Probiotics Stimulate Bone Formation in Obese Mice via Histone Methylations.

Rationale: Manipulation of the gut microbiome can prevent pathologic bone loss. However, the effects of probiotics on mitochondrial epigenetic remodeling and skeletal homeostasis in the high-fat diet (HFD)-linked obesity remains to be explored. Here, we examined the impact of probiotics supplementation on mitochondrial biogenesis and bone homeostasis through the histone methylation mechanism in HFD fed obese mice. Methods: 16S rRNA gene sequencing was performed to study the microbiota composition in the gut and microbial dysbiosis in obese mouse model. High resolution (microPET/CT) imaging was performed to demonstrate the obese associated colonic inflammation. Obese-associated upregulation of target miRNA in osteoblast was investigated using a microRNA qPCR array. Osteoblastic mitochondrial mass was evaluated using confocal imaging. Overexpression of mitochondrial transcription factor (Tfam) was used to investigate the glycolysis and mitochondrial bioenergetic metabolism using Tfam-transgenic (Tg) mice fed on HFD. The bone formation and mechanical strength was evaluated by microCT analysis and three-point bending analysis. Results: High-resolution imaging (µ-CT) and mechanical testing revealed that probiotics induced a significant increase of trabecular bone volume and bone mechanical strength respectively in obese mice. Probiotics or Indole-3-propionic acid (IPA) treatment directly to obese mice, prevents gut inflammation, and improved osteoblast mineralization. Mechanistically, probiotics treatment increases mitochondrial transcription factor A (Tfam) expression in osteoblasts by promoting Kdm6b/Jmjd3 histone demethylase, which inhibits H3K27me3 epigenetic methylation at the Tfam promoter. Furthermore, Tfam-transgenic (Tg) mice, fed with HFD, did not experience obesity-linked reduction of glucose uptake, mitochondrial biogenesis and mineralization in osteoblasts. Conclusions: These results suggest that the probiotics mediated changes in the gut microbiome and its derived metabolite, IPA are potentially be a novel agent for regulating bone anabolism via the gut-bone axis.

Hypothalamic long noncoding RNA AK044061 is involved in the development of dietary obesity in mice.

BACKGROUND: Long noncoding RNAs (lncRNAs) have been implicated in various important biological processes, however, its role in energy balance and obesity remains largely unknown. METHODS: Differentially expressed lncRNAs in the hypothalamus of diet-induced obesity (DIO) mice versus chow-fed mice were identified by RNA sequencing. Lentivirus-mediated overexpression and knockdown of a novel lncRNA, AK044061, were used to assess its role in energy balance and the development of DIO. RNA immunoprecipitation (RIP) and pull down assays were carried out to analyze the interaction between lncRNA AK044061 and RelA, an NF-κB subunit. RESULTS: LncRNA AK044061 was upregulated in the hypothalamus of DIO mice. Acute intracerebroventricular (i.c.v.) infusion of glucose reduced the expression of lncRNA AK044061, whereas an overnight of fasting enhanced its expression. RNA in situ hybridization data showed that AK044061 was expressed in the neurons of the arcuate nucleus (ARC). Lentivirus-mediated overexpression of AK044061 in ARC cells, or in the neurons of the ARC nucleus led to an obesity-like phenotype and related metabolic disorders. Furthermore, knockdown of lncRNA AK044061 in Agouti-related peptide (AgRP)-expressing neurons mitigated DIO and its related metabolic dysregulations. In mechanism, we showed that lncRNA AK044061 was associated with RelA and could enhance the NF-κB reporter activity. The effect of lncRNA AK044061 on energy balance is mediated by NF-κB. CONCLUSIONS: Our findings suggest that excessive lncRNA AK044061 in the ARC nucleus leads to energy imbalance and obesity. LncRNA AK044061 expressed in the AgRP neurons is important in the development of dietary obesity in mice.

An Ethanolic Extract of Artemisia dracunculus L. Enhances the Metabolic Benefits of Exercise in Diet-induced Obese Mice.

