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We show that brief periods of fasting induce functional changes similar to those induced by long-term dietary restriction in mice, and these changes include protection from ischemia/reperfusion (I/R) injury. In this study, we investigated the mechanisms of protection induced by fasting, and we determined the effect on liver regeneration after partial hepatectomy. Partial hepatic ischemia (75 minutes) was induced in ad libitum fed mice and in 1-to 3-day-fasted mice, and one-third or two-thirds hepatectomy was performed in ad libitum fed mice and 3-day-fasted mice. Preoperative fasting for 2 or 3 days significantly decreased hepatocellular I/R injury. Hepatic gene expression of heme oxygenase 1 (HO-1), superoxide dismutase 2 (SOD2), glutathione peroxidase 1 (Gpx1), and glutathione reductase (GSR) was significantly up-regulated in 3-day-fasted mice at the baseline and 6 hours after reperfusion. After reperfusion, p-selectin and interleukin-6 (IL-6) levels were significantly lower, and superoxide radical generation, lipid peroxidation, and neutrophil influx were significantly attenuated in 3-day-fasted mice. Preoperative fasting did not affect liver regeneration after one-third hepatectomy. Hepatic gene expression of IL-6 and transforming growth factor b1 was significantly higher in 3-day-fasted mice before and after one-third hepatectomy. Tumor necrosis factor a expression significantly increased after one-third hepatectomy in 3-day-fasted mice. After a 3-day fast and two-thirds hepatectomy, liver regeneration and subsequent postoperative recovery were compromised. In conclusion, up-regulation of the stress response gene HO-1 and the antioxidant enzymes SOD2, Gpx1, and GSR at the baseline and a better response after reperfusion likely underlie the protection induced by fasting against hepatic I/R injury. Preoperative fasting may be a promising new strategy for protecting the liver against I/R injury during liver transplantation and minor liver resections, although its effect on extended hepatectomy warrants further exploration. Liver Transpl 17:695-704, 2011. V C 2011 AASLD.Received July 5, 2010; accepted December 5, 2010.The temporary occlusion of the hepatic inflow (Pringle maneuver) or the hepatic inflow and outflow (total hepatic vascular occlusion) are techniques routinely used during extended liver surgeries such as hepatic resection and liver transplantation.1,2 These prolonged interruptions of hepatic blood flow result in ischemia/reperfusion (I/R) injury. Hepatic I/R injury is characterized by progressive hepatocellular injury and hepatocyte loss after reperfusion. It is considered to be a risk factor for Abbreviations: DC t , difference in the cycle threshold; DR, dietary restriction; Gpx1, glutathione peroxidase 1; GSR, glutathione reductase; HO-1, heme oxygenase 1; Hsp70, heat shock protein 70; IL-6, interleukin-6; I/R, ischemia/reperfusion; MDA, malondialdehyde; mRNA, messenger RNA; PCNA, proliferating cell nuclear antigen; PH, partial hepatectomy; qRT-PCR, quantitative reverse-transcription polymerase...
