Neurochemistry international
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Two intracellular cysteine proteases (calpains and caspases) and inducible nitric oxide synthase (iNOS) participate in the ischemic brain injury. In vitro nitric oxide (NO) regulates calpain and caspase-3 activation. The present study investigated whether aminoguanidine (AG), an iNOS inhibitor, protected brain against experimental stroke through inhibiting calpain and caspase-3 activation. ⋯ Enzymatic studies demonstrated the significant inhibition of the activities of mu- and m-calpain and caspase-3, and Western blot analysis revealed marked increases in the levels of MAP-2 and spectrin in penumbra and core in AG-treated rats versus vehicle-treated rats. AG also significantly enhanced the calpastatin levels in core, although it had no significant effects on that in penumbra. These data demonstrate that inhibiting calpain and caspase-3 activation is one mechanism of AG against experimental stroke, suggesting that NO produced by iNOS may be involved in calpain- and caspase-3-mediated ischemic cell death, at least in part.
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Post-translational modification of histone such as acetylation of N-terminal of lysine residues influences gene expression by modulating the accessibility of specific transcription factors to the promoter region, and is essential for a wide variety of cellular processes in the development of individual tissues, including the brain. However, few details concerning the acquisition of specific neurotransmitter phenotype have been obtained. ⋯ Furthermore, RT-PCR analysis using primer pairs for individual variants of ChAT mRNA (R1-4, N1, and M type) revealed that M type, not R1-4 and N1 type, ChAT mRNA were mainly transcribed, and chromatin immunoprecipitation assay indicated that the promoter region of M type ChAT gene was highly acetylated, in the dibutyryl cyclic AMP-induced neuronal differentiation of NG108-15 cells. The present findings demonstrate that the acquisition of neurotransmitter phenotype is epigenetically, at least the hyper-acetylation on the core promoter region of ChAT gene, regulated in NG108-15 neuronal cells.