Effect Of Weaning Age On Stress Related Hormones,antioxidant Capacities And Heat Stress Protein Gene Expressions In Piglets

This study was aimed to assess the effect of weaning age on stress related hormones of plasma,antioxidant capacities of tissue,and heat stress protein gene expressions in piglets,and explore the leveland the molecular mechanism of weaning stress on the piglets weaned in different days of the piglets,so that to provide the theoretical reference for study of piglets growth and disease weaned in different days and to provide practicalbasis for choosing weaning age scientifically.24 healthy piglets(Duroc×Landrace × Yorkshine)of similar weight and age were selected and they were divided into 4 groups(14 d weaned piglets,21 d weaned piglets,28 d weaned piglets and 35 d weaned piglets)randomly.There were 6 replications in each group including 1 piglet separately.All piglets were slaughtered at 42 days age and the samples were acquired.1.Effect of weaning age on stress related hormones and tissue antioxidant capacities in pigletsIn order to study the difference of plasma stress related hormones in piglets weaned in different age,the content of Adrenocorticotropic Hormone and cortisol was detected.Result:the content of ACTH was increase as weaning age earlier.The content of plasma ACTH in piglets weaned on 14 d and 21 d was significantly higher than that weaned on 35 d(P<0.05).The content of plasma cortisol was increase as weaning age earlier.The content of plasma cortisol in piglets weaned on 14 d was significantly higher than other(P<0.05).The content of plasma cortisol in piglets weaned on 21 d and 28 d were significantly higher than that weaned on 14 d(P<0.05).In order to research the effect of weaning age on antioxidant capacity of piglets tissue,the malondialdehyde(MDA)content,the total superoxide enzyme(T-SOD)activities,the glutathione peroxidase(GSH-Px)activities and the catalase(CAT)activities of liver,kidney,myocardium and longissimus dorsi in piglets weaned in different age were detected.Result:(1)the content of MDA in liver was increase as weaning age earlier.The content of liver MDA in piglets weaned on 14 d and 21 d were significantly higher than that in piglets weaned on 28 d and 35 d(P<0.05).The activities of T-SOD was decrease in liver as weaning age earlier.The activities of liver T-SOD in piglets weaned on 14 d weaned group was significantly lower than that in piglets weaned on 35 d(P<0.05).The activities of GSH-Pxwas decrease in liver as weaning age earlier.The activities of liver GSH-Px in piglets weaned on 14 d was significantly lower than that in piglets weaned on 28 d and 35 d(P<0.05).And the activities of liver GSH-Px in piglets weaned on 28 d was significantly lower than that in piglets weaned on 35 d(P<0.05).(2)The content of MDA in kidney was increase as weaning age earlier.The content of kidneyMDA in piglets weaned on 21 d was significantly lower than that in piglets weaned on14 d weaned group in piglets,but it was significantly higher than that in piglets weaned on28 d and 35d(P<0.05).The activities of T-SOD was decrease in kidney as weaning age earlier.Theactivities of kidney T-SOD in piglets weaned on 14 d was significantly lower than that in piglets weaned on35 d(P<0.05).The activities of GSH-Px was decrease in kidney as weaning age earlier.The activities of kidney GSH-Px in piglets weaned on 14 d was significantly lower than that in piglets weaned on28 d and 35 d(P < 0.05).And the activitiesof kidney GSH-Px in piglets weaned on 21 d was significantly lower than that in piglets weaned on 35 d(P<0.05).(3)As weaning age earlier,the content of MDA in myocardium was increase.The content of myocardium MDA in piglets weaned on 14 d was significantly higher than that in piglets weaned on35 d(P < 0.05).As weaning age earlier,the activities of T-SOD was decrease in myocardium.The activities ofmyocardium T-SOD in piglets weaned on 14 d was significantly lower than that in piglets weaned on28 d and 35 d(P<0.05).The activities of GSH-Px was decrease in piglets myocardium as weaning age earlier.As weaning age earlier,the activities of GSH-Px was significantly reduce in turn in piglets myocardium weaned on 4kinds of weaning age(P<0.05).