Age-dependent requirements of cultured spinal cord neurons

Biochemical response of spinal motor neurons (SMNs) to putative trophic factors present in the fetal calf serum (FCS) or released from the native glial cells was evaluated in ventral spinal cord cultures of 12- to 14- and 16- to 18-day embryos (before and after death of many SMNs in vivo) considering choline acetyltransferase and 2',3'-cyclic 3'phosphohydrolase as the biochemical markers of SMNs and oligodendrocytes respectively. Cultured SMNs of older embryos were more dependent than those of younger embryos on glial cells and on FCS putative trophic factors. FCS seemed more important than glial cells for survival of both older and younger SMNs and its withdrawal resulted in more prominent and longer neurite outgrowth. Our study demonstrates that the response of SMNs to trophic factors depends on the age of the rat embryos from which they were cultured.