Antioxidant effect of exercise: Exploring the role of the mitochondrial complex I superassembly

Mitochondrial respiratory complexes become assembled into supercomplexes (SC) under physiological conditions. One of the functional roles of these entities is the limitation of reactive oxygen species (ROS) produced by complex I (CI) of the respiratory chain. We sought to determine whether the systemic antioxidant effect of exercise is mediated by the assembly of mitochondrial CIs into SCs in rats. Male Wistar rats were exercise trained or remained sedentary for ten weeks; then, blood samples were collected, and the gastrocnemius muscle was isolated. The assembly of mitochondrial SCs and the lipid peroxidation of the mitochondrial and plasmatic fractions were assessed. Our results demonstrate that exercise induced the assembly of CI into SCs in the gastrocnemius and induced a systemic decrease in lipid peroxidation. We also found an inverse association between the superassembly of CIs and mitochondrial lipid peroxidation (p < 0.01) and protein carbonyls (p < 0.05). We conclude that exercise induces the chronic assembly of CIs into SCs, which provide mitochondrial protection against oxidative damage, at least in the studied muscle. Given the relevant role that mitochondria play in health and disease, these findings should help to elucidate the role of exercise as a therapeutic approach for metabolic diseases.

DMSO affects Aβ1–40's conformation and interactions with aggregation inhibitors as revealed by NMR

DMSO alters Abeta's conformation and its recognition by inhibitors.

Human CoQ10 deficiencies

Coenzyme Q10 (CoQ10 or ubiquinone) is a lipid-soluble component of virtually all cell membranes and has multiple metabolic functions. A major function of CoQ10 is to transport electrons from complexes I and II to complex III in the respiratory chain which resides in the mitochondrial inner membrane. Deficiencies of CoQ10 (MIM 607426) have been associated with four major clinical phenotypes: 1) encephalomyopathy characterized by a triad of recurrent myoglobinuria, brain involvement, and ragged-red fibers; 2) infantile multisystemic disease typically with prominent nephropathy and encephalopathy; 3) cerebellar ataxia with marked cerebellar atrophy; and 4) pure myopathy. Primary CoQ10 deficiencies due to mutations in ubiquinone biosynthetic genes (COQ2, PDSS1, PDSS2, and ADCK3 [CABC1]) have been identified in patients with the infantile multisystemic and cerebellar ataxic phenotypes. In contrast, secondary CoQ10 deficiencies, due to mutations in genes not directly related to ubiquinone biosynthesis (APTX, ETFDH, and BRAF), have been identified in patients with cerebellar ataxia, pure myopathy, and cardiofaciocutaneous syndrome. In many patients with CoQ10 deficiencies, the causative molecular genetic defects remain unknown; therefore, it is likely that mutations in additional genes will be identified as causes of CoQ10 deficiencies.

Melatonin administration prevents cardiac and diaphragmatic mitochondrial oxidative damage in senescence-accelerated mice

Cardiac and diaphragmatic mitochondria from male SAMP8 (senescent) and SAMR1 (resistant) mice of 5 or 10 months of age were studied. Levels of lipid peroxidation (LPO), glutathione (GSH), GSH disulfide (GSSG), and GSH peroxidase and GSH reductase (GRd) activities were measured. In addition, the effect of chronic treatment with the antioxidant melatonin from 1 to 10 months of age was evaluated. Cardiac and diaphragmatic mitochondria show an age-dependent increase in LPO levels and a reduction in GSH:GSSG ratios. Chronic treatment with melatonin counteracted the age-dependent LPO increase and GSH:GSSG ratio reduction in these mitochondria. Melatonin also increased GRd activity, an effect that may account for the maintenance of the mitochondrial GSH pool. Total mitochondrial content of GSH increased after melatonin treatment. In general, the effects of age and melatonin treatment were similar in senescence-resistant mice (SAMR1) and SAMP8 cardiac and diaphragmatic mitochondria, suggesting that these mice strains display similar mitochondrial oxidative damage at the age of 10 months. The results also support the efficacy of long-term melatonin treatment in preventing the age-dependent mitochondrial oxidative stress.

Mechanisms of N-methyl-D-aspartate receptor inhibition by melatonin in the rat striatum

N-methyl-D-aspartate (NMDA) receptor activation comprises multiple regulatory sites controlling Ca2+ influx into the cell. NMDA-induced increases in intracellular [Ca(+2)] lead to nitric oxide (NO) production through activation of neuronal NO synthase (nNOS). Melatonin inhibits either glutamate or NMDA-induced excitation, but the mechanism of this inhibition is unknown. In the present study, the mechanism of melatonin action in the rat striatum was studied using extracellular single unit recording of NMDA-dependent neuronal activity with micro-iontophoresis. Melatonin inhibited neuronal excitation produced by either NMDA or L-arginine. The effects of both NMDA and L-arginine were blocked by nitro-L-arginine methyl ester, suggesting that nNOS participates in responses to NMDA. However, excitation of NMDA-sensitive neurones induced by the NO donor sodium nitroprusside was only slightly modified by melatonin. Melatonin iontophoresis also counteracted excitation induced by tris(2-carboxyethyl)phosphine hydrochloride, showing that the redox site of the NMDA receptor may be a target for melatonin action. The lack of effects of the membrane melatonin receptor ligands luzindole, 4-phenyl-2-propionamidotetralin and 5-methoxycarbonylamino-N-acetyltryptamine, and the nuclear melatonin ligand, CGP 52608, a thiazolidine dione, excluded the participation of known membrane and nuclear receptors for melatonin. The data suggest that inhibition of NMDA-dependent excitation by melatonin involves both nNOS inhibition and redox site modulation.

Immigrant and Native-born Mexican-American parents' involvement in a public school: a preliminary study

Mexican-American parents of Texas elementary school students were surveyed to compare the types of school involvement in which immigrant and U.S.-born parents engage. Those completing the questionnaire included 246 mothers and 39 fathers born in Mexico as well as 95 mothers and 13 fathers born in the United States. More immigrant parents than U.S.-born parents indicated they helped their children with school work, attended school board meetings, volunteered at school, participated in parent-teacher conferences, went to school functions, served as room mother, engaged in school fundraising, and were present during parent advisory committee meetings.

Smokeless tobacco use by secondary students in a Mexican bordertown

Of secondary students living in a Mexican bordertown, 67 boys and 45 girls aged 13 to 18 years, 5 boys reported trying chewing tobacco, but none reported current use, and 61 students believed such use could cause cancer. Low prevalence may be related to low exposure to advertising.