Garcinol Promotes the Formation of Slow-Twitch Muscle Fibers by Inhibiting p300-Dependent Acetylation of PGC-1α.

The conversion of skeletal muscle fiber from fast-twitch to slow-twitch is crucial for sustained contractile and stretchable events, energy homeostasis, and anti-fatigue ability. The purpose of our study was to explore the mechanism and effects of garcinol on the regulation of skeletal muscle fiber type transformation. Forty 21-day-old male C57/BL6J mice (n = 10/diet) were fed a control diet or a control diet plus garcinol at 100 mg/kg (Low Gar), 300 mg/kg (Mid Gar), or 500 mg/kg (High Gar) for 12 weeks. The tibialis anterior (TA) and soleus muscles were collected for protein and immunoprecipitation analyses. Dietary garcinol significantly downregulated (p < 0.05) fast myosin heavy chain (MyHC) expression and upregulated (p < 0.05) slow MyHC expression in the TA and soleus muscles. Garcinol significantly increased (p < 0.05) the activity of peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α) and markedly decreased (p < 0.05) the acetylation of PGC-1α. In vitro and in vivo experiments showed that garcinol decreased (p < 0.05) lactate dehydrogenase activity and increased (p < 0.05) the activities of malate dehydrogenase and succinic dehydrogenase. In addition, the results of C2C12 myotubes showed that garcinol treatment increased (p < 0.05) the transformation of glycolytic muscle fiber to oxidative muscle fiber by 45.9%. Garcinol treatment and p300 interference reduced (p < 0.05) the expression of fast MyHC but increased (p < 0.05) the expression of slow MyHC in vitro. Moreover, the acetylation of PGC-1α was significantly decreased (p < 0.05). Garcinol promotes the transformation of skeletal muscle fibers from the fast-glycolytic type to the slow-oxidative type through the p300/PGC-1α signaling pathway in C2C12 myotubes.

Dietary embelin supplementation during mid-to-late gestation improves performance and maternal-fetal glucose metabolism of pigs.

This study aimed to evaluate the effects of dietary embelin supplementation during late gestation (from days 60 to 110) on performance and maternal-fetal glucose metabolism of pigs. Sixty sows (Duroc × Yorkshire × Landrace; parity = 1.68 ±â€…0.03; N = 20) were randomly divided into three gestation (day 60 of pregnancy) treatments, Control pigs (CON) were fed a basal diet, and the other animals were fed a basal diet supplemented with 200 or 600 mg/kg embelin per kg of feed. The body weight, backfat thickness and litter size of the sows, and birth weight and mortality of piglets were recorded. Sows' blood and piglets' umbilical cord blood were collected for the measurements of hematological parameters and anti-oxidative and immune indexes, and maternal-fetal glucose metabolism parameters, respectively. The colostrum and milk and fecal samples of the sows were also collected for analysis of milk composition and apparent total tract nutrient digestibility. Dietary embelin had no effect on the BW and backfat thickness of the sows but significantly increased the birth weight of piglets (P < 0.05) and decreased the mortality (P < 0.05). Moreover, the white blood cell counts (day 90), neutrophil count and mean cell hemoglobin (day 110), total anti-oxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) content of the sows were increased significantly (P < 0.05) in the embelin groups than that in the CON group, whereas the malondialdehyde (MDA) content was decreased (P < 0.05). Embelin significantly increased immunoglobulin A (IgA) and immunoglobulin G (IgG) content in plasma of piglets as well as those in colostrum and milk of sows than the CON treatment (P < 0.05). In addition, dry matter, ash, and ether extract in the colostrum were similar between groups (P > 0.05), whereas the embelin significantly increased the crude protein in the milk. The apparent total tract nutrient digestibility was similar between treatments (P > 0.05). The embelin treatment significantly increased the glucose levels and lactate dehydrogenase B (LDHB) activity in sows plasma, and decreased the lactate levels in both sows and fetuses plasma (P < 0.05). Collectively, this study indicates that sows fed with embelin in mid-to-late gestation showed improved maternal health and anti-oxidative status, milk protein content, and maternal-fetal glucose metabolism, showing promise in natural plant extract nutrition for sows.

Abnormal glucose metabolism in sows in late gestation can lead to incapacity of sow production, and even reproductive disorders. It has been confirmed that inefficient glucose utilization and oxidative damage are intimately related. Thus, studies about alleviating oxidative stress and facilitating glucose metabolism in pregnant sows can be relevant. As an excellent anti-oxidative plant extract, embelin has been widely used in dietary supplementation of rodents, however, the effect of dietary supplementation with embelin on the performance of sows and newborn piglets, as well as on the glucose metabolism has rarely been reported. The present study provides the first evidence that dietary supplementation with embelin during mid-to-late gestation improved maternal immune and oxidative status, the milk quality as well as the glucose metabolism of both sows and piglets, suggesting that embelin may be a promising natural plant extractive of nutrition for sows especially during mid-to-late pregnancy and lactation.

Embelin alleviates weaned piglets intestinal inflammation and barrier dysfunction via PCAF/NF-κB signaling pathway in intestinal epithelial cells.

