Sodium acetate regulates milk fat synthesis through the activation of GPR41/GPR43 signaling pathway

Short-Chain Fatty Acids (SCFAs) Modulate the Hepatic Glucose and Lipid Metabolism of Coilia nasus via the FFAR/AMPK Signaling Pathway In Vitro

The expansion of intensive aquaculture has heightened metabolic dysregulation in fish caused by high-glucose and high-lipid (HG-HL) diets, contributing to growth retardation and hepatic pathologies. Using Coilia nasus hepatocytes, this study investigated the regulatory effects of short-chain fatty acids (SCFAs) on glucose-lipid metabolism. In vitro HG-HL exposure elevated intracellular glucose, triglycerides (TG), and cholesterol; suppressed catalase (CAT) and superoxide dismutase (SOD); and dysregulated metabolic genes (upregulated phosphoenolpyruvate carboxykinase and acetyl-CoA carboxylase; downregulated glucokinase and hormone-sensitive lipase). Co-treatment with acetate and propionate reversed these anomalies, reducing TG and cholesterol, restoring antioxidant capacity (SOD and CAT), and normalizing gene expression patterns. Molecular docking suggested potential binding interactions between SCFAs and free fatty acid receptor (FFAR2/3). This study provided initial evidence suggesting SCFAs might attenuate HG-HL-induced metabolic stress in a teleost model, potentially involving FFAR-related pathways and AMPK-associated responses. The findings contribute to understanding SCFA-mediated metabolic regulation in fish, offering preliminary support for developing dietary interventions to manage aquacultural metabolic syndromes.

Ruminococcus bromii-generated acetate alleviated Clonorchis sinensis-induced liver fibrosis in mice

Introduction

Infection with Clonorchis sinensis (C. sinensis) has the potential to induce liver fibrosis and significantly alter the gut microbiota. However, it remains unclear how these changes in the gut microbiota, through the gut-liver axis, influence the progression of liver fibrosis. Furthermore, it is uncertain whether targeting the gut microbiota, based on the concept of the gut-liver axis, could be a potential therapeutic strategy for alleviating liver fibrosis.

Methods

The gut microbiota alterations in C. sinensis-infected mice at multiple time points were analyzed through 16S rDNA high-throughput sequencing. Ruminococcus bromii (R.bromii) therapeutic effect on C. sinensis infected mice was evaluated. Metabolic changes following produced by R. bromii were analyzed using short-chain fatty acids (SCFAs) metabolomics. Additionally, R. bromii conditioned medium (R.b CM) or its metabolites were co-cultured with two hepatic stellate cell lines (LX2 and JS1) in vitro to assess their anti-fibrotic effects. Finally, RNA sequencing was employed to investigate the specific mechanism by which acetate inhibits hepatic stellate cells (HSCs) activation.

Results

The abundance of R. bromii increased during the inflammatory stage of C. sinensis infection and decreased significantly during the fibrosis stage. Oral gavage of R. bromii significantly inhibited C. sinensis-induced liver fibrosis while restoring the intestinal barrier. The activation of HSCs was significantly inhibited in vitro upon incubation with R.b CM. Acetate was identified as a key metabolite generated from R. bromii in R.b CM, and acetate attenuated C. sinensis-induced liver fibrosis in vitro and in vivo. Mechanistically, acetate inhibited the activation of HSCs by activating the PI3K/AKT signaling pathway to prevent the progression of liver fibrosis in mice infected with C. sinensis.

Discussion

R. bromii exerted a protective effect on hepatic fibrosis by delivering acetate via the gut-liver axis to active the PI3K/AKT signaling pathway in HSCs. Furthermore, R. bromii can be used as a probiotic therapy to alleviate hepatic fibrosis.

