Effect of low-level laser treatment on cochlea hair-cell recovery after acute acoustic trauma.
We investigated the effect of low-level laser radiation on rescuing hair cells of the cochlea after acute acoustic trauma and hearing loss. Nine rats were exposed to noise. Starting the following day, the left ears (NL ears) of the rats were irradiated at an energy output of 100 to 165 mW/cm(2) for 60 min for 12 days in a row. The right ears (N ears) were considered as the control group. Frequency-specific hearing levels were measured before the noise exposure and also after the 1st, 3rd to 5th, 8th to 10th and 12th irradiations. After the 12th treatment, hair cells were observed using a scanning electron microscope. Compared to initial hearing levels at all frequencies, thresholds increased markedly after noise exposure. After the 12th irradiation, hearing threshold was significantly lower for the NL ears compared to the N ears. When observed using an electron microscope, the number of hair cells in the middle turn of the NL ears was significantly larger than that of the N ears. Our findings suggest that low-level laser irradiation promotes recovery of hearing thresholds after acute acoustic trauma.
Dankook University, Medical Laser Research Center, Cheonan, Republic of Korea.
Chung-Ku
CK
Rhee
Chan Woong
CW
Bahk
Se Hyung
SH
Kim
Jin-Chul
JC
Ahn
Jae Yun
JY
Jung
Phil-Sang
PS
Chung
Myung-Whan
MW
Suh
D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D001309:Auditory Threshold / Q000187:drug effects; D001933:Brain Stem / Q000473:pathology; D003051:Cochlea / Q000473:pathology*; D005072:Evoked Potentials, Auditory; D006198:Hair Cells, Auditory / Q000473:pathology*; D006309:Hearing; D006317:Hearing Loss, Noise-Induced; D007834:Lasers; D008297:Male; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008928:Mitochondria / Q000378:metabolism; D009622:Noise; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted
D000255:Adenosine Triphosphate