Dietary Myo-inositol Research Articles

New insights into the role of myo-inositol in regulating the skin immune response of grass carp (Ctenopharyngodon idella)

Myo-inositol (MI) is a crucial constituent of the cell membrane and has a pivotal role to play in transmembrane signal transduction, ion channel regulation, and cell transport. Fish skin is a vital mucosal immune organ, and there are few studies that have examined the effect of MI on fish skin.Therefore, the purpose of this study was to investigate the role of dietary MI in regulating the skin immune response of grass carp (Ctenopharyngodon idella). A total of 540 fish (221.33 ± 0.84 g) were fed six diets containing graded levels of MI (27.0, 137.9, 286.8, 438.6, 587.7, and 737.3 mg/kg) for 10 weeks. When the growth test was complete, a 14-day challenge was conducted with Aeromonas hydrophila in each group. Our results indicated that the most effective MI concentrations (approximately 438.6–737.3 mg/kg diet) resulted in the following outcomes: (1) MI reduced the morbidity of grass carp skin and increased the thickness of the dense dermis layer. (2) MI enhanced the physical barrier function of the skin, maybe via increasing antioxidant capacity, inhibiting apoptosis, and improving tight junction-related signaling pathways (nuclear factor erythroid 2-related factor 2, p38 mitogen-activated protein kinase, and myosin light chain kinase). (3) MI enhanced skin immune barrier function, possibly via regulating anti-inflammatory and pro-inflammatory cytokines, as well as the target of rapamycin (TOR) and nuclear factor kappa B (NFκB) pathways. This study led to the following conclusion based on its findings: the MI supplementation strengthened the fish skin barrier function and protected it against Aeromonas hydrophila. The dietary MI requirement in on-growing grass carp was estimated to be 370.90 mg/kg by a broken-line method analysis of skin morbidity.

Effect of dietary myo-inositol supplementation on the insulin resistance and the prevention of gestational diabetes mellitus: an open-label, randomized controlled trial.

Myo-inositol (MI) is an insulin-sensitizing dietary supplement, enhancing the transfer of glucose into the cell. Gestational diabetes mellitus (GDM) is characterized by abnormal glucose tolerance, which is associated with elevated insulin resistance. The present study aimed to assess the effect of MI supplementation during pregnancy on the incidence of GDM. We performed a single-center, open-label, randomized controlled trial. A cohort of 200 pregnant women at 11-13+6 weeks of gestation were randomly assigned in two groups: MI group (n = 100) and control group (n = 100). The MI group received MI and folic acid (4000 mg MI and 400 mcg folic acid daily), while the control group received folic acid alone (400 mcg folic acid daily) until 26-28 weeks of gestation, when the 75 g Oral Glucose Tolerance Test (OGTT) was performed for the diagnosis of GDM. Clinical and metabolic outcomes were assessed. The incidence of GDM was significantly higher in the MI group (14.9%) compared to the control group (28.5%) (P = 0.024). Women treated with MI had significantly lower OGTT glucose values, than those not treated with MI (P < 0.001). The insulin resistance as assessed by HOMA-IR was significantly lower in the MI group versus control (P = 0.045). Furthermore, MI group had significantly higher insulin sensitivity as measured by the Matsuda Index, compared to the control group (P = 0.037). MI supplementation seems to be an effective option to improve the glycemic control of pregnant women and prevent the onset of GDM. ISRCTN registry: ISRCTN16142533. Registered 09 March 2017.

Association of embryonic inositol status with susceptibility to neural tube defects, metabolite profile, and maternal inositol intake

AbstractMaternal nutrition contributes to gene–environment interactions that influence susceptibility to common congenital anomalies such as neural tube defects (NTDs). Supplemental myo‐inositol (MI) can prevent NTDs in some mouse models and shows potential for prevention of human NTDs. We investigated effects of maternal MI intake on embryonic MI status and metabolism in curly tail mice, which are genetically predisposed to NTDs that are inositol‐responsive but folic acid resistant. Dietary MI deficiency caused diminished MI in maternal plasma and embryos, showing that de novo synthesis is insufficient to maintain MI levels in either adult or embryonic mice. Under normal maternal dietary conditions, curly tail embryos that developed cranial NTDs had significantly lower MI content than unaffected embryos, revealing an association between diminished MI status and failure of cranial neurulation. Expression of inositol‐3‐phosphate synthase 1, required for inositol biosynthesis, was less abundant in the cranial neural tube than at other axial levels. Supplemental MI or d‐chiro‐inositol (DCI) have previously been found to prevent NTDs in curly tail embryos. Here, we investigated the metabolic effects of MI and DCI treatments by mass spectrometry‐based metabolome analysis. Among inositol‐responsive metabolites, we noted a disproportionate effect on nucleotides, especially purines. We also found altered proportions of 5‐methyltetrahydrolate and tetrahydrofolate in MI‐treated embryos suggesting altered folate metabolism. Treatment with nucleotides or the one‐carbon donor formate has also been found to prevent NTDs in curly tail embryos. Together, these findings suggest that the protective effect of inositol may be mediated through the enhanced supply of nucleotides during neural tube closure.

