Effect of dietary choline levels on growth performance, lipid deposition and metabolism in juvenile yellow catfish Pelteobagrus fulvidraco

Choline-mediated hepatic lipid homoeostasis in yellow catfish: unravelling choline's lipotropic and methyl donor functions and significance of ire-1α signalling pathway

Choline plays a crucial role in hepatic lipid homeostasis by acting as a major methyl-group donor. However, despite this well-accepted fact, no study has yet explored how choline's methyl-donor function contributes to preventing hepatic lipid dysregulation. Moreover, the potential regulatory role of Ire-1α, an ER-transmembrane transducer for the unfolded protein response (UPRer), in choline-mediated hepatic lipid homeostasis remains unexplored. Thus, this study investigated the mechanism by which choline prevents hepatic lipid dysregulation, focusing on its role as a methyl-donor and the involvement of Ire-1α in this process. To this end, a model animal for lipid metabolism, yellow catfish (Pelteobagrus fulvidraco) were fed two different diets (adequate or deficient choline diets) in vivo for 10 weeks. The key findings of studies are as follows: 1. Dietary choline, upregulated selected lipolytic and fatty acid β-oxidation transcripts promoting hepatic lipid homeostasis. 2. Dietary choline ameliorated UPRer and prevented hepatic lipid dysregulation mainly through ire-1α signalling, not perk or atf-6α signalling. 3. Choline inhibited the transcriptional expression level of ire-1α by activating site-specific DNA methylations in the promoter of ire-1α. 4. Choline-mediated ire-1α methylations reduced Ire-1α/Fas interactions, thereby further inhibiting Fas activity and reducing lipid droplet deposition. These results offer a novel insight into the direct and indirect regulation of choline on lipid metabolism genes and suggests a potential crosstalk between ire-1α signalling and choline-deficiency-induced hepatic lipid dysregulation, highlighting the critical contribution of choline as a methyl-donor in maintaining hepatic lipid homeostasis.

Dietary choline activates the Ampk/Srebp signaling pathway and decreases lipid levels in Pacific white shrimp (Litopenaeus vannamei)

An 8-week feeding trial was conducted in Pacific white shrimp (Litopenaeus vannamei) to evaluate the effects of dietary choline supplementation on choline transport and metabolism, hepatopancreas histological structure and fatty acid profile, and regulation of lipid metabolism. Six isonitrogenous and isolipidic diets were formulated to contain different choline levels of 2.91 (basal diet), 3.85, 4.67, 6.55, 10.70 and 18.90 g/kg, respectively. A total of 960 shrimp (initial weight, 1.38 ± 0.01 g) were distributed randomly into twenty-four 250-L cylindrical fiber-glass tanks, with each diet assigned randomly to 4 replicate tanks. The results indicated that dietary choline significantly promoted the deposition of choline, betaine and carnitine (P < 0.05). The diameters and areas of R cells, total lipid and triglyceride contents in hepatopancreas, and triglyceride and non-esterified fatty acid contents in hemolymph were negatively correlated with dietary choline level. The contents of functional fatty acids in hepatopancreas, the activity of acetyl-CoA carboxylase (Acc), and the mRNA expression of fas, srebp and acc were highest in shrimp fed the diet containing 4.67 g/kg choline, and significantly higher than those fed the diet containing 2.91 g/kg, the lowest level of choline (P < 0.05). The number of R cells, content of very low-density lipoprotein (VLDL), activities of carnitine palmitoyl-transferase (Cpt1), lipoprotein lipase and hepatic lipase, and the mRNA expression levels of cpt1, fabp, fatp, ldlr, and ampk in hepatopancreas increased significantly as dietary choline increased (P < 0.05). In addition, hepatopancreas mRNA expression levels of ctl1, ctl2, oct1, badh, bhmt, ck, cept, and cct were generally up-regulated as dietary choline level increased (P < 0.01). In conclusion, dietary choline promoted the deposition of choline and its metabolites by up-regulating genes related to choline transport and metabolism. Moreover, appropriate dietary choline level promoted the development of hepatopancreas R cells and maintained the normal accumulation of lipids required for development, while high dietary choline not only promoted hepatopancreas lipid export by enhancing VLDL synthesis, but also promoted fatty acid β-oxidation and inhibited de novo fatty acid synthesis by activating the Ampk/Srebp signaling pathway. These findings provided further insight and understanding of the mechanisms by which dietary choline regulated lipid metabolism in L. vannamei.

