Taurine is Involved in Energy Metabolism in Muscles,Adipose Tissue,and the Liver

Energy metabolism is a basic and general process, by which the body acquires and uses energy to maintain normal function, and taurine plays a vital role in energy metabolism. Taurine deficiency may cause a weak energy metabolism and energy metabolism dysfunction. Taurine biosynthetic ability is limited, and its supplementation in the diet can strengthen energy metabolism in muscle performance, cardiac function, liver activity, and adipose tissue. Combining taurine with other drugs may have a superior effect in energy metabolism. In many metabolic disorders, taurine, or the combination of taurine with other drugs, also functions as a repair treatment for damaged tissues, and acts as a promoter for the balance of energy metabolism. The present study discusses the potential roles of taurine in energy metabolism.     

Exploring the unknowns involved in the transformation of muscle to meat

Meat quality development, or the transformation of muscle to meat, involves a myriad of biochemical pathways that are largely well-studied in living muscle tissue. However, these pathways are less predictable when homeostatic ranges are violated. In addition, there is far less known about how various management or environmental stimuli impact these pathways, either by substrate load or altered cellular environment. Likewise, it is largely accepted that oxygen plays little to no role in the conversion of muscle to meat, as anaerobic metabolism predominates in the muscle tissue. Even so, the oxygen tension within the tissues does not fall precipitously at exsanguination. Therefore, transition to an anaerobic environment may impact energy metabolism postmortem. Antemortem handling, on the other hand, clearly impacts meat quality development, yet the exact mechanisms remain a mystery. In this paper, we will attempt to review those factors known to affect postmortem energy metabolism in muscle and explore those areas where additional work may be fruitful.     

Cannabinoid-1 receptor activation modulates lipid mobilization and adipogenesis in the adipose tissue of dairy cows

Amplified adipose tissue (AT) lipolysis and suppressed lipogenesis characterize the periparturient period of dairy cows. The intensity of lipolysis recedes with the progression of lactation; however, when lipolysis is excessive and prolonged, disease risk is exacerbated and productivity compromised. Interventions that minimize lipolysis while maintaining adequate supply of energy and enhancing lipogenesis may improve periparturient cows' health and lactation performance. Cannabinoid-1 receptor (CB1R) activation in rodent AT enhances the lipogenic and adipogenic capacity of adipocytes, yet the effects in dairy cow AT remain unknown. Using a synthetic CB1R agonist and an antagonist, we determined the effects of CB1R stimulation on lipolysis, lipogenesis, and adipogenesis in the AT of dairy cows. Adipose tissue explants were collected from healthy, nonlactating and nongestating (NLNG; n = 6) or periparturient (n = 12) cows at 1 wk before parturition and at 2 and 3 wk postpartum (PP1 and PP2, respectively). Explants were treated with the β-adrenergic agonist isoproterenol (1 μM) in the presence of the CB1R agonist arachidonyl-2′-chloroethylamide (ACEA) ± the CB1R antagonist rimonabant (RIM). Lipolysis was quantified based on glycerol release. We found that ACEA reduced lipolysis in NLNG cows; however, it did not exhibit a direct effect on AT lipolysis in periparturient cows. Inhibition of CB1R with RIM in postpartum cow AT did not alter lipolysis. To evaluate adipogenesis and lipogenesis, preadipocytes isolated from NLNG cows' AT were induced to differentiate in the presence or absence of ACEA ± RIM for 4 and 12 d. Live cell imaging, lipid accumulation, and expressions of key adipogenic and lipogenic markers were assessed. Preadipocytes treated with ACEA had higher adipogenesis, whereas ACEA+RIM reduced it. Adipocytes treated with ACEA and RIM for 12 d exhibited enhanced lipogenesis compared with untreated cells (control). Lipid content was reduced in ACEA+RIM but not with RIM alone. Collectively, our results support that lipolysis may be reduced by CB1R stimulation in NLNG cows but not in periparturient cows. In addition, our findings demonstrate that adipogenesis and lipogenesis are enhanced by activation of CB1R in the AT of NLNG dairy cows. In summary, we provide initial evidence which supports that the sensitivity of the AT endocannabinoid system to endocannabinoids, and its ability to modulate AT lipolysis, adipogenesis, and lipogenesis, vary based on dairy cows' lactation stage.     