(4)The content of MDA in longissimus dorsi was increase as weaning age earlier.The content of longissimus dorsi MDA in piglets weaned on 14 d and 21 d was significantly higher than that in piglets weaned on 28 d and 35 d(P<0.05).The activities of longissimus dorsi T-SOD,GSH-Px and CAT have no significantly difference in piglets weaned on 14 d,21 d,28 d or 35 d weaning group(P>0.05).2.Effect of weaning age on the expression of different tissues Heat stress protein(HSPs)gens in pigletsIn order to research the effect of weaning age on the 3 kinds of HSPs in piglets liver,kidney,myocardium and longissimus dorsi,the relative expression of mRNA and the expression of protein including Hsp70,Hsp90,Hsp27 in different age were detected.The results of gen detection:(1)The relative expression of liver Hsp70 mRNA in piglets weaned on 14 d was significantly higher than that in piglets weaned on 28 d and 35 d(P<0.05),but significantly lower than that in piglets weaned on 21 d(P<0.05).The relative expression of liver Hsp90 mRNA in piglets weaned on 14 d and 21 d were significantly higher than that in piglets weaned on 28 d and 35 d(P<0.05).The relative expression of liver Hsp27 mRNA in piglets weaned on 14 d was significantly higher than other groups(P<0.05).(2)The relative expression of kidney Hsp70 mRNA in piglets weaned on 14 d and 21 d was significantly higher than that in piglets weaned on 35 d(P < 0.05).The relative expression of kidney Hsp90 m RNA in piglets weaned on 21 d was significantly higher than that in piglets weaned on 28 d and 35 d(P<0.05),but significantly lower than that in piglets weaned on14 d(P < 0.05).(3)The relative expression of myocardium Hsp70 mRNA in piglets weaned on 21 d and 28 d were significantly higher than that in piglets weaned on 14 d and 35 d(P<0.05).The relative expression of myocardium Hsp90 mRNA in piglets weaned on 28 d was significantly higher than that in piglets weaned on 35 d(P < 0.05),but significantly lower than that in piglets weaned on 14 d(P<0.05).(4)The relative expression of longissimus dorsi Hsp70 m RNA in piglets weaned on 14 d was extremely significantly higher than that in piglets weaned on 21 d(P<0.01),and significantly higher than that in piglets weaned on 28 d(P < 0.05).The relative expression of longissimus dorsi Hsp27 mRNA in piglets weaned on 14 d and 21 d was extremely significantly higher than that in piglets weaned on 28 d and 35 d(P<0.01).The results of protein detection:(1)The expression of liver Hsp70 in piglets weaned on 21 d was significantly higher than that in piglets weaned on 35 d(P<0.05).The expression of liver Hsp90 in piglets weaned on 14 d and 28 d was significantly higher than that in piglets weaned on 35 d(P<0.05).The expression of liver Hsp27 in piglets weaned on 14 d,21 d and 28 d were significantly higher than that in piglets weaned on 35 d(P<0.05).(2)The expression of kidney Hsp70 in piglets weaned on 14 d,21 d and 28 d weaned group was significantly higher than that in piglets weaned on 35 d(P<0.05).The expression of kidney Hsp90 in piglets weaned on 14 d,28 d and 35 d weaned group was significantly higher thanthat in piglets weaned on 21 d(P<0.05).(3)The expression of myocardium Hsp70 in piglets weaned on 14 d was significantly higher than that in piglets weaned on 35 d(P<0.05).(4)The expression of longissimus dorsi Hsp70 in piglets weaned on 14 d and 21 d weaned group were significantly higher than that in piglets weaned on 28 d and 35 d(P < 0.05).The expression of longissimus dorsi Hsp90 in piglets weaned on 14 d and 35 d were significantly higher than that in piglets weaned on 21 d(P<0.05).The expression of longissimus dorsi Hsp27 in piglets weaned on 35 d was significantly higher than that in piglets weaned on 21 d(P<0.05).These results indicate that the relative expression of HSPs m RNA and the expression of HSPs were affected significantly by weaning age in piglet liver,kidney,myocardium and longissimus dorsie.The effect of weaning age on liver Hsp90 mRNA,liver Hsp27 m RNA,kidney Hsp70 mRNA,kidney Hsp90 mRNA,myocardium Hsp90 mRNA and longissimus dorsi Hsp27 mRNA are similar.The effect of weaning age on liver Hsp70,liver Hsp90,liver Hsp27 and kidney Hsp70 were similar with their corresponding mRNA.In a word,as weaning earlier the HSPs mRNA relative expression and HSPs protein expression were increase which means the piglets would suffer from more stress damage.