Dietary supplementation of pyridoxine can enhance the growth performance and improve the protein, lipid utilization efficiency of mandarin fish (Siniperca chuatsi)

This study aimed to assess the effect of pyridoxine supplementation in the mandarin fish diet on growth performance, protein and lipid metabolism, and liver and intestinal histology. Mandarin fish were fed six diets with different levels of pyridoxine (2.67 mg/kg (control), 4.41 mg/kg, 6.57 mg/kg, 10.25 mg/kg, 17.93 mg/kg, 33.12 mg/kg diet) for 8 weeks, and samples were collected for analysis. The findings demonstrated that feeding mandarin fish a diet with 6.57 mg/kg pyridoxine led to a significant increase in weight gain rate (WGR), protein efficiency ratio (PER), whole-body crude protein, whole-body crude lipid, serum protein, cholesterol (CHO), triacylglycerol (TG), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), and alkaline phosphatase (ALP), as well as significantly lower serum glucose (GLU) and feed conversion ratio (FCR), compared to the control group (P < 0.05). Furthermore, we found a significant upregulation of the relative expression of genes associated with hepatic lipid oxidation and synthesis (hl, lpl, pparα, cpt1, cs, srebp1, and fas) and proteolysis (ast, alt, and gdh) in fish fed a diet containing 6.57 mg/kg pyridoxine (P < 0.05). Regarding the histological analysis, we observed a notable decrease in the quantity of intestinal mucus-secreting cells when the fish fed a diet containing 10.25 mg/kg pyridoxine (P < 0.05). These findings suggest that dietary pyridoxine supplementation promotes mandarin fish growth by improving the efficiency of protein and lipid utilization. Additionally, we used a broken-line regression analysis to estimate the optimal dietary pyridoxine requirement for mandarin fish in the range of 6.17-6.41 mg/kg based on WGR, FCR, and PER.

Dietary choline promotes growth, antioxidant capacity and immune response by modulating p38MAPK/p53 signaling pathways of juvenile Pacific white shrimp (Litopenaeus vannamei)

The objective of the present study was to evaluate the effects of dietary choline levels on growth performance, antioxidant capacity, innate immunity and hemocyte apoptosis of Litopenaeus vannamei. Six isonitrogenous and isolipidic diets were formulated to contain different choline levels: 2.91 (basal diet), 3.85, 4.67, 6.55, 10.70 and 18.90 g kg^-1choline, respectively. The results indicated that shrimp fed diet with 4.67 g kg^-1 choline had the highest final body weight (FBW), percent weight gain (PWG), specific growth rate (SGR), feed efficiency (FE), and activities of alkaline phosphatase (AKP) and phenoloxidase (PO) in hemolymph among all treatments. Shrimp fed diet with 18.90 g kg^-1 choline exhibited significantly lower crude lipid in hepatopancreas than those fed diets with 2.91, 3.85, 4.67 and 6.55 g kg^-1 choline (P < 0.05). The concentration of reactive oxygen species (ROS) and apoptosis rate in hemocytes significantly decreased with the increase of dietary choline levels (P < 0.05). Shrimp fed diets with 6.55, 10.70 and 18.90 g kg^-1 choline had significantly higher scavenging ability of hydroxyl radical (SAHR) and total antioxidant capacity (T-AOC) in hemolymph than those fed diet with 2.91 g kg^-1 choline (P < 0.05). Dietary choline supplementation down-regulated the expression of genes related to apoptosis such as caspase-1, caspase-3, caspase-8, p53, and p38MAPK in hemocytes (P < 0.05), while up-regulated the expression of anti-apoptosis gene bcl2 in hemocytes (P < 0.05). Overall, the results of the present study demonstrated that appropriate dietary choline could improve growth performance and feed utilization, enhance antioxidant capacity and innate immunity, and mitigate apoptosis in Litopenaeus vannamei. Moreover, the inhibition of hemocyte apoptosis by dietary choline may be regulated by the p38MAPK-p53 signaling pathway.

