| Objectives The current study is aimed to investigate the disorder of blood-cerebrospinal fluid barrier(BCB)immune surveillance of diabetic rats as well as the mechanism of lead neurotoxicity in order to provide the basis for mechanism study of lead exposure on diabetes patients.Methods 1 Experimental animal treatment and grouping: 20 Wistar rats were randomly divided into control group and lead exposure group with 10 rats for each group.The spontaneously diabetic Goto-Kakizaki rats were randomly divided into diabetes mellitus group and diabetes mellitus + lead exposed group with 10 rats for each group.2 Random blood sugar levels were examined every two weeks using a blood glucose meter.3 Morris water maze test was used to determine the changes of learning and memory function in rats.4 Complete blood counts were measured by Hematology Analyzer machine.5 The lead contents in blood and hippocampal tissue were determined by inductively coupled plasma mass spectrometry(ICP-MS).6 ELISA and real-time PCR were used to detect the protein or m RNA expression of IFN-γ、IL-4、IL-6、IL-1β and TNF-α.7 The protein contents of IFN-γ、IL-6 and IL-1β in serum albumin and cerebrospinal fluid were measured by ELISA.8 Laser con-focal microscope was used to detect ICAM-1 and VCAM-1 expression in choroid plexus.9 Real-time PCR was used to test the m RNA expression of adhesion molecules(ICAM-1 and VCAM-1)and inflammatory cytokines(IFN-γ,IL-6 and IL-1β)in choroid plexus.Results 1 The growth and development of experiment rats: After the lead exposure,the body weight of rats in diabetes mellitus and diabetes mellitus + lead exposed group were significantly lower than that of control group and lead exposure group(P<0.05).2 The Effect of lead exposure on blood sugar of diabetes mellitus rats: There is no significant difference between diabetes mellitus + lead exposed group and diabetes mellitus group in terms of the random blood sugar.3 The effect of lead exposure on the function of learning and memory in diabetes mellitus rats: Compared with the control group,navigation time at the 3rd day of rats in lead exposure group and diabetes mellitus group was longer and times of passing the platform was less(P<0.05).Furthermore,the navigation time of rats in diabetes mellitus + lead exposed group was 3.47 folds and 1.19 folds than those in lead exposure group and diabetes mellitus group.The frequencies of passing the platform in diabetes mellitus + lead exposed group were decreased 59.09% and 55.00% than that in lead exposure group and diabetes mellitus group(P<0.05).4 The effect of lead exposure on blood number of diabetes mellitus rats:The blood number in diabetes mellitus + lead exposed group didn’t show the siginficant difference compare with diabetes mellitus group and lead exposure group.5 The effect of lead exposure on lead contents in blood and hippocampus of diabetes mellitus rats : Compared with the control group,the lead contents of blood and hippocampus in lead exposure group increased.Besides the lead contents in diabetes mellitus + lead exposed rats was higher than that in lead exposure group,(P<0.05).6 The effect of lead exposure on expression of inflammatory cytokines protein and m RNA in hippocampus of diabetic mellitus rats: Compared with control group,the protein and m RNA expression of IFN-γ and IL-6 in hippocampus of lead exposure group and diabetic mellitus rats were increased(P<0.05),and the contents of IFN-γ,IL-6 and IL-1β in the hippocampus of diabetes mellitus + lead exposed rats significantly increased(16.58%,18.73%),(47.60%,34.41%)and(63.29%,20.25%)than those in the lead exposure group and diabetes mellitus group(P<0.05).The m RNA expression of these inflammatory cytokines in the hippocampus of diabetes mellitus + lead exposed rats was the same as that of protein expression.The m RNA expressions of IFN-γ,IL-6 and IL-1β in the hippocampus of diabetes mellitus + lead exposed rats were significantly higher(1.50 folds,1.51 folds),(1.76 folds,1.64 folds)and(6.29 folds,2.25 folds)than those in lead exposure group or diabetes mellitus group.7 The effect of lead exposure on inflammatory cytokines in diabetes mellitus rats’ serum and cerebrospinal fluid: Compared with the control group,the levels of IFN-γ and IL-1β in serum of lead exposure group increased,and the content of IFN-γ protein in the cerebrospinal fluid of the lead exposure group and the diabetic mellitus group increased(P<0.05).In addition,the levels of IFN-γ,IL-6 and IL-1β in the serum of diabetes mellitus + lead exposed rats were significantly higher(27.43%,57.74%),(24.07%,29.84%)and(23.42%,43.64%)than those of lead exposure group and diabetes mellitus group.The level of IFN-γ in the cerebrospinal fluid was significantly higher than that in the lead exposure group and diabetes mellitus group by 1.36 folds and 1.31 folds(P <0.05),and the levels of IL-6 and IL-1β in diabetic mellitus + lead exposed rats were significantly higher than those in the lead exposure group by 1.15 folds and 1.51 folds.8 The effect of lead exposure on inflammatory cytokines m RNA expression in choroid plexus of diabetes mellitus rats: The m RNA levels of IFN-γ in the choroid plexus of the lead exposure group and the diabetes mellitus group were higher than that in the control group(P<0.05).Meanwhile,the m RNA expressions of IFN-γ,IL-6 and IL-1β in the choroid plexus of diabetes mellitus + lead exposed rats were significantly higher those in lead exposure group and diabetes mellitus group by(1.91 folds,2.90 folds),(2.45 folds,1.88 folds)and(4.54 folds,2.73 folds)(P<0.05).9 The Effect of lead exposure on ICAM-1 and VCAM-1 expression in choroid plexus of diabetes mellitus rats: The fluorescent intensity of ICAM-1 and VCAM-1 in the choroid plexus of lead exposure group and diabetes mellitus group were higher than that in the control group.ICAM-1 and VCAM-1 fluorescence intensity were significantly enhanced in the diabetes mellitus + lead exposed rats.10 The effect of lead exposure on m RNA expression of adhesion molecules in choroid plexus: Compared with the control group,the expression of ICAM-1 and VCAM-1 m RNA in the choroid plexus of lead exposure group and diabetes mellitus group increased,and the difference was statistically significant(P<0.05).The relative m RNA expression of ICAM-1 and VCAM-1 in diabetic rats were higher than those in lead exposure group(P<0.05).The m RNA expression of VCAM-1 in diabetes mellitus + lead exposed rats was significantly increased than that in diabetes mellitus group(P<0.05).Conclusions Lead exposure causes higher expressions of inflammatory cytokines and adhesion molecules and the immune function of the blood cerebrospinal fluid barrier is damaged in diabetic rats,which may be related to learning and memory impairment aggravation induced by lead exposure in diabetes mellitus rats. |
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