Interleukin-2 enhances dendritic development and spinogenesis in cultured hippocampal neurons

In this study, we investigated the effects of interleukin-2 (IL-2) on dendritic filopodia, dendritic arborization, and spine maturation during the development of cultured rat hippocampal neurons. The cultured hippocampal neurons were transfected with F-GFP (farnesylated enhanced green fluorescent protein) at DIV5 to display the subtle structure of dendrites, and were then treated with IL-2 at various concentrations for different time before living cell image observation. We found that both the dendritic arborization and the length of dendrites per neuron at DIV7, DIV10, and DIV14 were increased under IL-2 treatment in a dose-dependent manner, and the strongest IL-2 effects on both dendritic number and length were observed at DIV7. Also, there was a significant increase in the mobility of dendritic filopodia in neurons at DIV7 treated with 10 ng/mL IL-2 for 48 hr from DIV5. In addition, IL-2 caused an increase in spine density of neurons at DIV14 either treated with IL-2 from DIV5 to DIV7 or from DIV5 to DIV14, but did not affect neurons treated from DIV12 to DIV14. These results indicate that IL-2 affects the dendritic development and spinogenesis of cultured hippocampal neurons, especially during the early developmental stage.