ABSTRACT
Background: The neurite growth of dorsal root ganglion (DRG) explants is widely used for evaluating the promoting effects of neurotrophic factors on cultures. Counting the neurites directly is a tedious work because of the accuracy and the difficulty due to their branching and fasciculation. This study was aimed to compare quantitative measurement of neurite outgrowth, length and number of DRG explants in media containing estrogen (E2) and Schwann cell-conditioned medium (SCM). Methods: Schwann cells and DRG explants were harvested from nerve plexuses of P2-P3 rats and incubated separately. SCM was collected for treatment by adding into DRG culture. DRG explants were further incubated for 7 days with medium containing SCM, E2, SCM and E2. DRG cultures were stained for neurofilament to detect neurite growth. The neurite outgrowth, the length and number were measured by free software ImageTool. Results: The neurite outgrowth expressed as the percentage of pixels, occupied by the neurite extending from the ganglion, in the presence of E2 and SCM was the significantly increased parameter when compared to control. It was more reliable than the overestimated neurite outgrowth which resulted from the multiplying of neurite length and number. Conclusion: The neurite outgrowth was the parameter providing a robust means of evaluating the growth promoting activity of E2 and SCM. It could be rapidly measured. E2 might somehow increase the sensitivity of DRG neurons to the neurotrophic factors released from Schwann cells.