PURPOSE: The purpose of this study was to determine the effect of an ethanolic extract of Artemisia dracunculus L. (5011) combined with exercise on in vivo glucose and fat metabolism in diet-induced obese male mice. METHODS: After 8 wk of high-fat diet (HFD) feeding, 52 mice were randomly allocated to a voluntary wheel running group (HFD Ex), a 5011 + HFD sedentary group (5011 Sed), a 5011 + HFD Ex (5011 Ex), or an HFD sedentary group (HFD Sed) for 4 wk. Real-time energy expenditure and substrate utilization were measured by indirect calorimetry. A stable isotope glucose tolerance test was performed before and after the 4-wk wheel running period to determine changes in endogenous glucose production and glucose disposal. We also performed an analysis of genes and proteins associated with the early response to exercise and exercise adaptations in skeletal muscle and liver. RESULTS: When compared with HFD Ex mice, 5011 Ex mice had increased fat oxidation during speed- and distance-matched wheel running bouts. Both HFD Ex and 5011 Ex mice had reduced endogenous glucose during the glucose tolerance test, whereas only the 5011 Sed and the 5011 Ex mice had improved glucose disposal after the 4-wk experimental period when compared with HFD Sed and HFD Ex mice. 5011 Ex mice had increased Pgc1-α and Tfam expression in skeletal muscle when compared with HFD Ex mice, whereas Pdk4 expression was reduced in the liver of HFD Ex and 5011 Ex mice. CONCLUSIONS: Our study demonstrates that 5011, an ethanolic extract of A. dracunculus L., with a history of medicinal use, enhances the metabolic benefits of exercise to improve in vivo fat and glucose metabolism.

Intermittent Fasting and High-Intensity Exercise Elicit Sexual-Dimorphic and Tissue-Specific Adaptations in Diet-Induced Obese Mice.

: The molecular adaptations that underpin body composition changes and health benefits of intermittent fasting (IF) and high-intensity interval training (HIIT) are unclear. The present study investigated these adaptations within the hypothalamus, white adipose and skeletal muscle tissue following 12 weeks of IF and/or HIIT in diet-induced obese mice. Mice (C57BL/6, 8-week-old, males/females) were fed high-fat (59%) and sugar (30%) water (HF/S) for 12 weeks followed by an additional 12 weeks of HF/S plus either IF, HIIT, combination (IF+HIIT) or HF/S only control (CON). Tissues were harvested at 12 and 24 weeks and analysed for various molecular markers. Hypothalamic NPY expression was significantly lower following IF+HIIT compared to CON in females. In adipose tissue, leptin expression was significantly lower following IF and IF+HIIT compared to CON in males and females. Males demonstrated increased markers of fat oxidation (HADH, FABP4) following IF+HIIT, whereas females demonstrated reduced markers of adipocyte differentiation/storage (CIDEC and FOXO1) following IF and/or IF+HIIT. In muscle, SIRT1, UCP3, PGC1α, and AS160 expression was significantly lower following IF compared to CON in males and/or females. This investigation suggests that males and females undertaking IF and HIIT may prevent weight gain via different mechanisms within the same tissue.

A polymorphism in New Zealand inbred mouse strains that inactivates phosphatidylcholine transfer protein.

New Zealand obese (NZO/HlLt) male mice develop polygenic diabetes and altered phosphatidylcholine metabolism. The gene encoding phosphatidylcholine transfer protein (PC-TP) is sited within the support interval for Nidd3, a recessive NZO-derived locus on Chromosome 11 identified by prior segregation analysis between NZO/HlLt and NON/Lt. Sequence analysis revealed that the NZO-derived PC-TP contained a non-synonymous point mutation that resulted in an Arg120His substitution, which was shared by the related NZB/BlNJ and NZW/LacJ mouse strains. Consistent with the structure-based predictions, functional studies demonstrated that Arg120His PC-TP was inactive, suggesting that this mutation contributes to the deficiencies in phosphatidylcholine metabolism observed in NZO mice.

Altered monoamine metabolism in the hypothalamus of the genetically obese yellow (Ay/a) mouse.