Suitable dietary Myo-inositol supplementations improve growth, immunity and antioxidant properties of hybrid grouper (Epinephelus. fuscoguttatus♀ × E. lanceolatus♂) fed low-fishmeal diets

A six-week feeding trial was carried out to evaluate the effects of different dietary Myo-inositol (MI) levels on growth, feed efficiency, immunity, and antioxidant properties of juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) fed low-fishmeal diets. Seven experimental diets were made to contain 50, 100, 169, 241, 309, 386, and 459 mg/kg of MI (analyzed values, dry matter basis), being abbreviated as MI-50, MI-100, MI-169, MI-241, MI-309, MI-386, and MI-459, and each MI treatment had three replicates. Twelve fish (average initial body weight: 18.7 ± 0.1 g) were allocated to each replicate, being hand-fed their diets to apparent satiation on 8:00 am and 16:30 pm. The results indicated that within the range of 50–241 mg/kg dietary inositol, weight gain percentage (WG%), feed efficiency (FE) and protein efficiency ratio (PER) were increased with the increasing of MI, and above the 241 mg/kg, they were dropped, especially at 386 and 459 mg/kg. According to the broken-line regression analysis conducted to assess the relationship between WG% and dietary MI levels, the optimum MI dose was 267.9 mg/kg (dry weight) in the low-fishmeal diet of hybrid grouper. Condition factor (CF), viscerosomatic index (VSI), hepatosomatic index (HSI), and intestinal index (ISI) were significantly (P < 0.05) affected by dietary MI levels, varying with a similar trend as WG%. Fish fed MI-241 had the highest values of serum lysozyme (LZM), hepatic total antioxidant capacity (T-AOC) as well as the relative mRNA level of hepatic insulin-like growth factor-Ⅰ (IGF-Ⅰ) among all treatments. In conclusion, optimum dietary MI requirement for the maximal growth of hybrid grouper was 267.9 mg/kg, and suitable dietary MI supplementations improve growth, immunity, and antioxidant properties of juvenile hybrid grouper fed low-fishmeal diets.

Effects of myo-inositol on growth and biomarkers of environmental stress and metabolic regulation in Pacific white shrimp (Litopenaeus vannamei) reared at low salinity

This study explored the role of myo-inositol in alleviating the low salinity stress of White Shrimp (Litopenaeus vannamei). Juvenile shrimp (0.4 ± 0.02 g) in low salinity (salinity 3) water were fed diets with myo-inositol levels of 0, 272, 518, 1020 and 1950 mg/kg (crude protein is 36.82 %, crude lipid is 7.58 %), fed shrimp in seawater at a salinity of 25 were fed a 0 mg/kg myo-inositol diet as a control (Ctrl). The experiment was carried out in tanks (50 L) with satiety feeding, and the experiment lasted for 6 weeks. After sampling, the serum was used to measure immune function, the hepatopancreas homogenate was used to measure the antioxidant capacity and hepatopancreas damage state, the hepatopancreas was used for transcriptomics analysis, and the gills were used for qPCR to measure osmotic pressure regulation. The results showed that the final weight and survival of the shrimp in the 1020 mg/kg group increased significantly compared with those in the other low salinity groups, but the final weight and biomass increase were significantly lower than those in the Ctrl group. Dietary myo-inositol improved the antioxidant capacity of shrimp under low salinity. B-cell hyperplasia and hepatic duct damage were observed in the hepatopancreas in the 0 mg/kg group. The results of transcriptome analysis showed that myo-inositol could participate in the osmotic pressure regulation of shrimp by regulating carbohydrate metabolism, amino acid metabolism, lipid metabolism and other related genes. Myo-inositol significantly affected the expression of related genes in ion transporter and G protein-coupled receptor-mediated pathways. This study demonstrated that myo-inositol can not only act as an osmotic pressure effector and participate in the osmolar regulation of shrimp through the phosphatidylinositol signaling pathway mediated by G protein-coupled receptors but also relieve low salinity stress by mediating physiological pathways such as immunity, antioxidation, and metabolism in shrimp. The binomial regression analysis of biomass increases and survival showed that the appropriate amount of myo-inositol in the L. vannamei diet was 862.50–1275.00 mg/kg under low salinity.

