Thermal injury induces heat shock protein in the optic nerve head in vivo.
OBJECTIVE
To investigate the induction of heat shock protein (Hsp)70 in the optic nerve head by localized laser application in transpupillary thermotherapy (TTT).


METHODS
TTT was performed on the right eye of Norwegian brown rats with an 810-nm diode laser installed on a slit lamp biomicroscope. The laser was aimed at the center of the optic nerve head with a 50-microm spot size. Various exposures (range, 60-200 mW) were used with an exposure duration of 60 seconds, and the various exposure durations (range, 1-5 minutes) were used with a power of 100 mW. Twenty hours after laser irradiation, immunohistochemical staining and Western blot analyses were performed. For morphologic analysis of the optic nerve head, confocal scanning laser ophthalmoscopy and scanning electron microscopy were performed.


RESULTS
In the control eyes, Hsp70 was detected minimally in the optic nerve tissues by immunohistochemistry. After TTT, Hsp70 in the optic nerve tissue was induced more than in the control eyes. By Western blot, Hsp70 expression was found to increase progressively after TTT as the power was increased, but it also decreased slightly at powers >140 mW. The optimal setting of TTT without tissue damage was determined to be 100 mW for 60 seconds.


CONCLUSIONS
Transpupillary laser irradiation of the optic nerve head induces Hsp70 expression. This result can be applied to the neuroprotective experiments in glaucoma by enhancement of a natural cytoprotective stress response.
Kim
Joon Mo
JM
Department of Ophthalmology, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea.
Park
Ki Ho
KH
Kim
Yu Jeong
YJ
Park
Hyun Jun
HJ
Kim
Dong Myung
DM
D000818:Animals; D015153:Blotting, Western; D005131:Eye Injuries / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D019084:Fluorescent Antibody Technique, Indirect; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D006979:Hyperthermia, Induced / Q000009:adverse effects*; D007124:Immunoenzyme Techniques; D007834:Lasers / Q000009:adverse effects; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000293:injuries* / Q000378:metabolism / Q000648:ultrastructure; D009901:Optic Nerve Diseases / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D011680:Pupil; D051381:Rats; D011914:Rats, Inbred BN
D005904:Glial Fibrillary Acidic Protein; D018840:HSP70 Heat-Shock Proteins