Male mice receiving vitamin E (5.0 g alpha-tocopherol acetate/kg of food) from 28 wk of age showed a 40% increased median life span, from 61 +/- 4 wk to 85 +/- 4 wk, and 17% increased maximal life span, whereas female mice equally supplemented exhibited only 14% increased median life span. The alpha-tocopherol content of brain and liver was 2.5-times and 7-times increased in male mice, respectively. Vitamin E-supplemented male mice showed a better performance in the tight-rope (neuromuscular function) and the T-maze (exploratory activity) tests with improvements of 9-24% at 52 wk and of 28-45% at 78 wk. The rates of electron transfer in brain mitochondria, determined as state 3 oxygen uptake and as NADH-cytochrome c reductase and cytochrome oxidase activities, were 16-25% and 35-38% diminished at 52-78 wk. These losses of mitochondrial function were ameliorated by vitamin E supplementation by 37-56% and by 60-66% at the two time points considered. The activities of mitochondrial nitric oxide synthase and Mn-SOD decreased 28-67% upon aging and these effects were partially (41-68%) prevented by vitamin E treatment. Liver mitochondrial activities showed similar effects of aging and of vitamin E supplementation, although less marked. Brain mitochondrial enzymatic activities correlated negatively with the mitochondrial content of protein and lipid oxidation products (r2 = 0.58-0.99, P < 0.01), and the rates of respiration and of complex I and IV activities correlated positively (r2 = 0.74-0.80, P < 0.01) with success in the behavioral tests and with maximal life span.

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Navarro A, Ló pez-Cepero JM, Bá ndez MJ, Sá nchez-Pino M-J, Gó mez C, Cadenas E, Boveris A. Hippocampal mitochondrial dysfunction in rat aging. Am J Physiol Regul Integr Comp Physiol 294: R501-R509, 2008. First published December 12, 2007 doi:10.1152/ajpregu.00492.2007.-Hippocampus mitochondrial dysfunction with impaired electron transfer and increased oxidative damage was observed upon rat aging. Hippocampal mitochondria of aged (12 mo) and senescent (20 mo) rats showed, compared with young (4 mo) rats, marked decreases in the rate of state 3 respiration with NAD-dependent substrates (32-51%) and in the activities of mitochondrial complexes I (57-73%) and IV (33-54%). The activity of mitochondrial nitric oxide synthase was also decreased, 53-66%, with age. These losses in enzymatic activity were more marked in the hippocampus than in brain cortex or in whole brain. The histochemical assay of mitochondrial complex IV in the hippocampus showed decreased staining upon aging. Oxidative damage, determined as the mitochondrial content of thiobarbituric-acid reactive substances (TBARS) and protein carbonyls, increased in aged and senescent hippocampus (66 -74% in TBARS and 48 -96% in carbonyls). A significant statistical correlation was observed between mitochondrial oxidative damage and enzymatic activity. Mitochondrial dysfunction with shortage of energy supply is considered a likely cause of dysfunction in aged hippocampus. mitochondrial nitric oxide synthase; reduced nicotinamide adenide dinucleotide dehydrogenase; cytochrome oxidase; oxidative damage MAMMALIAN AGING is characterized by a gradual and continuous loss, starting at full adulthood, of the quality of physiological functions and responses. The losses are more marked in the functions that depend on the integrated response of the central nervous system (19) than in the functions of the renal or cardiovascular systems. Mitochondria were brought to attention in mammalian aging biology because of the central role of mitochondria in producing biochemical energy (ATP) to meet cellular requirements in aerobic cells and to the decline of basal metabolic rate and of physical performance that are characteristic of aging (32).The free radical theory of aging, based on the pioneer works of Gerschman et al. (18) and Harman (20), considers that aging is caused by the continuous inactivation of biologically essential macromolecules and subcellular structures due to chemical modifications produced by reactions mediated by oxygen free radicals. When the free radical theory of aging is focused in mitochondria, it emerges as the mitochondrial theory of aging (6,21,32,47). Mitochondria are considered likely pacemakers of tissue aging because of their continuous production of superoxide radical (O 2•Ϫ ) and of nitric oxide (NO) and to the mitochondrial sensitivity to free radical-mediated oxidative damage (32).Aged mammalian brain shows a decreased capacity to produce ATP by oxidative phosphorylation, and it is considered that this decreased capacity for energy production ...

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Garcia-Martinez EM et al., 2 AbstractMinocycline, an antibiotic of the tetracycline family, has attracted considerable interest for its theoretical therapeutic applications in neurodegenerative diseases. However, the mechanism of action underlying its effect remains elusive. Here we have studied the effect of minocycline under excitotoxic conditions. Fluorescence and bioluminescence imaging studies in rat cerebellar granular neuron cultures using fura-2/AM and mitochondria-targeted aequorin revealed that minocycline, at concentrations higher than those shown to block inflammation and inflammation-induced neuronal death, inhibited NMDA-induced cytosolic and mitochondrial rises in Ca 2+ concentrations in a reversible manner. Moreover, minocycline added in the course of NMDA stimulation decreased Ca 2+ intracellular levels, but not when induced by depolarization with a high K + medium. We also found that minocycline, at the same concentrations, partially depolarized mitochondria by about 5-30 mV, prevented mitochondrial Ca 2+ uptake under conditions of environmental stress, and abrogated NMDAinduced reactive oxygen species (ROS) formation. Consistently, minocycline also abrogates the rise in ROS induced by 75 M Ca 2+ in isolated brain mitochondria. In search for the mechanism of mitochondrial depolarization, we found that minocycline markedly inhibited state 3 respiration of rat brain mitochondria, although distinctly increased oxygen uptake in state 4. Minocycline inhibited NADH-cytochrome c reductase and cytochrome c oxidase activities, whereas the activity of succinate-cytochrome c reductase was not modified, suggesting selective inhibition of complex I and IV. Finally, minocycline affected activity of voltage-dependent anion channel (VDAC) as determined in the reconstituted system. Taken together, our results indicate that mitochondria are a critical factor in minocycline-mediated neuroprotection.