Figure 7. Differential Primary Sensory and Descending Neuron Inputs onto Glutamatergic and GABAergic Penk+ Neurons.
(A) DRG sections from PenkCre mice in which AAV helpers and GFP-expressing RVdG were injected in the dorsal horn, as in Figure 1J, showing that DRG neurons with both small- and large-diameter cell bodies express GFP and thus project onto Penk+ spinal neurons.
(B) Immunostaining indicating that GFP+ DRG neurons shown in (A) include Ret+ myelinated (NF200+) mechanoreceptors and CGRP+ unmyelinated (NF200−) nociceptors.
(C) Skin analysis confirmed that GFP+ DRG neurons were cutaneous afferents, including myelinated mechanoreceptors forming circumferential and longitudinal lanceolate endings around hair follicles, and nociceptors forming epidermal free nerve endings.
(D) Molecular identity of GFP+ DRG neurons.
(E) Experimental approach used to determine whether Penk+ neurons receive inputs from primary afferent neurons expressing DOR or MOR.
(F) Penk+ neurons showing a delayed firing pattern (top left) present a decrease in EPSC amplitude and increase in PPR (bottom left) following light stimulation. In contrast, Penk+ neurons presenting a tonic firing pattern (top right) do not show any change in EPSC amplitude or PPR (bottom right). Gray and blue traces represent paired EPSCs before and 1,000 ms after light stimulation, respectively.
(G) Quantification of (F) (two-way ANOVA, Bonferroni post hoc test, *p < 0.05, **p < 0.01, ***p < 0.001).
“S” indicates dorsal root stimulation artifacts. Scale bars represent 50 μm. All bar graphs represent mean ± SEM.
See also Figure S7.