Myocilin gene expression in the trabecular meshwork of rats in a steroid-induced ocular hypertension model.
OBJECTIVE
To investigate the expression pattern of myocilin in the trabecular meshwork of normal and dexamethasone-induced ocular hypertensive rat eyes.


METHODS
An ocular hypertension model was generated by application of topical dexamethasone to rat eyes 4 times daily for 1, 2, and 4 weeks. Age-matched untreated eyes served as controls. The intraocular pressure (IOP) was monitored by electronic Tono-pen under anesthesia. The protein and mRNA levels of myocilin in the trabecular meshwork and endothelial lining of Schlemm's canal were investigated by immunohistochemistry and in situ hybridization, respectively. For semiquantitative evaluation, areas with positive staining were analyzed by a computer-assisted image-processing system with NIH software.


RESULTS
The IOP in rat eyes was elevated after 2 weeks of topical dexamethasone treatment. Despite the IOP elevation, the protein and mRNA levels of myocilin in the trabecular meshwork and around Schlemm's canal in the steroid-treated eyes were not different from those of controls.


CONCLUSIONS
No discernible changes in myocilin expression in the chamber angle indicate that myocilin may not be directly linked to ocular hypertension, at least not in rat eyes after relatively short-term steroid application.
Sawaguchi
Keiko
K
Department of Ophthalmology and Visual Sciences, Ryukyu University School of Medicine, Okinawa, Japan.
Nakamura
Yoshimi
Y
Nakamura
Yuko
Y
Sakai
Hiroshi
H
Sawaguchi
Shoichi
S
D000818:Animals; D003598:Cytoskeletal Proteins / Q000235:genetics*; D003907:Dexamethasone / Q000633:toxicity; D004195:Disease Models, Animal; D005136:Eye Proteins / Q000235:genetics*; D015870:Gene Expression; D005938:Glucocorticoids / Q000633:toxicity*; D006023:Glycoproteins / Q000235:genetics*; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D007429:Intraocular Pressure; D009798:Ocular Hypertension / Q000139:chemically induced / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014065:Tonometry, Ocular; D014129:Trabecular Meshwork / Q000378:metabolism*; D000099179:Myocilin
D003598:Cytoskeletal Proteins; D003907:Dexamethasone; D005136:Eye Proteins; D005938:Glucocorticoids; D006023:Glycoproteins; D012333:RNA, Messenger; D000099179:Myocilin