Effects of Myo-Inositol on the Growth Performance, Digestive Enzyme Activity, and Antioxidation of Juvenile Hucho taimen

Hucho taimen is a cold-water fish with high economic value. Myo-inositol (MI) can accelerate lipid metabolism and promote growth in fish species. The present study aimed to assess the effect of MI on the growth performance, digestive enzyme activity, and antioxidation of juvenile H. taimen. Accordingly, an 8-week feeding trial was conducted. The results demonstrated that increasing MI concentration promoted growth performance in H. taimen. Among the MI concentrations tested, a dose of 328 mg MI/kg corresponded with the lowest feed conversion ratio (FCR) and the highest growth rate. Compared with fish fed a diet of 128 mg MI/kg, the lipase activity in the pyloric caeca significantly increased in fish fed 528 mg MI/kg, while superoxide dismutase (SOD) activity was significantly higher in fish fed 728 mg MI/kg. Consistently, the 128 mg MI/kg diet presented the highest malonaldehyde (MDA) levels. In conclusion, our study revealed that enhanced growth performance, digestive enzyme activity, and antioxidant capacity increased as MI concentration increased. The optimum level of dietary MI in H. taimen was 270–321 mg/kg, based on the FCR and specific growth rate (SGR) on the broken-line regression.

Myo-inositol improves osmoregulation by promoting lipid utilization in Nile tilapia (Oreochromis niloticus)

This research explores the influence of myo-inositol (MI) on the hypertonic stress adaptation of Nile tilapia (Oreochromis niloticus) by increasing lipid utilization under long-term salinity stress. A two-factor interactive experiment was used, and diets containing either normal lipids (NL, 7%) or high lipids (HL, 15%) contained three MI concentrations of 0, 400, and 1200 mg/kg in each lipid diet. Fish were fed six diets under 20 psu (practical salinity units [psu]) for eight weeks. Under long-term hypertonic stress, dietary MI supplementation significantly improved the growth performance of O. niloticus (P < 0.05). Dietary 1200 mg/kg MI supplementation significantly promoted protein deposition and reduced fat accumulation in the whole fish (P < 0.05). The HL diet significantly caused lipid accumulation in the liver, while dietary 1200 mg/kg MI addition alleviated lipid accumulation by promoting the expression of genes related to lipolysis (PPAR-α; ATGL and CPT) and inhibiting the expression of genes related to lipid synthesis (SREBP; DGAT and FAS) (P < 0.05). In addition, 400 mg/kg MI significantly reduced serum lipids (TG and LDL-C) (P < 0.05). qPCR showed that the purity of dietary 1200 mg/kg MI significantly upregulated the expression of an ion transporter-related gene (NKA) in gills (P < 0.05). Meanwhile, 400 mg/kg and 1200 mg/kg MI significantly affected the content of fatty acids in the liver and gill (P < 0.05). In addition, dietary 1200 mg/kg MI supplementation significantly increased the antioxidant capacity in the liver of O. niloticus. In conclusion, dietary supplementation with 1200 mg/kg MI could regulate lipid metabolism, promote lipid utilization and improve the osmotic regulation ability of O. niloticus.

Regulatory role of myo-inositol in the ovarian development of female Chinese mitten crab (Eriocheir sinensis)

The ovarian development of female crab can directly affect the nutritional value, broodstock fertility and health status of offspring and are essential for the success of the crab industry. This study evaluates the influences of dietary myo-inositol (MI) on the ovarian development of female Chinese mitten crab (Eriocheir sinensis). Three diets containing different MI levels (0, 1600 and 3200 mg/kg) were fed to 144 crabs (initial weight: 72.38 ± 2.53 g) for 13 weeks. Crabs fed the diets with 1600, and 3200 mg/kg MI supplementation had significantly higher gonadosomatic index and yolk granule deposition in the ovary than those fed diets without MI supplementation. Crabs fed 1600 and 3200 mg/kg MI supplementation significantly enhanced vitellogenin synthesis in the hepatopancreas, vitellogenin contents in the hemolymph and vitellogenin receptor mRNA level in the ovary compared with those fed diets without MI supplementation. Simultaneously, cyclic adenosine monophosphate content and gene expression of retinoid X receptor, protein kinase A and ecdysteroid receptor in the hepatopancreas, and ecdysteroid content in hemolymph significantly increased when 1600 and 3200 mg/kg MI were supplemented in diets. Moreover, crabs fed 1600 and 3200 mg/kg MI supplementation had significantly higher lipid content in the ovary than those fed the diets without MI supplementation. The neutral lipid content in the hepatopancreas tended to decrease as the dietary MI level increased, while the polar lipid content in the hepatopancreas and the neutral and polar lipid contents in the ovary tended to increase. Dietary MI supplementation significantly enhanced the expression of genes related to lipid catabolism, lipid absorption and transport in the hepatopancreas, and gene expression related to lipid absorption in the ovary, suggesting that MI could promote the transport of lipids to the ovary from the hepatopancreas for ovarian development. This study indicates that dietary 1600 mg/kg MI supplementation is sufficient to promote the ovarian development of E. sinensis.

