| The small intestine plays an important role in digestion and absorption in piglets,and is also an important immune organ in piglets.Due to the imperfect immune system of piglets,they are easily affected by factors such as oxidative stress in the piglet stage,which induces oxidative damage to the piglet body.When piglets are exposed to oxidative stress,the piglet gut suffers first.How to alleviate the oxidative damage of piglets and improve the antioxidant function and growth performance of piglets has become a research hotspot.The previous research of the research group confirmed that tea tree oil has a certain antioxidant function and can improve the growth performance of piglets.terpine-4-ol（TER）is the main component of tea tree oil.This study was divided into in vivo and in vitro to explore the regulatory effect of terpine-4of on the growth performance and intestinal oxidative damage of piglets.The oxidative damage provides a certain theoretical reference.Experiment 1:Effects of terpine-4-ol on growth performance and antioxidant function after stimulation by lipopolysaccharide（LPS）in piglets.In this experiment,40 boars of 28-day-old piglets were selected.All piglets were weighed at 28 days of age and divided into 5 groups,namely control group（CON group,fed with basal diet）,lipopolysaccharide group（LPS group,fed with basal diet）,low,medium and high doses 4-Terpineol group（LTP,MTP,HTP group,fed basal diet+30,60,90 mg/kg TER）.The control group was injected with normal saline 6 hours before sampling,and the LPS group and the terpine-4-olgroup were injected with 100 mg/kg LPS.Each group was set up with 8 pens,and each pig was reared in a single pen.After the experiment,6 pigs were randomly selected from each group and slaughtered for sampling after weighing.The study results showed that:1)The final weight,average daily gain and daily feed intake of piglets in MTP and HTP groups were significantly higher than those in CON.（P<0.01）.The diarrhea rate in the TER group was lower than that in the CON group.2)Compared with CON group,serum CAT,GSH-Px activity and T-AOC in LPS group were significantly decreased,and MDA content was increased（P<0.01）.Serum CAT activity and SOD activity in MTP group were significantly higher than those in LPS group（P<0.01）.And the serum MDA content of MTP group and HTP group was significantly lower than that of MTP group（P<0.01）.3)Compared with the LPS group and the LTP group,the content of MDA in the duodenal mucosa of the CON group,the MTP group and the HTP group was significantly decreased（P<0.01）.Compared with the LPS group,the activities of CAT and GSH-Px in the jejunal mucosa of the CON,LTP and MTP groups were significantly increased（P<0.05）.The jejunal mucosa T-AOC in the MTP group was significantly higher than that in the LPS group（P<0.05）.The ileal CAT and GSH-Px activities were significantly increased in the CON and terpine-4-ol groups compared with the LPS group（P<0.05）,and the MDA content of ileal mucosa in MTP group and HTP group was significantly lower than that in LPS group（P<0.05）.（4）Compared with CON group,LPS can significantly increase the content of MDA in the intestine（P<0.01）,decreased CAT and GSH-Px activity in jejunum and ileum media of piglets（P<0.05）.4-Terpineol can significantly increase CAT and GSH-Px activities in jejunum and ileum compared with LPS group（P<0.05）,decreases MDA content in duodenal and ilea]mucosa（P<0.05）.The jejunal mucosa T-AOC in the MTP group was significantly higher than that in the LPS group（P<0.01）.Compared with the LPS group,the gene expression of Gpxl in the ileal mucosa of the HTP group was significantly increased.（P<0.05）.（5）In mitochondrial morphology,compared with CON,mitochondria in LPS group had obvious rounding and swelling.Compared with the LPS group,the mitochondrial swelling in the LTP,MTP and HTP groups was alleviated.（6）The expression levels of Keapl,Nrf2 and HO-1 genes in duodenal mucosa of MTP group were significantly higher than those of CON group,LPS group and LTP group（P<0.05）.Compared with the LPS group,the expression of NQO1 gene in the duodenal mucosa of the MTP group and the HTP group was significantly increased（P<0.01）.The expression levels of Nrf2 and NQO1 genes in the jejunal mucosa and ileal mucosa of the MTP group were significantly higher than those of the LPS group（P<0.01）.