Modulation of voltage-gated Ca²⁺ channels in rat retinal ganglion cells by gabapentin

Abstract

The α2δ auxiliary subunits of voltage-gated Ca2+ channels (VGCCs) are important modulators of VGCC function. Gabapentin interacts with α2δ1 and α2δ2 subunits and is reported to reduce Ca2+ channel current amplitude (ICa). This study aimed to determine the effects of gabapentin on VGCCs in retinal ganglion cells (RGCs). Whole cell patch clamp was used to record ICa in isolated RGCs, and calcium imaging was used to measure Ca2+ transients from RGCs in situ. Immunohistochemistry was used to detect the presence of α2δ1-containing VGCCs in isolated RGCs in the absence and presence of gabapentin pretreatment. Acute administration of gabapentin reduced ICa and Ca2+ transients compared to control conditions. In isolated RGCs, pretreatment with gabapentin (4–18 h) reduced ICa, and cell surface α2δ1 staining was reduced compared to nonpretreated cells. Acute administration of gabapentin to isolated RGCs that had been pretreated further reduced ICa. These results show that gabapentin has both short-term and long-term mechanisms to reduce ICa in isolated RGCs. Some Ca2+ channel blockers have been shown to protect RGCs in retinal trauma suggesting that modulation of VGCCs by gabapentin may prevent the deleterious effects of elevated Ca2+ levels in RGCs in trauma and disease.

The Auxiliary Calcium Channel Subunit α2δ4 Is Required for Axonal Elaboration, Synaptic Transmission, and Wiring of Rod Photoreceptors

“…It is possible that the function of α2δ4 in cones is redundant with another, cone-specific α2δ member, which compensates partially for its loss. Indeed, the presence of other α2δ isoforms in the photoreceptor synaptic layer has been documented (Farrell et al, 2014; Perez de Sevilla Muller et al, 2015). Alternatively, cones may use different molecular mechanisms for synaptogenesis.…”

Genetic Networks in Mouse Retinal Ganglion Cells

“…Furthermore, the network was enriched in transmembrane ion transporters. This included several calcium- and sodium-gated channel subunits, all of which have been previously localized to RGCs (Lipton and Tauck, 1987 ; Farrell et al, 2014 ).…”

Macroglia-derived thrombospondin 2 regulates alterations of presynaptic proteins of retinal neurons following elevated hydrostatic pressure

“…As was shown in the immunofluorescence assay, the immunofluorescence intensity of α2δ-1 in the GBP group was weaker than in the 12 h group ( Fig 9D ). This indicated that GBP could effectively decease the cell surface expression of α2δ-1 so that GBP could block the interaction of TSP2 with α2δ-1[ 35 ].…”

“…Then, the cultures were washed 3 times as described above and incubated with Alexa-conjugated secondary antibodies (1:500, Jackson Immuno Research, West Grove, PA, USA) for 2 h. After washing three times in PBS, the cultures were covered with Vectashield mounting medium containing DAPI (Vector Laboratories, Burlingame, USA). The cells immunostained with the α2δ-1 antibody were not permeabilized with Triton-X to limit antibody staining to the cell surface[ 35 ]. For immunofluorescence intensity analysis, all the cell cultures were stained simultaneously under the same setting.…”