Effects of Different Feed Additives on Intestinal Metabolite Composition of Weaned Piglets.

To study the effects of different feed additives on the weaning stress of Tibetan piglets, we selected 28 healthy, 30-day-old Tibetan weaned piglets and divided them into four groups, namely, the control group (basal feed without any antibiotic additions) (Nor), the group with the addition of the antibiotic lincomycin (Ant), the group with the addition of fifteen-flavor black pills of Tibetan medicine (Tib), and the group with the addition of fecal bacterial supernatant (Fec). We measured growth performance, blood physiological indexes, and metabolomics. The results showed that the Ant, Tib, and Fec groups significantly reduced the ratio of diarrhea to feed/weight (F/G) and increased the average daily gain (ADG) compared with the Nor group (p < 0.01). The Nor group had significantly lower leukocyte counts, hemoglobin levels, and erythrocyte counts compared with the other three groups at 21 d (p < 0.05). These physiological indexes tended to stabilize at 42 d. We found that there were beneficial metabolites and metabolic pathways for gastrointestinal function. Specifically, the porphyrin metabolic pathway was elevated in the Ant group, and the tryptophan metabolic pathway was significantly elevated in the Tib and Fec groups compared with the Nor group (p < 0.05). In conclusion, adding fecal bacterial supernatant and fifteen-flavor black pills of Tibetan medicine to the feed reduced the rate of diarrhea and improved the growth performance of the piglets. Moreover, it had an effect on the microorganisms and their metabolites and pathways in the gastrointestinal tract of the animals, which might be the main reason for influencing the diarrhea rate of weaned Tibetan piglets and the growth and development of the piglets. This study provides a new approach for anti-stress applications in weaned Tibetan piglets and the development of substitute anti-products.

Effect of maternal dietary supplementation with phytosterol esters on muscle development of broiler offspring.

Recently, embryo muscle development, which is crucial for postnatal skeletal muscle growth, has been investigated widely. Nutrients in ovo were suggested to be critical in embryo muscle development since the chick growth mostly relies on nutrients in eggs at the early developmental stage. Phytosterol esters (PE), which are derived from the reactions between phytosterols and fatty acids, were demonstrated to have important effects on lipid and cholesterol metabolism regulation. In order to reveal the effect of maternal lipid metabolism on the deposition of nutrients in eggs and the development of embryonic muscles, broiler hens were fed with a diet supplemented with 5% PE or control diet. Lipid deposition in eggs and growth of the hatched chicks were studied. We found that PE increased bile acid (BA) deposition in the eggs and serum of hens (p=0.02 and p<0.01, respectively), altered insulin and glucose level differentially in female and male offspring, and promoted body weight (p=0.02 for male and female on day 49), muscle fiber density (p=0.02 for female on day 49), and myogenin and myogenic determination factor (myoD) expression (p=0.03 and p=0.02 on day 49) by the activation of BA receptors in female, but not in male, offspring. Our study determined for the first time that PE promoted muscle development of chicks hatching from eggs laid by the hens, through regulating bile acid (BA) deposition and this may be attributed to the activation of BA receptors.

Dietary thymol supplementation promotes skeletal muscle fibre type switch in longissimus dorsi of finishing pigs.

As one of the key points related to meat quality, skeletal muscle fibre type is determined by energy metabolism and genetic factors, but its transformation could be also greatly influenced by many factors. Thymol, the primary effective ingredients of thyme, is well known for its anti-oxidation and anti-inflammatory, while little is known about its effect on skeletal muscle oxidative metabolism and fibre type switch. Therefore, in order to investigate its effects and possibility to be applied in livestock production, 36 150-day-old fattening Pigs were fed with different diet for six-week experiment. As a result, the drip loss ratio of longissimus dorsi (LD) was significantly reduced (p < .05). Oxidative metabolism-related enzyme activity, the mRNA levels and protein expression of COX5B and PGC1α, mRNA level of myosin heavy chain I (MyHC I) and protein level of MyHC IIa were significantly upregulated (p < .05). While compared with control group, the protein expression of MyHC IIb was significantly decreased (p < .05). The result revealed that thymol could promote the oxidative metabolism in the muscle of pigs and improve the meat quality to a certain extent.

Ca2+-Calcineurin-NFAT pathway mediates the effect of thymol on oxidative metabolism and fiber-type switch in skeletal muscle.

