The present study evaluated effects of dietary supplementation with tryptophan (Trp) on muscle growth, protein synthesis and antioxidant capacity in hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂. Fish were fed six different diets containing 2·6 (control), 3·1, 3·7, 4·2, 4·7 and 5·6 g Trp/kg diet for 56 d, respectively. Results showed that dietary Trp significantly (1) improved muscle protein content, fibre density and frequency of fibre diameter; (2) up-regulated the mRNA levels of PCNA, myf5, MyoD1, MyoG, MRF4, IGF-I, IGF-II, IGF-IR, PIK3Ca, TOR, 4EBP1 and S6K1; (3) increased phosphorylation levels of AKT, TOR and S6K1; (4) decreased contents of MDA and PC, and increased activities of CAT, GST, GR, ASA and AHR; (5) up-regulated mRNA levels of CuZnSOD, CAT, GST, GPx, GCLC and Nrf2, and decreased Keap1 mRNA level; (6) increased nuclear Nrf2 protein level and the intranuclear antioxidant response element-binding ability, and reduced Keap1 protein level. These results indicated that dietary Trp improved muscle growth, protein synthesis as well as antioxidant capacity, which might be partly related to myogenic regulatory factors, IGF/PIK3Ca/AKT/TOR and Keap1/Nrf2 signalling pathways. Finally, based on the quadratic regression analysis of muscle protein and MDA contents, the optimal Trp requirements of hybrid catfish (21·82–39·64 g) were estimated to be 3·94 and 3·93 g Trp/kg diet (9·57 and 9·54 g/kg of dietary protein), respectively.

A12-week experiment was conducted to evaluate the influences of thiamine ongrowth performance, and intestinal mitochondrial biogenesis and function of Megalobramaamblycephala fed a high-carbohydrate (HC) diet. Fish (24·73 (sem 0·45) g) were randomly assigned to one of four diets: two carbohydrate (CHO) levels (30 and 45 %) and two thiamine levels (0 and 1·5 mg/kg). HC diets significantly decreased DGC, GRMBW, FIMBW, intestinal activities of amylase, lipase, Na+, K+-ATPase, CK, complexes I, III and IV, intestinal ML, number of mitochondrial per field, ΔΨm, the P-AMPK: T-AMPK ratio, PGC-1β protein expression as well as the transcriptions of AMPKα1, AMPKα2, PGC-1β, mitochondrial transcription factor A, Opa-1, ND-1 and COX-1 and 2, while the opposite was true for ATP, AMP and reactive oxygen species, and the transcriptions of dynamin-related protein-1, fission-1 and mitochondrial fission factor. Dietarythiamine concentrations significantly increased DGC, GRMBW, intestinal activities of amylase, Na+, K+-ATPase, CK, complexes I and IV, intestinal ML, number of mitochondrial per field, ΔΨm, the P-AMPK:T-AMPK ratio, PGC-1β protein expression as well as the transcriptions of AMPKα1, AMPKα2, PGC-1β, Opa-1, ND-1, COX-1 and 2, SGLT-1 and GLUT-2. Furthermore, a significant interaction between dietary CHO and thiamine was observed in DGC, GRMBW, intestinal activities of amylase, CK, complexes I and IV, ΔΨm, the AMP:ATP ratio, the P-AMPK:T-AMPK ratio, PGC-1β protein expression as well as the transcriptions of AMPKα1, AMPKα2, PGC-1β, Opa-1, COX-1 and 2, SGLT-1 and GLUT-2. Overall, thiamine supplementation improved growth performance, and intestinal mitochondrial biogenesis and function of M. amblycephala fed HC diets.

Several studies have reported a significant association between the metabolic syndrome (MetS) and mortality around the world. Caveolin-1 (CAV-1) has been widely studied in dyslipidaemia, and several studies have indicated that CAV-1 genetic variations may correlate with dietary intake of fatty acids. This study aimed to investigate the interaction of CAV-1 rs3807992 with types of dietary fatty acid in the MetS risk. This cross-sectional study was carried out on 404 overweight and obese females. Dietary intake was obtained from a 147-item FFQ. The CAV-1 genotype was measured using the PCR-restriction fragment length polymorphism method. Anthropometric values and serum levels (TC, LDL, HDL, TAG and FBS) were measured by standard methods. It was observed that the (AA + AG) group had significantly higher BMI, waist circumference and DBP (P = 0·02, P = 0·02, and P = 0·01, respectively) and lower serum LDL, HDL and TC (P < 0·05) than the GG group. It was found that A allele carriers were at higher odds of the MetS (P = 0·01), abdominal obesity (P = 0·06), increased TAG concentration (P = 0·01), elevated blood pressure (BP) (P = 0·01), increased glucose concentration (P = 0·45) and decreased HDL-cholesterol concentration (P = 0·03). Moreover, the interaction of CAV-1 and SFA intake was significant in terms of the MetS (P = 0·03), LDL (P = 0·03) and BP (P = 0·01). Additionally, the (AA + AG) group was significantly related to PUFA intake in terms of the MetS (P = 0·04), TAG (P = 0·02), glucose (P = 0·02) and homoeostasis model assessment insulin resistance (P = 0·01). Higher PUFA consumption might attenuate the CAV-1 rs3807992 associations with the MetS, and individuals with greater genetic predisposition appeared to have a higher risk of the MetS, associated with higher SFA consumption.

