Effects of high fat diet on lipid accumulation, oxidative stress and autophagy in the liver of Chinese softshell turtle (Pelodiscus sinensis)

Impact of Kiwifruit Consumption on Cholesterol Metabolism in Rat Liver: A Gene Expression Analysis in Induced Hypercholesterolemia

BACKGROUND/OBJECTIVES

Cholesterol is vital in various bodily functions, such as maintaining cell membranes, producing hormones, etc. However, imbalances, like hypercholesterolemia, can lead to diseases such as cancer, kidney disease, non-alcoholic fatty liver disease, and cardiovascular conditions. This study explores the impact of kiwifruit consumption, specifically Actinidia arguta cultivar Geneva and Actinidia deliciosa cultivar Hayward, on cholesterol and lipid metabolism in rat liver.

METHODS

Rats were divided into groups: a 1% cholesterol control group (Ch), a 5% Geneva kiwifruit-supplemented group (ChGENE), and a 5% Hayward kiwifruit-supplemented group (ChHAYW). Gene expression was analyzed using Gene Spring v.14. Gene ontology, pathway analysis, miRNA, and transcription factor prediction were performed using DAVID, Reactome, and miRNet. In addition, we used Agilent Literature Search software to gain further insights.

RESULTS

Statistical analysis identified 72 genes in ChGENE-Ch and 2 genes in ChHAYW-Ch comparison. Key genes involved in cholesterol metabolism pathways, including PCSK9, SCD1, SLC27A5, HMGCR, and DHCR24, showed lower expression in the kiwifruit-supplemented groups. The genes mentioned above showed lower expression in the kiwifruit-supplemented group, probably contributing to the liver lipid level reduction. Further analysis identified miRNA-26a, miRNA-29a/b/c, miRNA-33a/b, and miRNA-155 targeting hub genes.

CONCLUSIONS

Our findings suggest that dietary supplementation with kiwifruit, particularly the Geneva cultivar, reduces fat accumulation in the liver of rats with hypercholesterolemia, likely through downregulation of critical genes involved in cholesterol metabolism. These studies highlight the potential of kiwifruit as a part of a dietary strategy to manage cholesterol levels.

Glycerol monolaurate enhances growth performance, lipid metabolism, and inflammatory response in common carp fed high lipid diets

A feeding trial was conducted to investigate the effects of glycerol monolaurate (GML) on growth performance, lipid metabolism, inflammation, and related gene expression in common carp fed a high lipid diet. Juvenile common carp were distributed into 18 cages and fed one of six isonitrogenous diets: a normal lipid diet (control diet, CT), a high lipid diet (HL), and high lipid diets supplemented with 0.5, 1, 2, and 4 g kg-1 GML (designated as GML-0.5, GML-1, GML-2, and GML-4, respectively), with three replicates per treatment. After 56 days of feeding, the results indicated that the final body weight (FBW) and specific growth rate (SGR) in the GML-1 and GML-2 groups were significantly higher than those observed in the CT, HL, and GML-4 groups (P < 0.05). The crude lipid content in the hepatopancreas of the GML-1 and GML-2 groups was significantly lower than that in the HL group (P < 0.05). Morphological analysis of the hepatopancreas revealed a reduction in vacuole presence with GML supplementation (P < 0.05). Additionally, GML supplementation significantly enhanced the development of intestinal structures of common carp. The inclusion of GML significantly influenced the quality of the fillet, as evidenced by notable increases in hardness, gumminess, chewiness, and shear force compared to the HL group (P < 0.05). Additionally, the dripping loss of raw fillets in the GML groups decreased than that observed in the HL group (P < 0.05). Furthermore, GML-1 and GML-2 groups exhibiting the lowest serum TG levels among all groups (P < 0.05). Conversely, serum high density lipoprotein cholesterol (HDL) levels significantly increased with GML supplementation, with the GML-2 group demonstrating the highest HDL content (P < 0.05). Key genes of lipid synthesis in the hepatopancreas were down-regulated, whereas genes involved in lipolysis were up-regulated in the GML-1 and GML-2 groups relative to the HL group (P < 0.05). KEGG functional annotation analysis of differentially expressed genes in the hepatopancreas of fish fed GML-supplemented diets revealed significant alterations in the PPAR signaling pathway. GML effectively enhanced the antioxidant enzyme activities of hepatopancreas, intestine, spleen, kidney, and serum following high lipid feeding accompanied with the significant up-regulation of antioxidant genes in the hepatopancreas and intestine of the GML-1 and GML-2 groups. Simultaneously, pro-inflammatory factors in these tissues were significantly down-regulated, while anti-inflammatory factors were markedly up-regulated in the GML-1 and GML-2 groups compared to the HL group (P < 0.05). In summary, common carp fed high lipid diets supplemented with 1-2 g kg-1 GML exhibited improved growth performance, enhanced fillet quality, regulated lipid metabolism, promoted intestinal structural development, and bolstered both antioxidant and immune capacities.