Dietary Choline Mitigates High-Fat Diet-Impaired Chylomicrons Assembly via UPRer Modulated by perk DNA Methylation

High-fat diets (HFD) lead to impairment of chylomicrons (CMs) assembly and adversely influence intestinal lipid homeostasis. However, the mechanisms of HFD impairing CMs assembly have yet to be fully understood. Additionally, although choline, as a lipid-lowering agent, has been widely used and its deficiency has been closely linked to non-alcoholic steatohepatitis (NASH), the contribution of choline by functioning as a methyl donor in alleviating HFD-induced intestinal lipid deposition is unknown. Thus, this study was conducted to determine the mechanism of HFD impairing CMs assembly and also tested the effect of choline acting as a methyl donor in this process. To this end, in this study, four diets (control, HFD, choline and HFD + choline diet) were fed to yellow catfish for 10 weeks in vivo and their intestinal epithelial cells were isolated and incubated for 36 h in fatty acids (FA) with or without choline solution combining si-perk transfection in vitro. The key findings from this study as follows: (1) HFD caused impairment of CMs assembly main by unfolded protein response (UPRer). HFD activated perk and then induced UPRer, which led to endoplasmic reticulum dysfunction and further impaired CMs assembly via protein-protein interactions between Perk and Apob48. (2) Choline inhibited the transcriptional expression level of perk via activating the -211 CpG methylation site, which initiated the subsequent ameliorating effect on HFD-impaired CMs assembly and intestinal lipid dysfunction. These results provide a new insight into direct crosstalk between UPRer and CMs assembly, and also emphasize the critical contribution of choline acting as a methyl donor and shed new light on choline-deficient diet-induced NASH.

Dietary choline prevents high fat-induced disorder of hepatic cholesterol metabolism through SREBP-2/HNF-4α/CYP7A1 pathway in a freshwater teleost yellow catfish Pelteobagrus fulvidraco

Lipid overload-induced hepatic cholesterol accumulation is a major public health problem worldwide, and choline has been reported to ameliorate cholesterol accumulation, but its mechanism remains unclear. Our study found that choline prevented high-fat diet (HFD)-induced cholesterol metabolism disorder and enhanced choline uptake and phosphatidylcholine synthesis in the liver tissues; choline incubation prevented fatty acid (FA)-induced cholesterol accumulation and FA-induced inhibition of bile acid synthesis. Moreover, compared to single FA incubation, choline incubation or FA + choline co-incubation increased the mRNA abundances and protein levels of HNF4α and up-regulated the degradation of cholesterol into bile acids. Mechanistically, choline prevented the FA-induced accumulation of SREBP2 protein and the interaction between SREBP2 and HNF4α, thereby enhancing the DNA binding capacity of the HNF4α to the CYP7A1 promoter, and promoting the degradation of cholesterol into bile acids. Our study elucidated the novel regulatory mechanisms of choline preventing HFD-induced cholesterol accumulation and increasing bile acid synthesis by SREBP-2/HNF-4α/CYP7A1 pathway.

Choline Chloride Induces Growth Performance of Indian Major Carps and Air-Breathing Fish Species with an Outcome of Quality Food-Fish under a Semi-Intensive Culture System: A Biochemical Investigation