Niacin deficiency causes pellagra, the symptoms of which include dermatitis, diarrhoea and dementia. Investigating the mechanism underlying these phenotypes has been challenging due to the lack of an appropriate animal model. Here, we report a mouse model of pellagra-related nausea induced by feeding mice a low-niacin diet and administering isoniazid (INH), which is thought to induce pellagra. Mice fed a normal or low-niacin diet received INH (0·3 or 1·0 mg/mg per animal, twice daily, 5 d), and nausea was evaluated based on pica behaviour, which considered the rodent equivalent of the emetic reflex. Furthermore, the effect of therapeutic niacin administration on nausea was evaluated in this model. Urinary and hepatic metabolite levels were analysed by LC coupled with MS. INH-induced pica was observed in mice fed a low-niacin diet but not in those fed a normal diet. Levels of urinary metabolites, such as 1-methyl-2-pyridone-5-carboxamide, kynurenic acid and xanthurenic acid, were significantly reduced in the mice treated with INH compared with those that did not receive INH. Furthermore, niacin supplementation prevented pica and restored the levels of some metabolites in this mouse model. Our findings suggest that INH-related nausea is pellagra-like. We also believe that our newly established method for quantifying pica is a useful tool for investigating the mechanisms of pellagra-related nausea.

Obesity is defined as increased adiposity, which leads to metabolic disease. The growth of adipose tissue depends on its capacity to expand through hyperplasia or hypertrophy, in order to buffer energy surplus. Also, during the establishment of obesity, adipose tissue expansion reflects adipose lipid metabolism (lipogenesis and/or lipolysis). It is well known that dietary factors can modify lipid metabolism promoting or preventing the development of metabolic abnormalities that concur with obesity. Trans-palmitoleic acid (TP), a biomarker of dairy consumption, has been associated with reduced adiposity in clinical studies. Thus, we aimed to evaluate the effect of TP over adiposity and lipid metabolism-related genes in a rodent model of diet-induced obesity (DIO). To fulfil this aim, we fed C57BL/6 mice with a Control or a High-Fat diet, added with or without TP (3 g/kg diet), during 11 weeks. Body weight and food intake were monitored, fat pads were weighted, histology of visceral adipose tissue was analysed and lipid metabolism-related gene expression was explored by qPCR. Results show that TP consumption prevented weight gain induced by high-fat diet, reduced visceral adipose tissue weight and adipocyte size, while increasing the expression of lipolytic molecules. In conclusion, we show for the first time that TP influences adipose tissue metabolism, specifically lipolysis, resulting in decreased adiposity and reduced adipocyte size in a DIO mice model.

Calorie restriction (CR) has been shown to be one of the most effective methods in alleviating the effects of ageing and age-related diseases. Although the protective effects of CR have been reported, the exact molecular mechanism still needs to be clarified. This study aims to determine differentially expressed (DE) miRNAs and altered gene pathways due to long-term chronic (CCR) and intermittent (ICR) CR in the brain of mice to understand the preventive roles of miRNAs resulting from long-term CR. Ten weeks old mice were enrolled into three different dietary groups; ad libitum, CCR or ICR, and fed until 82 weeks of age. miRNAs were analysed using GeneChip 4.1 microarray and the target of DE miRNAs was determined using miRNA target databases. Out of a total 3,163 analysed miRNAs, 55 of them were differentially expressed either by different CR protocols or by ageing. Brain samples from the CCR group had increased expression levels of mmu-miR-713 while decreasing expression levels of mmu-miR-184-3p and mmu-miR-351-5p compared to the other dietary groups. Also, current results indicated that CCR showed better preventive effects than that of ICR. Thus, CCR may perform its protective effects by modulating these specific miRNAs since they are shown to play roles in neurogenesis, chromatin and histone regulation. In conclusion, these three miRNAs could be potential targets for neurodegenerative and ageing-related diseases and may play important roles in the protective effects of CR in the brain.