Effects of Dietary Fish Oil Supplementation on the Growth, Proximate Composition, and Liver Health of Chinese Stripe-Necked Turtle (Mauremys sinensis)

Dietary lipids provide energy for animals and can also be converted into other nutrients (such as non-essential amino acids), which play a role in saving protein. The Chinese stripe-necked turtle is a protected and endangered species that has been bred in captivity; however, basic data on lipid requirements remain unavailable. In this study, 360 Mauremys sinensis (body weight of 65.32 ± 0.15 g) were randomly divided into six groups with three replicates per group; the turtles were fed experimental diets supplemented with various levels of fish oil (i.e., 1% (control group, CG), 3.5% (HF-1), 6% (HF-2), 8.5% (HF-3), 11% (HF-4), and 13.5% (HF-5)) for 10 weeks. The results showed that compared with CG, increasing the fish oil level promoted the growth performance of turtles, and the HF-3 group achieved the best effect. The HF-4 group showed the highest increases in the hepatosomatic index and viscerosomatic index. In addition, increased lipid levels also increased the crude lipid content and reduced the crude protein content in muscle tissue. Oil red O staining showed that the liver lipid content increased with the level of supplemented fish oil, which is consistent with the results of the hepatosomatic index. Compared with CG, triglyceride, total cholesterol, and low-density lipoprotein cholesterol increased significantly in both the liver and serum when fish oil levels exceeded 8.5% (p < 0.05), while high-density lipoprotein cholesterol decreased significantly. Aspartate transaminase and cerealthirdtransaminase levels in serum increased significantly when fish oil levels exceeded 8.5% (p < 0.05). Moreover, the activities of antioxidant enzymes (GSH-Px, SOD, T-AOC, and CAT) and MDA showed similar results, indicating that high fish oil levels (8.5-13.5%) caused liver tissue damage in M. sinensis. Increased fish oil levels significantly upregulated the expression levels of cytokines (IFN-γ, TNF-α, TGF-β1, IL-10, and IL-12) (p < 0.05), downregulated the expression levels of antioxidant enzyme-related genes (cat, mn-sod, and gsh-px), and increased apoptosis of liver cells. Supplementation of the diet with 3.5-6% fish oil improved the growth performance of M. sinensis, and the turtles maintained a beneficial immune status. The results provide a scientific basis for optimizing the commercial feed formula of M. sinensis.

Peripheral hearing sensitivity is similar between the sexes in a benthic turtle species despite the larger body size of males

Sexually dimorphic hearing sensitivity has evolved in many vertebrate species, and the sex with a larger body size typically shows more sensitive hearing. However, generalizing this association is controversial. Research on sexually dimorphic hearing sensitivity contributes to an understanding of auditory sense functions, adaptations, and evolution among species. Therefore, the hypothesized association between body size and hearing needs further validation, especially in specific animal groups. In this study, we assessed hearing sensitivity by measuring auditory brainstem responses (ABRs) in both sexes of 3-year-old Chinese softshell turtles (Pelodiscus sinensis). In this species, male bodies are larger than those of female, and individuals spend most of their lives in the mud at the bottom of freshwater habitats. We found that for both sexes, the hearing sensitivity bandwidth was 0.2-0.9 kHz. Although males were significantly larger than females, no significant differences in ABR thresholds or latencies were found between males and females at the same stimulus frequency. These results indicate that P. sinensis hearing is only sensitive to low-frequency (typically <0.9 kHz) sound signals and that sexually dimorphic hearing sensitivity is not a trait that has evolved in P. sinensis. Physiological and environmental reasons may account for P. sinensis acoustic communication via low-frequency sound signals and the lack of sexually dimorphic hearing sensitivity in these benthic turtles. The results of this study refine our understanding of the adaptation and evolution of the vertebrate auditory system.