The present study was intended to determine the possible influences of direct field application of choline chloride into pond water in addition to farm-made-aqua-feed under a semi-intensive culture system on the growth and biochemical parameters of two Indian major carps (IMCs), Catla catla (Catla) and Labeo rohita (Rahu), and two air-breathing species, Clarias batrachus (Magur) and Anabas testudineus (Koi), cultured in a ratio of 2:5:1:1 (Catla/Rahu/Magur/Koi) in three experimental ponds for a period of 90 days during the breeding season (June to August). Results were compared with control (C: fed only with farm-made-aqua-feed) and treatment (T: P1 and P2: farm-made-aqua-feed plus choline chloride into pond water directly at the rate of 350 g bigha^-1 fortnightly or 350 g per 1600 square meter fortnightly). A significant increasing trend was observed in the growth parameters including total length-final (TLF), standard length-final (SLF), mean weight-final (MWF), % gain of mean total length (MTL), % gain of mean standard length (MSL), % weight gain (WG), specific growth rate (SGR) % per day, and survivability %. However, a reverse pattern was noticed in the food conversion ratio (FCR) both in IMCs and air-breathing fish species under choline supplementation. Serum biochemical responses, e.g., total protein (PRO), lactate dehydrogenase (LDH), glucose (GLU), and calcium (Ca) showed significant enhancement, and alkaline phosphatase (ALP), alanine amino transaminase (ALT), aspartate amino transaminase (AST), cholesterol (CHOLES), and triglycerides (Trig) showed gradual significant reduction during the breeding season under choline exposure. Treated fishes showed prevention from liver dysfunction and fatty liver formation, and increased body crude protein content. Results indicated favorable growth and yield, which may benefit fish farmers during their culture practices, and the output fish species under choline supplementation resulted in quality food-fish for human consumption.

Dietary Choline Alleviates High-Fat Diet-Induced Hepatic Lipid Dysregulation via UPRmt Modulated by SIRT3-Mediated mtHSP70 Deacetylation

The mitochondrial unfolded protein response (UPRmt) is known as a conservative mechanism in response to mitochondrial dysfunction. Thus, based on UPRmt, this study was conducted to determine the mechanism of a high-fat diet (HFD) inducing mitochondrial dysfunction and its role in stimulating hepatic lipid dysregulation. The choline-activated alleviating effect was also evaluated. In vivo, yellow catfish were fed three diets (control, HFD, and HFD + choline diet) for 10 weeks. In vitro, hepatocytes isolated from yellow catfish and the HepG2 cell line were cultured and incubated with fatty acid (FA) for 48 h. (1) HFD-induced mitochondrial dysfunction via SIRT3/mtHSP70-mediated UPRmt. HFD inhibited the subcellular localization of SIRT3 into the mitochondrion, resulting in the up-regulating of mtHSP70 acetylation via lysine residues 493 and 507. The mtHSP70 acetylation promoted the stability of mtHSP70, which then led to the UPRmt and further mitochondrial dysfunction. (2) SIRT3/mtHSP70-mediated UPRmt regulated HFD/FA-induced hepatic lipid dysregulation. SIRT3/mtHSP70-mediated UPRmt reduced FA ß-oxidation via mitochondrial dysfunction and then led to lipid dysregulation. Additionally, the mtHSP70-ACOX1 interaction was confirmed. (3) Choline alleviated HFD-induced UPRmt via up-regulating the localization of SIRT3 into the mitochondrion, which in turn led to the subsequent ameliorating effect on HFD-induced hepatic lipid dysregulation. Through SIRT3-mediated mtHSP70 deacetylation, dietary choline alleviates HFD-induced hepatic lipid dysregulation via UPRmt. This provides the first proof of acetylation regulating UPRmt and the crosstalk between UPRmt and FA ß-oxidation.

Effects of dietary choline on liver lipid composition, liver histology and plasma biochemistry of juvenile yellowtail kingfish (Seriola lalandi)