I had been working on the endocrine and signalling role of white adipose tissue (WAT) since 1994 following the identification of the ob (Lep) gene(1), this after some 15 years investigating the physiological role of brown adipose tissue. The ob gene, a mutation in which it is responsible for the profound obesity of ob/ob (Lepob/Lepob) mice, is expressed primarily in white adipocytes and encodes the pleiotropic hormone leptin. The discovery of this adipocyte hormone had wide-ranging implications, including that white fat has multiple functions that far transcend the traditional picture of a simple lipid storage organ.

The effect and the mechanism of high glucose on fish muscle cells are not fully understood. In the present study, muscle cells of olive flounder (Paralichthys olivaceus) were treated with high glucose (33 mM) in vitro. Cells were incubated in three kinds of medium containing 5 mM glucose, 5 mM glucose and 28 mM mannitol (as an isotonic contrast) or 33 mM glucose named the Control group, the Mannitol group and the high glucose (HG) group, respectively. Results showed that high glucose increased the ADP:ATP ratio and the reactive oxygen species (ROS) level, decreased mitochondrial membrane potential (MMP), induced the release of cytochrome C (CytC) and cell apoptosis. High glucose also led to cell glycogen accumulation by increasing the glucose uptake ability and affecting the mRNA expressions of glycogen synthase and glycogen phosphorylase. Meanwhile, it activated AMP-activated protein kinase (AMPK), inhibited the activity of mammalian target of rapamycin (mTOR) signalling pathway and the expressions of myogenic regulatory factors (MRF). The expressions of myostatin-1 (mstn-1) and E3 ubiquitin ligases including muscle RING-finger protein 1 (murf-1) and muscle atrophy F-box protein (mafbx) were also increased by the high glucose treatment. No difference was found between the Mannitol group and the Control group. These results demonstrate that high glucose has the effects of inducing apoptosis, increasing glycogen accumulation and inhibiting protein synthesis on muscle cells of olive flounder. The mitochondria-mediated apoptotic signalling pathway, AMPK and mTOR pathways participated in these biological effects.

Several studies have been conducted to investigate the relation between 25-hydroxyvitamin D [25(OH)D] level and diabetic neuropathy (DN). However, there is still no clear conclusion due to differences in study design and cut-off values used in the published work, in addition to the absence of a comprehensive meta-analysis (MA) on the topic. The present systematic review and MA therefore aims at clarifying the association between vitamin D level and peripheral DN in patients with type 2 diabetes mellitus. Primary research studies that explored the association between 25(OH)D level and diabetic peripheral neuropathy in type 2 diabetes were located from Medline, EMBASE, Web of Science, Cochrane Library, CINHAL and Google Scholar. Twenty-six studies met the inclusion criteria with 6277 participants where 2218 were diabetic with DN, 2959 were diabetic without DN and 406 were healthy. Diabetic patients with DN showed significantly lower serum 25(OH)D compared with patients without DN (standardised mean difference (SMD) of −0·92 (95 % CI −1·18, −0·65, I2 = 93·3 %, P < 0·0001). The pooled OR value of vitamin D deficiency was higher in patients with DN, 1·84 (95 % CI 1·46, 2·33, P < 0·0001) and 2·87 (95 % CI 1·10, 7·52, P = 0·03) when using fixed-effects and random-effects models, respectively. Vitamin D deficiency has been found to be highly prevalent among diabetic patients with neuropathy. Since 25(OH)D has been implicated in glucose haemostasis and showed benefit in reducing neuropathy symptoms, its supplementation is warranted for this population of patients.

Seasonal energy intake of Tibetan sheep on the harsh Qinghai-Tibetan Plateau (QTP) fluctuates greatly and is often well below maintenance requirements. The aim of this study was to gain insight into how the hypothalamus regulates energy homoeostasis in Tibetan sheep. We compared Tibetan and Small-tailed Han sheep (n 24 of each breed), which were each allocated randomly into four groups and offered one of four diets that differed in digestible energy densities: 8·21, 9·33, 10·45 and 11·57 MJ/kg DM. Sheep were weighed every 2 weeks, and it was assumed that the change in body weight (BW) reflected the change in energy balance. The arcuate nucleus of the hypothalamus in Tibetan sheep had greater protein expressions of neuropeptide Y (NPY) and agouti-related peptide (AgRP) when in negative energy balance, but lesser protein expressions of proopiomelanocortin (POMC) and cocaine and amphetamine-regulated transcript (CART) when in positive energy balance than Small-tailed Han sheep. As a result, Tibetan sheep had a lesser BW loss when in negative energy balance and stored more energy and gained more BW when in positive energy balance than Small-tailed Han sheep with the same dietary intake. Moreover, in the hypothalamic adenosine monophosphate-activated protein kinase (AMPK) regulation pathway, Tibetan sheep had greater adenosine monophosphate-activated protein kinase-α 2 protein expression than Small-tailed Han sheep, which supported the premise of a better ability to regulate energy homoeostasis and better growth performance. These differences in the hypothalamic NPY/AgRP, POMC/CART and AMPK pathways between breeds conferred an advantage to the Tibetan over Small-tailed Han sheep to cope with low energy intake on the harsh QTP.