Glutamate increases the lean percentage and intramuscular fat content and alters gut microbiota in Shaziling pigs

This study aimed to explore the effects of glutamate (Glu) supplementation on the growth performance, carcass traits, meat quality, composition of amino acids and fatty acids in the longissimus dorsi muscle, and the colonic microbial community of Shaziling pigs. A total of 48 healthy male Shaziling pigs (150 d, 31.56 ± 0.95 kg) were randomly assigned to two groups, and fed a basal diet with no supplement (control group) or supplemented with 1% Glu (Glu group) for 51 d, and 6 pigs per group were finally slaughtered. Glu significantly increased the average daily gain (P = 0.039), lean percentage (P = 0.023), and intramuscular fat (IMF) content (P = 0.015), and decreased the fat percentage (P = 0.021) of Shaziling pigs. In the muscle, Glu increased the concentrations of inosine-5'-monophosphate (P = 0.094), Fe (P = 0.002), Cu (P = 0.052), and monounsaturated fatty acids (MUFAs) (P = 0.024), and decreased the content of C18:2n6 (P = 0.011), n-6 polyunsaturated fatty acids (n-6 PUFAs) (P = 0.014), and PUFAs (P = 0.014). Moreover, Glu significantly upregulated the mRNA expression of adipogenesis-related genes (FAS, SREBP-1C) (P = 0.032, P = 0.026) and muscle growth-related genes (MyHCⅡb, MyHCⅡx) (P = 0.038, P = 0.019) in the muscle, and increased the relative abundance of Spirochaetota (P < 0.001) and the acetic acid content in the colon (P = 0.039). Correlation analysis indicated that the acetic acid content was positively correlated with the relative Spirochaetota abundance and the IMF content, and a negative trend with the fat percentage of Shaziling pigs. In conclusion, these results indicated that Glu could simultaneously increase the lean percentage and IMF content and decrease the fat percentage of Shaziling pigs, and these beneficial effects may be related to increased colonic Spirochaetota abundance and acetic acid concentrations.

Dietary macronutrient composition and partial soybean meal replacement with slow-release urea: Effects on performance, digestibility, rumen fermentation, and nitrogen metabolism in dairy cows

A 2 × 2 factorial arrangement of treatments was used to investigate the interactive effects of dietary macronutrient composition (high-starch, low-fat, low-fiber [HsLFF] diet or low-starch, high-fat, high-fiber [LsHFF] diet) and N source (soybean meal [SBM] or partially replaced by slow-release urea [SRU]) on lactation performance, rumen fermentation, N utilization efficiency, nutrient digestibility, blood metabolites, and feeding behavior in cows. A replicated 4 × 4 Latin square design was used involving 12 multiparous Holstein cows (milk yield of 40.5 ± 5.6 kg/d, BW of 590 ± 20 kg; 81 ± 12 DIM). The HsLFF diet contained 300 g/kg starch, 31.3 g/kg fat, and 301 g/kg NDF, without straw or additional fat. In contrast, the LsHFF diet contained 195.5 g/kg starch, 60.8 g/kg fat, and 367.5 g/kg NDF, enriched with wheat straw (100 g/kg), and additional fat (34 g/kg). The diets were formulated to be iso-nitrogenous and isocaloric. Cows fed the HsLFF diet had greater DM intake, digestibility of DM and CP, milk yield, and milk protein percentage, but lower intakes of NDF, and physically effective NDF, and milk fat percentage than cows fed the LsHFF diet. Replacing SBM with SRU significantly increased milk solids yield without affecting other lactation performance or BW. Cows fed the LsHFF diet had higher ruminal pH and branched-chain VFA proportions but lower total VFA concentrations compared with the HsLFF diet, while those on the LsHFF-SRU diet had the highest ruminal ammonia levels. Compared with the HsLFF diet, cows fed LsHFF had lower NE intake, milk energy output and energy requirement for maintenance, although energy balances were similar among groups. The HsLFF diet improved N utilization, resulting in higher N content in milk and lower N excretion in feces. Blood metabolite studies showed significant interactions between the main factors, particularly for blood glucose and creatinine, with the lowest levels in cows fed the LsHFF-SRU and LsHFF-SBM diets. In addition, alanine aminotransferase levels were higher in cows fed the LsHFF diet than in cows fed the HsLFF diet. This could indicate early-stage liver stress due to the metabolic imbalance caused by a high-fat, low-starch diet, which can alter energy metabolism. Cows on the HsLFF-SRU diet had the highest glucose levels, indicating possible changes in carbohydrate metabolism or a higher metabolic rate. The concentration of BUN increased steadily after feeding in the LsHFF diet and peaked after 4 h in the LsHFF-SRU diet, with no difference between N sources in the HsLFF diet. Partial replacement of SRU with SBM had no effect on BUN. The interaction between the main factors had a significant effect on MUN content, which was highest in LsHFF-SRU and lowest in HsLFF-SRU, with no difference between the N sources in the HsLFF diets. Overall, while diets with reduced starch and increased fiber and fat compromised lactation performance, partially substituting SRU with SBM helped maintain milk production and milk nitrogen efficiency. However, the LsHFF-SRU diet was less efficient in N utilization, as shown by higher levels of ruminal ammonia, BUN and MUN.

