Effects of Tityustoxin on Central Nervous System

Abstract

Tityustoxin mimics many effects of electrical stimulation causing cell depolarization that increases the uptake of Na⁺ and Ca²⁺ ions and the release of acetylcholine in rat brain cortical slices and synaptosomes. Tityustoxin caused mobilization of acetylcholine from the cytoplasmic and crude vesicular fractions. The release of acetylcholine by tityustoxin is Na⁺ and Ca^{2 +} dependent and is inhibited by tetrodotoxin. Tityustoxin-stimulated release of acetylcholine is blocked by ω-Agatoxin an antagonist of P-type calcium channel. The toxin activates the voltage dependent sodium channel stimulating the turnover of inositol phosphates. Chemical groups in the cell membrane, particularly SH groups, are essential for the tityustoxin-induced release of acetylcholine. Tityustoxin increased the incorporation of ³²P into synapsin I and the effect is blocked by calmodulin inhibitors. Tityustoxin increased the release of norepinephrine, glutamate, γ-aminobutyric and excitatory aminoacids. It is concluded that tityustoxin is an important tool in studies of neurotransmitter release and signal transduction.