Gabapentin (1(aminomethyl) cyclohexane acetic acid; GBP) is a recently developed anticonvulsant, for which the mechanism of action remains quite elusive. Besides its possible interaction with glutamate synthesis and/or GABA release, in cerebral membranes gabapentin has been shown to bind directly to the α2δ subunit of the calcium channel. Therefore, we have tested the possibility that gabapentin affects high threshold calcium currents in central neurons. Calcium currents were recorded in whole-cell patch-clamp mode in neurons isolated from neocortex, striatum and external globus pallidus of the adult rat brain. A large inhibition of calcium currents by gabapentin was observed in pyramidal neocortical cells (up to 34%). Significantly, the gabapentin-mediated inhibition of calcium currents saturated at particularly low concentrations (around 10 μM), at least in neocortical neurons (IC50 about 4 μM). A less significant inhibition was seen in medium spiny neurons isolated from striatum (- 12.4%) and in large globus pallidus cells (- 10.4%). In all these areas, however, the GBP- induced block was fast and largely voltage-independent. Dihydropyridines (nimodipine, nifedipine) prevented the gabapentin response. ω-conotoxin GVIA and ω-conotoxin MVIIC, known to interfere with the currents driven by α 1b and α 1a calcium channels, did not prevent but partially reduced the response. These findings imply that voltage-gated calcium channels, predominately the L-type channel, are a direct target of gabapentin and may support its use in different clinical conditions, in which intracellular calcium accumulation plays a central role in neuronal excitability and the development of cellular damage.
- Calcium currents
- Neuroprotective agents
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience
- Drug Discovery