Effect of photobiomodulation therapy (660 nm and 830 nm) on carrageenan-induced edema and pain behavior in mice

Highlights

• The present study demonstrated that PBM was effective in minimizing pain and edema in the acute inflammatory process in an experimental model.

• The 830 nm wavelength (5.88 J energy) was more effective in improving edema in the acute inflammatory process in an experimental model.

• In pain analysis, the energy of 2.94 J was more effective regardless of the wavelength used in the acute inflammatory process in an experimental model.

ABSTRACT

BACKGROUND AND OBJECTIVES:

Photobiomodulation (PBM) is an important therapeutic tool for inflammatory process modulation. In this study, the anti-inflammatory and analgesic effect of two different energies and two different wavelengths (660 nm and 830 nm) were investigate and compared through the model of carrageenan-induced paw edema in mice.

METHODS:

Male Swiss mice, 36 animals (n=6 animals/group) were divided into six groups: Group 1 (saline-control), Group 2 (carrageenan), Group 3 (carrageenan + laser 660 nm, 5.88 J), Group 4 (carrageenan + laser 660 nm, 2.94 J), Group 5 (carrageenan + laser 830 nm, 5.88 J), and Group 6 (carrageenan + laser 830 nm, 2.94 J). PBM was applied 1h after the carrageenan injection which induced paw edema and hyperalgesia, which were measured by means of a plethysmometer and by flicker test using a water bath at 38ºC (±0.5ºC), respectively. Left paws of mice injected with carrageenan exhibited local edema that persisted for up to 6h after its administration. All animals were evaluated before, 1, 2, 3, 4, and 6 h after the injection of carrageenan.

RESULTS:

PBM, specially the 830 nm wavelength with 2.94 J of energy, reduced the paw edema induced by carrageenan. In addition, the 660 nm wavelengths (5.88 J / 2.94 J) and 830 nm (2.94 J) inhibited thermal hyperalgesia induced by carrageenan after 4 h of paw injection.

CONCLUSION:

There was evidence that the PBM 830 nm (2.94 J) produced a more pronounced anti-inflammatory effect, while the 660 nm (5.88 J / 2.94 J) energy laser was more effective to inhibit the hyperalgesia response induced by the carrageenan injection.

Keywords:
Edema; Hyperalgesia; Inflammation; Low level laser therapy; Pain.