Ponte, M. E. | Search bioRxiv

bioRxiv2024

Reduced Liver Mitochondrial Energy Metabolism Impairs Food Intake Regulation Following Gastric Preloads and Fasting

ObjectiveThe capacity of the liver to serve as a peripheral sensor in the regulation of food intake has been debated for over half a century. The anatomical position and physiological roles of the liver suggest it is a prime candidate to serve as an interoceptive sensor of peripheral tissue and systemic energy state. Importantly, maintenance of liver ATP levels and within-meal food intake inhibition is impaired in human subjects with obesity and obese pre-clinical models. Previously, we have shown decreased hepatic mitochondrial energy metabolism (i.e., oxidative metabolism & ADP-dependent respiration) in male liver-specific, heterozygous PGC1a mice results in increased short-term diet-induced weight gain with increased within meal food intake. Herein, we tested the hypothesis that decreased liver mitochondrial energy metabolism impairs meal termination following nutrient oral pre-loads. MethodsLiver mitochondrial respiratory response to changes in {Delta}GATP and adenine nucleotide concentration following fasting were examined in male liver-specific, heterozygous PGC1a mice. Further, food intake and feeding behavior during basal conditions, following nutrient oral pre-loads, and following fasting were investigated. ResultsWe observed male liver-specific, heterozygous PGC1a mice have reduced mitochondrial response to changes in {Delta}GATP and tissue ATP following fasting. These impairments in liver energy state are associated with larger and longer meals during chow feeding, impaired dose-dependent food intake inhibition in response to mixed and individual nutrient oral pre-loads, and greater acute fasting-induced food intake. ConclusionThese data support previous work proposing liver-mediated food intake regulation through modulation of peripheral satiation signals.

physiology↗

bioRxiv2020

Reduced Liver-Specific PGC1a Increases Susceptibility for Short-Term Diet-induced Weight Gain in Male Mice

Central integration of peripheral neural signals is one mechanism by which systemic energy homeostasis is regulated. Previous work described increased acute food intake following chemical reduction of hepatic fatty acid oxidation and ATP levels, which was prevented by common hepatic branch vagotomy (HBV). However, possible offsite actions of the chemical compounds confound the precise role of liver energy metabolism. Herein, we used a liver-specific PGC1a heterozygous (LPGC1a) mouse model, with associated reductions in mitochondrial fatty acid oxidation and respiratory capacity, to assess the role of liver energy metabolism in systemic energy homeostasis. LPGC1a male mice have 70% greater high-fat/high-sucrose (HFHS) diet-induced weight gain and 35% greater positive energy balance compared to wildtype (WT) (p<0.05). The greater energy balance was associated with altered feeding behavior and lower activity energy expenditure during HFHS in LPGC1a males. Importantly, no differences in HFHS-induced weight gain or energy metabolism was observed between female WT and LPGC1a mice. WT and LPGC1a mice underwent sham or HBV to assess whether vagal signaling was involved in HFHS-induced weight gain of male LPGC1a mice. HBV increased HFHS-induced weight gain (85%, p<0.05) in male WT, but not LPGC1a mice. As above, sham LPGC1a males gain 70% more weight during short-term HFHS feeding than sham WT (p<0.05). These data demonstrate a sexspecific role of reduced liver energy metabolism in acute diet-induced weight gain, and the need of more nuanced assessment of the role of vagal signaling in short-term diet-induced weight gain. Key Points SummaryO_LIReduced liver PGC1a expression results in reduced mitochondrial fatty acid oxidation and respiratory capacity in male mice. C_LIO_LIMale mice with reduced liver PGC1a expression (LPGC1a) demonstrate greater short-term high-fat/high-sucrose diet-induced weight gain compared to wildtype. C_LIO_LIGreater positive energy balance during HFHS feeding in male LPGC1a mice is associated with altered food intake patterns and reduced activity energy expenditure. C_LIO_LIFemale LPGC1a mice do not have differences in short-term HFHS-induced body weight gain or energy metabolism compared to wildtype. C_LIO_LIDisruption of vagal signaling through common hepatic branch vagotomy increases short-term HFHS-induced weight gain in male wildtype mice, but does not alter male LPGC1a weight gain. C_LI

physiology↗