[Investigation of a growth factor for cultured rat fetal spinal motor neurons].

The hypothesis that amyotrophic lateral sclerosis (ALS) might be the disorder of "motor nerve growth factor" has been proposed, being based on the results of the research in tissue culture. The evidence of putative growth factor for spinal motor neurons has been searched, but not found yet. To investigate the growth factor for cultured rat fetal ventral spinal cord neurons two experiments were carried out. One experiment was to evaluate the rat fetal age-related dependency or requirement of putative growth factor in fetal calf serum and non-neuronal cells in cultured ret fetal ventral spinal cord neurons. Another experiment was the evaluation of the possibility as the growth factor of insulin, 5-alpha dihydrotestosterone, epidermal growth factor and fibroblast growth factor for cultured rat fetal ventral spinal cord neurons. The following results were obtained from these experiments; Insulin was found to be acting like a growth factor for rat fetal ventral spinal cord neurons, showing neurite promoting effect and choline acetyltransferase activity stimulating effect. 5-alpha dihydrotestosterone had neurite promoting effect on cultured rat fetal ventral spinal cord neurons without choline acetyltransferase activity stimulating effect. Epidermal growth factor and fibroblast growth factor which are regarded as insulin-related growth factor did not show apparent neurotrophic effect on cultured rat fetal ventral spinal cord neurons. There was a big difference in dependency or requirement of putative growth factor in fetal calf serum and non-neuronal cell between cultured rat fetal 13-15 day old ventral spinal cord neurons and cultured rat fetal 16-18 day old fetal ventral spinal cord neurons. It is necessary to consider about the rat fetal age on the evaluation of the effect of putative growth factor for cultured rat fetal ventral spinal cord neurons.