J. Peng

Effects of dietary n-6:n-3 fatty acid ratio and vitamin E on semen quality, fatty acid composition and antioxidant status in boars

The aim of the present study was to evaluate the effects of dietary n-6:n-3 fatty acid (FA) ratio and vitamin E on the semen quality, FA composition and antioxidant status of boars. Forty-eight Landrace boars were randomly distributed in a 3×2 factorial design with three n-6:n-3 FA ratios (14.4, 6.6 and 2.2) by the inclusion of three oil sources (soybean, fish/soybean, fish) and two vitamin E levels (200 and 400mg/kg). During the 8 weeks of treatment, semen parameters were evaluated. Serum, sperm and seminal plasma samples were taken at 0 and 8 weeks to monitor the FA composition and antioxidant status. Results showed that the 6.6 and 2.2 dietary ratios very effectively increased docosahexaenoic acid (DHA) and n-3 polyunsaturated fatty acid (PUFA) and decreased docosapentaenoic acid (DPA) and n-6:n-3 ratio in spermatozoa. The 6.6 dietary ratio contributed to a greater progressive sperm motility (P<0.05) than the 14.4 and 2.2 dietary ratio, and this ratio also enhanced the superoxide dismutase (SOD) and total antioxidant capacity (TAC) (P<0.05) in seminal plasma more significantly than the other two ratios at week 8. Compared with 200mg/kg supplementation of vitamin E, 400mg/kg supplementation of vitamin E increased the progressive sperm motility, SOD of sperm, TAC and SOD of seminal plasma and serum, and decreased sperm malondialdehyde (MDA) (P<0.05). In conclusion, the 6.6 dietary ratio and 400mg/kg vitamin E supplementation improve progressive sperm motility by modifying the sperm FA composition and antioxidant status.

GPR120 promotes adipogenesis through intracellular calcium and extracellular signal-regulated kinase 1/2 signal pathway

Numerous researches have demonstrated that GPR120 (also called FFAR4) exerts novel functions in insulin resistance and adipogenesis. However, the molecular mechanism of GPR120-mediated adipogenic differentiation is still unclear. This study was aimed to interpret the relevant function mechanism of GPR120 in the differentiation of 3T3-L1 adipocytes. The results showed that GPR120 expression was dramatically increased along with the adipogenic differentiation of 3T3-L1 adipocytes and the adipogenic ability was significantly inhibited in shGPR120-transfected cells. TUG-891, a selective agonist of GPR120, promoted the intracellular triglyceride accumulation in a dose-dependent manner and did not enhance adipogenesis in shGPR120-transfected cells. Markedly, TUG-891 increased the activation of PPARγ in a GPR120-dependent pathway as assessed by luciferase reporter assay. Furthermore, in the adipogenic differentiation process of 3T3-L1 adipocytes, TUG-891 increased the [Ca(2+)]i and phosphorylation level of ERK1/2. Pretreatment with inhibitors of either ERK1/2 (U0126) or [Ca(2+)]i (BAPTA-AM) notably attenuated the GPR120-mediated adipogenesis. These results show that GPR120 promotes adipogenesis by increasing PPARγ expression via [Ca(2+)]i and ERK1/2 signal pathway in 3T3-L1 adipocytes.

A carvacrol-thymol blend decreased intestinal oxidative stress and influenced selected microbes without changing the messenger RNA levels of tight junction proteins in jejunal mucosa of weaning piglets.