Circadian Rhythm Alteration of the Core Clock Genes and the Lipid Metabolism Genes Induced by High-Fat Diet (HFD) in the Liver Tissue of the Chinese Soft-Shelled Turtle (Trionyx sinensis)

Physiology disorders of the liver, as it is an important tissue in lipid metabolism, can cause fatty liver disease. The mechanism might be regulated by 17 circadian clock genes and 18 fat metabolism genes, together with a high-fat diet (HFD). Due to their rich nutritional and medicinal value, Chinese soft-shelled turtles (Trionyx sinensis) are very popular among the Chinese people. In the study, we aimed to investigate the influence of an HFD on the daily expression of both the core clock genes and the lipid metabolism genes in the liver tissue of the turtles. The two diets were formulated with 7.98% lipid (the CON group) and 13.86% lipid (the HFD group) to feed 180 juvenile turtles, which were randomly divided into two groups with three replicates per group and 30 turtles in each replicate for six weeks, and the diet experiment was administrated with a photophase regimen of a 24 h light/dark (12L:12D) cycle. At the end of the experiment, the liver tissue samples were collected from nine turtles per group every 3 h (zeitgeber time: ZT 0, 3, 6, 9, 12, 15, 18, 21 and 24) for 24 h to investigate the daily expression and correlation analysis of these genes. The results showed that 11 core clock genes [i.e., circadian locomotor output cycles kaput (Clock), brain and muscle arnt-like protein 1 and 2 (Bmal1/2), timeless (Tim), cryptochrome 1 (Cry2), period2 (Per2), nuclear factor IL-3 gene (Nfil3), nuclear receptor subfamily 1, treatment D, member 1 and 2 (Nr1d1/2) and retinoic acid related orphan receptor α/β/γ β and γ (Rorβ/γ)] exhibited circadian oscillation, but 6 genes did not, including neuronal PAS domain protein 2 (Npas2), Per1, Cry1, basic helix-loop-helix family, member E40 (Bhlhe40), Rorα and D-binding protein (Dbp), and 16 lipid metabolism genes including fatty acid synthase (Fas), diacylglycerol acyltransferase 1 (Dgat1), 3-hydroxy-3-methylglutaryl-CoA reductase (Hmgcr), Low-density lipoprotein receptor-related protein 1-like (Ldlr1), Lipin 1 (Lipin1), Carnitine palmitoyltransferase 1A (Cpt1a), Peroxisome proliferator activation receptor α, β and γ (Pparα/β/γ), Sirtuin 1 (Sirt1), Apoa (Apoa1), Apolipoprotein B (Apob), Pyruvate Dehydrogenase kinase 4 (Pdk4), Acyl-CoA synthase long-chain1 (Acsl1), Liver X receptors α (Lxrα) and Retinoid X receptor, α (Rxra) also demonstrated circadian oscillations, but 2 genes did not, Scd and Acaca, in the liver tissues of the CON group. However, in the HFD group, the circadian rhythms' expressional patterns were disrupted for the eight core clock genes, Clock, Cry2, Per2, Nfil3, Nr1d1/2 and Rorβ/γ, and the peak expression of Bmal1/2 and Tim showed delayed or advanced phases. Furthermore, four genes (Cry1, Per1, Dbp and Rorα) displayed no diurnal rhythm in the CON group; instead, significant circadian rhythms appeared in the HFD group. Meanwhile, the HFD disrupted the circadian rhythm expressions of seven fat metabolism genes (Fas, Cpt1a, Sirt1, Apoa1, Apob, Pdk4 and Acsl1). Meanwhile, the other nine genes in the HFD group also showed advanced or delayed expression peaks compared to the CON group. Most importantly of all, there were remarkably positive or negative correlations between the core clock genes and the lipid metabolism genes, and their correlation relationships were altered by the HFD. To sum up, circadian rhythm alterations of the core clock genes and the lipid metabolism genes were induced by the high-fat diet (HFD) in the liver tissues of T. sinensis. This result provides experimental and theoretical data for the mass breeding and production of T. sinensis in our country.