N-3 long-chain (≥C20) PUFA (LC-PUFA) are vital fatty acids for fish and humans. As a main source of n-3 LC-PUFA for human consumers, the n-3 LC-PUFA content of farmed fish is important. Previously, we identified fatty acid-binding protein (fabp)-4 as a candidate gene for regulating the n-3 LC-PUFA content. Herein, we further assessed the role of fabp4 in this process. First, a 2059 bp promoter sequence of fabp4 in Trachinotus ovatus was cloned and, using progressive deletion, determined −2006 bp to −1521 bp to be the core promoter sequence. The PPAR-γ binding sites were predicted to occur in this region. A luciferase reporter assay showed that the promoter activity of fabp4 decreased following mutation of the PPARγ binding site and that PPARγ increased the fabp4 promoter activity in a dose-dependent manner, implying that T. ovatus fabp4 is a target of PPARγ. The overexpression of fabp4 or PPARγ increased the DHA content in hepatocytes, whereas suppression of their expression diminished this effect, suggesting that both fabp4 and PPARγ play an active role in regulating DHA content. Moreover, the inhibition of fabp4 attenuated the increase in PPARγ-mediated DHA content, and the overexpression of fabp4 alleviated this effect. Collectively, our findings indicated that fabp4, which is controlled by PPARγ, plays an important role in DHA content regulation. The new regulation axis can be considered a promising novel target for increasing the n-3 LC-PUFA content in T. ovatus.

Sarcopenic obesity is regarded as a risk factor for the progression and development of non-alcoholic fatty liver disease (NAFLD). Since male sex is a risk factor for NAFLD and skeletal muscle mass markedly varies between the sexes, we examined whether sex influences the association between appendicular skeletal muscle mass to visceral fat area ratio (SVR), that is, an index of skeletal muscle mass combined with abdominal obesity, and the histological severity of NAFLD. The SVR was measured by bioelectrical impedance in a cohort of 613 (M/F = 443/170) Chinese middle-aged individuals with biopsy-proven NAFLD. Multivariable logistic regression and subgroup analyses were used to test the association between SVR and the severity of NAFLD (i.e. non-alcoholic steatohepatitis (NASH) or NASH with the presence of any stage of liver fibrosis). NASH was identified by a NAFLD activity score ≥5, with a minimum score of 1 for each of its categories. The presence of fibrosis was classified as having a histological stage ≥1. The SVR was inversely associated with NASH in men (adjusted OR 0·62; 95 % CI 0·42, 0·92, P = 0·017 for NASH, adjusted OR 0·65; 95 % CI 0·43, 0·99, P = 0·043 for NASH with the presence of fibrosis), but not in women (1·47 (95 % CI 0·76, 2·83), P = 0·25 for NASH, and 1·45 (95 % CI 0·74, 2·83), P = 0·28 for NASH with the presence of fibrosis). There was a significant interaction for sex and SVR (Pinteraction = 0·017 for NASH and Pinteraction = 0·033 for NASH with the presence of fibrosis). Our findings show that lower skeletal muscle mass combined with abdominal obesity is strongly associated with the presence of NASH only in men.

The current epidemic of type 2 diabetes mellitus (T2DM) significantly affects human health worldwide. Activation of brown adipocytes and browning of white adipocytes are considered as a promising molecular target for T2DM treatment. Mulberry leaf, a traditional Chinese medicine, has been demonstrated to have multi-biological activities, including anti-diabetic and anti-inflammatory effects. Our experimental results showed that mulberry leaf significantly alleviated the disorder of glucose and lipid metabolism in T2DM rats. In addition, mulberry leaf induced browning of inguinal white adipose tissue (IWAT) by enhancing the expressions of brown-mark genes as well as beige-specific genes, including uncoupling protein-1 (UCP1), peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), peroxisome proliferator-activated receptor alpha (PPARα), PRD1-BF-1-RIZ1 homologous domain containing protein 16 (PRDM16), cell death inducing DFFA-like effector A (Cidea), CD137 and transmembrane protein 26 (TMEM26). Mulberry leaf also activated brown adipose tissue (BAT) by increasing the expressions of brown-mark genes including UCP1, PGC-1α, PPARα, PRDM16 and Cidea. Moreover, mulberry leaf enhanced the expression of nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM) genes that are responsible for mitochondrial biogenesis in IWAT and BAT. Importantly, mulberry leaf also increased the expression of UCP1 and carnitine palmitoyl transferase 1 (CPT-1) proteins in both IWAT and BAT via a mechanism involving AMP-activated protein kinase (AMPK) and PGC-1α pathway. In conclusion, our findings identify the role of mulberry leaf in inducing adipose browning, indicating that mulberry leaf may be used as a candidate browning agent for the treatment of T2DM.

