Stimulation of dopamine release by activation of the voltage-sensitive sodium channel by scorpion venom neurotoxin

Abstract

Scorpion venom neurotoxins open sodium channels and thus may enhance neurotransmitter release by increasing membrane permeability to sodium. This study carried out in vivo examined the effects of the scorpionAndroctonus australis neurotoxin (ScAaTx) on the levels of dopamine (DA) in push-pull perfusates of the striatum of chloral hydrate-anaesthetised rats. ScAaTx (2.5, 5.0 and 10.0 ng/µl) stimulated DA release in a dose-dependent manner. The release of DA induced by ScAaTx (10 ng/µl) was completely blocked when the brain site was perfused with Ca²⁺-free CSF containing 2 mM EGTA or in the presence of TTX (10^-5 M). These results indicate that the potent stimulatory effects of ScAaTx on neostriatal DA release in vivo are mediated via voltage-sensitive sodium channels.