Thymol is a major component of thyme, and it has been reported that thymol administration reduces body weight, plasma insulin and blood glucose in type-2 diabetes. Skeletal muscle is the most important metabolism organs in the body; however, to date, there is no report on the effect of thymol on skeletal muscle. Our goal was to determine whether thymol has an effect on the different types of skeletal muscle fibers and their metabolism characteristics. Hence, we performed in vivo and in vitro experiments. In vivo, SD rats (4 weeks old) were fed with different concentrations of thymol for 4 weeks, and in vitro C2C12 myotubes were directly treated with thymol for 2 days. The rats fed with 0.025% thymol showed a significantly lower body weight, subcutaneous white adipose tissue index and gastrocnemius muscle index (P < 0.05), while their proportion of brown adipose tissue significantly increased (P < 0.05). The protein and mRNA expression of MyHC I and MyHC IIa in the gastrocnemius muscle of the rats significantly increased (P < 0.05), while the protein level of MyHC II and mRNA expression of MyHC IIb decreased (P < 0.05). Furthermore, 0.025% thymol supplement significantly reduced (P < 0.05) the activity of lactate dehydrogenase (LDH) in the gastrocnemius muscle of the rats, but their succinate dehydrogenase (SDH) and hexokinase (HK) activities increased (P < 0.05). Also, the expression of the fatty acid oxidation-related genes in the gastrocnemius muscle of the rats decreased with the thymol supplement (P < 0.05). In vitro, similar results were obtained. Furthermore, the Ca2+-calcineurin-NFAT pathway, which is an important pathway to regulate the transformation of skeletal muscle fiber type, was studied. We found that the effects of thymol on the myosin heavy chain isoforms, genes related to metabolism and the activation of the Ca2+-calcineurin-NFAT pathway were all reversed by a Ca2+ chelator (P < 0.05). Thus, thymol can promote the oxidative metabolism and fiber type switch in skeletal muscle, and the Ca2+-calcineurin-NFAT pathway plays an important role in it.

Succinate induces skeletal muscle fiber remodeling via SUNCR1 signaling.

The conversion of skeletal muscle fiber from fast twitch to slow-twitch is important for sustained and tonic contractile events, maintenance of energy homeostasis, and the alleviation of fatigue. Skeletal muscle remodeling is effectively induced by endurance or aerobic exercise, which also generates several tricarboxylic acid (TCA) cycle intermediates, including succinate. However, whether succinate regulates muscle fiber-type transitions remains unclear. Here, we found that dietary succinate supplementation increased endurance exercise ability, myosin heavy chain I expression, aerobic enzyme activity, oxygen consumption, and mitochondrial biogenesis in mouse skeletal muscle. By contrast, succinate decreased lactate dehydrogenase activity, lactate production, and myosin heavy chain IIb expression. Further, by using pharmacological or genetic loss-of-function models generated by phospholipase Cß antagonists, SUNCR1 global knockout, or SUNCR1 gastrocnemius-specific knockdown, we found that the effects of succinate on skeletal muscle fiber-type remodeling are mediated by SUNCR1 and its downstream calcium/NFAT signaling pathway. In summary, our results demonstrate succinate induces transition of skeletal muscle fiber via SUNCR1 signaling pathway. These findings suggest the potential beneficial use of succinate-based compounds in both athletic and sedentary populations.

Lauric Acid Accelerates Glycolytic Muscle Fiber Formation through TLR4 Signaling.

Lauric acid (LA), which is the primary fatty acid in coconut oil, was reported to have many metabolic benefits. TLR4 is a common receptor of lipopolysaccharides and involved mainly in inflammation responses. Here, we focused on the effects of LA on skeletal muscle fiber types and metabolism. We found that 200 µM LA treatment in C2C12 or dietary supplementation of 1% LA increased MHCIIb protein expression and the proportion of type IIb muscle fibers from 0.452 ± 0.0165 to 0.572 ± 0.0153, increasing the mRNA expression of genes involved in glycolysis, such as HK2 and LDH2 (from 1.00 ± 0.110 to 1.35 ± 0.0843 and from 1.00 ± 0.123 to 1.71 ± 0.302 in vivo, respectively), decreasing the catalytic activity of lactate dehydrogenase (LDH), and transforming lactic acid to pyruvic acid. Furthermore, LA activated TLR4 signaling, and TLR4 knockdown reversed the effect of LA on muscle fiber type and glycolysis. Thus, we inferred that LA promoted glycolytic fiber formation through TLR4 signaling.

Diversity effect of capsaicin on different types of skeletal muscle.

