Citation

Garcia RC, Dati LM, Fukuda S, Torres LH, Moura S, de Carvalho ND, Carrettiero DC, Camarini R, Levada-Pires AC, Yonamine M, Neto ON, Abdalla FMF, Sandoval MR, Afeche SC, Marcourakis T. Toxicol. Sci. 2012; 128(1): 223-234.

Affiliation

Department of Clinical and Toxicological Analysis, School of Pharmaceutical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 580, Bl. 13B, 05508-900, São Paulo/SP, Brazil.

Copyright

(Copyright © 2012, Oxford University Press)

DOI

10.1093/toxsci/kfs140

PMID

22523227

Abstract

Smoking crack cocaine involves the inhalation of cocaine and its pyrolysis product, anhydroecgonine methyl ester (AEME). There is evidence that cocaine is neurotoxic, but the neurotoxicity of AEME has never been evaluated. AEME seems to have cholinergic agonist properties in the cardiovascular system; however, there are no reports on its effects in the central nervous system. The aim of this study was to investigate the neurotoxicity of AEME and its possible cholinergic effects in rat primary hippocampal cell cultures that were exposed to different concentrations of AEME, cocaine and to a cocaine-AEME combination. We also evaluated the involvement of muscarinic cholinergic receptors in the neuronal death induced by these treatments using concomitant incubation of the cells with atropine. Neuronal injury was assessed using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. The results of the viability assays showed that AEME is a neurotoxic agent that has greater neurotoxic potential than cocaine after 24 and 48 hours of exposure. We also showed that incubation for 48 hours with the combination of both compounds in equipotent concentrations had an additive neurotoxic effect. Although both substances decreased cell viability in the MTT assay, only cocaine increased LDH release. Caspase 3 activity was increased after incubation with 1 mM cocaine and after 6 hours of 0.1 and 1 mM AEME exposure. Atropine prevented the AEME-induced neurotoxicity, which suggests that muscarinic cholinergic receptors are involved in AEME's effects. In addition, binding experiments confirmed that AEME has an affinity for muscarinic cholinergic receptors. Nevertheless, atropine was not able to prevent the neurotoxicity produced by cocaine and the cocaine-AEME combination, suggesting that these treatments activated other neuronal death pathways. Our results suggest a higher risk for neurotoxicity after smoking crack cocaine than after cocaine use alone.

Language: en