The paper by K. L. Blaxter and J. L. Clapperton (1965) ‘Prediction of the amount of methane produced by ruminants. Br J Nutr 19, 511–522’ has been cited 656 times according to Web of Science and continues to be cited with increasing frequency to the present day. The analysis described in the paper, or meta-analysis as it would be known now, is of methane production from cattle and sheep based on forty-eight trials using closed-circuit respiration chambers, all carried out at the Hannah Research Institute, Ayr, UK, between 1955 and 1965. Methane emissions per unit of diet fed were shown to vary depending on diet, level of feeding and individual animal. As such, previous notions that methane emissions were essentially proportional to energy intake were set aside. The main reasons for the paper’s continuing citation are the set of equations that can be used to predict methane emissions from ruminants when the technically demanding respiration chambers are unavailable, and that it was the first definitive study to describe the complexities of methane emissions with respect to animals and diets. The paper thus provided abundant insights of the relations between ruminant methane emissions and nutritional biology, and rumen microbiology, in particular, that have informed countless research projects in the intervening half-century. Given the importance of methane as a greenhouse gas in the climate change scenario, these insights are at least as relevant today as they were in 1965.

Excessive hepatic glycogen accumulation commonly impairs hepatocytes function and further produces negative effects on growth and health status of carnivorous fish. A 9-week feeding trial was conducted to explore the potential regulation of resveratrol (RSV) on high-carbohydrate-induced glycogen deposition and immune response of largemouth bass. Results showed that high dietary carbohydrate (10 % inclusion of starch) led to hepatic glycogen accumulation and post-prandial hyperglycemia compared with the diet with 5 % starch, which was both alleviated with the inclusion of RSV. The use of RSV promoted the expression of sirtuin 1, which was down-regulated by high dietary carbohydrate. Meanwhile, RSV inclusion promoted the expression of genes involved in insulin pathway and glycolysis and inhibited the expression of gluconeogenesis-related genes. Additionally, high dietary carbohydrate significantly reduced lysozyme content but increased complement C4 content, which were both reversed with RSV supplementation. Meanwhile, RSV inclusion inhibited the expression of pro-inflammatory cytokines but promoted anti-inflammatory cytokines expression, compared with the high carbohydrate treatment. In conclusion, RSV inclusion was beneficial in alleviating high-dietary-carbohydrate-induced glycogen accumulation and immune response in largemouth bass.

Poor utilisation efficiency of carbohydrate always leads to metabolic phenotypes in fish. The intestinal microbiota plays an important role in carbohydrate degradation. Whether the intestinal bacteria could alleviate high-carbohydrate diet (HCD)-induced metabolic phenotypes in fish remains unknown. Here, a strain affiliated to Bacillus amyloliquefaciens was isolated from the intestine of Nile tilapia. A basal diet (CON), HCD or HCD supplemented with B. amy SS1 (HCB) was used to feed fish for 10 weeks. The beneficial effects of B. amy SS1 on weight gain and protein accumulation were observed. Fasting glucose and lipid deposition were decreased in the HCB group compared with the HCD group. High-throughput sequencing showed that the abundance of acetate-producing bacteria was increased in the HCB group relative to the HCD group. Gas chromatographic analysis indicated that the concentration of intestinal acetate was increased dramatically in the HCB group compared with that in the HCD group. Glucagon-like peptide-1 was also increased in the intestine and serum of the HCB group. Thus, fish were fed with HCD, HCD supplemented with sodium acetate at 900 mg/kg (HLA), 1800 mg/kg (HMA) or 3600 mg/kg (HHA) diet for 8 weeks, and the HMA and HHA groups mirrored the effects of B. amy SS1. This study revealed that B. amy SS1 could alleviate the metabolic phenotypes caused by HCD by enriching acetate-producing bacteria in fish intestines. Regulating the intestinal microbiota and their metabolites might represent a powerful strategy for fish nutrition modulation and health maintenance in future.