Dietary cultured supernatant mixture of Cetobacterium somerae and Lactococcus lactis improved liver and gut health, and gut microbiota homeostasis of zebrafish fed with high-fat diet

Postbiotics have the ability to improve host metabolic disorders and immunity. In order to explore whether the postbiotics SWFC (cultured supernatant mixture of Cetobacterium somerae and Lactococcus lactis) repaired the adverse effects caused by feeding of high-fat diet (HFD), zebrafish were selected as the experimental animal and fed for 6 weeks, with dietary HFD as the control group, and HFD containing 0.3 g/kg and 0.4 g/kg SWFC as the treatment groups. The results indicated that addition of SWFC in the diet at a level of 0.3 and 0.4 g/kg didn't affect the growth performance of zebrafish (P > 0.05). Supplementation of dietary SWFC0.3 relieved lipid metabolism disorders through significant increasing in the expression of pparα and cpt1, and decreasing the expression of cebpα, pparγ, acc1 and dgat-2 genes (P < 0.05). Moreover, the content of triacylglycerol was markedly lower in the liver of zebrafish grouped under SWFC0.3 (P < 0.05). Dietary SWFC0.3 also improved the antioxidant capacity via increasing the expression level of ho-1, sod and gstr genes, and significant inducing malondialdehyde content in the liver of zebrafish (P < 0.05). Besides, dietary SWFC0.3 also notably improved the expression level of lysozyme, c3a, defbl1 and defbl2 (P < 0.05). The expression level of pro-inflammatory factors (nf-κb, tnf-α, and il-1β) were significantly decreased and the expression level of anti-inflammatory factor (il-10) was markedly increased in the postbiotics 0.3 g/kg group (P < 0.05). Feeding with SWFC0.3 supplemented diet for 6 weeks improved the homeostasis of gut microbiota and increased the survival rate of zebrafish after challenged with Aeromonus veronii Hm091 (P < 0.01). It was worth noting that the positive effect of dietary SWFC at a level of 0.3 g/kg was considerably better than that of 0.4 g/kg. This may imply that the effectiveness and use of postbiotics is limited by dosage.

Adipocyte-hepatocyte crosstalk in cellular models of obesity: Role of soluble factors

Hepatic steatosis is often a consequence of obesity. Adipose tissue is an important endocrine regulator of metabolic homeostasis in the body. In obesity, adipocytes become hypertrophic and develop an inflammatory phenotype, altering the panel of secreted adipokines. Moreover, excess fatty acids are, in part, released by adipocytes and delivered to the liver. These multiple pathways of adipose-liver crosstalk contribute to the development and progression of liver disease: TNFα induces hepatocyte dysfunction, excess of circulating fatty acids promotes hepatic steatosis and inflammation, whilst adipokines mediate and exacerbate liver injury. In this study, we investigated in vitro the effects and mechanisms of the crosstalk between adipocytes and hepatocytes, as a function of the different adipocyte status (mature vs hypertrophic) being mediated by soluble factors. We employed the conditioned medium method to test how mature and hypertrophic adipocytes distinctively affect the liver, leading to metabolic dysfunction. The media collected from adipocytes were characterized by high triglyceride content and led to lipid accumulation and fat-dependent dysfunction in hepatocytes. The present findings seem to suggest that, in addition to triglycerides, other soluble mediators, cytokines, are released by mature and hypertrophic adipocytes and influence the metabolic status of liver cells. Understanding the precise factors involved in the pathogenesis and pathophysiology of NAFLD in obesity will provide important insights into the mechanisms responsible for the metabolic complications of obesity, paving the way for new possible approaches.

Effect of starvation and refeeding on reactive oxygen species, autophagy and oxidative stress in Chinese perch (Siniperca chuatsi) muscle growth