Recent studies indicate that intestinal oxidative stress and microbiota imbalance is involved in weaning-induced intestinal dysfunction in piglets. We have investigated the effect of feeding a carvacrol-thymol blend supplemented diet on intestinal redox status, selected microbial populations and the intestinal barrier in weaning piglets. The piglets (weaned at 21 days of age) were randomly allocated to two groups with six pens per treatment and 10 piglets per pen. At weaning day (21 days of age), six piglets were sacrificed before weaning to serve as the preweaning group. The weaned group was fed with a basal diet, while the weaned-CB group was fed with the basal diet supplemented with 100 mg/kg carvacrol-thymol (1 : 1) blend for 14 days. On day 7 post-weaning, six piglets from each group were sacrificed to determine intestinal redox status, selected microbial populations, messenger RNA (mRNA) transcript levels of proinflammatory cytokines and biomarkers of intestinal barrier function. Weaning resulted in intestinal oxidative stress, indicated by the increased concentration of reactive oxygen species and thiobarbituric acid-reactive substances present in the intestine. Weaning also reduced the population of Lactobacillus genus and increased the populations of Enterococcus genus and Escherichia coli in the jejunum, and increased mRNA levels of tumor necrosis factor α (TNF-α), interleukin 1β and interleukin 6 (IL-6). In addition, decreased mRNA levels of zonula occludens and occludin in the jejunal mucosa and increased plasma diamine oxidase concentrations indicated that weaning induced dysfunction of the intestinal barrier. On day 7 post-weaning, supplementation with the carvacrol-thymol blend restored weaning-induced intestinal oxidative stress. Compared with the weaned group, the weaned-CB group had an increased population of Lactobacillus genus but reduced populations of Enterococcus genus and E. coli in the jejunum and decreased mRNA levels of TNF-α. The results indicated that weaning induced intestinal oxidative stress and dysfunction of the intestinal barrier. Dietary supplementation with 100 mg/kg carvacrol-thymol (1 : 1) decreased the intestinal oxidative stress and influenced selected microbial populations without changing the biomarkers of intestinal barrier in weaning piglets.

Cloning and characterization of spliced variants of the porcine G protein coupled receptor 120.

The polyunsaturated fatty acids (PUFAs) receptor GPR120 exerts a significant impact on systemic nutrient homeostasis in human and rodents. However, the porcine GPR120 (pGPR120) has not been well characterized. In the current study, we found that pGPR120 had 3 spliced variants. Transcript 1 encoded 362-amino acids (aa) wild type pGPR120-WT, which shared 88% homology with human short form GPR120. Transcript 1 was the mainly expressed transcript of pGPR120. It was expressed predominantly in ileum, jejunum, duodenum, spleen, and adipose. Transcript 3 (coding 320-aa isoform) was detected in spleen, while the transcript 2 (coding 310-aa isoform) was only slightly expressed in spleen. A selective agonist for human GPR120 (TUG-891) and PUFAs activated SRE-luc and NFAT-luc reporter in HEK293T cells transfected with construct for pGPR120-WT but not pGPR120-V2. However, 320-aa isoform was not a dominant negative isoform. The extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation levels in cells transfected with construct for pGPR120-WT were well activated by PUFAs, especially n-3 PUFA. These results showed that although pGPR120 had 3 transcripts, transcript 1 which encoded pGPR120-WT was the mainly expressed transcript. TUG-891 and PUFAs, especially n-3 PUFA, well activated pGPR120-WT. The current study contributed to dissecting the molecular regulation mechanisms of n-3 PUFA in pigs.

SIRT1 suppresses adipogenesis by activating Wnt/β-catenin signaling in vivo and in vitro.

Sirtuin 1 (SIRT1) regulates adipocyte and osteoblast differentiation. However, the underlying mechanism should be investigated. This study revealed that SIRT1 acts as a crucial repressor of adipogenesis. RNA-interference-mediated SIRT1 knockdown or genetic ablation enhances adipogenic potential, whereas SIRT1 overexpression inhibits adipogenesis in mesenchymal stem cells (MSCs). SIRT1 also deacetylates the histones of sFRP1, sFRP2, and Dact1 promoters; inhibits the mRNA expression of sFRP1, sFRP2, and Dact1; activates Wnt signaling pathways; and suppresses adipogenesis. SIRT1 deacetylates β-catenin to promote its accumulation in the nucleus and thus induces the transcription of genes that block MSC adipogenesis. In mice, the partial absence of SIRT1 promotes the formation of white adipose tissues without affecting the development of the body of mice. Our study described the regulatory role of SIRT1 in Wnt signaling and proposed a regulatory mechanism of adipogenesis.

