[Effects of low-dose tritiated water on the developing central nerve system and their mechanisms]

To provide experimental data for evaluating tritium risk of nuclear-energy plant and instituting safety protection standard of nuclear effects of low-dose tritiated water(HTO) on the developing central nerve system.

Pregnant adult C57BL/6J strain mice and Wistar rats were irradiated with beta-rays from HTO by a single intraperitoneal injection on the 12.5th and 13th day of gestation. The activity of HTO was (x 10(4) Bq/g. B.W) 24.09, 48.18 and 144.54, respectively. Neurobehavior and learning and memory ability were tested. Ca2+ currents of hippocampal neurons were examined by patch-clamp. Apoptosis of brain cells was detected morphologically and biochemically by DNA electrophoresis. SDS-PAGE and Western blotting were used to detect P53 protein in the cultures.

After irradiation with beta-rays from HTO in utero, the offspring showed hyperactivity in their young age period and then showed depression-hypoactivity in adulthood. The exposed animals had difficulties in both learning and memory retention and the developing neurons of the central nerve system showed lower Ca2+ currents, higher number of apoptosis, a typical "ladder pattern" DNA and increasing P53 protein.

Lower Ca2+ currents, higher number of apoptosis of brain cells and abnormal expression of P53 protein were the substance basis of the damage of central nerve system caused by tritium.