Changes in hypothalamic monoamine metabolism were investigated in the genetically obese yellow (Ay/a) mouse. At the age of 6 weeks when there was no difference in body weight between black (a/a) and yellow (Ay/a) mice, the contents of norepinephrine (NE), dopamine (DA) and their main metabolites (MHPG, DOPAC) were already significantly reduced in yellow (Ay/a) mice. Reduction of 5-hydroxytryptamine (5-HT) level and an increasing 5-HIAA/5-HT ratio has been observed. When a significant increase in body weight in the yellow (Ay/a) mouse at the age of 12 weeks was present, both NE and DA contents have been increased in the hypothalamus of the obese mouse. MHPG level was lower than in the lean mouse, resulting in an increase of MHPG/NE ratio. The present study suggests that the observed reduction in hypothalamic NE and DA metabolism might be involved in the development of overweight gain in the yellow (Ay/a) mouse.

Hypercorticism and manganese metabolism in brown adipose tissue of the obese mouse.

In ob/ob mice, we showed previously that brown adipose tissue (BAT) has an abnormally low manganese (Mn) content associated with low Mn-superoxide dismutase (MnSOD) and succinate dehydrogenase (SDH) activities. These anomalies can be corrected partially by supplementing the diet with Mn. The present work was designed to find out whether the hypercorticism of the obese mouse plays a role in this anomalous Mn metabolism in BAT. Mn content and MnSOD and SDH activities were determined in BAT from control and adrenalectomized (ADX) obese mice and from control and corticosterone-supplemented lean mice. Adrenalectomy of the obese mouse restored BAT Mn content, SDH activity and lipid peroxidative activity to normal but had little effect on MnSOD activity. Corticosteroid supplementation in the lean mouse did not reproduce the anomalies of Mn metabolism found in the untreated obese mouse. These results show that hypercorticism alone is not responsible for the anomalies of Mn metabolism. It is possible that the hyperinsulinemia of the obese mouse is involved in this process since adrenalectomy corrected hyperinsulinemia in the obese mouse, but corticosteroid supplementation of the lean mouse did not reproduce the high plasma insulin levels or the anomalies in body composition typical of the untreated obese mouse.

Metabolic effects of dietary manganese supplementation in ob/ob mice.

When fed a manganese-sufficient (20 ppm) diet, obese (ob/ob) mice have reduced levels of Mn in liver and brown adipose tissue (BAT), and depressed activities of succinate dehydrogenase (SDH) and manganese-containing superoxide dismutase (MnSOD) in BAT, compared to lean mice. Dietary Mn supplementation (200 ppm Mn) increased the Mn concentration in BAT in lean and obese mice and the Mn content of liver in the ob/ob mouse. Mn supplementation also led to an increase in the specific activities of SDH and MnSOD in BAT of lean and obese mice. In the obese mouse, these changes were paralleled by changes in the histological appearance of the tissue. The results indicate that the metabolism of Mn is altered in the liver and BAT of ob/ob mice, and that these alterations are responsive to dietary Mn supplementation.

Investigation into the hypogonadism of the obese mouse (genotype ob/ob).

Features of the reproductive axis in the genetically hypogonadal, obese mouse (genotype, ob/ob) were examined at 5-8 months of age and compared with those of wild-type litter mates. Hypothalamic concentrations of dopamine and 5-hydroxytryptamine were normal. Those of 5-hydroxyindoleacetic acid, noradrenaline and LH-RH were raised. LH-RH was biologically active. Pituitary concentration of LH was normal, but that of FSH was raised. Serum concentrations of LH and FSH, compared with those of wild-type animals, were normal and low, respectively. Gonad and accessory sex organs weights were reduced. These findings suggest that the release of FSH but not LH is defective in the ob/ob mouse. Preliminary in-vitro experiments indicated that the pituitary gland responded normally or even supernormally towards LH-RH in its release of LH. The defect in the reproductive axis of the obese mouse may be due to inadequate release of LH-RH although an insensitivity of the pituitary gland towards LH-RH in its release of FSH cannot be excluded.

Somatostatin: widespread abnormality in tissues of spontaneously diabetic mice.

Diabetic mice of the C57BL/6J obob and C57BL/Ks dbdb strains show a reduction in pancreatic somatostatin concentration accompanied in the obob strain by a striking decrease in the number of somatostatin-containing cells in the islets. Somatostatin concentration is also decreased in the stomach but increased in the hypothalamus. These findings suggest different control mechanisms for somatostatin in the hypothalamus compared to the gut and pancreas and exclude a primary genetic abnormality of somatostatin cells in the mutants.