The effects of dietary myo-inositol on growth and physiological, biochemical, and molecular responses in the Pacific white shrimp Litopenaeus vannamei

Myo-inositol serves as an essential nutrient in many animal species. However, the optimal requirements of myo-inositol and the mechanisms by which myo-inositol is involved in nutritional regulation in crustaceans are unclear. An 8-week trial was conducted to comparatively evaluate the effects of 6 levels of dietary myo-inositol (20, 528, 1030, 2060, 3180 and 4235 mg/kg diet) on growth performance, body composition, serum metabolite composition, hepatopancreatic metabolite content, and digestive enzyme activity in juvenile Pacific white shrimp Litopenaeus vannamei (0.78 ± 0.039 g). The weight gain and conditioning factors of shrimp fed myo-inositol were significantly higher than those of the 20 mg/kg myo-inositol group. The maximal hepatosomatic index was found in the 1030 mg/kg myo-inositol group. On the other hand, serum triglyceride, total cholesterol, and low-density lipoprotein contents in the control group were significantly lower than those in the other groups, and glucose content in the hepatopancreas in the control group was significantly lower than that in the 2060 and 3180 mg/kg myo-inositol groups. Metabolome and transcriptome analyses revealed that myo-inositol significantly affected glycerophospholipid metabolism, transport and catabolism in lysosomes, pancreatic secretion, and bile secretion pathways. The highest growth was achieved with the inclusion of 528 mg/kg dietary myo-inositol. This study has suggested that myo-inositol may promote growth in L. vannamei by improving lipid utilization.

The essentiality of dietary myo-inositol to oriental river prawn (Macrobrachium nipponense): Evidence in growth performance, lipid metabolism and mitochondrial function

The essentiality of dietary myo-inositol to aquatic animals is species-dependent. Meanwhile, the mechanisms underlying its beneficial effects on the growth performance and intermediary metabolism are still poorly understood. This dose-response study was designed to investigate the optimum myo-inositol demand of oriental river prawn (Macrobrachium nipponense). In addition, the potential effects on lipid metabolism and mitochondrial function were also characterized to elucidate how myo-inositol benefits the growth performance and physiological functions of aquatic animals. Prawns (average body weight 0.17 g) were randomly divided into 6 groups, and fed six diets with graded myo-inositol levels (1700, 2160, 3120, 3970, 5350 and 6000 mg/kg). After the 10-week feeding trial, the survival rate, feed intake, hemolymph high-density lipoprotein cholesterol content and mitochondrial complex II activity all showed no statistical difference. However, the specific growth rate, weight gain, protein efficiency ratio, hemolymph cholesterol content, and the hepatopancreas activities of complex III and IV all increased remarkably as dietary myo-inositol levels increased up to 5350 mg/kg, while an opposite was result was noted in the feed conversion ratio. In addition, hemolymph triglyceride content and hepatopancreas complex V activity both exhibited distinct linear effects peaking at the 3120 mg/kg group. The moderate doses of myo-inositol markedly up-regulated the transcriptions of fatty acid binding protein, acyl-CoA binding protein, scavenger receptor class B type I, carnitine palmitoyltransferase I, cytochrome c oxidase 1 and 2 and AMP-activated protein kinase α, but down-regulated those of acetyl-CoA carboxylase, fatty acid synthase and cytochrome b. Overall, dietary supplementation of 2787.00-5484.87 mg/kg myo-inositol ameliorated the growth performance and mitochondrial function of oriental river prawn coupled with the enhanced lipid transport, lipolysis and fatty acid β-oxidation.

