The effect of calcium ionophore A23187 on neurites from embryonic mouse spinal cord explants in culture

The calcium channel ionophore A23187 has been shown to cause a striking red uction in both the rate of neurite outgrowth and in growth cone motility; i t has also been shown that these changes may be reversed when the ionophore is removed from the culture medium. The evidence supports the view that a specific concentration range of calcium is essential for outgrowth and moti lity and that calcium influences neuronal growth by an effect on actin stru ctures within the growth cone. Using time-lapse video microscopy techniques , the effects of calcium ionophore A23187 on the rate of neurite outgrowth and growth cone motility in cultured embryonic mouse spinal cord neurons we re examined. Concentrations in the range of 1-100 mu M resulted in an inhib ition of neuronal outgrowth, a loss of filopodia and a significant reductio n in survival after seven hours. The results show that although the treatme nt with A23187 inhibited growth at all concentrations used, motility was in hibited only at the highest concentration indicating that the optimum calci um concentration for motility is higher than that for growth and that calci um mediates its effects on growth and motility at a very local level.