Conventional External Irradiation Of The Whole Skull Of Cisplatin By Rat Blood - Brain Barrier In Rats And Its Significance

Objective:The study was designed to investigate the effect of drug permeability in rat blood-brain-barrier(BBB)after different doses of whole brain conventional fractionation irradiation by mearsuring cisplatin(DDP) concentration in brain tissue.Methods: According to different irradiation doses,50 adult Wistar rats were divided randomly into 5 groups:the normal control group(0Gy);10Gy;20Gy;30Gy;and 40Gy group.Utilized 1.0cm-thick tissue conpensator,then all rats were exposed to conventional fractionation (2Gy/d,5d/w)with 6MV-X ray.DDP(1.0mg/kg) was injected into the periton cavity 16 hours after whole brain irradiation.Brain tissue and blood were collected 20 minute later.Those samples were used to assay DDP concentiation using HPLC.Results:The average concentration of DDP in blood serum of the control,10Gy,20Gy,30Gy and 40Gy groups was not considered to be stastically significant(F=0.16,q=0.0718～0.8735,P＞0.05),in every group,the concentration of DDP in blood serum and brain tissue was considered to be stastically significant(P＜0.01).The DDP concentration increased gradually as the accrescence of irradiation doses,The DDP concentration increased significantly in 20Gy and 30Gy groups.Compared with the30Gy group,the concentration of DDP in the 40Gy group increased slightly.All the data was handled with analysis of variance.The average concentration of DDP in brain tissue of the control, 10Gy,20G,30Gy and 40Gy groups was considered to be stastically significant(F=63.12, q=2.2313～18.0053,P＜0.05).Conclusion:Irradiation can directly damage the function of BBB and increase the permeability of BBB,BBB would be opened gradually following the increase of irradiation dose.It would be considered as the optimum time of chemotherapy when the whole brain irradiation ranges from 20Gy to 30Gy.