Study On Effect Of Cysteamine On Immune Function Of Piglets And Its Mechanism

An experiment was conducted to examine the effects of cysteamine(CS)on serum antioxidative enzyme activities,cell-mediated immunity(CMI),humoral immunity, small intestinal mucosa immunity,and serum growth hormone levels and the expression of GHR mRNA in spleen and thymus of piglets,in order to study the effects of different dosage of cysteamine on Immune function of piglets.Ninety "Duroc×Landrace×Yorkshire".crossbred piglets were randomly divided into 3 groups of 30 piglets each by weight and sex.The piglets in GroupⅠwere fed a basal diet;the piglets in GroupⅡwere fed the basal diets plus 120mg·kg^-1CS;the piglets in GroupⅢwere fed the basal diets plus 200mg·kg^-1CS.Blood samples in 20 piglets each group were taken from the anterior vena cava at 14,24,32 and 45 days of age for measuring serum superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)activities;the contents of serum immunoglobulin levels(IgA,IgM and IgG);the lymphocyte transformation rates and white blood cell phagocytosis rates;the levels of serum interleukin-2(IL-2)and growth hormone(GH).At the end of the trial(d 45),6 piglets from each group were slaughtered.The proximal duodenum,1/4 proximal jejunum,1/4 distal jejunum and middle ileum were gathered for measuring the numbers of intraepithelial lymphocytes and goblet cells.Thymus and spleen were taken to determine the comparative concentrations of mRNA in growth hormone receptor by RT-PCR.The results were as follows:(1)Cysteamine can significantly increase the activities of serum antioxidative enzyme of pigletsDuring the whole experimental period,the serum SOD and GSH-Px activities of piglets,in GroupⅠ,Ⅱ,Ⅲkept ascending trend.Compared with GroupⅠ,serum SOD activities of piglets in GroupⅢincreased by 11.1%(P＜0.05)at d 24;serum SOD activities of piglets in GroupⅡ,Ⅲincreased by 13.6%(P＜0.01)and 15.42%(P＜0.01) at d 32,respectively.Compared with GroupⅡ,serum SOD activities of piglets in GroupⅢincreased significantly at d 45.Compared with GroupⅠ,the serum GSH-Px activities of piglets in GroupⅡ,Ⅲincreased by 19.22%(P＜0.01),26.09%(P＜0.01) at d 24,and increased by 42.72%(P＜0.01),52.65%(P＜0.01)at d 32,respectively. Compared with GroupⅡ,the serum GSH-Px activities of piglets in GroupⅢincreased significantly at d 45.(2)Cysteamine can significantly increase lymphocyte transformation rates in piglets Compared with GroupⅠ,lymphocyte transformation rates in GroupⅡ,Ⅲincreased by 15.03%(P＜0.01),19.08%(P＜0.01)at d 32,and increased by 17.93% (P＜0.01),24.70%(P＜0.01)at d 45,respectively.Compared with GroupⅡ, lymphocyte transformation rates in GroupⅢincreased by 5.74%(P＜0.05)at d 45.(3)Cysteamine can significantly increase white blood cell phagocytosis rates in pigletsThere are no significant distinction among GroupⅠ,Ⅱ,Ⅲat d 14 and d 24. Campared with GroupⅠ,white blood cell phagocytosis rates of piglets in GroupⅢincreased by 9.68%(P＜0.05)at d 32.Compared with GroupⅠ,white blood cell phagoeytosis rates of piglets in GroupⅡ,Ⅲincreased by 11.44%(P＜0.01)and 26.37% (P＜0.01)at d 45 respectively.Compared with GroupⅡ,white blood cell phagocytosis rates in GroupⅢincreased by 13.39%(P＜0.01)at d 45.