S100-BETA PROMOTES THE EXTENSION OF MICROTUBULE-ASSOCIATED PROTEIN2 (MAP2)-IMMUNOREACTIVE NEURITES RETRACTED AFTER COLCHICINE TREATMENT IN RAT SPINAL-CORD CULTURE

S100 beta, a glial derived calcium-binding protein with neurotrophic a ctivity in the central nervous system, stimulates neurite extension of fetal raphe. cortex, spinal cord, and dorsal root ganglion neurons. T he effects of S100 beta on neurite length and microtubule associated p rotein2 (MAP2) immunoreactivity (IR) after microtubule disruption with colchicine were investigated in primary rat spinal cord culture. The incubation with S100 beta (20 ng/ml) for 3 h after exposure to colchic ine (10(-6) M) for 30 min altered the distribution of MAP2-IR. The len gth of MAP2-IR neurites increased by 65% compared to that in colchicin e treatment alone. MAP2-IR intensity in the cell body was reduced by 2 6% compared to that in colchicine treatment alone. These results indic ate that neurites shrink when the microtubular cytoskeletal system is disrupted and S100 beta rapidly promotes re-assembly and/or stabilizat ion. (C) 1997 Elsevier Science ireland Ltd.