Effects of fasting on oxidative stress in rat liver mitochondria

Abstract

While moderate caloric restriction has beneficial effects on animal health state, fasting may be harmful. The present investigation was designed to test how fasting affects oxidative stress, and to find out whether the effects are opposite to those previously found in caloric restriction studies. We have focused on one of the main determinants of aging rate: the rate of mitochondrial free radical generation. Different parameters related to lipid and protein oxidative damage were also analyzed. Liver mitochondria from rats subjected to 72 h of fasting leaked more electrons per unit of O(2) consumed at complex III, than mitochondria from ad libitum fed rats. This increased leak led to a higher free radical generation under state 3 respiration using succinate as substrate. Regarding lipids, fasting altered fatty acid composition of hepatic membranes, increasing the double bond and the peroxidizability indexes. In accordance with this, we observed that hepatic membranes from the fasted animals were more sensitive to lipid peroxidation. Hepatic protein oxidative damage was also increased in fasted rats. Thus, the levels of oxidative modifications, produced either indirectly by reactive carbonyl compounds (N(epsilon)-malondialdehyde-lysine), or directly through amino acid oxidation (glutamic and aminoadipic semialdehydes) were elevated due to the fasting treatment in both liver tissue and liver mitochondria. The current study shows that severe food deprivation increases oxidative stress in rat liver, at least in part, by increasing mitochondrial free radical generation during state 3 respiration and by increasing the sensitivity of hepatic membranes to oxidative damage, suggesting that fasting and caloric restriction have different effects on liver mitochondrial oxidative stress.

Effect of fasting and fasting-refeeding on the structure, metabolism and transport functions of renal cortical proximal tubules from different kidney regions

“…Since cholesterol and phospholipids are essential membrane components they could be utilized in the repair and regeneration of cellular membranes affected by fasting. Increased cellular NADPH could also be utilized to reduce oxidative stress as has been observed in intestine and liver by fasting [18]. In contrast refeeding of fasted rats was also able to bring down the enzyme activities towards the control values as the burden of fasting may have been ameliorated.…”

Short Period Starvation in Rat: The Effect of Aloe Vera Gel Extract on Oxidative Stress Status Ion

“…Lipid oxidation increased (Orellana et al, 1992;Wasselin et al, 2014) or was not changed (MarczukKrynicka et al, 2003) during starvation. Starvation has been reported to have pro-oxidative effect as a consequence of both elevated ROS generation and defeat in neutralization of ROS (Crescimanno et al, 1989;Domenicali et al, 2001;Robinson et al, 1997;Sorensen et al, 2006). However, one study has reported…”

“…It caused electron transport chain to be more active and finally enhanced ROS generation (Wasselin et al, 2014). Sorensen and co-workers have shown 72 h starvation increased free radical production and changed membrane composition in rat liver (Sorensen et al, 2006). Antioxidant system components act against oxidative stress in body.…”

“…Plasma level of vitamin C after treatment with hydroalcoholic Aloe vera gel extract at doses 100 and 200 mg/kg was significantly increased (P<0.05). Robinson et al, 1997;Sorensen et al, 2006). Food deprivation or starvation results in reduction in critical metabolic substrate.…”

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

“…67 Indeed, unlike CR, fasting has previously been shown to increase ROS release. 73 Thus, from a redox standpoint, it is critical to consider the specific diet adopted.…”