Enhancement of protein deposition and meat quality of male Chinese mitten crab (Eriocheir sinensis): Application of myo-inositol in crustacean nutrition

The nutritional value and meat quality influence the consumer preference for crab. Dietary nutrition manipulation is a practical way to regulate flesh quality. This study evaluates the effects of dietary myo-inositol on the nutritional value and meat flavor of male Chinese mitten crab (Eriocheir sinensis). Three diets supplemented with different myo-inositol levels (0, 1600 and 3200 mg/kg) were fed to the crabs for 12 weeks. Dietary myo-inositol supplementation significantly increased the content of highly unsaturated fatty acids in the muscle and enhanced muscle protein deposition by up-regulating the expression of genes related to protein synthesis in the crab muscle. Metabolome analysis showed that the differential metabolites were enriched in the amino acid metabolic process in the groups with myo-inositol supplementation. Moreover, the content of total umami-free amino acids increased when crabs were fed diets with myo-inositol supplementation, which may relate to the production of umami flavor in crabs. Therefore, myo-inositol supplementation may be a practical approach to improving the meat quality of male E. sinensis.

The interactive effect of dietary inclusion levels and preparation methods of myo-inositol on growth performance, antioxidant function and lipid metabolism homeostasis of Cyprinus carpio var. jian

To evaluate the interactive effect of inclusion levels (IL) and preparation methods (PM) of myo-inositol (MI) on growth performance, hepatic antioxidant capacity and lipid metabolism of Cyprinus carpio var. jian, five isonitrogenous and isoenergetic diets were formulated at a high level of dietary fat content (11.3%, HF basic diet), supplemented with 400 mg/kg or 800 mg/kg of enzyme biocatalysis MI (E-MI) (400E-MI, 800E-MI) and chemical acid hydrolysis MI (C-MI) (400 C-MI, 800 C-MI). 300 healthy C. Carpio var. jian (1.5 ± 0.1 g) were randomly fed one of the five experimental diets in triplicates (20 fish per tank) for 66 days. After the 66 days feeding trial, the growth performance, plasma biochemistry, hepatic antioxidant enzyme activities, and gene expressions related to lipid metabolism were determined. Two-way ANOVA analysis showed that PM and IL of dietary MI had an interactive effect on growth performance, antioxidant capacity and lipid metabolism of C. Carpio var. jian. The IL significantly affected protein deposition rate (PDR), activities of hepatic CAT, T-SOD and GPx (P < 0.05). Specifically, final average weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and PDR in the 400E-MI group and 800 C-MI group were significantly higher than those in the 400 C-MI group (P < 0.05). The oil red O staining results showed that a large amount of lipid accumulation in the liver tissues of the HF group, while the hepatic lipid accumulations of 400 C-MI, 400E-MI and 800 E-MI were significantly reduced (P < 0.05). The expressions of lipid metabolization-related genes showed that the myo-inositol PM and IL had an interactive effect on mRNA expressions of hepatic ACO, ACSL, PPARβ and SIRT1 (P < 0.05). The mRNA expression levels of ACC, AMPK, PPARβ and SREBP-1 were significantly affected by IL (P < 0.05). Specifically, The mRNA expressions of LPL, PPARβ and SIRT1 of 400 C-MI, 400E-MI and 800 E-MI groups were significantly higher than those of the HF basic group. Overall, the supplementation of C-MI and E-MI in the HF diet improved the protein deposition and liver antioxidant ability, promoted lipid metabolism through activating AMPK and SIRT1 of C. Carpio var. jian fed HF diet.

New insights into the influence of myo-inositol on carbohydrate metabolism during osmoregulation in Nile tilapia (Oreochromis niloticus).