Short-chain fatty acid valerate reduces voluntary alcohol intake in male mice

BACKGROUND

Despite serious health and social consequences, effective intervention strategies for habitual alcohol binge drinking are lacking. The development of novel therapeutic and preventative approaches is highly desirable. Accumulating evidence in the past several years has established associations between the gut microbiome and microbial metabolites with drinking behavior, but druggable targets and their underlying mechanism of action are understudied.

RESULTS

Here, using a drink-in-the-dark mouse model, we identified a microbiome metabolite-based novel treatment (sodium valerate) that can reduce excessive alcohol drinking. Sodium valerate is a sodium salt of valeric acid short-chain fatty acid with a similar structure as γ-aminobutyric acid (GABA). Ten days of oral sodium valerate supplementation attenuates excessive alcohol drinking by 40%, reduces blood ethanol concentration by 53%, and improves anxiety-like or approach-avoidance behavior in male mice, without affecting overall food and water intake. Mechanistically, sodium valerate supplementation increases GABA levels across stool, blood, and amygdala. It also significantly increases H4 acetylation in the amygdala of mice. Transcriptomics analysis of the amygdala revealed that sodium valerate supplementation led to changes in gene expression associated with functional pathways including potassium voltage-gated channels, inflammation, glutamate degradation, L-DOPA degradation, and psychological behaviors. 16S microbiome profiling showed that sodium valerate supplementation shifts the gut microbiome composition and decreases microbiome-derived neuroactive compounds through GABA degradation in the gut microbiome.

CONCLUSION

Our findings suggest that sodium valerate holds promise as an innovative therapeutic avenue for the reduction of habitual binge drinking, potentially through multifaceted mechanisms. Video Abstract.

Maternal supplementation with konjac glucomannan improves maternal microbiota for healthier offspring during lactation

BACKGROUND

The maternal diet during gestation and lactation affects the health of the offspring. Konjac glucomannan (KGM) is a significantly functional polysaccharide in food research, possessing both antioxidant and prebiotic properties. However, the mechanisms of how KGM regulates maternal nutrition remain insufficient and limited. This study aimed to investigate maternal supplementation with KGM during late gestation and lactation to benefit both maternal and offspring generations.

RESULTS

Our findings indicate that KGM improves serum low density lipoprotein cholesterol (LDL-C) and antioxidant capacity. Furthermore, the KGM group displayed a significant increase in the feed intake-related hormones neuropeptide tyrosine (NPY), Ghrelin, and adenosine monophosphate-activated kinase (AMPK) levels. KGM modified the relative abundance of Clostridium, Candidatus Saccharimonas, unclassified Firmicutes, and unclassified Christensenellaceae in sow feces. Acetate, valerate, and isobutyrate were also improved in the feces of sows in the KGM group. These are potential target bacterial genera that may modulate the host's health. Furthermore, Spearman's correlation analysis unveiled significant correlations between the altered bacteria genus and feed intake-related hormones. More importantly, KGM reduced interleukin-6 (IL-6) levels in milk, further improved IL-10 levels, and reduced zonulin levels in the serum of offspring.