Symposium review: Adipose tissue endocrinology in the periparturient period of dairy cows

The involvement of adipose tissue (AT) in metabolism is not limited to energy storage but turned out to be much more complex. We now know that in addition to lipid metabolism, AT is important in glucose homeostasis and AA metabolism and also has a role in inflammatory processes. With the discovery of leptin in 1994, the concept of AT being able to secrete messenger molecules collectively termed as adipokines, and acting in an endo-, para-, and autocrine manner emerged. Moreover, based on its asset of receptors, many stimuli from other tissues reaching AT via the bloodstream can also elicit distinct responses and thus integrate AT as a control element in the regulatory circuits of the whole body's functions. The protein secretome of human differentiated adipocytes was described to comprise more than 400 different proteins. However, in dairy cows, the characterization of the physiological time course of adipokines in AT during the transition from pregnancy to lactation is largely limited to the mRNA level; for the protein level, the analytical methods are limited and available assays often lack sound validation. In addition to proteinaceous adipokines, small compounds such as steroids can also be secreted from AT. Due to the lipophilic nature of steroids, they are stored in AT, but during the past years, AT became also known as being able to metabolize and even to generate steroid hormones de novo. In high-yielding dairy cows, AT is substantially mobilized due to increased energy requirements related to lactation. As to whether the steroidogenic system in AT is affected and may change during the common loss of body fat is largely unknown. Moreover, most research about AT in transition dairy cows is based on subcutaneous AT, whereas other depots have scarcely been investigated. This contribution aims to review the changes in adipokine mRNA and—where available—protein expression with time relative to calving in high-yielding dairy cows at different conditions, including parity, body condition, diet, specific feed supplements, and health disorders. In addition, the review provides insights into steroidogenic pathways in dairy cows AT, and addresses differences between fat depots where possible.     

Matrix effects on the bioavailability of resveratrol in humans

The pharmacokinetics of resveratrol in 11 healthy male volunteers has been assessed in a randomized, crossover, controlled clinical trial after the administration of three grape products: red wine (250 mL), grape juice (1/L), or tablets (red wine extracts enriched with trans-resveratrol). Doses of trans-resveratrol independently of the product administered, were about 14 μg/kg. Biological samples were collected and analysed by capillary gas chromatography–mass spectrometry. cis-Resveratrol, trans-resveratrol and dihydroresveratrol were determined in plasma and urine. Plasma concentration of trans-resveratrol after hydrolysis increased as a response to all grape products and that of cis-resveratrol after wine and grape juice. Free forms of these phenolic compounds were deemed undetectable in plasma. Despite similar trans-resveratrol doses being administered, its bioavailability from wine and grape juice was 6-fold higher, than that from tablets. Resveratrol was better absorbed from natural grape products than from tablets, pointing out the importance of the matrix in its bioavailability.     

Feeding microalgae at a high level to finishing heifers increases the long‐chain n‐3 fatty acid composition of beef with only small effects on the sensory quality

The aim of the study was to determine the effect of feeding a low and high level of microalgae (MA, high in C22:6n‐3) on the fatty acid (FA) composition and sensory attributes of beef. Thirty Charolais cross Limousin/Friesian heifers were fed one of the three diets (n = 10 per treatment): Control (no MA), low MA (LMA; inclusion rate of 15 g kg^?1) or high MA (HMA; inclusion rate of 30 g kg^?1) for 95 days before slaughter. Heifers fed HMA had a higher (P < 0.05) content of C20:5n‐3: eicosapentaenoic acid (EPA) and C22:6n‐3: docosahexaenoic acid (DHA) in the longissimus thoracis muscle than those receiving the Control (mean values for EPA of 0.5, 0.92, 1.20 and DHA of 0.31, 0.89 and 1.05 % of total FA for Control, LMA and HMA, respectively), and a lower n‐3 to n‐6 ratio (2.9, 1.9 and 1.6 in Control, LMA and HMA, respectively; P < 0.001). Steaks from animals fed either of the MA diets had a marginally higher (P < 0.05) ‘seaweedy flavour’ that was positively correlated with muscle C22:6n‐3 concentration. Steaks from animals fed HMA were rated as being higher (P < 0.05) in tenderness and had a lower (P < 0.05) shear force than those from Control fed animals. It is concluded that feeding microalgae at high levels can beneficially improve the health attributes of beef with only a few effects on sensory quality.     