A two-factor (2 × 3) orthogonal test was conducted to investigate the effects of dietary myo-inositol (MI) on the osmoregulation and carbohydrate metabolism of euryhaline fish tilapia (Oreochromis niloticus) under sustained hypertonic stress (20 practical salinity units [psu]). 6 diets containing either normal carbohydrate (NC, 30%) or high carbohydrate (HC, 45%) levels, with 3 levels (0, 400 and 1,200 mg/kg diet) of MI, respectively, were fed to 540 fish under 20 psu for 8 weeks. Dietary MI supplementation significantly improved growth performance and crude protein content of whole fish, and decreased the content of crude lipid of whole fish (P < 0.05). Curled, disordered gill lamella and cracked gill filament cartilage were observed in the gill of fish fed diets without MI supplementation. The ion transport capacity in gill was significantly improved in the 1,200 mg/kg MI supplementation groups compared with the 0 mg/kg MI groups (P < 0.05). Moreover, the contents of Na+, K+, Cl− in serum were markedly reduced with the dietary MI supplementation (P < 0.05). The fish fed 1,200 mg/kg MI supplementation had the highest MI content in the gills and the lowest MI content in the serum (P < 0.05). Additionally, the fish fed with 1,200 mg/kg MI supplementation had the highest MI synthesis capacity in gills and brain (P < 0.05). Dietary MI markedly promoted the ability of carbohydrate metabolism in liver (P < 0.05). Moreover, fish in the 1,200 mg/kg MI groups had the highest antioxidant capacity (P < 0.05). This study indicated that high dietary carbohydrate would intensify stress, and impair the ability of osmoregulation in tilapia under a long-term hypersaline exposure. The supplementation of MI at 1,200 mg/kg in the high carbohydrate diet could promote carbohydrate utilization and improve the osmoregulation capacity of tilapia under long-term hypertonic stress.

Regulatory role of myo-inositol in vegetable oil-mediated lipid metabolism and health of Chinese mitten crab (Eriocheir sinensis)

Vegetable oils (VOs) are widely used in the aquatic feed industry because of their stable source and low price, but they can cause a series of adverse effects on aquatic animals. Myo-inositol (MI) plays a vital role in regulating lipid metabolism and the health of aquatic animals. However, it remains unclear whether MI has a regulatory role on the utilization of different VOs. An 8-week study was conducted to investigate the effects of MI on the growth, lipid metabolism, and health of the Chinese mitten crab under four oil sources, including palm oil (PO), olive oil (OO), safflower oil (SO), and perilla oil (PFO) in diets. The highest growth performance and the lowest lipid levels in the whole body, hepatopancreas and muscle were observed in crabs fed the PFO diet without MI supplementation. Dietary MI markedly reduced the lipid deposition in the hepatopancreas when crabs were fed the PO and OO diets. Moreover, dietary MI increased the expression of genes related to the uptake and β-oxidation of fatty acid when crabs were fed the PO and OO diets. A high correlation was observed between dietary fatty acid composition and fatty acid composition in the hepatopancreas and muscle. The highest malondialdehyde content was observed in the PFO group. Dietary MI could decrease malondialdehyde content in the hepatopancreas when crabs were fed the PO and PFO diets. However, the lowest inflammation-related genes expression was observed in crabs fed the PFO diet without MI supplementation. Dietary MI could decrease the mRNA levels of these genes when crabs were fed the PO and OO diets. This study indicates that MI is a functional nutrient to improve the low lipid utilization and inflammatory responses caused by dietary palm oil and olive oil in E. sinensis.

Effect of antenatal dietary myo-inositol supplementation on the incidence of gestational diabetes mellitus and fetal outcome: protocol for a double-blind randomised controlled trial

IntroductionGestational diabetes mellitus (GDM) affects 23.6% of Qatari women and is associated with maternal and perinatal morbidity and long-term risk of developing type 2 diabetes. A number of challenges exist...

Toxicity of chronic copper exposure on Chinese mitten crab (Eriocheir sinensis) and mitigation of its adverse impact by myo-inositol

Copper (Cu) is a widespread pollutant in water and has posed a significant threat to aquatic animals' health. It is essential to find a strategy to reduce the adverse effects of copper on aquatic organisms. This study investigated the role of myo-inositol (MI) in the reducing chronic toxicity induced by copper in Chinese mitten crab (Eriocheir sinensis). Two diets, including 0 mg/kg and 1600 mg/kg MI were fed to crabs exposed to 0 μg/L and 40 μg/L Cu2+ for 7 weeks. Dietary MI could improve the decreased weight gain and specific growth rate induced by copper exposure. Copper exposure increased the copper levels in the whole body and hepatopancreas, increased the malondialdehyde content, and suppressed the antioxidant enzymes system of the crabs. Simultaneously, copper exposure induced DNA fragmentation, decreased the gene expression/activities of immune-related genes/enzymes and the expression of the anti-apoptotic genes, and increased the gene expression of heat shock protein 70 and pro-apoptotic genes. The mitochondrial dysfunction, increased the gene expression of inflammation-related genes and caused the higher activity of damage-related enzymes in the crabs under Cu exposure. The administration of dietary MI markedly ameliorated the copper-induced oxidative stress, immune and hepatopancreas damage, mitochondrial dysfunction, apoptosis and inflammatory responses. This study indicates that dietary MI supplementation can effectively alleviate the negative effect of chronic copper exposure on E. sinensis.

