EFFECTS OF SINGLE-DOSE AND FRACTIONATED-IRRADIATION ON FETAL MOUSE-BRAIN AGGREGATES

Foetal mouse brain cells were grown in vitro. 1 Gy X-irradiation was g iven as a single dose on culture day 2 (corresponding to embryonic day 17 in vivo) or in daily fractions (4 x 0.25 Gy), starting on day 2 in culture. The growth (size) and biochemical differentiation of the agg regates were studied up to day 40 in culture. Aggregates given a singl e dose (1 Gy) were smaller with lower protein and DNA amount than cont rols up to day 30-40 in culture. When the dose was fractionated, a par tial recovery occurred by day 20, and values returned to control level s by day 30-40. The specific activity of acetylcholinesterase (AChE) w as significantly higher after 10-20 days, in the irradiated (1 Gy) agg regates. In fractionated irradiated aggregates, the increase of specif ic activity of AChE was evident only after 10 days in culture. Compare d with fractionated X-irradiation, where recovery was observed after 2 0-40 days in culture, a single dose of irradiation produced more perma nent changes in the amounts of DNA and protein and in the size and neu rochemical activities of aggregates. (C) 1997 Elsevier Science Ltd.