Acute administration of methionine and/or methionine sulfoxide impairs redox status and induces apoptosis in rat cerebral cortex

Abstract

High plasma levels of methionine (Met) and its metabolites such as methionine sulfoxide (MetO) may occur in several genetic abnormalities. Patients with hypermethioninemia can present neurological dysfunction; however, the neurotoxicity mechanisms induced by these amino acids remain unknown. The aim of the present work was to study the effects of Met and/or MetO on oxidative stress, genotoxicity, cytotoxicity and to evaluate whether the cell death mechanism is mediated by apoptosis in the cerebral cortex of young rats. Forty-eight Wistar rats were divided into groups: saline, Met 0.4 g/Kg, MetO 0.1 g/Kg and Met 0.4 g/Kg + MetO 0.1 g/Kg, and were euthanized 1 and 3 h after subcutaneous injection. Results showed that TBARS levels were enhanced by MetO and Met+MetO 1 h and 3 h after treatment. ROS was increased at 3 h by Met, MetO and Met+MetO. SOD activity was increased in the Met group, while CAT was reduced in all experimental groups 1 h and 3 h after treatment. GPx activity was enhanced 1 h after treatment by Met, MetO and Met+MetO, however it was reduced in the same experimental groups 3 h after administration of amino acids. Caspase-3, caspase-9 and DNA damage was increased and cell viability was reduced by Met, MetO and Met+MetO at 3 h. Also, Met, MetO and Met+MetO, after 3 h, enhanced early and late apoptosis cells. Mitochondrial electrochemical potential was decreased by MetO and Met+MetO 1 h and 3 h after treatment. These findings help understand the mechanisms involved in neurotoxicity induced by hypermethioninemia.

Keywords: DNA damage; apoptosis; caspases; methionine; methionine sulfoxide; oxidative stress.