Mouse spinal cord cellular mapping of dopamine D2 receptors-containing cells.

The spinal cord (SC) serves as the primary relay for sensory information originating in the periphery and transmitted to the brain for processing. Sensitive primary afferent fibers project to the dorsal horn, which contains a highly diverse array of neurons forming a complex network of excitatory and inhibitory circuits. Previous studies have indicated that this neuronal network can be modulated by the monoaminergic system, particularly through the spinal dopaminergic circuit, partly via dopamine D2 receptors (D2R). However, the identity of the cells expressing D2R within the spinal cord remains largely unknown. By combining whole-mount immunostaining, volume imaging and Ribotag methodology, we analyzed the distribution and characterized the molecular identity of D2R-expressing cells of the mouse spinal cord. Our study revealed that D2R are expressed by neurons, but not glial cells, distributed preferentially in the dorsal horn of the spinal cord. Furthermore, SC D2R neurons were not motorneurons but instead belong to molecularly distinct classes of excitatory and inhibitory neuronal populations. By providing a detailed molecular characterization of D2R-expressing cells in the spinal cord, the present work lays the foundation for more targeted investigations into the specific functional roles of D2Rs in sensory information processing.