Choline plays a crucial role in lipid metabolism for fish, and its deficiency in aquafeed has been linked to compromised health and growth performance. A 56-d experiment was conducted to examine the effects of dietary choline on lipid composition, histology and plasma biochemistry of yellowtail kingfish (Seriola lalandi; YTK; 156 g initial body weight). The dietary choline content ranged from 0·59 to 6·22 g/kg diet. 2-Amino-2-methyl-1-propanol (AMP) (3 g/kg) was added to diets, except for a control diet, to limit de novo choline synthesis. The results showed that the liver lipid content of YTK was similar among diets containing AMP and dominated by NEFA. In contrast, fish fed the control diet had significantly elevated liver TAG. Generally, the SFA, MUFA and PUFA content of liver lipid in fish fed diets containing AMP was not influenced by choline content. The SFA and MUFA content of liver lipid in fish fed the control diet was similar to other diets except for a decrease in PUFA. The linear relationship between lipid digestibility and plasma cholesterol was significant, otherwise most parameters were unaffected. When AMP is present, higher dietary choline reduced the severity of some hepatic lesions. The present study demonstrated that choline deficiency affects some plasma and liver histology parameters in juvenile YTK which might be useful fish health indicators. Importantly, the present study elucidated potential reasons for lower growth in choline-deficient YTK and increased the knowledge on choline metabolism in the fish.

Effects of dietary sodium butyrate on growth, digestive enzymes, body composition and nutrient retention-related gene expression of juvenile yellow catfish (Pelteobagrus fulvidraco)

An 8-week feeding trial was conducted to evaluate the effects of sodium butyrate (SB) on growth, digestive enzymes, body composition and nutrient retention-related gene expression of juvenile yellow catfish (Pelteobagrus fulvidraco). Five isonitrogenous and isolipidic diets (420 g/kg protein and 90 g/kg lipid) were formulated to contain 0 (control), 250, 500, 1,000 or 2,000 mg/kg SB. Triplicate groups of 40 fish (BW = 1.26 ± 0.01 g) per tank (300-L cylindrical fiberglass tanks) for each diet were fed to apparent satiation twice daily. Stomach, hepatopancreas and intestine samples were obtained for digestive enzymes activities analyses. A real-time quantitative PCR analysis was performed to determine the relative expression of target of rapamycin (TOR) and lipoprotein lipase (LPL) in the hepatopancreas and intestine. Fish fed the diets supplemented with SB at 500 and 1,000 mg/kg showed significantly higher specific growth rate and significantly lower feed conversion ratio compared to the control (P < 0.05). Dietary SB inclusion did not alter activities of intestinal amylase, creatine kinase and sodium–potassium adenosine triphosphatase (Na⁺/K⁺-ATPase), but increased activities of hepatic trypsin, stomachic lipase, intestinal lipase, alkaline phosphatase and γ-glutamyl transpeptidase for fish fed 1,000 mg/kg SB compared to the control (P < 0.05). Intestine length index, intestine somatic index, fold height and muscular thickness of distal intestine were significantly higher in 1,000 mg/kg SB groups compared to the control (P < 0.05). Significantly higher levels of whole-body crude protein, ash, calcium, phosphorus, nutrition retention and relative mRNA of intestinal TOR were observed in 1,000 mg/kg SB group (P < 0.05). Whole-body lipid content and hepatopancreas LPL mRNA expression in 2,000 mg/kg SB group were significantly higher than the control (P < 0.05). Relative mRNA levels of intestinal LPL and hepatopancreas TOR were significantly higher in the 500 mg/kg SB group compared to those in other groups (P < 0.05). The increased growth performance, digestive enzymes and nutrient retention in fish fed the diets supplemented with SB at 500 and 1,000 mg/kg suggests that SB can be a desirable growth promoter as an antibiotic alternative in diets.

Growth performance, physiological parameters, and transcript levels of lipid metabolism-related genes in hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) fed diets containing Siberian ginseng

