Received: July 4, 2008.

Accepted: August 26, 2008.

Abstract published online: September 18, 2008.

Full paper published online: May 30, 2009.

NEUROTRANSMITTER EVALUATION IN THE HIPPOCAMPUS OF RATS AFTER INTRACEREBRAL INJECTION OF TsTX SCORPION TOXIN

Nencioni ALA (1), Barreto SA (2), Lebrun I (2), Florio JC (3), Lourenço GA (1), Dorce VAC (1)

(1) Laboratory of Pharmacology, Butantan Institute, São Paulo, São Paulo State, Brazil; (2) Laboratory of Biochemistry and Biophysics, Butantan Institute, São Paulo, São Paulo State, Brazil; (3) Laboratory of Pharmacology, School of Veterinary Medicine and Zootechny, University of São Paulo, USP, São Paulo, São Paulo State, Brazil.

ABSTRACT: TsTX is an α-type sodium channel toxin that stimulates the discharge of neurotransmitters from neurons. In the present study we investigated which neurotransmitters are released in the hippocampus after TsTX injection and if they are responsible for electrographic or histopathological effects. Microdialysis revealed that the toxin increased glutamate extracellular levels in the hippocampus; however, levels of gamma-aminobutyric acid (GABA), glycine, 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were not significantly altered. Neurodegeneration in pyramidal cells of hippocampus and electroencephalographic alterations caused by the toxin were blocked by pretreatment with riluzole, a glutamate release inhibitor. The present results suggest a specific activity of TsTX in the hippocampus which affects only glutamate release.

KEY WORDS: scorpion toxin, microdialysis, hippocampus, neurotransmitters, neurodegeneration, riluzole.

CONFLICTS OF INTEREST: There is no conflict.

CORRESPONDENCE TO:

VALQUIRIA ABRÃO CORONADO DORCE, Laboratório de Farmacologia, Instituto Butantan, Av. Dr. Vital Brasil, 1500, São Paulo, SP, 05503-900, Brasil. Phone: +55 11 3726 7222, ext. 2133. Fax: +55 11 3726 1505. Email: vdorce@butantan.gov.br.