Delta Opioid Receptors Presynaptically Regulate Cutaneous Mechanosensory Neuron Input to the Spinal Cord Dorsal Horn

The study revealed that the opioid system, particularly through delta opioid receptors (DOR), played a significant role in regulating cutaneous mechanosensation, including both touch and pain. DORs were found on myelinated mechanoreceptors associated with structures like Meissner corpuscles and Merkel cell-neurite complexes. These receptors also appeared on a subset of nociceptors coexpressing mu and delta opioid receptors. Activation of DORs at the central terminals of these mechanoreceptors inhibited synaptic input to the spinal dorsal horn by blocking voltage-gated calcium channels. This mechanism suggested that targeting DOR could be a potential strategy for managing injury-induced mechanical hypersensitivity.