Capsaicin is a major pungent content in green and red peppers which are widely used as spice, and capsaicin may activate different receptors. To determine whether capsaicin has different effects on different types of skeletal muscle, we applied different concentrations (0, 0.01, and 0.02%) of capsaicin in the normal diet and conducted a four-week experiment on Sprague-Dawley rats. The fiber type composition, glucose metabolism enzyme activity, and different signaling molecules' expressions of receptors were detected. Our results suggested that capsaicin reduced the body fat deposition, while promoting the slow muscle-related gene expression and increasing the enzyme activity in the gastrocnemius and soleus muscles. However, fatty acid metabolism was significantly increased only in the soleus muscle. The study of intracellular signaling suggested that the transient receptor potential vanilloid 1 (TRPV1) and cannabinoid receptors in the soleus muscle were more sensitive to capsaicin. In conclusion, the distribution of TRPV1 and cannabinoid receptors differs in different types of muscle, and the different roles of capsaicin in different types of muscle may be related to the different degrees of activation of receptors.

Phytol Promotes the Formation of Slow-Twitch Muscle Fibers through PGC-1α/miRNA but Not Mitochondria Oxidation.

Phytol is a side chain of chlorophyll belonging to the side-chain double terpenoid. When animals consume food rich in chlorophyll, phytol can be broken down to phytanic acid after digestion. It was reported that feeding animals with different varieties and levels of forage could significant improve pH and marbling score of steer and lamb carcasses, but the internal mechanism for this is still not reported. The marbling score and pH of muscle was mainly determined by skeletal muscle fiber type, which is due to expression of different myosin heavy-chain (MHC) isoforms. Here, we provide evidence that phytol can indeed affect the diversity of muscle fiber types both in vitro and in vivo and demonstrate that phytol can increase the expression of MHC I (p < 0.05), likely by upgrading the expression of PPARδ, PGC-1α, and related miRNAs. This fiber-type transformation process may not be caused by activated mitochondrial metabolism but by the structural changes in muscle fiber types.

Fermentation effects of oligosaccharides of Radix Ophiopogonis on alloxan-induced diabetes in mice.

In this study, oligosaccharides extracted from Ophiopogon japonicus vinegar (OOV) by alcoholic and acetic acid fermentation with water extracts from Radix Ophiopogon and oligosaccharides extracted from Radix Ophiopogonis (OOJ) were investigated. Characterization of the extracts indicated that OOV are proteoglycans, whereas OOJ are not. Moreover, compared with OOJ, monosaccharide compositions of OOV only include fructose and galactose and not glucose. MALDI-TOF-mass spectrometric results showed that the molecular weight of OOV was smaller after fermentation. Changes in the characteristics of OOV would inevitably lead to changes in its hypoglycemic properties. The OOV inhibition activity against α-glucosidase was stronger than that of OOJ. The inhibition activity became stronger with higher dosages of OOV. The hypoglycemic effect of OOV on alloxan-induced diabetic mice was stronger than that of OOJ. More important, the ability of OOV to reduce damage on islets in diabetic mice was stronger than that of OOJ. Overall, alcoholic and acetic acid fermentation improved the hypoglycemic activity of OOJ.

In vitro evaluation of cutaneous allergic reaction induced by chemicals using dendritic cells / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the use of dendritic cells derived from mice bone marrow to evaluate the cutaneous allergic reaction induced by chemical sensitizers.</p><p><b>METHODS</b>Dendritic cells derived from mice bone marrow were cultured and administrated with 2, 4-dinitrochlorobenzene (DNCB), nickel sulfate (NiSO4), sodium dodecyl sulfate (SDS) and hexyl cinnamic aldehyde (HCA), respectively. Cell membrane molecule CD86 and extracellular IL-1 beta, IL-6 and IL-12 were detected after 0, 1, 6, 12, 24, 36, 48 hour's administration, respectively.</p><p><b>RESULTS</b>CD86 expression reached the highest level after exposure to DNCB for 48 h, and increased by about 279% compared with the control (P < 0.05), while it was lower than that of control after administrated with NiSO4 and HCA for 1 h and 6 h, and SDS for 36 h, respectively (P < 0.05). Extracellular IL-1 beta increased greatly after exposure to NiSO4 just for 1 h, with the maximum at 48 h (298 pg/ml, P < 0.05), and after exposure to HCA for 6 h, with maximum at 48 h (84 pg/ml, P < 0.05). However, it didn't fluctuate significantly after administrated with DNCB and SDS respectively, compared with the control. Extracellular IL-6 increased significantly after exposure to NiSO4 for 1 h, with the maximum at 24 h (2152 pg/ml, P < 0.05). After exposure to HCA, extracellular IL-6 reached the maximum at 1 h (1403 pg/ml), and then it was decreased quickly, but still higher than the control (P < 0.05), while it didn't change significantly after treatment with DNCB and SDS, compared with the control (P > 0.05). Extracellular IL-12 was not detected out among all the groups.</p><p><b>CONCLUSION</b>Chemical sensitizer DNCB could induce the high expression of CD86 on DC membrane, and NiSO4 and HCA could induce DC to release IL-1 beta and IL-6. However, the irritant SDS had no such effect.</p>