Effects of different amounts of konjac flour inclusion in gestation diets on physio-chemical properties of diets, postprandial satiety in pregnant sows, lactation feed intake of sows and piglet performance

This study was conducted to investigate the effects of different amounts of konjac flour (KF) inclusion in the gestation diet on the physio-chemical properties of diets, postprandial satiety in pregnant sows, lactation feed intake of sows and piglet performance during two successive reproductive cycles. Multiparous Landrace sows (n=140) were assigned randomly to one of four experimental diets, and four gestation diets were formulated to contain varying amounts of KF at 0%, 0.6%, 1.2% or 2.2%, respectively. The water binding capacity (WBC) (P<0.01), swelling capacity (P<0.01) of gestation diets, the concentration of total short chain fatty acids (P<0.05) after in vitro fermentation of gestation diets increased linearly with increasing inclusion amounts of KF. During the second reproductive cycle, increasing dietary KF linearly increased plasma concentrations of short chain fatty acids (SCFA) 4h postprandial (P<0.05) and glucagon-like peptide (GLP-1) 2h postprandial (P<0.05), but decreased the plasma concentration of cortisol (linearly, P<0.05) 1h postprandial. In addition, there was a linear decrease of the non-feeding oral behavior of gestating sows (P<0.01) when dietary KF increased. There were linear increases in lactation feed intake of sows during entire lactation period (P<0.01) with increasing amounts of KF in the gestation diet. In addition, the number of piglets weaned (linearly, P<0.01; quadratic, P=0.01), average piglet weights and litter weights on day 21 of lactation (linearly, P<0.01) increased with increasing inclusion amounts of KF. In conclusion, inclusion of dietary fiber with great WBC, swelling capacity and fermentation capacity in the gestation diet was beneficial for enhancing postprandial satiety in pregnant sows, increasing lactation feed intake and improved number of piglets weaned per litter through greater pre-weaning survival.

Identification of zinc finger protein Bcl6 as a novel regulator of early adipose commitment.

Adipose tissue is a key determinant of whole-body metabolism and energy homeostasis. Unravelling the transcriptional regulatory process during adipogenesis is therefore highly relevant from a biomedical perspective. In these studies, zinc finger protein B-cell lymphoma 6 (Bcl6) was demonstrated to have a role in early adipogenesis of mesenchymal stem cells. Bcl6 is enriched in preadipose versus non-preadipose fibroblasts and shows upregulated expression in the early stage of adipogenesis. Gain- and loss-of-function studies revealed that Bcl6 acts as a key regulator of adipose commitment and differentiation both in vitro and ex vivo. RNAi-mediated knockdown of Bcl6 in C3H10T1/2 cells greatly inhibited adipogenic potential, whereas Bcl6 overexpression enhanced adipogenic differentiation. This transcription factor also directly or indirectly targets and controls the expression of some early and late adipogenic regulators (i.e. Zfp423, Zfp467, KLF15, C/EBPδ, C/EBPα and PPARγ). We further identified that Bcl6 transactivated the signal transducers and activators of transcription 1 (STAT1), which was determined as a required factor for adipogenesis. Moreover, overexpression of STAT1 rescued the impairment of adipogenic commitment and differentiation induced by Bcl6 knockdown in C3H10T1/2 cells, thereby confirming that STAT1 is a downstream direct target of Bcl6. This study identifies Bcl6 as a positive transcriptional regulator of early adipose commitment.

MiR-377 promotes white adipose tissue inflammation and decreases insulin sensitivity in obesity via suppression of sirtuin-1 (SIRT1)

Obesity is associated with a wide range of metabolic disorders including inflammation and insulin-resistance. Sirtuin-1 (SIRT1) is an important regulator of metabolic homeostasis and stress response pathways in white adipose tissue. However, involvement of microRNAs (miRNAs) in regulating SIRT1 during obesity-induced inflammation and insulin-resistance remains unclear. Here, we found that miR-377 was upregulated in adipose tissue and showed a negative correlation with SIRT1 in chronic high fat diet (HFD)-fed mice. MiR-377 belongs to a large miRNA cluster and functions as an important tumor suppressor in several human malignancies. Recently, it has also gained considerable attention in oxidative stress and diabetic nephropathy. In our present study, we found that overexpression of miR-377 decreased SIRT1 protein abundance and caused inflammation and insulin-resistance in differentiated 3T3-L1 cells. Conversely, miR-377 inhibition increased SIRT1 mRNA and protein levels, ameliorated inflammation and improved insulin sensitivity. Furthermore, we demonstrated that miR-377 targets the 3′-UTR of SIRT1 mRNA directly, and downregulates SIRT1 protein abundance. Inhibition of SIRT1 by EX527 significantly eliminated the downregulation of the inflammation and insulin-resistance levels induced by the miR-377 inhibitor. Furthermore, SIRT1 deficiency intensified adipose tissue inflammation and insulin-resistance, resulting in hepatic steatosis in chronic-HFD-fed mice. In conclusion, our findings suggest that miR-377 promotes white adipose tissue inflammation and decreases insulin sensitivity in obesity, at least in part, through suppressing SIRT1.

