Effects And Possible Mechanism Of Grape Seed Procyanidins On Alleviating Hepatic Oxidative Damage In Weaned Piglets

The aim of this trail was to reveal the protective effects and possible mechanism of supplementation of grape seed procyanidins (GSPs) in diet on hepatic oxidative damage in weaned piglets. Thirty healthy weaned piglets (Landrance X Yorkshire,28days old) were random allotted to5treatments, which including the normal group (corn-soybeen meal basal diet, injected with saline), the stressed group (corn-soybeen meal basal diet, injected with Diquat), the stressd+50GSPs group (basal diet+50mg/kg GSPs, injected with Diquat), the stressd+100GSPs group (basal diet+100mg/kg GSPs, injected with Diquat), and the the stressd+50VE group (basal diet+50mg/kg vitamin E, injected with Diquat). Each treatment was replicated6cages containing1piglet per cage. The trail lasted for17days. On day10, all the stressd piglets (the stressed group, the stressed+50GSPs group, the stressed+100GSPs group and the stressed+50VE group) were abdominal injected with Diquat (10mg/kg BW), and piglets in the normal group were injected with the same volume sterile saline. The body weights of all the piglets were recorded on day0,10,17. Blood were sampled on day17for the determination of anti-superoxide anion capacity, anti-hydroxyl radical capacity, T-AOC, the activities of SOD, GSH-px and CAT, the MDA content, the ALT and AST activities in serum. Piglets in all groups were killed excepted for the stressed+50GSPs group. Liver samples were taken for the apoptosis rate anaylsis and the determination of antioxidative anzyme activities, MDA and VE content. The caspase-12contents in liver were determined by ELISA methold, and the mRNA expression of factors related with hepatic Nrf2pathway, inflammatory response and ER-stress were determined by real time-PCR.1. Dietary addition of GSPs and VE had no significant effects on the ADFI, ADG and F/G of weaned piglets before Diquat injection. After Diquat challenge,50mg/kg GSPs enhanced the ADFI, and the addition of GSPs or VE all increased the feed conversion ratio.2. Supplementation of GSPs increased serum anti-superoxide anion capacity, anti-hydroxyl radical capacity, the activities of SOD, GSH-px and CAT in oxidative-stressed piglets, and decreased the MDA content. In addition, there were no significant difference in50mg/kg GSPs and50mg/kg VE groups on antioxidant capacities in serum, while the effect of100mg/kg GSPs in serum antioxidant capacities was better than that of50mg/kg VE.3. Diquat injection enhanced the hepatocellular apoptosis rate and activities of serum ALT and AST, decreased the hepatic anti-superoxide anion capacity, anti-hydroxyl radical capacity, T-AOC, SOD and CAT activities, VE content, as well as the mRNA expressions of SOD, GSH-px and CAT in liver. The mRNA expression of TNF-α, IL-1β, IL-6, IL-8and Bax were up-regulated by oxidative sress, but the mRNA expression of IL-10and Bcl-2were down-regulated. At the same time, Diquat injection down-regulated the mRNA expression of Keap-1, and up-regulated the mRNA expressions of Nrf2, HO-1and NQO1in liver. Furthermore, the hepatic mRNA aboundance of ER-stress related molecular chaperone as GRP78, ATF6, XBP-1, PDIA4and CHOP were enhanced, while the Ire-1mRNA expression level and caspase-12content were decreased.4. Under oxidative stress condition,100mg/kg GSPs inhibited the hepatocyte apoptosis, inhanced the acitivities of ALT and AST in liver and decreased serum ALT and AST activities. GSPs increased anti-superoxide anion capacity, anti-hydroxyl radical capacity, T-AOC, the activities of SOD, GSH-px and CAT, the VE content in liver, and decreased hepatic MDA content. Hepatic mRNA expressions of TNF-α IL-1β IL-6. IL-8and Bax were decreased while SOD and Bcl-2mRNA expression were up-regulated by GSPs. The mRNA expression of IL-10did not affected by GSPs. Under oxidative stress condition, GSPs diminished the effect of ROS on Nrf2pathway by suppressing the mRNA expressions of Nrf2, HO-1and NQO1, promoting Keap-1mRNA expression. Furthermore, GSPs alleviated the GRP78mRNA expression, and suppressed the up-regulation of XBP-1, ATF6, PDIA4and CHOP mRNA expressions caused by oxidative stress. The caspase-12content in liver was also decreased by GSPs.In conclusion, oxidative stress would cause hepatic oxidative damage and impaire the growth performance in weaned piglets. Supplementation of GSPs could alleviate the damage by improve the anti-oxidative abilities, decrease the inflammation response, and decrease hepatocellular apoptosis rate through the resistance of mitochondrial and ER apoptosis pathway.