EFFECTS OF AN 11-DAY SPACEFLIGHT ON THE CHOROID-PLEXUS OF DEVELOPING RATS

Cellular distributions of ezrin, a cytoskeletal protein involved in ap ical cell differentiation in choroid plexus, and carbonic anhydrase II , which is partly involved in the cerebrospinal fluid production, were studied by immunocytochemistry, at the level of choroidal epithelial cells from the lateral, third and fourth ventricles in normal or exper imental fetuses, in parallel with the ultrastructure of apical microvi lli, observed by transmission electron microscopy. We compared choroid plexuses from developing normal rats (gestational day 15 to birth) wi th choroid plexuses from 20-day-old rat fetuses, developed for 11 days in space, aboard a space shuttle (NASA STS-66 mission, NIH-R1 experim ents), from gestational day 9 to day 20. The main changes observed in fetuses developed in space were demonstrated by immunocytochemistry an d concerned the distribution of ezrin and carbonic anhydrase II. Thus, in fetuses developing in space, ezrin was strongly detected in the ch oroidal cytoplasm and weakly associated to the membrane in the apical domain of the choroid plexus from the fourth ventricle. Such alteratio ns suggested that choroid plexus from rat fetal brain displays a delay ed maturation under a micro-gravitational environment. In contrast, in tense immunoreactions to anti-carbonic anhydrase II antibodies showed that this enzyme is very abundant in rats developed in space, compared to ground control fetuses. (C) 1997 Elsevier Science B.V.