Myo-inositol prevents the gill rot in fish caused by Flavobacterium columnare infection

The gills are some of the most metabolically active organs in fish and are involved in gas exchange, osmotic regulation, acid-base balance, and ammonia nitrogen waste excretion. Here, we explored the actions of graded levels of dietary myo-inositol [27.0 (un-supplemented), 137.9, 286.8, 438.6, 587.7, and 737.3 mg/kg diet)] on the physical barrier functioning and signaling in the gills of grass carp (Ctenopharyngodon idella) for 10-weeks, and then infected by Flavobacterium columnare. It was found that optimal myo-inositol levels (approximately 137.9–438.6 mg myo-inositol /kg diet): (1) decreased the oxidative products such as malondialdehyde (MDA) and protein carbonyl (PC), while increased the activities and mRNA levels of SOD (CuZnSOD and MnSOD), CAT, GPx (GPx1a, GPx1b, GPx4a and GPx4b), GST (GSTO1, GSTO2, GSTP1 and GSTP2) and GR enzymes, possibly related to the Nrf2/Keap1 signaling pathway, suggesting that myo-inositol inhibited oxidative injury in fish gills; (2) inhibited cell apoptosis related to the down-regulation of caspases-2, −3, −7, −8, and-9 mRNA levels, possibly linked to the inhibition of the JNK/FasL/caspase 8 and p38MAPK/(Apaf-1, Bax, Bcl-2, Mcl-1, IAP)/caspase 9/caspase 3 signaling pathways; (3) promoted cell proliferation by up-regulating cyclins B, D, and E mRNA levels, possibly related to the E2F4 signaling; (4) maintained intercellular structural integrity by up-regulating tight junctional complexes (ZO-1, ZO-2, occludin, and claudins b, −c, f, −3c, −7a, −7b, and − 11), and down-regulating pore-forming TJs (claudins-12,-15a, and-15b) mRNA levels, possibly associated with the down-regulation of MLCK signaling. Based on the inhibition of gill rot and MDA content, the optimal myo-inositol intake was calculated as 285.8 and 305.4 mg/kg diet for grass carp (initial 221 g-final 792 g), respectively.

Myo-inositol improves growth performance and regulates lipid metabolism of juvenile Chinese mitten crab (Eriocheir sinensis) fed different percentage of lipid.

This study evaluated the effects of dietary myo-inositol (MI) on growth performance, antioxidant status and lipid metabolism of juvenile Chinese mitten crab (Eriocheir sinensis) fed different percentage of lipid. Crabs (4·58 (sem 0·05) g) were fed four diets including a normal lipid diet (N, containing 7 % lipid and 0 mg/kg MI), N with MI supplementation (N + MI, containing 7 % lipid and 1600 mg/kg MI), a high lipid diet (H, containing 13 % lipid and 0 mg/kg MI) and H with MI supplementation (H + MI, containing 13 % lipid and 1600 mg/kg MI) for 8 weeks. The H + MI group showed higher weight gain and specific growth rate than those in the H group. The dietary MI could improve the lipid accumulations in the whole body, hepatopancreas and muscle as a result of feeding on the high dietary lipid (13 %) in crabs. Besides, the crabs fed the H + MI diets increased the activities of antioxidant enzymes but reduced the malondialdehyde content in hepatopancreas compared with those fed the H diets. Moreover, dietary MI enhanced the expression of genes involved in lipid oxidation and exportation, yet reduced lipid absorption and synthesis genes expression in the hepatopancreas of crabs fed the H diet, which might be related to the activation of inositol 1,4,5-trisphosphate receptor (IP3R)/calmodulin-dependent protein kinase kinase-β (CaMKKβ)/adenosine 5'-monophosphate-activated protein kinase (AMPK) signalling pathway. This study demonstrates that MI could increase lipid utilisation and reduce lipid deposition in the hepatopancreas of E. sinensis fed a high lipid diet through IP3R/CaMKKβ/AMPK activation. This work provides new insights into the function of MI in the diet of crustaceans.

