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  • American Physiological Society  (2)
  • 1
    In: Journal of Applied Physiology, American Physiological Society, Vol. 128, No. 5 ( 2020-05-01), p. 1251-1261
    Abstract: Both lipid oversupply and poor mitochondrial function (low respiration and elevated H 2 O 2 emission) have been implicated in the development of hepatic steatosis and liver injury. Mitophagy, the targeted degradation of low-functioning mitochondria, is critical for maintaining mitochondrial quality control. Here, we used intralipid injection combined with acute (4 day) and chronic (4–7wk) high-fat diets (HFD) to examine whether hepatic mitochondrial respiration would decrease and H 2 O 2 emission would increase with lipid overload. We tested these effects in male and female wild type (WT) mice and mice null for a critical mediator of mitophagy, BCL-2/adenovirus EIB 19-kDa interacting protein knockout (BNIP3 KO) housed at thermoneutral temperatures. Intralipid injection was successful in elevating serum triglycerides and nonesterified fatty acids but had no impact on hepatic mitochondrial respiratory function or H 2 O 2 emission. However, female mice had greater mitochondrial respiration on the acute HFD and lower H 2 O 2 emission across both HFD durations and were protected against hepatic steatosis. Unexpectedly, BNIP3 KO animals had greater hepatic mitochondrial respiration, better coupled respiration, and increased electron chain protein content after the 4-day HFD, compared with WT animals. Altogether, these data suggest that acute lipid overload delivered by a single intralipid bolus does not alter hepatic mitochondrial outcomes, but rather sex and genotype profoundly impact hepatic mitochondrial respiration and H 2 O 2 emission. NEW & NOTEWORTHY This is the first study focusing on hepatic mitochondrial respiratory outcomes in response to lipid overload via a high-fat diet (HFD) combined with intralipid injection. Novel findings include no effect of intralipid injection on mitochondrial outcomes of interest despite increased circulating lipid concentrations. However, we report pronounced differences in hepatic mitochondrial respiration, complex protein expression, and H 2 O 2 production by sex and BCL-2/adenovirus EIB 19-kDa interacting protein (BNIP3) genotype. Specifically, female mice had lower H 2 O 2 emission globally and on an acute HFD, females had greater hepatic mitochondrial respiration than males while BNIP3 knockout (KO) animals had greater mitochondrial coupling and complex protein expression than wild-type (WT) animals.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2020
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 2
    Online Resource
    Online Resource
    American Physiological Society ; 2019
    In:  American Journal of Physiology-Endocrinology and Metabolism Vol. 317, No. 2 ( 2019-08-01), p. E298-E311
    In: American Journal of Physiology-Endocrinology and Metabolism, American Physiological Society, Vol. 317, No. 2 ( 2019-08-01), p. E298-E311
    Abstract: The impact of sexual dimorphism and mitophagy on hepatic mitochondrial adaptations during the treatment of steatosis with physical activity are largely unknown. Here, we tested if deficiencies in liver-specific peroxisome proliferative activated-receptor-γ coactivator-1α (PGC-1α), a transcriptional coactivator of biogenesis, and BCL-2/ADENOVIRUS EIB 19-kDa interacting protein (BNIP3), a mitophagy regulator, would impact hepatic mitochondrial adaptations (respiratory capacity, H 2 O 2 production, mitophagy) to a high-fat diet (HFD) and HFD plus physical activity via voluntary wheel running (VWR) in both sexes. Male and female wild-type (WT), liver-specific PGC-1α heterozygote (LPGC-1α), and BNIP3 null mice were thermoneutral housed (29–31°C) and divided into three groups: sedentary-low-fat diet (LFD), 16 wk of (HFD), or 16 wk of HFD with VWR for the final 8 wk (HFD + VWR) ( n = 5–7/sex/group). HFD did not impair mitochondrial respiratory capacity or coupling in any group; however, HFD + VWR significantly increased maximal respiratory capacity only in WT and PGC-1α females. Males required VWR to elicit mitochondrial adaptations that were inherently present in sedentary females including greater mitochondrial coupling control and reduced H 2 O 2 production. Females had overall reduced markers of mitophagy, steatosis, and liver damage. Steatosis and markers of liver injury were present in sedentary male mice on the HFD and were effectively reduced with VWR despite no resolution of steatosis. Overall, reductions in PGC-1α and loss of BNIP3 only modestly impacted mitochondrial adaptations to HFD and HFD + VWR with the biggest effect seen in BNIP3 females. In conclusion, hepatic mitochondrial adaptations to HFD and treatment of HFD-induced steatosis with VWR are more dependent on sex than PGC-1α or BNIP3.
    Type of Medium: Online Resource
    ISSN: 0193-1849 , 1522-1555
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2019
    detail.hit.zdb_id: 1477331-4
    SSG: 12
    Location Call Number Limitation Availability
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