In high-density aquaculture, fish health can suffer because of excessive feeding, which causes fatty liver disease. Siberian ginseng (Acanthopanax senticosus) has been used as a feed additive to promote animal growth, immunity, and lipid metabolism. In this study, we explored the effects of A. senticosus on the physiology of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂). A control group and five groups fed diets containing A. senticosus (0.5, 1, 2, 4, and 8 g A. senticosus/kg feed) were established and maintained for 8 weeks. Dietary supplementation with A. senticosus at 4 g/kg promoted growth of the hybrid yellow catfish. Serum total cholesterol (TC) and triacylglycerol (TG) levels at 2 g/kg A. senticosus (TC: 1.31 mmol/L; TG: 1.08 mmol/L) were significantly lower than in the control group (TC: 1.51 mmol/L; TG: 1.41 mmol/L), and 4 g/kg A. senticosus (17.20 μmol/g tissue) reduced the liver TG level compared with the control group (21.36 μmol/g tissue) (P <0.05). Comparative transcriptomic analysis of liver tissue between the control group and the group showing optimum growth (4 g/kg A. senticosus) revealed 820 differentially expressed genes and 44 significantly enriched pathways, especially lipid metabolism pathways such as unsaturated fatty acid and fatty acid metabolism. The transcript levels of five lipid metabolism-related genes were determined by quantitative real-time PCR. The results showed that 2–4 g/kg A. senticosus supplementation reduced the FADS2, ELOVL2, CYP24a, and PLPP3 transcript levels and 4 g/kg A. senticosus increased the DIO2 transcript level (P <0.05), leading to altered synthesis of TG and thyroxine and reduced fat deposition in the liver. Our results show that dietary A. senticosus affects the regulation of fat metabolism and promotes the growth of hybrid yellow catfish. A. senticosus is a healthy feed additive, and the appropriate dietary supplementation rate is 2–4 g/kg.

Dietary choline supplementation attenuated high-fat diet-induced inflammation through regulation of lipid metabolism and suppression of NFκB activation in juvenile black seabream (Acanthopagrus schlegelii)

The present study aimed to investigate whether dietary choline can regulate lipid metabolism and suppress NFκB activation and, consequently, attenuate inflammation induced by a high-fat diet in black sea bream (Acanthopagrus schlegelii). An 8-week feeding trial was conducted on fish with an initial weight of 8·16 ± 0·01 g. Five diets were formulated: control, low-fat diet (11 %); HFD, high-fat diet (17 %); and HFD supplemented with graded levels of choline (3, 6 or 12 g/kg) termed HFD + C1, HFD + C2 and HFD + C3, respectively. Dietary choline decreased lipid content in whole body and tissues. Highest TAG and cholesterol concentrations in serum and liver were recorded in fish fed the HFD. Similarly, compared with fish fed the HFD, dietary choline reduced vacuolar fat drops and ameliorated HFD-induced pathological changes in liver. Expression of genes of lipolysis pathways were up-regulated, and genes of lipogenesis down-regulated, by dietary choline compared with fish fed the HFD. Expression of nfκb and pro-inflammatory cytokines in liver and intestine was suppressed by choline supplementation, whereas expression of anti-inflammatory cytokines was promoted in fish fed choline-supplemented diets. In fish that received lipopolysaccharide to stimulate inflammatory responses, the expression of nfκb and pro-inflammatory cytokines in liver, intestine and kidney were all down-regulated by dietary choline compared with the HFD. Overall, the present study indicated that dietary choline had a lipid-lowering effect, which could protect the liver by regulating intrahepatic lipid metabolism, reducing lipid droplet accumulation and suppressing NFκB activation, consequently attenuating HFD-induced inflammation in A. schlegelii.

Dietary Radix Bupleuri extracts improves hepatic lipid accumulation and immune response of hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀)

In this study, two experiments were performed to explore the effect of Radix Bupleuri extracts (RBE) on growth, lipid deposition and metabolism and immune response of hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀) using in vitro and in vivo models. In vitro, we used 2 ml/L 20% lipid emulsion (LE)-induced steatosis in hybrid grouper primary hepatocytes, then RBE (200, 400 and 800 μg/ml) was added to the hepatocytes after (post-treatment) the incubation with 20% LE (2 ml/L) in the culture medium. We found that RBE markedly increased cell viability, which were consistent with hepatocytes morphological structure examination and lipid metabolism and immune related genes study. The above result suggested that RBE has a protective effect on this model of hepatocytes damage. In vivo, five graded levels of RBE at 0, 200, 400, 800 and 1600 mg/kg diet were supplemented to a basal diet with 15% lipid levels (high lipid), and fed to a total of 300 hybrid grouper with an average initial weight of 25.58 ± 0.05 g for 8 weeks. Growth performance, liver histology, plasma biochemical parameters, and expression of genes involved in lipid metabolism and immune-related were measured. The study indicated that dietary RBE significantly improved growth performance and feed utilization and reduced hepatosomatic index. Dietary supplementation with 200-800 mg/kg RBE diets effectively decreased serum ALP, ALT, AST and LDH contents in fish. Furthermore, adipogenesis relative mRNA levels of DGAT2, G6PD, ME1 and DGKα in fish fed 200-400 mg/kg RBE diets were lower (P < 0.05) than in those fed RBE0 diets, while dietary supplementation with 200-800 mg/kg RBE diets up-regulated lipolysis-related genes (CPT1, LPL and PPARα) expression in the liver of hybrid grouper. Moreover, dietary RBE down-regulated the expression of apoptosis-related genes (caspase-9), up-regulated the expression of antioxidant genes (CAT) and immune-related genes (MHC2, IKKα and TGF-β1). Thus, our data suggest that RBE suppressed lipid accumulation and enhanced immune capability in hybrid grouper both in vitro and in vivo. These results offer new insight into RBE as a hepatoprotective in fish.

