Cystine reduces mitochondrial dysfunction in C2C12 myotubes under moderate oxidative stress induced by H2O2.

Moderate oxidative stress induces temporal impairment in mitochondrial ATP production. As glutathione (GSH) content is reduced to eliminate oxidative stress by oxidation-reduction reaction, intracellular GSH content is crucial for maintaining mitochondrial function under oxidative stress. GSH precursors such as N-acetyl cysteine (NAC) and cysteine are known to suppress oxidative stress based on the supply of cysteine residues being rate-limiting for GSH synthesis. However, it remains unclear whether cystine (Cys2) can suppress mitochondrial dysfunction under oxidative stress conditions. Therefore, we examined whether Cys2 could attenuate mitochondrial dysfunction under moderate oxidative stress without scavenging reactive oxygen species (ROS) in the medium. C2C12 myotubes were incubated for 120 min in a Cys2-supplemented medium and subsequently exposed to hydrogen peroxide (H2O2). Heme oxygenase-1 (HO-1) gene expression, intracellular cysteine and GSH content, intracellular ATP level, and maximal mitochondrial respiration were assessed. Cys2 treatment significantly increased GSH content in a dose-dependent manner under oxidative stress. Cys2 treatment significantly decreased HO-1 expression induced by H2O2 exposure. In addition, maximal mitochondrial respiration rate was decreased by H2O2 exposure, but improved by Cys2 treatment. In conclusion, Cys2 treatment mitigates oxidative stress-induced mitochondrial dysfunction by maintaining GSH content under moderate oxidative stress without scavenging ROS in the medium.

Discovery and evaluation of selective N-type calcium channel blockers: 6-unsubstituted-1,4-dihydropyridine-5-carboxylic acid derivatives.

A structure-activity relationship study of 6-unsubstituted-1,4-dihydropyridine and 2,6-unsubstituted-1,4-dihydropyridine derivatives was conducted in an attempt to discover N-type calcium channel blockers that were highly selective over L-type calcium channel blockers. Among the tested compounds, (+)-4-(3,5-dichloro-4-methoxy-phenyl)-1,4-dihydro-pyridine-3,5-dicarboxylic acid 3-cinnamyl ester was found to be an effective and selective N-type calcium channel blocker with oral analgesic potential.

Dietary histidine ameliorates murine colitis by inhibition of proinflammatory cytokine production from macrophages.

BACKGROUND & AIMS: Elemental diet (ED) is effective for human Crohn's disease (CD). Although some of this effectiveness may be due to its low antigenic load and low fat content, the mechanisms remain unclear. We sought to assess the role of histidine, one of the constituent amino acids of ED, in controlling colitis. METHODS: The interleukin (IL)-10-deficient (IL-10(-/-)) cell transfer model of colitis was used. SCID mice with colitis induced by transfer of IL-10(-/-) cells were maintained on experimented diets containing either single amino acids or a mixture. The severity of colitis was assessed by wet colon weight. Colonic tumor necrosis factor (TNF)-alpha messenger RNA (mRNA) expression was detected by quantitative reverse-transcription polymerase chain reaction. Mouse peritoneal macrophages were stimulated by lipopolysaccharides (LPS), with or without amino acids. The concentration of cytokines in the supernatant was determined by enzyme-linked immunosorbent assay. Inhibitor of nuclear factor (NF)-kappaB-alpha and nuclear p65 were confirmed by immunoblotting. RESULTS: In the IL-10(-/-) transfer model, dietary histidine, but not alanine, reduced histologic damage and colon weight and TNF-alpha mRNA expression. Histidine inhibited LPS-induced TNF-alpha and IL-6 production by mouse macrophages in a concentration-dependent manner, whereas alanine or histidine-related metabolites had no such effect. Histidine inhibited LPS-induced NF-kappaB in macrophages. CONCLUSIONS: These results showed that histidine could be a novel therapeutic agent for CD by inhibition of NF-kappaB activation, following down-regulation of proinflammatory cytokine production by macrophages. Thus, our studies provided new insights into the roles of amino acid metabolism in the pathophysiology of CD and for therapeutic strategies.

Discovery, structure-activity relationship study, and oral analgesic efficacy of cyproheptadine derivatives possessing N-type calcium channel inhibitory activity.

Antiallergic drug cyproheptadine (Cyp) is known to have inhibitory activities for L-type calcium channels in addition to histamine and serotonin receptors. Since we found that Cyp had an inhibitory activity against N-type calcium channel, Cyp was optimized to obtain more selective N-type calcium channel blocker with analgesic action. As a consequence of the optimization, we found 13 with potent N-type calcium channel inhibitory activity which had lower inhibitory activities against L-type calcium channel, histamine (H1), and serotonin (5-HT2A) receptors than those of Cyp. 13 showed an oral analgesic activity in rat formalin-induced pain model.