The α2δ-1-NMDA Receptor Complex Is Critically Involved in Neuropathic Pain Development and Gabapentin Therapeutic Actions

Highlights

• α2δ-1 forms a heteromeric complex with NMDARs, mainly through its C terminus domain

• α2δ-1 is essential for nerve injury-induced pre- and postsynaptic NMDAR hyperactivity

• α2δ-1 promotes synaptic and surface expression of α2δ-1-NMDAR complexes

• α2δ-1-bound NMDARs are critical for neuropathic pain development and gabapentin actions

Summary

α2δ-1, commonly known as a voltage-activated Ca²⁺ channel subunit, is a binding site of gabapentinoids used to treat neuropathic pain and epilepsy. However, it is unclear how α2δ-1 contributes to neuropathic pain and gabapentinoid actions. Here, we show that Cacna2d1 overexpression potentiates presynaptic and postsynaptic NMDAR activity of spinal dorsal horn neurons to cause pain hypersensitivity. Conversely, Cacna2d1 knockdown or ablation normalizes synaptic NMDAR activity increased by nerve injury. α2δ-1 forms a heteromeric complex with NMDARs in rodent and human spinal cords. The α2δ-1-NMDAR interaction predominantly occurs through the C terminus of α2δ-1 and promotes surface trafficking and synaptic targeting of NMDARs. Gabapentin or an α2δ-1 C terminus-interfering peptide normalizes NMDAR synaptic targeting and activity increased by nerve injury. Thus, α2δ-1 is an NMDAR-interacting protein that increases NMDAR synaptic delivery in neuropathic pain. Gabapentinoids reduce neuropathic pain by inhibiting forward trafficking of α2δ-1-NMDAR complexes.