Effects of feeding regimen on weight gain, semen characteristics, libido, and lameness in 170- to 250-kilogram Duroc boars1

A 2-period field trial was conducted to determine the effects of feeding regimen on weight gain, semen characteristics, libido, and lameness in 170- to 200-kg (period 1) and 200- to 250-kg (period 2) boars. Sixty-one Duroc boars were allotted to 1 of 3 dietary treatments and 15 g/d fish oil was also provided for each experimental boar, to maintain the n-6:n-3 intake ratio at approximately 6.1:1. The energy intakes of the 3 treatment groups were controlled by basing the feed intake on a corn-soybean meal-based diet (3.11 Mcal/kg of ME) to create: 1) low energy intake group (L, = 20, 7.3 Mcal/d of ME), 2) medium energy intake group (M, = 20, 7.7 Mcal/d of ME), and 3) high energy intake group (H, = 21, 8.3 Mcal/d of ME) in period 1. Feed intake was then increased to 7.6, 8.2, and 8.6 Mcal/d of ME for the 3 groups, respectively, in period 2. During the 28-wk experimental period, boar weight gain, testis volume, semen characteristics, libido, toe measurements, claw lesions, and lameness were examined, and the number of boars culled in each group was recorded to calculate the culling rate. Although there were no differences in testis volume, sperm concentration, and motility, the percentage of abnormal sperm, the percentage of claw lesions, and claw lesion scores differed among treatments ( > 0.05), and ADG was significantly increased with the increase of energy intake between the 2 periods ( < 0.05). The M and H boars had significantly greater total sperm number and functional sperm number than the L boars ( < 0.05), while no significant difference was observed between the M and H groups ( > 0.05). Nonetheless, the H boars took more time to mount the collection dummy and produce an ejaculate and, in particular, showed a greater percentage of lameness than the L and M boars ( < 0.05). Therefore, the medium energy intake regimen (energy intakes of 7.7 and 8.2 Mcal/d of ME with ADG of 454.5 and 375.3 g/d in 2 periods, respectively) improved the total sperm number and functional sperm number, and meanwhile decreased the occurrence of lameness in 170- to 250-kg Duroc boars.

miR-221 negatively regulates inflammation and insulin sensitivity in white adipose tissue by repression of sirtuin-1 (SIRT1)

It is well known that obesity‐induced white adipose tissue inflammation is an important reason for insulin‐resistance and type 2 diabetes mellitus. Sirtuin‐1 (SIRT1) is an important regulator of inflammtion response pathways in white adipose tissue. Here, we found that miR‐221 negatively regulated SIRT1 in white adipose tissue during inflammation and HFD‐induced obesity. MiR‐221 is a putative oncogene which has been found overexpressed in a number of human tumors. Recently, it has also found that miR‐221 was increased in obese adipose tissue and may be involved in inflammation and insulin‐resistance. However the specific mechanism remains to be elucidated. In our present study, we found that overexpression of miR‐221 decreased the protein abundance of SIRT1 and caused inflammation and insulin‐resistance in differentiated 3T3‐L1 cells. Conversely, miR‐221 inhibition increased the protein levels, ameliorated inflammation, and improved insulin sensitivity. Moreover, inhibition of SIRT1 by EX527 significantly diminished the downregulation of the inflammation and insulin‐resistance levels induced by the miR‐221 inhibitor. In conclusion, our data suggest that miR‐221 promotes white adipose tissue inflammation and decreases insulin sensitivity in obesity, at least in part, through suppressing SIRT1.