Enhancement of neurotrophic factors in astrocyte for neuroprotective effects in brain disorders using low-intensity pulsed ultrasound stimulation

Background: Astrocytes play an important role in the growth and survival of developing neurons by secreting neurotrophic factors. Objective: The goal of this study was to investigate how low-intensity pulsed ultrasound (LIPUS) stimulation directly affects brain astrocyte function. Methods: Here, we report that LIPUS stimulation increased protein levels of BDNF, GDNF, VEGF, and GLUT1 in rat brain astrocytes as measured by western blot analysis. Histological outcomes including demyelination and apoptosis were examined in rats after administration of aluminum chloride (AlCl3). Results: At the mechanistic level, integrin inhibitor (RGD peptide) attenuated the LIPUS-induced neurotrophic factor expression. The data suggest that neurotrophic factor protein levels may be promoted by LIPUS through activation of integrin receptor signaling. In addition, LIPUS stimulation protected cells against aluminum toxicity as demonstrated by an increase in the median lethal dose for AlCl3 from 3.77 to 6.25 mM. In in vivo histological evaluations, LIPUS significantly reduced cerebral damages in terms of myelin loss and apoptosis induced by AlCl3. Conclusions: The results of this study demonstrate that transcranial LIPUS is capable of enhancing the protein levels of neurotrophic factors, which could have neuroprotective effects against neurodegenerative diseases.