The Effect of Spider Toxin PhTx3-4, omega-Conotoxins MVIIA and MVIIC on Glutamate Uptake and on Capsaicin-Induced Glutamate Release and [Ca2+](i) in Spinal cord Synaptosomes

作者：Goncaves Jomara M; Ferreira Juliano; Prado Marco Antonio M; Cordeiro Marta N; Richardson Michael; do Nascimento Pinheiro Ana Cristina; Romano Silva Marco A; de Castro Junior Celio Jose; Souza Alessandra H; Gomez Marcus Vinicius^*

来源：Cellular and Molecular Neurobiology, 2011, 31(2): 277-283.

DOI：10.1007/s10571-010-9618-5

• Spider and conus toxins
• Capsaicin
• Glutamate release
• Glutamate uptake intracellular calcium
• Spinal cord synaptosomes

In spinal cord synaptosomes, the spider toxin PhTx3-4 inhibited capsaicin-stimulated release of glutamate in both calcium-dependent and -independent manners. In contrast, the conus toxins, omega-conotoxin MVIIA and omega-conotoxin MVIIC, only inhibited calcium-dependent glutamate release. PhTx3-4, but not omega-conotoxin MVIIA or omega-conotoxin MVIIC, is able to inhibit the uptake of glutamate by synaptosomes, and this inhibition in turn leads to a decrease in the Ca2+-independent release of glutamate. No other polypeptide toxin so far described has this effect. PhTx3-4 and omega-conotoxins MVIIC and MVIIA are blockers of voltage-dependent calcium channels, and they significantly inhibited the capsaicin-induced rise of intracellular calcium [Ca2+](i) in spinal cord synaptosomes, which likely reflects calcium entry through voltage-gated calcium channels. The inhibition of the calcium-independent glutamate release by PhTx3-4 suggests a potential use of the toxin to block abnormal glutamate release in pathological conditions such as pain.

• 出版日期2011-3