A β-hydroxybutyrate shunt pathway generates anti-obesity ketone metabolites

Medium-Chain Triglyceride Dietary Supplements Reduce Glucose Metabolism of Gait-Related Skeletal Muscle in Older Adults: A Longitudinal 18F-FDG PET/CT Analysis

BACKGROUND/OBJECTIVES

Dietary supplementation with medium-chain triglycerides (MCTs) improves walking balance and cognitive function in healthy older adults. This study aimed to determine the biological effects of MCTs on gait-related skeletal muscles in healthy older adults by analyzing muscle density and glucose metabolism.

METHODS

18F-FDG-PET/CT imaging data from 63 participants (18 g/day of MCTs and matching placebo in the form of a jelly stick [6 g each, ingested 3 times/day]) in a randomized clinical trial were analyzed. The three-dimensional regions of interest were set as muscles associated with walking balance (bilateral triceps, psoas, and vastus medialis). Each muscle's mean standardized uptake value (SUVmean) and Hounsfield units (HU) were calculated for relative quantitative measurements.

RESULTS

MCT supplementation for 3 months decreased the SUVmean (p < 0.001) and increased the HU of the psoas (r = -0.61) and vastus medialis muscles (r = -0.59) (p < 0.001); no changes were apparent in participants supplemented with long-chain triglycerides. The changes in the SUVmean for each muscle were correlated negatively with those of plasma β-hydroxybutyrate in MCT-supplemented participants (r = -0.57 [psoas] and -0.59 [vastus medialis]; p < 0.001).

CONCLUSION

A 3-month MCT supplementation suppressed glucose metabolism and increased the muscle density in gait-related skeletal muscles, consistent with previous findings that MCT supplementation stabilizes balance functions during walking in healthy older adults.

Exercise intensity determines circulating levels of Lac-Phe and other exerkines: a randomized crossover trial

INTRODUCTION

Exercise metabolomics research has revealed significant exercise-induced metabolic changes and identified several exerkines as mediators of physiological adaptations to exercise. However, the effect of exercise intensity on metabolic changes and circulating exerkine levels remains to be examined.

OBJECTIVES

This study compared the metabolic responses to moderate-intensity and vigorous-intensity aerobic exercise.

METHODS

A two-period crossover trial was conducted under controlled conditions at the Max Rubner-Institute in Karlsruhe, Germany. Seventeen young, healthy, and physically active men performed 30 min moderate-intensity (50% VO2peak) and vigorous-intensity (75% VO2peak) aerobic exercise using two bicycle ergometer protocols in a randomized sequence. Blood samples obtained immediately before exercise and at four time points after exercise were analyzed in an untargeted metabolomics approach, and separate linear mixed models were applied to over 1000 metabolites.

RESULTS

Vigorous-intensity exercise induced a greater metabolic response than moderate-intensity exercise. Several intensity-dependent metabolites were identified, primarily involved in amino acid metabolism and energy conversion pathways, including N-lactoyl-amino acids, TCA cycle intermediates, N-acetylated amino acids, and acylcholines. The exerkines N-lactoyl-phenylalanine, lactate, and succinate were among the most intensity-dependent metabolites. N-acetylated amino acids and acylcholines were systematically altered by exercise intensity, indicating potential physiological functions.

CONCLUSION

Exercise intensity significantly affects exercise-induced metabolic alterations and changes in exerkine levels. Our results expand the knowledge about exerkine dynamics and emphasize the role of exercise intensity in promoting physiological adaptations to exercise. The trial was registered on October 5, 2017, at the German Clinical Trials Register under the Registration Number DRKS00009743 (Universal Trial Number of WHO: U1111-1200-2530).

Enhancer binding as a KEysTONE of fasting response

Fasting is a recurrent daily energy stress that benefits healthspan and lifespan. While ketones fuel fasting in vertebrates, the underlying transcriptional mechanism remains incompletely understood. Recently, Korenfeld et al. revealed peroxisome proliferator-activated receptor alpha (PPARα)-dependent enhancer priming as a keystone for ketone production, increasing our understanding of mechanisms underlying metabolic benefits of alternate-day fasting (ADF).

"Shunt-ing" down obesity with novel endogenous metabolites

Obesity is a growing public health issue that has recently been transformed through the advent of new medicines. However, our understanding of the pathways and mechanisms that regulate energy balance in mammals is still developing. Recent discoveries on this front include an exciting new finding that there exists a novel class of metabolites in humans and mice that can regulate obesity in rodents.

Acetoacetate Ameliorates Hepatic Fibrosis by Targeting Peroxisome Proliferator-Activated Receptor Gamma to Restore Lipid Droplets in Activated Hepatic Stellate Cells

Background: Hepatic fibrosis (HF) is a progressive liver disease characterized by the activation of hepatic stellate cells (HSCs) and changes in lipid metabolism. Abnormal ketone body (KD) levels, including acetoacetate (AcAc) and beta-hydroxybutyrate (BHB), have been observed in patients with HF, but the mechanisms linking ketone metabolism to fibrosis progression remain unclear. Objectives: This study aimed to investigate the role of AcAc in modulating HSCs activation and its potential mechanisms in HF. Methods: We examined the effects of AcAc on HSCs activation by Western blot analysis and RT-PCR both in vivo and in vitro. The impact of AcAc on lipid droplet accumulation in HSCs was assessed using total cholesterol (TC), triglyceride (TG), and Retinol (RET) kits, along with Nile Red and Oil Red O staining. RT-PCR screening was performed to analyze the expression of genes involved in lipid droplet formation and lipid metabolism. Results: Our findings show that AcAc inhibited HSCs activation by restoring LD levels. Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) was identified as a key regulator through gene screening. AcAc primarily regulated PPARγ expression, and knocking down PPARγ significantly aggravated HF progression. Conclusions: The ability of AcAc to restore LD levels and regulate PPARγ suggests that it may represent a promising therapeutic strategy for HF by inhibiting HSCs activation.