Hormone-sensitive lipase protein expression and extent of phosphorylation in subcutaneous and retroperitoneal adipose tissues in the periparturient dairy cow

Lipomobilization is essential for dairy cows to balance the energy requirement for milk production in early lactation. This study aimed to determine the role of hormone-sensitive lipase (HSL) and its activation by phosphorylation at Ser 660 (HSLp660) and 563 (HSLp563) in different adipose tissue depots as influenced by time and postpartum diet in dairy cows. Biopsy samples were obtained from s.c. (SCAT) and retroperitoneal (RPAT) adipose tissues of 20 Holstein cows 21 d prepartum, and 1 and 21 d postpartum. After d 1 postpartum, cows were randomly assigned to 2 groups (n = 10). Groups received diets with either a concentrate-to-roughage ratio on a dry matter basis of 30:70% (low-concentrate, LC, group) or 60:40% (high-concentrate group), fed until the third biopsy sampling 21 d postpartum. Dry matter intake, milk yield, and milk composition were recorded. Blood samples were taken weekly, starting 21 d prepartum and analyzed for nonesterified fatty acids, β-hydroxybutyrate (BHBA), glucose, and insulin. Protein expression of HSL and its extent of phosphorylation in adipose tissue were measured by semiquantitative Western blotting. Total HSL expression was lower in both adipose tissues 1 d after calving compared with prepartum sampling (SCAT: 4.10 ± 0.5 vs. 2.4 ± 0.3; RPAT: 11.1 ± 1.3 vs. 6.6 ± 1.1). Phosphorylation at Ser 660 was higher 21 d postpartum compared with 21 d prepartum in RPAT (2.9 ± 0.3 vs. 4.6 ± 0.6). Phosphorylation at Ser 563 was higher 21 d postpartum than 21 d prepartum in SCAT (0.6 ± 0.1 vs. 3.9 ± 1.1), and in RPAT a difference was observed between 21 d prepartum and 1 d postpartum (1.0 ± 0.1 vs. 3.3. ± 0.6). On d 21 postpartum, the LC group showed a lower extent of Ser 563 phosphorylation in RPAT (3.9 ± 0.8 vs.10.0 ± 1.9) and a higher concentration of serum BHBA (0.77 ± 0.05 vs. 0.47 ± 0.11) than did the high-concentrate group. An inhibitory influence of higher BHBA concentrations on HSL phosphorylation in the LC group could be a possible explanation. On comparing RPAT to SCAT, HSL expression and the extent of Ser 660 and 563 phosphorylation was higher in RPAT at 21 d prepartum (HSL: 4.1 ± 0.5 vs. 11.1 ± 1.2; HSLp660 1.3 ± 0.2 vs. 2.9 ± 0.3; HSLp563: 0.6 ± 0.1 vs. 1.0 ± 0.1). In conclusion, the postpartum feeding regimen influenced the phosphorylation pattern, especially in RPAT, implying a regulatory role for different phosphorylation sites in adaptive lipolysis of dairy cows. It is suggested that RPAT is more sensitive to periparturient challenges than is SCAT.     