CONCLUSION

In conclusion, maternal dietary supplementation with KGM during late gestation and lactation improves maternal nutritional status by modifying maternal microbial and increasing lactation feed intake, which benefits the anti-inflammatory capacity of the offspring serum. © 2024 Society of Chemical Industry.

Acetate Upregulates GPR43 Expression and Function via PI3K-AKT-SP1 Signaling in Mammary Epithelial Cells during Milk Fat Synthesis

This study investigated the mechanism underlying acetate-induced orphan G-protein-coupled receptor 43 (GPR43) expression and milk fat production. The mammary epithelial cells of dairy cows were treated with acetate, and the effects of GPR43 on acetate uptake and the expression of lipogenesis-related genes were determined by gas chromatography and quantitative polymerase chain reaction (qPCR), respectively. RNAi, inhibitor treatment, and luciferase assay were used to determine the effect of phosphoinositide 3-kinase-protein kinase B-specificity protein 1 (PI3K-AKT-SP1) signaling on acetate-induced GPR43 expression and function. The results showed that GPR43 was highly expressed in lactating cow mammary tissues, which was related to milk fat synthesis. 12 mM acetate significantly increased the GPR43 expression in mammary epithelial cells of dairy cows. In acetate-treated cells, GPR43 overexpression significantly increased the cellular uptake of acetate, the intracellular triacylglycerol (TAG) content, and acetate-induced lipogenesis gene expression. Acetate activated PI3K-AKT signaling and promoted SP1 translocation from the cytosol into the nucleus, where SP1 bound to the GPR43 promoter and upregulated GPR43 transcription. Moreover, the activation of PI3K-AKT-SP1 by acetate facilitated the trafficking of GPR43 from the cytosol to the plasma membrane. In conclusion, acetate upregulated GPR43 expression and function via PI3K-AKT-SP1 signaling in mammary epithelial cells, thereby increasing milk fat synthesis. These results provide an experimental strategy for improving milk lipid synthesis, which is important to the dairy industry.

Short-chain-fatty acid valerate reduces voluntary alcohol intake in male mice

Background

Despite serious health and social consequences, effective intervention strategies for habitual alcohol binge drinking are lacking. Development of novel therapeutic and preventative approaches is highly desirable. Accumulating evidence in the past several years has established associations between the gut microbiome and microbial metabolites with drinking behavior, but druggable targets and their underlying mechanism of action are understudied.

Results

Here, using a drink-in-the-dark mouse model, we identified a microbiome metabolite-based novel treatment (sodium valerate) that can reduce excessive alcohol drinking. Sodium valerate is a sodium salt of valeric acidshort-chain-fatty-acid with similar structure as γ-aminobutyric acid (GABA). Ten days of oral sodium valerate supplementation attenuates excessive alcohol drinking by 40%, reduces blood ethanol concentration by 53%, and improves anxiety-like or approach-avoidance behavior in male mice, without affecting overall food and water intake. Mechanistically, sodium valerate supplementation increases GABA levels across stool, blood, and amygdala. It also significantly increases H4 acetylation in the amygdala of mice. Transcriptomics analysis of the amygdala revealed that sodium valerate supplementation led to changes in gene expression associated with functional pathways including potassium voltage-gated channels, inflammation, glutamate degradation, L-DOPA degradation, and psychological behaviors. 16S microbiome profiling showed that sodium valerate supplementation shifts the gut microbiome composition and decreases microbiome-derived neuroactive compounds through GABA degradation in the gut microbiome.

Conclusion

Our findings suggest that the sodium valerate holds promise as an innovative therapeutic avenue for the reduction of habitual binge drinking, potentially through multifaceted mechanisms.