Effects Of Plant Quercetin On Immune Functions Of Microtus Fortis

The co-evolution between Mammal Herbivorous and plants is one of the important research field of Modern Ecology.Mammal Herbivorous feed on plants to obtain nutrients and energy,while plants derive various poisonous Plant Secondary Metabolites(PSMs)to protect itself from the intake of herbivores.PSMs can decrease animal energy and inhibit protein utilization by increasing metabolic load,besides affecting its growth,reproduction or survival through damaging the integrity of the liver and renal cell membrane and inhibiting enzyme activity.So far,there are few reports about the effects of secondary metabolites on the immune function of small mammals.Microtus fortis(Mf)is the main murine in the Dongting lake area,which seriously endangers the growth of local crops.Quercetin,as a widespread phytogenic flavonoid compound,is the major secondary metabolite found in the Mf's natural food.The study shown that when the population density of Mf was low,the content of quercetin was less than 3%,while the content of quercetin was up to11.5%with the outbreak of Mf.Under natural conditions,the population density of mammal herbivorous is low,having abundant food and feeding naturally.However,there are few report about that when the mammal herbivorous intake the specific PSMs,whether the plant secondary metabolites can enhance their immune function and improve their survival rates.In our studies,continuously feeding the Mf for 20days with 0,1.5%,3%,5%and 8%of quercetin,subsequently,(1)To determine the Mf's body weight;(2)To determine the thymus and spleen index;(3)To determine proliferation of T lymphocyte,B lymphocyte,macrophage and phagocytosis of macrophages;(4)To determine CD4~+,CD8~+and its percentage;(5)To determine the levels of immunoglobulin and cytokines in serum.The main results as follows:1)There was no significant difference in Mf's body weight between different groups with the consumption of different concentrations of quercetin.Compared to control group,the plant quercetin concentration with less than 5%can improve the spleen and thymus index of the Mf,and feeding on 5%of plant quercetin concentration,the spleen index and thymus index increased by 14.48%and 14.48%respectively,however,the plant quercetin concentration reaching 8%,the spleen index and thymus index were less than 5%.The result shows that the optimal concentration of quercetin could significantly enhance the immune organ index of the Mf,while the high concentration of quercetin could reduce the immune organ index of the Mf.2)There was a significant difference in the function of T lymphocytes and B lymphocytes between different groups with different quercetin concentrations.Compared to the LPS stimulation source group,B lymphocyte proliferation activity significantly enhanced(P<0.01)with 1.25?mol/mL quercetin concentration cultured for 48h,and when quercetin concentration is more than 15?mol/mL,B lymphocyte proliferation activity significantly reduced(P<0.01);Compared to ConA stimulation source group,T lymphocyte proliferation activity significantly enhanced(P<0.05)when the quercetin concentration is below 15?mol/mL,the other groups having no significant difference(P>0.05).The result indicates that a certain concentration of quercetin at the cellular level can significantly improve the ability of the activated immune cells proliferation,but high concentration of quercetin inhibit immune cell proliferation.3)There was a significant difference in the proliferation function and phagocytic function of the macrophages between groups with different concentrations of quercetin.In 48 h,compared with the source of PHA stimulation group,when quercetin concentration is less than 5?mol/mL,macrophage proliferation activity significantly enhanced(P<0.01),but the other group of macrophage proliferation ability difference has no significance(P>0.05).In addition,plant quercetin concentration within 5%can significantly increase the phagocytosis of macrophage,whereas the index of macrophage cell with 8%quercetin concentration was significantly lower than 5%quercetin concentration.It shows that a certain concentration of quercetin at the cellular level can significantly increase the phagocytic cells proliferation activated ability,and also enhance the phagocytosis of macrophage,but high concentration of quercetin on the activation of immune cells and macrophage phagocytosis have adverse effects.4)When the daily food containing different concentrations of quercetin was consumed,the ratio of CD4~+/CD8~+was normal in the Mf feeded with quercetin at5%concentration,while the CD4~+/CD8~+ratio in the 8%concentration group was lower than the normal value.It indicates that the concentration of quercetin at 5%can maintain the stability of CD4~+/CD8~+ratio.However high concentration of plant quercetin can increase the amount of CD8~+cells and reduce CD4~+cells,consequently reducing the immunity of the Mf.5)After intaking of the daily ration containing different concentration of quercetin,compared to the control group,the concentration of quercetin plants within 5%can significantly increase the individual levels of IgA,IgG,IgM secretion(P<0.05),but quercetin concentration reaches 8%which IgA,IgG,IgM levels in the serum were less than 5%concentration group(P<0.05).It indicates that the concentration of quercetin can significantly increase the level of immunoglobulin secretion of east voles,while high concentration of quercetin can reduce east voles immunoglobulin secretion level.6)There was a significant difference in the secretion level of the Oriental vole cytokines between groups.Compared to the control group,the concentration of quercetin within 5%can significantly increase the anti-inflammatory factor IL-2,IL-4 and IL-10,while reduces the pro-inflammatory cytokines IL-1,IL-18 and IFN-?and TNF-?.Compared to the 5%concentration group,the anti-inflammatory factor decreased and the proinflammatory factor increased with 8%quercetin concentration.It shows that the concentration of quercetin can significantly improve the east voles anti-inflammatory factor and reduce the secretion of proinflammatory factor,but high concentrations of plant quercetin may reduce the secretion of anti-inflammatory factor and promote the secretion of prion-flammatory factor.In conclusion,the low quercetin concentration can significantly improve the east voles organs of thymus and spleen index,improve the proliferation ability of lymphocytes,macrophages,and promote the phagocytosis of macrophage,maintaining the stability of the CD4~+/CD8~+,and also promote immune globulin,anti-inflammatory factor and inhibit the secretion of proinflammatory factor.While high concentration of quercetin will limit the east voles immune organ index,lower immune cell proliferation,the phagocytosis of macrophage,and the ratio of CD4~+/CD8~+,promote anti-inflammatory factor and inhibit the secretion of proinflammatory factor and immunoglobulin.The results show that when the east voles was feeded with daily ration containing quercetin concentration within 5%,the body's plant quercetin can improve the immunity of the Mf,and thus increase the survival rate of Mf;More than 5%quercetin concentration,the amount of quercetin in the Mf exceeded its detoxification ability,and the toxic effect in the tissues of the organism,inhibiting its immune function.