We show that brief periods of fasting induce functional changes similar to those induced by long-term dietary restriction in mice, and these changes include protection from ischemia/reperfusion (I/R) injury. In this study, we investigated the mechanisms of protection induced by fasting, and we determined the effect on liver regeneration after partial hepatectomy. Partial hepatic ischemia (75 minutes) was induced in ad libitum fed mice and in 1-to 3-day-fasted mice, and one-third or two-thirds hepatectomy was performed in ad libitum fed mice and 3-day-fasted mice. Preoperative fasting for 2 or 3 days significantly decreased hepatocellular I/R injury. Hepatic gene expression of heme oxygenase 1 (HO-1), superoxide dismutase 2 (SOD2), glutathione peroxidase 1 (Gpx1), and glutathione reductase (GSR) was significantly up-regulated in 3-day-fasted mice at the baseline and 6 hours after reperfusion. After reperfusion, p-selectin and interleukin-6 (IL-6) levels were significantly lower, and superoxide radical generation, lipid peroxidation, and neutrophil influx were significantly attenuated in 3-day-fasted mice. Preoperative fasting did not affect liver regeneration after one-third hepatectomy. Hepatic gene expression of IL-6 and transforming growth factor b1 was significantly higher in 3-day-fasted mice before and after one-third hepatectomy. Tumor necrosis factor a expression significantly increased after one-third hepatectomy in 3-day-fasted mice. After a 3-day fast and two-thirds hepatectomy, liver regeneration and subsequent postoperative recovery were compromised. In conclusion, up-regulation of the stress response gene HO-1 and the antioxidant enzymes SOD2, Gpx1, and GSR at the baseline and a better response after reperfusion likely underlie the protection induced by fasting against hepatic I/R injury. Preoperative fasting may be a promising new strategy for protecting the liver against I/R injury during liver transplantation and minor liver resections, although its effect on extended hepatectomy warrants further exploration. Liver Transpl 17:695-704, 2011. V C 2011 AASLD.Received July 5, 2010; accepted December 5, 2010.The temporary occlusion of the hepatic inflow (Pringle maneuver) or the hepatic inflow and outflow (total hepatic vascular occlusion) are techniques routinely used during extended liver surgeries such as hepatic resection and liver transplantation.1,2 These prolonged interruptions of hepatic blood flow result in ischemia/reperfusion (I/R) injury. Hepatic I/R injury is characterized by progressive hepatocellular injury and hepatocyte loss after reperfusion. It is considered to be a risk factor for Abbreviations: DC t , difference in the cycle threshold; DR, dietary restriction; Gpx1, glutathione peroxidase 1; GSR, glutathione reductase; HO-1, heme oxygenase 1; Hsp70, heat shock protein 70; IL-6, interleukin-6; I/R, ischemia/reperfusion; MDA, malondialdehyde; mRNA, messenger RNA; PCNA, proliferating cell nuclear antigen; PH, partial hepatectomy; qRT-PCR, quantitative reverse-transcription polymerase...
The loss of energy homeostasis seen during aging, is causally linked to multiple age-related pathologies. The AMP-activated protein kinase (AMPK) directly senses cellular energy levels, which are reflected in the ratio between AMP:ATP. However, the genetic regulation of vertebrate aging by the AMPK pathway remains poorly understood. Here, we manipulate ATP production by mutating APRT, a key enzyme in AMP biosynthesis, and extend vertebrate lifespan in a male-specific manner. Using a multi-omics approach, we demonstrate that the APRT mutation restores metabolic plasticity, and identify a distinct transcriptional signature linking mitochondria with the sex-related differences in longevity. Accordingly, APRT mutant cells display a reduction in mitochondrial functions and ATP levels, and an increase in AMPK activity, resembling a persistent state of energy starvation. In-vivo, a fasting-like response was observed exclusively in male mutants, including resistance to a high-fat diet. Finally, intermittent fasting eliminated the longevity benefits mediated by the APRT mutation in males. Together, these data identify AMP biosynthesis as a sex-specific mediator of vertebrate longevity and metabolic health.
Classical evolutionary theories propose tradeoffs between reproduction, damage repair, and lifespan. However, the specific role of the germline in shaping vertebrate aging remains largely unknown. Here, we use the turquoise killifish (N. furzeri) to genetically arrest germline differentiation at discrete stages, and examine how different ‘flavors’ of infertility impact life-history. We first constructed a comprehensive single-cell gonadal atlas, providing cell-type-specific markers for downstream phenotypic analysis. Next, investigating our genetic models revealed that only germline depletion enhanced female damage repair, while arresting germline differentiation did not. Conversely, germline-depleted males were significantly long-lived, indicating that the mere presence of the germline can negatively affect lifespan. Transcriptomic analysis highlighted enrichment of pro-longevity pathways and genes, with functional conservation in germline-depletedC. elegans. Finally, germline depletion extended male healthspan through rejuvenated metabolic functions. Our results suggest that different germline manipulation paradigms can yield pronounced sexually dimorphic phenotypes, implying alternative mechanisms to classical evolutionary tradeoffs.
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