ABSTRACT
OBJECTIVE To investigate the effects of lead exposure on the permeability,secretion and transportation function of blood-cerebro-spinal fluid barrier (BCB)of rats in order to provide the theo-rical basis for elucidating the mechanis m of lead induced neurotoxicity.MEHTODS 60 SPF SD rats were rando mly divided into 4 groups,including a control group and three doses lead exposed groups. Rat in the lead exposure groups were given drinking water containning 0.05%,0.1 % and 0.2% lead acetate (at dose of 80,160,320 mg·kg -1 )for 8 weeks.Laser scanning confocal microscopy was uti-lized to determine the lead content in seru m,cerebrospinal fluid (CSF)and choroid plexus sa mples. Morris maze was used to test learning and me mory.Fe moral artery perfusion of Evans blue (EB)and fluorescein sodiu m (NaFI)was performed to measure BCB permeability function.Confocal laser scan-ning was applied to detect junction adhesion molecule (JAM)and occludin protein expression in choroid plexus.ELISA was used to measure the concentration of transthyretin (TTR)and leptin in seru m and CSF.RESULTS The lead content in seru m,choroid plexus and CSF significantly increased,especially the lead level in CSF.Morris water maze data showed that escape latency of rat in lead acetate 160 and 320 mg·kg -1 group were 52 ±12,(89 ±19)s,respectively,longer than that of control group 〔(28 ±7)s, P<0.05〕.The ti mes across platform of rats in lead acetate 160 and 320 mg·kg -1 group were lower than that of control group(P <0.05).The NaFI content in CSF of rats in all lead acetate exposure groups were 0.94 ±0.09,1 .02 ±0.03 and (1 .08 ±0.18)mg·L -1 ,respectively,and were higher than those of control group〔(0.74 ±0.04)mg·L -1 〕;While the EB content in CSF of rat in lead acetate 160 and 320 mg·kg -1 group were higher than the control group(P <0.05),which indicated that lead acetate exposure at low dose can lead to the increase of permeability of BCB.Laser scanning confocal micro-scope i mages showed that the JAM protein expression of choroid plexus in lead acetate 160 and 320 mg·kg -1 group were 44.9% and 42.9% of the control group.Sa me decline was seen in terms of occludin expression.The TTR content of CSF of rats in lead acetate 80 mg·kg -1 group was (32.3 ± 1 1 .7)ng·g -1 protein,lower than that of the control group,and the difference was significant.This decline was also noted in lead acetate 160 and 320 mg·kg -1 group.The data of TTR in CSF suggested that the low dose lead acetate exposure can disrupt the BCB secretion function.The leptin levels in CSF of lead acetate 160 and 320 mg·kg -1 group were lower than that in the control group (P <0.05 ). CONCLUSION Lead exposure did disrupt the permeability,transportation and secretion function of BCB.Our data suggest that BCB dysfunction might be involved in the mechanis m of lead induced neurotoxicity.