On the mechanism of photobiomodulation widely used in laser sports medicine and rehabilitation

 

Introduction

As the lack of any demonstrable cytotoxic and genotoxic effects of photobiomodulation on mammalian cells in culture [1], photobiomodulation [2] has been widely used in laser sports medicine and rehabilitation as low intensity laser therapy or laser acupuncture.  As its mechanism is obscure, the situation that it sometimes did not work has physicians confused.  As much research has shown that there is photobiomodulation which is mediated by signal transduction [3-6] for a cell, its mechanism was studied in this paper. 

Methods

Photobiomodulation mechanism was studied by using time quantum theory of radiation-matter interaction put forward by Liu CY et al [7]  and cellular photobiomodulation phenomena.

Results

Light-cell interaction of photobiomodulation is non-resonant so that there is an optimum intensity even for the same dose which is defined as the product of irradiation intensity and irradiation time. The non-resonant transition rate is extraordinarily small, but can be amplified by the coherent state of the identical and independent molecules. The best candidate molecules of the identical and independent molecules are membrane receptors. The key is the conformational changes of membrane receptors, which is realized by light induced electron excitation [8].  At this point, all the effects of low intensity  monochromatic light  from UVA (320-400 nm) to IR on cells could be called photobiomodulation.  Light induced conformational changes of membrane receptors was suggested to be correlated with subsequent signal transduction pathways by the biological information model of photobiomodulation on cells, which was supported by the experimental research of ours and others, and its successful applications.

Discussion / Conclusions

The membrane receptor collectively mediated phototransduction might be the possible mechanism of photobiomodulation on cells. The situation that photobiomodulation sometimes did not work might be because the used light intensity was not near to the optimal intensity, or the membrane receptor mediated photobiomodulation was blocked by a chemical molecule.

 

References

[1]. Logan ID, McKenna PG, Barnett YA. (1995). An investigation of the cytotoxic and mutagenic potential of low intensity laser irradiation in Friend erythroleukaemia cells. Mutat Res. 347(2):67-71.

[2]. Eells JT, Henry MM, Summerfelt P, Wong-Riley MT, Buchmann EV, Kane M, Whelan NT, Whelan HT. (2003). Therapeutic photobiomodulation for methanol-induced retinal toxicity. Proc Natl Acad Sci U S A. 100(6):3439-44.

[3]. Duan R, Liu TC, Li Y, Guo H, Yao LB. (2001). Signal transduction pathways involved in low intensity He-Ne laser-induced respiratory burst in bovine neutrophils: a potential mechanism of low intensity laser biostimulation.  Lasers Surg Med. 29(2):174-8.

[4]. Shefer G, Oron U, Irintchev A, Wernig A, Halevy O. (2001). Skeletal muscle cell activation by low-energy laser irradiation: a role for the MAPK/ERK pathway.  J Cell Physiol. 187(1): 73-80.

[5]. Zhang Y, Dong Z, Nomura M, Zhong S, Chen N, Bode AM, Dong Z. (2001). Signal transduction pathways involved in phosphorylation and activation of p70S6K following exposure to UVA irradiation. J Biol Chem. 276(24):20913-23.

[6]. Bode AM and Dong Z. (2003). Mitogen-activated protein kinase activation in UV-induced signal transduction. Sci. STKE, 2003 (167): re2 (http://stke.sciencemag.org/cgi/content/full/sigtrans;2003/167/re2).

[7]. Conrad M. (1994). Amplification of superpositional effects through electronic conformational interactions.  Chaos Solitons & Fractals. 4 (3): 423-438.

[8]. Liu CY, Chen QM and Li ZG. (1993). Time and radiation time quantization and their application to the transport through a quantum dot turnstile. Physica A. 196(4): 615-624 .

* It is supported by National Science Foundation of China (60178003&60278012), Team Project, Key Project and general project of Guangdong Science Foundation of China (20003061, 20011480& 20031526),  Visiting Foundation of State Key Laboratory of laser Technology, Huazhong University of Science and Technology and Guangdong Qibaishi Fellow Foundation(Q02087).