The Effect of Low Level Laser Therapy on Proliferation and Differentiation of PC12 Cells

Abstract

Abstract The discovery of low level laser (LLL) therapy that can stimulate proliferation or inhibit apoptosis of neurons would be of great importance for new therapeutics against neurodegenerative disorder such as Parkinson’s disease. LLL therapy has been reported to modulate biological processes, depending on wavelength, frequency and power density to have a positive effect on tissue regeneration and wound healing. Numerous studies have demonstrated the promotion effect on nerve regeneration, although the underlying molecular mechanisms remain to be elucidated. Rat pheochromocytoma cell line (PC12 cells) possesses neuronal characteristics as in vitro models to show a critical step in neuronal development, regeneration, differentiation, and respond to injury. PC12 cell line is widely used as a cell culture system for studies neurobiological and neurochemical that retain the dopaminergic characteristic by the addition of NGF. Addition of nerve growth factor (NGF), PC12 cells exhibit growth of neurite with the increased expression of neuronal-specific genes such as growth associated protein (GAP-43), type III β-tubulin and synapsin 1. The purpose of our study was to evaluate the effectiveness of LLL therapy on the NGF-induced differentiation and proliferation in PC12 cell line by evaluating the morphological measurement, MTT assay, and immunoblotting assay for protein associated with neuronal differentiation. We found that LLL did not affect the proliferation of PC12 as measure by cell counting and MTT assay. However, LLL reduced the progression of differentiation manifested as the morphological change, and inhibited the expression of Gap-43 and Synaptophysin 1. These results indicated that LLL could have a negative effect on the NGF-induced PC12 cell differentiation, a potential neruotoxicity on the developing neuron.