, which also expressed many chemotropic guidance cues d₂. e Single-nucleus RNA-seq from the Pr5 revealed that Slc17a6⁺ sensory trigeminal projection neurons expressed Galr1 at P7 e₁, offering receptor complementation for thalamic galanin expression, like other receptors for chemotropic guidance cues of the thalamus e₂. Panels b, c are representative of three independent experiments in n = 3 mice. Scale bars = 400 µm b, c; 7 μm (insets).