In skeletal muscle, autophagy regulates the development and growth of muscle fibres and maintains the normal muscle metabolism. Under starvation and refeeding conditions, the effect of reactive oxygen species (ROS) levels on skeletal muscle autophagy is still unclear, although the excessive accumulation of ROS has been shown to increase autophagy in cells. The purpose of this study was to explore the effects of starvation and diet after starvation on the autophagy of adult Chinese perch muscle, and to determine the level of ROS in the muscle. We performed zero (Normal control), three and seven starvation treatments on adult Chinese perch, and returned to normal feeding for 3 days after starvation for 7 days. In the muscles of the adult Chinese perch muscle after 3 days of starvation, the autophagy marker protein LC3 and the number of autophagosomes remained basically the same as in the normal feeding situation. However, on starvation for 7 days, the mitochondrial autophagy was sensitive and the number of autophagosomes increased, but the antioxidant-related molecules (malondialdehyde, catalase, glutathione S-transferase, glutathione and anti-superoxide anion) decreased and the accumulation of ROS was obvious. In addition, the extended starvation time also increased the level of LC3 protein. However, by refeeding after starvation this nutritional stress resulted in a decrease in ROS levels and a partial restoration of antioxidant enzyme activity. Our data show that in the adult Chinese perch muscle, starvation could reduce the antioxidant activity through the accumulation of ROS, and that the number of autophagosomes continues to increase. Refeeding after starvation could effectively compensate for the level of ROS, and restore the mRNA abundance of antioxidant genes and the activity of antioxidant enzymes to reduce autophagy and improve feed efficiency. Further research should optimize starvation conditions to reduce autophagy in muscles and maintain normal muscle metabolism.

Multiple toxicity endpoints induced by carbon nanofibers in Amazon turtle juveniles: Outspreading warns about toxicological risks to reptiles

The toxicity of carbon-based nanomaterials (CNs) has been observed in different organisms; however, little is known about the impact of water polluted with carbon nanofibers (CNFs) on reptiles. Thus, the aim of the current study was to assess the chronic effects (7.5 months) of 1 and 10 mg/L of CNF on Podocnemis expansa (Amazon turtle) juveniles (4 months old) based on different biomarkers. Increased total organic carbon (TOC) concentrations observed in the liver and brain (which suggests CNF uptake) were closely correlated to changes in REDOX systems of turtles exposed to CNFs, mainly to higher nitrite, hydrogen peroxide and lipid peroxidation levels. Increased levels of antioxidants such as total glutathione, catalase and superoxide dismutase in the exposed animals were also observed. The uptake of CNFs and the observed biochemical changes were associated with higher frequency of erythrocyte nuclear abnormalities (assessed through micronucleus assays), as well as with both damage in erythrocyte DNA (assessed through comet assays) and higher apoptosis and necrosis rates in erythrocytes of exposed turtles. Cerebral and hepatic acetylcholinesterase (AChE) increased in turtles exposed to CNFs, and this finding suggested the neurotoxic effect of these nanomaterials. Data in the current study reinforced the toxic potential of CNFs and evidenced the biochemical, mutagenic, genotoxic, cytotoxic, and neurotoxic effects of CNFs on P. expansa.

Schinus terebinthifolius fruits intake ameliorates metabolic disorders, inflammation, oxidative stress, and related vascular dysfunction, in atherogenic diet-induced obese rats. Insight of their chemical characterization using HPLC-ESI-QTOF-MS/MS

ETHNOPHARMACOLOGY RELEVANCE

Schinus terebinthifolius is traditionally used for its anti inflammatory capacity, and indicated as a cardioprotective agent, whereas, its preventive effect against atherogenic diet fed (AD) induced metabolic disorders and the underlying mechanisms has not yet been explored.

AIM OF THE STUDY

This study was undertaken to investigate the ameliorative role of Schinus terebinthifolius fruits extract (STFE) against cardiovascular problem, oxidative and inflammatory status related to obesity in rats fed an atherogenic diet.

MATERIALS AND METHODS

The metabolites profile in STFE was evaluated using HPLC-DAD-ESI-QTOF-MS/MS analysis. In Wistar rats, atherogenic diet was added for 9 weeks to induce lipid accumulation simultaneously with STFE (50 mg/kg b. w) or saline treatment. Biochemical, oxidant, and inflammatory criteria together with hepatic and arterial integrity examination were assessed.

