[Effect of cranial irradiation on the blood-cerebrospinal fluid and blood-brain barrier].

The influence of fractionated cranial irradiation with 24 Gy on blood-CSF and blood-brain barrier permeability for methotrexate (MTX) and serum proteins was studied in young rabbits. In unirradiated control animals and 1, 4, 14 and 26 weeks following cranial irradiation MTX 57.5 mg/kg body weight was given by an infusion. 24 hours after the start of the MTX-infusion blood, CSF and brain was collected. MTX was measured by a radioimmunoassay, albumin and IgG by immunnephelometry. MTX in serum and brain tissue did not change significantly in the different groups before and after cranial irradiation. MTX in CSF was significantly higher 4 and 14 weeks following cranial irradiation compared to the unirradiated control group, demonstrating a significant blood-CSF barrier disturbance without blood-brain barrier disturbance. Increased MTX concentration were paralleled by significantly increased albumin concentrations in the CSF. IgG penetration across the blood-CSF barrier remained unchanged after irradiation.