BACKGROUND: Intestinal barrier plays key roles in maintaining intestinal homeostasis. Inflammation damage can severely destroy the intestinal integrity of mammals. This study was conducted to investigate the protective effects of embelin and its molecular mechanisms on intestinal inflammation in a porcine model. One hundred sixty 21-day-old castrated weaned pigs (Duroc × Landrace × Yorkshire, average initial body weight was 7.05 ± 0.28 kg, equal numbers of castrated males and females) were allotted to four groups and fed with a basal diet or a basal diet containing 200, 400, or 600 mg embelin/kg for 28 d. The growth performance, intestinal inflammatory cytokines, morphology of jejunum and ileum, tight junctions in the intestinal mucosa of piglets were tested. IPEC-1 cells with overexpression of P300/CBP associating factor (PCAF) were treated with embelin, the activity of PCAF and acetylation of nuclear factor-κB (NF-κB) were analyzed to determine the effect of embelin on PCAF/NF-κB pathway in vitro. RESULTS: The results showed that embelin decreased (P < 0.05) serum D-lactate and diamine oxidase (DAO) levels, and enhanced the expression of ZO-1, occludin and claudin-1 protein in jejunum and ileum. Moreover, the expression levels of critical inflammation molecules (interleukin-1ß, interleukin-6, tumor necrosis factor-α, and NF-κB) were down-regulated (P < 0.05) by embelin in jejunal and ileal mucosa. Meanwhile, the activity of PCAF were down-regulated (P < 0.05) by embelin. Importantly, transfection of PCAF siRNAs to IPEC-1 cell decreased NF-κB activities; embelin treatment downregulated (P < 0.05) the acetylation and activities of NF-κB by 31.7%-74.6% in IPEC-1 cells with overexpression of PCAF. CONCLUSIONS: These results suggested that embelin ameliorates intestinal inflammation in weaned pigs, which might be mediated by suppressing the PCAF/NF-κB signaling pathway.

PGC-1α Promotes Ureagenesis in Mouse Periportal Hepatocytes through SIRT3 and SIRT5 in Response to Glucagon.

Excess ammonia is produced during fasting when amino acids are used for glucogenesis. Together with ureagenesis, glucogenesis occurs in periportal hepatocytes mediated mainly through the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). In vivo experiments showed that fasting strongly stimulated mice glucagon secretion, hepatic PGC-1α, sirtuin 3 (SIRT3) and sirtuin 5 (SIRT5) expression and ureagenesis enzymatic activity such as carbamoyl phosphate synthetase 1 (CPS1) and ornithine transcarbamoylase (OTC). Interestingly, (15)N-labeled urea and (13)C-labeled glucose production in wild-type mice were significantly increased compared with PGC-1α null mice by [(15)N,(13)C]alanine perfused liver. Glucagon significantly stimulated ureagenesis, expression of SIRT3, SIRT5 and the activities of CPS1 and OCT but did not stimulate PGC-1α silencing hepatocytes in mice periportal hepatocytes. Contrarily, PGC-1α overexpression significantly increased the expression of SIRT3, SIRT5 and the activities of CPS1 and OTC, but induced no significant changes in CPS1 and OTC expression. Morever, SIRT3 directly deacetylates and upregulates the activity of OTC, while SIRT5 deacetylates and stimulates the activity of CPS1. During fasting, PGC-1α facilitates ureagenesis in mouse periportal hepatocytes by deacetylating CPS1 and OTC modulated by mitochondrial deacetylase, SIRT3 and SIRT5. This mechanism may be relevant to ammonia detoxification and metabolic homeostasis in liver during fasting.

Role of BAF60a/BAF60c in chromatin remodeling and hepatic lipid metabolism.

The switching defective/sucrose non-fermenting (SWI/SNF) complexes play an important role in hepatic lipid metabolism regulating both transcriptional activation and repression. BAF60a is a core subunit of the SWI/SNF chromatin-remodeling complexes that activates the transcription of fatty acid oxidation genes during fasting/glucagon. BAF60c, another subunit of SWI/SNF complexes, is recruited to form the lipoBAF complex that activates lipogenic genes, promoting lipogenesis and increasing the triglyceride level in response to feeding/insulin. Interestingly, hepatocytes located in the periportal and perivenous zones of the liver display a remarkable heterogeneity in the activity of various enzymes, metabolic functions and gene expression. Especially, fatty-acid oxidation was shown to be mostly periportal, whereas lipogenesis was mostly perivenous. Therefore, the present review highlights the role of of SWI/SNF regulating lipid metabolism under nutritional and hormonal control, which may be associated with hepatocyte heterogeneity.

Effects of eicosapentaenoic acid and docosahexaenoic acid on chylomicron and VLDL synthesis and secretion in Caco-2 cells.

The present research was undertaken to determine the effects of EPA (20 : 5 n-3) and DHA (22 : 6 n-3) on chylomicron and VLDL synthesis and secretion by Caco-2 cells. Cells were incubated for 12 to 36 h with 400 µM OA, EPA, and DHA; then 36 h was chosen for further study because EPA and DHA decreased de novo triglycerides synthesis in a longer incubation compared with OA (P < 0.01). Neither the uptake nor oxidation was different in response to the respective fatty acids (P > 0.05). Compared with OA, intercellular and secreted nascent apolipoprotein B48 and B100 were decreased by EPA and DHA (P < 0.01). Both DHA and EPA resulted in a lower secretion of chylomicron and VLDL (P < 0.01). In contrast to OA, EPA and DHA were preferentially incorporated into phospholipids instead of triacylglycerols (P < 0.01). These discoveries demonstrated that exposure of DHA and EPA reduced the secretion of chylomicron and VLDL partly by regulating the synthesis of TG and apoB.