(4)Cysteamine can significantly increase the serum immunoglobulin levels in pigletsDuring the whole experimental period,the levels of serum IgM,IgA,IgG in pigs of GroupⅠ,Ⅱ,Ⅲkept ascending trend.Compared with d 14,serum IgM levels of GroupⅠ,Ⅱ,Ⅲincreased by 15.08%,25.10%(P＜0.01)and 18.64%at d 45,respectively. There were no significant distinction among GroupⅠ,Ⅱ,Ⅲduring the whole experimental period.Compared with GroupⅠ,serum IgA levels in GroupⅡ,Ⅲincreased by 10.52%(P＜0.05)and 15.69%(P＜0.01)at d 32,respectively.Compared with GroupⅠ,serum IgA levels in GroupⅢincreased by 19.14%(P＜0.01),and compared with GroupⅡ,serum IgA levels in GroupⅡincreased by 12.75%(P＜0.01) at d 45.Compared with GroupⅠ,serum IgG levels in GroupⅡ,Ⅲincreased by 43.54% (P＜0.01),50.01%(P＜0.01)at d 32,and increased by 24.39%(P＜0.05),36.52% (P＜0.01)at d 45,respectively.Compared with GroupⅡ,serum IgG level in GroupⅢincreased by 9.64%(P＜0.05).(5)Cysteamine can significantly increase the numbers of IELs in pigletsCompared with GroupⅠ,the numbers of IELs in both GroupⅡand GroupⅢincreased significantly at d 45.At proximal duodenum,compared with GroupⅠ,the number of IELs in GroupⅡ,Ⅲincreased by 10.68%(P＜0.05),26.68%(P＜0.01), respectively;and compared with GroupⅡ,GroupⅢincreased by 14.46%(P＜0.05).At proximal jejunum,compared with GroupⅠ,the number of IELs in GroupⅡ,Ⅲincreased by 21.43%(P＜0.01)and 37.16%(P＜0.01),respectively.Compared with GroupⅠ,the number of IELs in GroupⅡ,Ⅲincreased by 19.35%(P＜0.05)and 29.03% (P＜0.01),respectively.Compared with GroupⅡ,the number of IELs in GroupⅢincreased by 8.11%(P＜0.05)at distal jejunum.Compared with GroupⅠ,the number of IELs in GroupⅡ,Ⅲincreased by 25.94%(P＜0.05)and 37.06%(P＜0.01),respectively. Compared with GroupⅡ,the number of IELs in GroupⅢincreased by 37.06% (P＜0.01)at middle ileum.(6)Cysteamine can significantly increase the numbers of GCs at all positions of small intestinal mucosa in pigletsCompared with GroupⅠ,the number of GCs in GroupⅡ,Ⅲincreased significantly at d 45.At proximal duodenum,compared with GroupⅠ,the number of GCs in GroupⅡ,Ⅲincreased by 50.15%(P＜0.05),130.33%(P＜0.01),respectively;and compared with GroupⅡ,GroupⅢincreased by 53.40%(P＜0.05).At proximal jejunum, compared with GroupⅠ,the number of GCs in GroupⅡ,Ⅲincreased by 69.28% (P＜0.05),138.57%(P＜0.01),respectively;and compared with GroupⅡ,the number of GCs in GroupⅢincreased by 40.93%(P＜0.05).Compared with GroupⅠ,the number of GCs in GroupⅡ,Ⅲincreased by 46.38%(P＜0.05),94.00%(P＜0.01) respectively;and compared with GroupⅡ,the number of GCs in GroupⅢincreased by 32.53%(P＜0.05)at distal jejunum.Compared with GroupⅠ,the number of GCs in GroupⅡ,Ⅲincreased by 63.19%(P＜0.01),110.58%(P＜0.01)at middle ileum.(7)Cysteamine can significantly increase the levels of serum inerleukin-2 in pigletsThere were no significant distinction among GroupⅠ,GroupⅡand GroupⅢat d 14.Compared with GgroupⅠ,the serum nerleukin-2 levels in GroupⅢincreased by 8.94%(P＜0.05)at d 24;the levels of serum inerleukin-2 in GroupⅡ,Ⅲincreased by 10.43%(P＜0.01),14.99%(P＜0.01)at d 32,respectively;and the levels of serum inerleukin-2 in GroupⅡ,Ⅲincreased by 7.62%(P＜0.05),17.22(P＜0.01)at d 45, respectively.Compared with GroupⅡ,the levels of serum inerleukin-2 in GroupⅢincreased by 8.92%(P＜0.05)at d 45.(8)Cysteamine can significantly increase the levels of serum GH in pigletsCompared with GroupⅠ,the serum GH levels in GroupⅡ,Ⅲincreased by 62.89%(P＜0.05),61.01%(P＜0.05)at d 32,respectively;and the serum GH levels in GroupⅡ,Ⅲincreased by 49.30%(P＜0.01),46.86%(P＜0.01)at d 45,respectively.(9)Cysteamine can significantly increase the expression amount of GHR mRNA in thymus and spleen of pigletsCompared with GroupⅠ,the expression amount of GHR mRNA in thymus of piglets in GroupⅡ,Ⅲincreased by 4.26%(P＜0.05)and 6.83%(P＜0.01)at d 45, respectively.Compared with GroupⅠ,the expression amount of GHR mRNA in spleen of piglets in GroupⅢincreased by 4.67%(P＜0.05).there were no significant distinction between GroupⅡand GroupⅢat d 45.The experiment showed that the diets adding proper dosage of cysteamine can significantly enhance inmmune function in piglets...