Growth, osmotic response and transcriptome response of the euryhaline teleost, Oreochromis mossambicus fed different myo-inositol levels under long-term salinity stress

Myo-inositol (MI) as a major intracellular osmolyte can be accumulated to protect cells from a variety of stress. The present study was to evaluate the effects of dietary MI on growth, osmotic response and transcriptional response in the liver of euryhaline fish Oreochromis mossambicus under long-term salinity stress. Five isonitrogenous and isolipidic diets were formulated to include 0 (MI0), 200 (MI200), 400 (MI400), 800 (MI800) and 1600 (MI1600) mg/kg MI. In this study, dietary 400 mg/kg MI significantly increased the weight gain and specific growth rate of O. mossambicus compared with the group without dietary MI supplementation under salinity stress. Moreover, dietary MI decreased serum glucose and insulin levels of fish under long-term salinity stress. Fish fed 400 mg/kg MI supplementation had significantly higher serum cortisol, sodium (Na+) and chloride ion (Cl−) than those fed a diet without MI supplementation. A total of 132.17 million and 115.8 million clean reads were obtained from the 0 mg/kg MI (MI0) and 400 mg/kg (MI400) MI group respectively. Compared with the MI0 group, the expression of 704 genes was significantly changed (521-up and 183-down) in the MI400 group under long-term salinity stress. Transcriptome results indicate that myo-inositol can regulate lipid and pyruvic acid metabolism, increase phospholipid synthesis-related mRNA levels and improve antioxidant properties of O. mossambicus under long-term salinity stress. This study suggests that optimum MI supplementation is 400 mg/kg in the diet based on weight gain against dietary MI and this result provides a nutritional solution for tilapia to cope with salinity stress.

Alleviation of the Adverse Effect of Dietary Carbohydrate by Supplementation of Myo-Inositol to the Diet of Nile Tilapia (Oreochromis niloticus).

Simple SummaryRecently, the price escalation of fishmeal has made aquaculture nutritionists to consider using carbohydrate in aquafeed to spare the use of dietary protein. However, the high carbohydrate diet could induce lipid metabolism disorder, impair antioxidant capacity, reduce nonspecific immunity and decrease resistance to a pathogen in farmed fish. Myo-inositol is regarded as a vitamin-like essential nutrient for most aquatic animals. Previous studies have shown that dietary supplementation with myo-inositol can reduce lipid accumulation in tissues and decrease the chance of becoming a fatty liver. To explore the mechanism of myo-inositol on alleviating the adverse effect of the high carbohydrate diet in Nile tilapia, six diets contained either low carbohydrate (30%) or high carbohydrate (45%) with three levels of myo-inositol supplementation (0, 400 and 1200 mg/kg diet) to each level of the carbohydrate diet. After an 8-week trial, the result showed that additive myo-inositol in the diet could significantly improve the growth performance and increase the crude protein content of fish. The addition of myo-inositol could effectively decrease the lipid accumulation induced by the high carbohydrate diet by accelerating the transportation of cholesterol back to the liver and promoting the lipid decomposition.This study investigated the effect of dietary myo-inositol (MI) on alleviating the adverse effect of the high carbohydrate diet in Nile tilapia (Oreochromis niloticus). Six diets contained either low carbohydrate (LC 30%) or high carbohydrate (HC 45%) with three levels of MI supplementation (0, 400 and 1200 mg/kg diet) to each level of the carbohydrate diet. After an 8-week trial, the fish fed 400 mg/kg MI under HC levels had the highest weight gain and fatness, but the fish fed 1200 mg/kg MI had the lowest hepatosomatic index, visceral index and crude lipid in the HC group. The diet of 1200 mg/kg MI significantly decreased triglyceride content in the serum and liver compared with those fed the MI supplemented diets regardless of carbohydrate levels. Dietary MI decreased triglyceride accumulation in the liver irrespective of carbohydrate levels. The content of malondialdehyde decreased with increasing dietary MI at both carbohydrate levels. Fish fed 1200 mg/kg MI had the highest glutathione peroxidase, superoxide dismutase, aspartate aminotransferase and glutamic-pyruvic transaminase activities. The HC diet increased the mRNA expression of key genes involved in lipid synthesis (DGAT, SREBP, FAS) in the fish fed the diet without MI supplementation. Dietary MI significantly under expressed fatty acid synthetase in fish fed the HC diets. Moreover, the mRNA expression of genes related to lipid catabolism (CPT, ATGL, PPAR-α) was significantly up-regulated with the increase of dietary MI levels despite dietary carbohydrate levels. The gene expressions of gluconeogenesis, glycolysis and MI biosynthesis were significantly down-regulated, while the expression of the pentose phosphate pathway was up-regulated with the increase of MI levels. This study indicates that HC diets can interrupt normal lipid metabolism and tend to form a fatty liver in fish. Dietary MI supplement can alleviate lipid accumulation in the liver by diverging some glucose metabolism into the pentose phosphate pathway and enhance the antioxidant capacity in O. niloticus.