The increased trafficking of the calcium channel subunit α2δ-1 to presynaptic terminals in neuropathic pain is inhibited by the α2δ ligand pregabalin

CS Bauer, M Nieto-Rostro, W Rahman… - Journal of …, 2009 - Soc Neuroscience
CS Bauer, M Nieto-Rostro, W Rahman, A Tran-Van-Minh, L Ferron, L Douglas, I Kadurin
Journal of Neuroscience, 2009Soc Neuroscience
Neuropathic pain results from damage to the peripheral sensory nervous system, which may
have a number of causes. The calcium channel subunit α2δ-1 is upregulated in dorsal root
ganglion (DRG) neurons in several animal models of neuropathic pain, and this is causally
related to the onset of allodynia, in which a non-noxious stimulus becomes painful. The
therapeutic drugs gabapentin and pregabalin (PGB), which are both α2δ ligands, have
antiallodynic effects, but their mechanism of action has remained elusive. To investigate this …
Neuropathic pain results from damage to the peripheral sensory nervous system, which may have a number of causes. The calcium channel subunit α2δ-1 is upregulated in dorsal root ganglion (DRG) neurons in several animal models of neuropathic pain, and this is causally related to the onset of allodynia, in which a non-noxious stimulus becomes painful. The therapeutic drugs gabapentin and pregabalin (PGB), which are both α2δ ligands, have antiallodynic effects, but their mechanism of action has remained elusive. To investigate this, we used an in vivo rat model of neuropathy, unilateral lumbar spinal nerve ligation (SNL), to characterize the distribution of α2δ-1 in DRG neurons, both at the light- and electron-microscopic level. We found that, on the side of the ligation, α2δ-1 was increased in the endoplasmic reticulum of DRG somata, in intracellular vesicular structures within their axons, and in the plasma membrane of their presynaptic terminals in superficial layers of the dorsal horn. Chronic PGB treatment of SNL animals, at a dose that alleviated allodynia, markedly reduced the elevation of α2δ-1 in the spinal cord and ascending axon tracts. In contrast, it had no effect on the upregulation of α2δ-1 mRNA and protein in DRGs. In vitro, PGB reduced plasma membrane expression of α2δ-1 without affecting endocytosis. We conclude that the antiallodynic effect of PGB in vivo is associated with impaired anterograde trafficking of α2δ-1, resulting in its decrease in presynaptic terminals, which would reduce neurotransmitter release and spinal sensitization, an important factor in the maintenance of neuropathic pain.
Soc Neuroscience