Agonists of the G protein-coupled receptor 109A-mediated pathway promote antilipolysis by reducing serine residue 563 phosphorylation of hormone-sensitive lipase in bovine adipose tissue explants

A balanced lipolytic regulation in adipose tissues based on fine-tuning of prolipolytic and antilipolytic pathways is of vital importance to maintain the metabolic health in dairy cows. Antilipolytic pathways, such as the G protein-coupled receptor 109A (GPR109A)-mediated pathway and the insulin signaling pathway in bovine adipose tissues may be involved in prohibiting excessive lipomobilization by reducing triglycerol hydrolysis. This study aimed to evaluate the in vitro antilipolytic potential of the mentioned pathways in bovine adipose tissue explants. Therefore, subcutaneous and retroperitoneal adipose tissue samples (approximately 100 mg) of German Holstein cows were treated for 90 min ex vivo with nicotinic acid (2, 8, or 32 μM), nicotinamide (2, 8, or 32 μM), β-hydroxybutyrate (0.2, 1, or 5 mM), or insulin (12 mU/L), with a concurrent lipolytic challenge provoked with 1 μM isoproterenol. Lipolytic and antilipolytic responses of the adipose tissues were assessed by measuring free glycerol and nonesterified fatty acid release. To identify molecular components of the investigated antilipolytic pathways, protein abundance of GPR109A and the extent of hormone-sensitive lipase (HSL) phosphorylation at serine residue 563 were detected by Western blotting. Treatment with nicotinic acid or β-hydroxybutyrate decreased the lipolytic response in adipose tissue explants and concurrently reduced the extent of HSL phosphorylation, but treatment with nicotinamide or insulin did not. Subcutaneous adipose tissue constitutively expressed more GPR109A protein, but no other depot-specific differences were observed. This study provides evidence that the GPR109A-mediated pathway is functionally existent in bovine adipose tissues, and confirms that HSL phosphorylation at serine residue 563 is also important in antilipolytic regulation in vitro. This antilipolytic pathway may be involved in a balanced lipid mobilization in the dairy cow.     

大豆异黄酮抗大鼠T细胞衰老及抗氧化作用研究

为研究大豆异黄酮抗大鼠T细胞衰老和抗氧化作用，选用老龄SD大鼠，观察大豆异黄酮对T细胞CD28表达水平及肝脏氧化应激水平的影响。实验设立青年对照组、老龄对照组和大豆异黄酮0．33、0．99g／kgBW剂量组，其中剂量组按剂量灌胃给予大豆异黄酮，对照组灌胃给予等量纯净水。4周后，分别制备肝细胞匀浆和肝单细胞悬液，用硫代巴比妥酸（TBA）比色法测定肝匀浆中丙二醛（MDA）含量，分光光度法测定超氧化物歧化酶（SOD）活力，用流式细胞仪结合双氢罗丹明123（Rh123）和双氢-乙酰乙酸二氯荧光黄（82DCFDA）染色法分别检测肝细胞线粒体膜电位（MMP）及活性氧（ROS）水平；另取外周血测定T淋巴细胞表面CD8／CD28表达情况。结果显示：青年对照组及大豆异黄酮剂量组的肝组织MDA含量均较老年对照组低，而SOD活力及肝细胞MMP水平均较老年对照组高（P〈0．05）；大豆异黄酮剂量组肝细胞内的ROS水平较老年对照组低（P〈0．01）。老年对照组大鼠外周血CD28^＋和CD28^＋／CD8^＋T细胞比例低于青年对照组，而CD28^-／CD8^＋T细胞比例高于青年对照组，给予大豆异黄酮样品组三者比例均介于两对照组之间。提示衰老大鼠外周血T细胞CD28表达降低，肝细胞线粒体膜稳定性下降，氧自由基清除能力下降，过氧化脂质分解的终产物增多；大豆异黄酮可提高老龄大鼠T细胞CD28表达水平，增加肝细胞抗氧化酶活性，稳定线粒体膜电位，减少活性氧产生。     

SMYD3-associated pathway is involved in the anti-tumor effects of sulforaphane on gastric carcinoma cells

Food Science and Biotechnology - Sulforaphane (SFN), a natural compound derived from cruciferous vegetables, has been proved to possess potent anti-cancer activity. SMYD3 is a histone...