LIPUS enhance elongation of neurites in rat cortical neurons through inhibition of GSK-3beta.

OBJECTIVE Low-intensity pulsed ultrasound (LIPUS) has been reported to enhance proliferation and to alter protein production in various kinds of cells. In the present study, we measured the neurites length after LIPUS treatment to define the effectiveness of LIPUS stimulation on neurons, and then we examined the acticity of GSK-3beta to study the intracellular mechanism of neurite's outgrowth. METHODS LIPUS was applied to cultured primary rat cortical neurons for 5 minutes every day with spatial- and temporal average intensities (SATA) of 10 mW/cm(2), a pulse width of 200 microseconds, a repetition rate of 1.5 KHz, and an operation frequency of 1 MHz. Neurons were photographed on the third day after LIPUS treatment and harvested at third, seventh, and tenth days for immunoblot and semi-quantitative RT-PCR analysis. RESULTS Morphology change showed that neurite extension was enhanced by LIPUS. There was also a remarkable decrease of proteins, including p-Akt, p-GSK-3beta, and p-CRMP-2, observed on the seventh and tenth days, and of GSK-3beta mRNA expression, observed on the seventh day, in neurons treated with LIPUS. CONCLUSION LIPUS can enhance elongation of neurites and it is possible through the decreased expression of GSK-3beta.