RESULTS

A total of thirty three metabolites were identified using HPLC-DAD-ESI-QTOF-MS, among them masazino-flavanone was the major compound (2645.50 μg/g DW). The results indicated that STFE supplementation during 9 weeks (50 mg/kg b. w.) significantly attenuated the altered lipid profile by decreasing the levels of TC, TG, LDL-C and increasing the HDL-C content both in plasma and liver, when compared with the AD-group. The histological analysis using ORO staining revealed a decrease in the lipid droplet deposit in the cytoplasm of hepatocytes of STFE + AD group. The addition of STFE could improve the glycemic status of AD-treated rats by decreasing the glucose and insulin secretion, and ameliorating the hepatic glycogen synthesis. The harmful effects of atherogenic diet on hepatic oxidative stress indicators (MDA, PC, GSH, SOD, CAT, and GPx), biochemical markers (AST, ALT, LDH and ALP), and liver function, were found to be decreased by the addition of STFE. Moreover, the reduction of inflammatory markers (CRP, IL-6 and TNF-α), associated to alleviating of aortic oxidative stress and integrity, highlighted the positive anti-atherogenic effect of STFE.

CONCLUSION

Overall, the pleiotropic protective effect observed with S. terebinthifolius fruits might be related to the presence of various bioactive compounds.

Modulation of physiological oxidative stress and antioxidant status by abiotic factors especially salinity in aquatic organisms

Exposure to a variety of environmental factors such as temperature, pH, oxygen and salinity may influence the oxidative status in aquatic organisms. The present review article focuses on the modulation of oxidative stress with reference to the generation of reactive oxygen species (ROS) in aquatic animals from different phyla. The focus of the review article is to explore the plausible mechanisms of physiological changes occurring in aquatic animals due to altered salinity in terms of oxidative stress. Apart from the seasonal variations in salinity, global warming and anthropogenic activities have also been found to influence oxidative health status of aquatic organisms. These effects are discussed with an objective to develop precautionary measures to protect the diversity of aquatic species with sustainable conservation. Comparative analyses among different aquatic species suggest that salinity alone or in combination with other abiotic factors are intricately associated with modulation in oxidative stress in a species-specific manner in aquatic animals. Osmoregulation under salinity stress in relation to energy demand and supply are also discussed. The literature survey of >50 years (1960-2020) indicates that oxidative stress status and comparative analysis of redox modulation have evolved from the analysis of various biotic and/or abiotic factors to the study of cellular signalling pathways in these aquatic organisms.

Exposure to waterborne cadmium induce oxidative stress, autophagy and mitochondrial dysfunction in the liver of Procypris merus

The present study was performed to determine the effect of waterborne cadmium (Cd) exposure on oxidative stress, autophagy and mitochondrial dysfunction, and to explore the mechanism of Cd-induced liver damage in freshwater teleost Procypris merus. To this end, P. merus were exposed to waterborne 0, 0.25 and 0.5 mg/L Cd for 30 days (equal to 0, 2.22 and 4.45 μmol Cd/l). The waterborne Cd exposure significantly increased hepatic Cd accumulation and impaired histological structure of the liver of P. merus. both low and high-dose waterborne Cd exposure induced oxidative stress in the liver of P. merus, through increases Malondialdehyde (MDA) and reactive oxide species (ROS) accumulation in the liver. The Cd-induced oxidative stress in liver may result from reduction of enzyme activities (superoxide dismutases (SOD), catalases (CAT), GSH-S-transferases (GST)) and transcriptional expression of antioxidant related genes (gpx1, gpx2, cata, gsta1, sod1). Furthermore, the present study showed that waterborne Cd exposure decreased the transcriptional factor (nrf2) expression, which might lead to the down-regulation of antioxidant gene expression. Transmission electron microscopy (TEM) observations demonstrated that waterborne Cd exposure induced autophagy in the liver of P. merus. Gene expression analysis showed that waterborne Cd exposure also induced mRNA expression of a set of genes (beclin1, ulk1, atg5, lc3a, atg4b, atg9a, and p62) involved in the autophagy process, indicating that the influence of Cd on autophagy involved transcription regulation of autophagy gene expression. Waterborne Cd exposure induced a sharp decrease in ATP content in the liver of P. merus. In addition, the expression of mitochondrial function genes (sdha, cox4i1, cox1, atp5f1, and mt-cyb) are significantly decreased in the liver of P. merus in Cd treated groups, manifesting the suppression of Cd on mitochondrial energy metabolism. Taken together, our experiments demonstrate that waterborne Cd exposure induced oxidative stress, autophagy and mitochondrial dysfunction in the liver of P. merus. These results may contribute to the understanding of mechanisms that hepatotoxicity of Cd in teleost.