Objective: To measure mobility of dendritic filopodia, complexity of dendritic arborization using method of live imaging in cultured rat hippocampal neurons and to analyze their morphological characters quantitatively.
Methods: Vectors expressing Green Fluorescent Protein- Fibrous Actin (GFP-F-Actin) and F-GFP were co-transfected into cultured rat hippocampal neurons at 5 d in vitro (DIV 5). Neurons expressing GFP were photographed and analyzed with Metamorph software.
Result: Dendritic filopodia was observed to move actively from DIV 7 to DIV 9. The mean density of filopodia was (10.78 +/-3.78)/100 microm, (10.68 +/-2.96)/100 microm and (9.99 +/-3.67)/100 microm (P >0.05), and there were (30.18 +/-14.03)% to (87.36 +/-20.88)% filopodia were mobile (P <0.001). During DIV 7-DIV 14, the total length of dendritic branches grew from (410.74 +/-185.98) microm to (1238.21 +/-418.32)microm (P <0.001) and the number of dendritic branches increased from 18.93 +/-7.23 to 33.60 +/-10.46 (P<0.001). The density of spine was (37.17 +/-6.46)/100 microm at DIV 14.
Conclusion: The combination of live imaging with quantitative analysis is a useful method to study dendritic morphological development in vitro, including indicators of dendritic filopodia, dendritic arborization and spines.