Modulation of lipid metabolism in juvenile yellow catfish (Pelteobagrus fulvidraco) as affected by feeding frequency and environmental ammonia

In the intensive culture systems, excessive feeding leads to ammonia accumulation, which results in lipid metabolism disorder. However, little information is available on the modulation of lipid metabolism in fish as affected by feeding frequency and ammonia stress. In this study, weight gain increased as feeding frequency increased from one to four times daily, but feed conversion ratio is opposite. The highest survival was found in ammonia group when fish was fed two times daily. Liver ammonia content increased as feeding frequency increased from one to four times daily, and the highest brain ammonia content was found when fish was fed four times daily. The highest liver 6-phospho-gluconate dehydrogenase (6PGD), fatty acid synthase (FAS), carnitine palmitoyltransferase (CPT), and lipoprotein lipase (LPL) contents were found in control group when fish was fed four times daily; in comparison, the highest liver 6PGD, FAS, CPT, and LPL contents were found in ammonia group when fish was fed two times daily. Liver 6PGD, FAS, CPT 1, SREBP-1, and PPARα mRNA expression in control group increased significantly as feeding frequency increased from one to four times daily, and the highest expression of 6PGD, G6PD, and FAS was observed in ammonia group when fish was fed two times daily. This study indicated that the optimal feeding frequency is two times daily when yellow catfish exposed to ammonia.

Supplementary choline attenuates olive oil lipid emulsion-induced enterocyte apoptosis through suppression of CELF1/AIF pathway

Enterocyte apoptosis induced by lipid emulsions is a key cause of intestinal atrophy under total parenteral nutrition (TPN) support, and our previous work demonstrated that olive oil lipid emulsion (OOLE) could induce enterocyte apoptosis via CUGBP, Elav‐like family member 1 (CELF1)/ apoptosis‐inducing factor (AIF) pathway. As TPN‐associated complications are partially related to choline deficiency, we aimed to address whether choline supplementation could attenuate OOLE‐induced enterocyte apoptosis. Herein we present evidence that supplementary choline exhibits protective effect against OOLE‐induced enterocyte apoptosis both in vivo and in vitro. In a rat model of TPN, substantial reduction in apoptotic rate along with decreased expression of CELF1 was observed when supplementary choline was added to OOLE. In cultured Caco‐2 cells, supplementary choline attenuated OOLE‐induced apoptosis and mitochondria dysfunction by suppressing CELF1/AIF pathway. Compared to OOLE alone, the expression of CELF1 and AIF was significantly decreased by supplementary choline, whereas the expression of Bcl‐2 was evidently increased. No obvious alterations were observed in Bax expression and caspase‐3 activation. Mechanistically, supplementary choline repressed the expression of CELF1 by increasing the recruitment of CELF1 mRNA to processing bodies, thus resulting in suppression of its protein translation. Taken together, our data suggest that supplementary choline exhibits effective protection against OOLE‐induced enterocyte apoptosis, and thus, it has the potential to be used for the prevention and treatment of TPN‐induced intestinal atrophy.