Atividade induzida pelo extrato de algas cianofíceas contendo anatoxina-a(s) sobre o sistema nervoso central e periférico de vertebrados

Abstract

The anatoxin-a (S) is known as the only naturally occurring organophosphate from secondary metabolism of green algae. These compounds have been reported to cause not reversible inhibitory activity upon the enzyme acetylcholinesterase. The aim of this work was to investigate the biological activities induced by the green algae extracts containing-anatoxin-a(S) on the central and peripheral nervous system of vertebrates. It was used adult SPF female mice (Swiss) and newborn chicks (Hy Line W36). Hippocampal slice preparations were used to measure cell viability and chick biventer cervicis muscle preparations for the neuromuscular activity. Statistical analysis was performed using ANOVA and Student "t" tests. Results were considered significant when p<0.05. At in vitro biventer cervicis muscle preparations the assay of the extract of green algae containing-anatoxin-a(S) (2, 4 and 8g/ml) demonstrated a dose and time-dependent effect upon the muscle twitch tension (n=6, p<0.05). With the concentration of 2g/ml there was a transitory increase in the amplitude of muscle twitches followed by partial inhibition of the muscle twitches in 120 min recordings. With the higher concentrations there was 100% blockage of muscle twitches that was not preceded of facilitation in 120 min recordings. The cell viability assays in hippocampal slices showed that the extracts (1, 2, 4 and 8g/ml) induced both neuroprotection and neurotoxicity (n = 6, p<0.05). Thus, the concentrations of 2 and 8g/ml induced only neuroprotection while those with 4g/ml induced decrease in the cell viability (n=6, p<0.05, respectively). The assay with trichlorfon, a common organophosphate, induced only decrease in cell viability. It is concluded that in vertebrates at in vitro models the extract of cyanobacteria containing anatoxin-a (S) induces both neurotoxicity and neuroprotection at central nervous system and neuromuscular blocking actions, similarly to other organophosphate compounds with anticholinesterase activity.