Bidirectional Effects Of Hydrogen Peroxide On The Neuritic Growth Of In Vitrocultured Rat Hippocampal Neurons

Objective: To investigate whether the different concentrations of hydrogen peroxidecould promote the neuritic outgrowth of hippocampal neurons, bringing thepossibility toward a better understanding of the role of reactive oxygen species (ROS)in signal transconduction related to the neural development and growth.Methods: Primary hippocampal neurons were prepared from postnatal rats (0~1d)and cultured. After a24h initial culture period, the different concentrations ofhydrogen peroxide (0.01,0.1,1,10and100μmol/L) were added into culture medium,respectively. The growth state of the hippocampal neurons was observed on the2daysand5daysunder the inverted microscope and the photos were captured by usingan imaging system. An image analysis software was used to analyze the outgrowthand development of neuronal neurites including the length of the longest neurite(whether or not the axon), the total length of neuritis, the total number of branchpoints and the number of neurites from the cell body in each neuron.Results: The length of the longest neuriteandthe total length of neuritis at twocultured time points (2and5days) were significantly increased at the lowconcentration of hydrogen peroxide (0.01μmol/Land0.1μmol/L) as compared tothose in the control, but there was no significant difference in the total number ofbranch points and the number of neurites from the cell body of the hippocampalneurons. In contrast, the length of the longest neurite, the total length of neuritis, thetotal number of branch points and the number of neurites from the cell body of thehippocampal neurons were significantly decreased at the high concentration ofhydrogen peroxide (100μmol/L).Conclusions: Hydrogen peroxide promotes the neuritic outgrowth and developmentof the hippocampal neurons at the low concentration, and shows a depression effect atthe high concentration, suggesting that hydrogen peroxide may influence the neuriticoutgrowth and development of the hippocampal neurons in a bidirectional regulationmechanism.