DEGENERATION OF CAJAL-RETZIUS CELLS IN THE DEVELOPING CEREBRAL-CORTEXOF THE MOUSE AFTER ABLATION OF MENINGEAL CELLS BY 6-HYDROXYDOPAMINE

In the central nervous system, the neurotoxic drug 6-hydroxydopamine ( 6-OHDA) selectively deletes central catecholaminergic neurons and meni ngeal cells. Meningeal cells are known to contribute to brain developm ent and their specific degeneration leads to disorganized neuronal pos itioning. We have analyzed whether a particular population of cortical pioneer neurons, the Cajal-Retzius (CR) cells, which lie just below m eningeal cells, is also affected by 6-OHDA treatment. We show that app lication of 6-OHDA to the cortical surface leads to a rapid degenerati on of CR cells, without affecting other cortical neurons. The ablation of CR cells was prevented by normetanephrine, which blocks the 6-OHDA uptake into meningeal cells. These results indicate that the disappea rance of CR cells after 6-OHDA treatment may be a result of the ablati on of the meningeal cells and suggest a trophic dependence of CR cells upon meningeal cells.