（7）Compared with the LPS group,the protein expression levels of Nrf2 and Keapl in the jejunal mucosa of the LTP group and the MTP group were significantly increased （P<0.05）.In the ileal mucosa,the protein levels of Keapl and Nrf2 were significantly increased in the CON,MTP and HTP groups compared with the LPS group（P<0.05）.Compared with the LPS group,the protein levels of NQO1 and p-Nrf2 in the HTP group were significantly increased（P<0.05）.To sum up,adding 60 mg/kg 4-terpineol to the diet of weaned piglets can increase the average daily gain and feed intake of piglets,reduce the feed-to-weight ratio and diarrhea rate,and improve the growth performance and feed intake of piglets.Intestinal antioxidant function,improved mitochondrial morphology,and then alleviated the oxidative damage of piglet intestine caused by LPS.This mechanism of alleviating oxidative damage may be related to the expression of Nrf2-related genes.Experiment 2:The regulatory effects of terpine-4-ol on the oxidative damage in IPI-2I cells.In this experiment,IPI-2I cells were stimulated with H2O2 and terpine-4-ol,and the changes in cell viability were observed.The experiment confirmed that the concentration of H2O2 was 1000μl and stimulated for 6 hours to establish an oxidative stress model,and the concentration of terpine-4-ol was 0.01%.6h stimulation was the optimal stimulation concentration.In order to determine the regulatory effect of terpine4-ol on the oxidative damage of IPI-2I cells,the control group（CON group,DMEM）,the hydrogen peroxide group（H2O2 group,1000 μM H2O2+DMEM）,the terpine-4-ol group（TER group,0.01%TER+DMEM）,terpine-4-ol+hydrogen peroxide group（HTE group,1000μM H2O2+0.01%TER+DMEM）were stimulated for 6 h and collected cells and supernatant for detection,further study of 4-terpene Modulatory effects of pinol on oxidative damage in IPI-2I cells.The test results showed that（1）Compared with the CON group,the LDH activity in the supernatant of the cells in the H2O2 group was increased（P<0.01）,while the LDH activity in HTE group was significantly lower than that in the H2O2 group（P<0.05）.（2）Compared with the CON group,the intracellular ROS level in the H2O2 group was significantly increased（P<0.01）,and compared with the H2O2 group,the ROS content in the HTE group was significantly decreased（P<0.01）.（3）Compared with the CON group,the activities of CAT and GSH-Px in the H2O2 group were significantly decreased（P<0.05）.,and the MDA content was significantly increased（P<0.05）.Compared with the H2O2 group,the activities of CAT and GSH-Px in the HTE group were significantly increased（P<0.05）.Compared with the H2O2 group,T-AOC was significantly higher in the HTE group（P<0.01）.（4）Compared with the H2O2 group,the CAT gene expression in the CON group and the HTE group was significantly increased（P<0.01）.（5）Compared with the CON group,the gene expression of Nrf2,Keapl and NQO1 in the H2O2 group was significantly decreased（P<0.01）.Compared with the H2O2 group,the expression levels of Keapl and NQO1 genes in the HTE group were significantly increased（P<0.05）.（6）In terms of protein expression level,the Nrf2 and p-Nrf2 protein contents in the cytoplasm in the H2O2 group were significantly higher than those in the CON group.However,the content of Nrf2 and p-Nrf2 protein in the cytoplasm in the HTE group was significantly lower than that in the H2O2 group.（7）Compared with the H2O2 group,the percentage of late apoptotic cells and the percentage of total apoptotic cells in the HTE group were significantly decreased（P<0.01）.（8）Compared with CON group,the expression levels of caspase3,BCL-2 and BAX genes in H2O2 group and HTE group were significantly increased（P<0.05）.Compared with the H2O2 group,the ratio of BCL-2/BAX gene expression was significantly increased（P<0.05）.It can be seen that 4-terpineol can alleviate the decrease of cell viability of IPI-2I cells induced by H2O2,reduce the percentage of apoptosis of IPI-2I cells,reduce the content of ROS and MDA in IPI-2I cells induced by H2O2,and improve the cell viability of IPI-2I cells.The anti-oxidative ability of the cells can alleviate the oxidative damage of cells,and this mechanism of alleviating oxidative damage may be related to the expression of Nrf2-related genes.In conclusion,an appropriate amount of tea tree oil extract active ingredient terpine4-ol can increase the average daily gain and feed intake of piglets,reduce piglet feedto-weight ratio and diarrhea rate,and improve piglet growth performance and intestinal antioxidant.It can reduce the ROS content in the intestinal epithelial cells of piglets,improve the antioxidant capacity of intestinal epithelial cells,and relieve the oxidative damage of the piglet intestinal tract. |
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