| Chitosanoligosaccharide(COS)has great biological activities as a new food material,and has great potencial in the fields of functional food and medicine.However,due to the lack of research,the cause and mechanism of eye redness and angular cheilitis caused by taking COS is still not clear.It limited the application of COS in the field of new foods material.In this study,mice were used as the research objects to investigatethe intervention effects and mechanism of COS on the vitamin A metabolism and vitamin B2 absorption.This research provided the certain theoretical basis and technical support for the development of COS in new food material field.In vivo experiment,the mice were randomly divided into three groups with ten mice in each group:control group,was given distilled water by gavage once a day;COS-L group,was given 76 mg/Kg·BW COS by gavage once a day;COS-H group,was given 760 mg/Kg·BW COS by gavage once a day.The feeding trail lasted five weeks.In the experiment period,feed consumption and animals body characteristics were recorded daily.The body weight was measured in each week.The mice in all groups were normol and did not die.The mice in COS-H group have rough coats,yellowish shades,frequent activities and irritability.However,no decrease in food consumption,body weight gain.No significant changes on body weight and viscera index among the mice of the three groups were detected(p>0.05).Then,the effect of COS on the levels of vitamin A,RBP4 and CYP450 in serum and tissue of mice were determined by enzyme linked immunosorbent assay(ELISA)assay;the mRNA and protein expression levels of genes in vitamin A metabolism was determined by real-time PCR(RT-PCR)and western blotting.The reaults showed that the COS reduce the vitamin A,RBP4 concentrations in serum and liver of mice,and the significant does-dependent was found in these indexes(p<0.05).In comparsion with control group,the significant decrease in the total protein and CYP450 contents were shown in COS groups(p<0.05).COS significantly inhibited the mRNA expression levels of RBP4,CRBP1,LRAT,CYP26A1 and STRA6 in the tissue of mice,and the significant does-dependent was found in these indexes(p<0.05).Furthermore,the effect of COS on protein expression levels of RBP4,CRBP1,LRAT and CYP26A1 is similar with the mRNA expression levels.However,there was not significant difference in STRA6 protein expression levels between three groups.it induced that the decreases of RBP4,CRBP1,LRAT,STRA6 and CYP26A1 mRNA or protein expression by COS partly account for the decrease of concentrations vitamin A in serum and liver.Finally,the effect of COS on the vitamin B2 and its der-ivatives concentrations,the RFK,Fladl enzyme activities and concentrations in serum and tissue of mice were determined by ELISA assay;the mRNA expression levels of genes in vitamin B2 absorption were determined by RT-PCR;the protein expression level of RFT2 was determined by immunohistochemistry and western blotting.The reaults showed that the COS reduce the vitamin B2 and its derivatives concentrations in serum and intestine of mice(p<0.05).The significant does-dependent was just found in vitamin B2 concentrations.COS can significantly reduce the RFK,Fladl enzyme activities and concentrations.In conparsion with the control group,the significant decrease in the mRNA expression levels of RFT1,RFT2,RFT3 and the significant decrease in the protein expression level of RFT2 were shown in COS groups(p<0.05).It induced that COS reduced the levels of vitamin B2 in serum and intestine by inhibiting the mRNA expression of RFT1,RFT2,RFT3 and protein expression of RFT2.COS reduced the levels of FMN,FAD by decreasing the enzyme activities and concentrations of RFK,Fladl.This study explored the mechanism of COS on the vitamin A metabolism and vitamin B2 absorption.The results showed that COS decreased the levels of vitamin A and vitamin B2 by inhibiting the mRNA expression and protein expression of genes in vitamin A metabolism and vitamin B2 absorption. |
PDF Full Text Request