Efeito neuroprotetor de Anacardium Microcapum-duke em dano induzido por 6-ohda em córtex cerebral de Pintainhos

Abstract

Parkinson's disease (PD) is a degenerative, chronic and progressive disease, which affects the central nervous system and it is responsible for degeneration of dopaminergic neurons. It is known that genetic and environmental factors such as exposure to agrochemical, oxidative stress and mitochondrial dysfunction are associated with progression of the disease. 6hydroxydopamine (6-OHDA) is a structural analogue of catecholamine dopamine, used as a model of neurotoxicity by similar mechanism in PD. The mechanism of cytotoxicity attributed to 6-OHDA is linked to the production of reactive oxygen species (ROS) from inhibition of mitochondrial respiration and its autoxidation. The search for alternative therapies such as antioxidants has grown over the years, seeking to mitigate the progress of PD through bioactive plant compounds. This study aimed to evaluate the neuroprotective effect of Anacardium microcarpum on the damage induced by neurotoxin 6-OHDA in cortical slices of chicks. Slices were incubated for 2 h in the presence of neurotoxin and different concentrations of hydroalcoholic extract (AMHE) and ethyl acetate (AMEAF) and methanol (AMMF) fractions of A. microcarpum. AMHE, AMMF and AMEAF (1-1000 μg/mL) did not show cytotoxicity per se in the cortical slices. AMMF and AMEAF restored the drop in viability caused by 6OHDA (500 μM) from the concentration of 100 μg/mL. 6-OHDA increased GST and TrxR activity while GPx activity and total GSH levels was decreased with an augmented ratio GSH / GSSG. These effects were not observed in the presence of AMMF and 6-OHDA. Furthermore, 6-OHDA inhibited the complex I of the mitochondrial respiratory chain but this effect was not reversed by fraction as well as the self-oxidation of 6-OHDA was not avoided by the plant. Phosphorylation of p38, JNK1/2, ERK1/2 and AKT as well as PARP cleavage was evaluated against treatment with neurotoxin and methanolic fraction. The methanolic fraction and 6OHDA did not alter phosphorylation of MAPKs, as well as expression of these proteins, not did it result in the cleavage of the PARP protein in the time studies. However, in the presence of fraction and 6-OHDA there was a significant increase in ERK1/2 phosphorylation without altering its expression. The involvement of ERK1/2 and AKT proteins in protective mechanism of fraction was analyzed through the use of inhibitors. It was observed that in presence of inhibitor, the extract was not able to protect against the damage promoted by 6-OHDA. Our results suggest that the extract presented antioxidant action against oxidative stress resulted from the inhibition of mitochondrial respiration and neurotoxin autoxidation. In addition, it is suggested that antiapoptotic proteins ERK1/2 and AKT are involved in neuroprotective effect of the fraction. Our data show for the first time a neuroprotective action of A. microcarpum against neuronal damage induced by 6-OHDA in cerebral slices and highlights the potential of this plant as a source of bioactive compounds with therapeutic potential