Long-term calorie restriction reduces proton leak and hydrogen peroxide production in liver mitochondria

Abstract

. Longterm calorie restriction reduces proton leak and hydrogen peroxide production in liver mitochondria. Am J Physiol Endocrinol Metab 288: E674 -E684, 2005. First published November 23, 2004 doi: 10.1152/ajpendo.00382.2004.-Calorie restriction (CR) without malnutrition increases maximal life span in diverse species. It has been proposed that reduction in energy expenditure and reactive oxygen species (ROS) production could be a mechanism for life span extension with CR. As a step toward testing this theory, mitochondrial proton leak, H 2O2 production, and markers of oxidative stress were measured in liver from FBNF 1 rats fed control or 40% CR diets for 12 or 18 mo. CR was initiated at 6 mo of age. Proton leak kinetics curves, generated from simultaneous measures of oxygen consumption and membrane potential, indicated a decrease in proton leak after 18 mo of CR, while only a trend toward a proton leak decrease was observed after 12 mo. Significant shifts in phosphorylation and substrate oxidation curves also occurred with CR; however, these changes occurred in concert with the proton leak changes. Metabolic control analysis indicated no difference in the overall pattern of control of the oxidative phosphorylation system between control and CR animals. At 12 mo, no significant differences were observed between groups for H 2O2 production or markers of oxidative stress. However, at 18 mo, protein carbonyl content was lower in CR animals, as was H 2O2 production when mitochondria were respiring on either succinate alone or pyruvate plus malate in the presence of rotenone. These results indicate that long-term CR lowers mitochondrial proton leak and H 2O2 production, and this is consistent with the idea that CR may act by decreasing energy expenditure and ROS production. energy expenditure; aging; oxidative stress; food restriction CALORIE RESTRICTION (CR) without malnutrition is the only intervention that has consistently been shown to increase maximum life span in laboratory rodents (60). In addition to increasing life span in rodents, CR also delays the onset of diabetes, hypertension, and many types of cancer as well as other age-related physiological and pathological conditions (60). This shows that CR not only extends life span but also retards the rate of biological aging. The mechanism(s) responsible for the actions of CR, however, is still unknown.Two theories of aging, the rate of living theory (42) and the free radical theory (24), have been proposed as possible mechanisms for the retardation of aging and diseases by CR (56). However, both of these theories may contain the same mechanism, since mitochondria are central to both energy metabolism and reactive oxygen species (ROS) production. Because both processes contain a common mitochondrial link, it is reasonable to assume that alterations in energy expenditure (defined here as any process that converts food or stored energy to heat and work) could influence ROS production. Thus both theories may be linked by common reduction in mitochondrial ROS pr...

Liver mitochondrial properties from the obesity-resistant Lou/C rat

“…Such discrepancies were also found when CR was extended to 4-6 months 29,35 or 12-18 months. 26,28 In the present study, we found that isolated liver mitochondria from Lou/C rats, which display an inborn LCI, [1][2][3][7][8][9]14,15 produced more H 2 O 2 than Wistar rats fed ad libitum or even pair-fed. The enhanced H 2 O 2 generation displayed by Lou/C mitochondria takes place at many levels of the electron transport chain.…”

“…28 Nevertheless, the widespread notion of a reduced rate of H 2 O 2 generation by liver mitochondria with CR was recently challenged by some authors. 26,29 Thus, a similar reduction in caloric intake (B40%) for 4-8 weeks was found either to decrease 25 or to enhance 29 mitochondrial H 2 O 2 production. Such discrepancies were also found when CR was extended to 4-6 months 29,35 or 12-18 months.…”

“…The ROS generation in liver is well documented, [25][26][27][28][29][30] and many cellular sources of ROS production have been identified, including plasma membrane NADPH oxidase and xanthine, peroxisomal and endoplasmic reticular oxidases. However, it is now generally accepted that mitochondrial electron transport chain represents the major source of ROS.…”

“…However, it is now generally accepted that mitochondrial electron transport chain represents the major source of ROS. [25][26][27][28][29][30][31] While it was initially thought that complex III was the main or even the only site of ROS generation, 32 recent investigations unequivocally demonstrated that respiratorychain complex I is the major generator of free radicals in liver mitochondria. 16,31 One of the most important finding of our study is the demonstration that in the absence of any inhibitor, hepatic mitochondria energized with G/M/S generated H 2 O 2 to a significant extent (Figure 1).…”

Caloric restriction and redox state: Does this diet increase or decrease oxidant production?

“…[51][52][53] Another large body of work demonstrates that ROS release from mitochondria or tissues from CR animals is decreased. 37,[53][54][55][56][57][58][59][60][61][62][63][64][65][66][67] Other publications found no changes in ROS production with CR 46,[68][69][70][71] and many propose that CR-induced decreases in ROS release depend on tissues examined, time on the diet, animal age when the diet was initiated, and gender. No experimental publication was located demonstrating that CR in rodents enhances ROS generation in non-inflammatory tissues.…”