Neuroprotective effects of lutein in a rat model of retinal detachment.
BACKGROUND
Retinal detachment (RD) is a leading cause of blindness, and although final surgical re-attachment rate has greatly improved, visual outcome in many macula-off detachments is disappointing, mainly because of photoreceptor cell death. We previously showed that lutein is anti-apoptotic in rodent models of ischemia/reperfusion injury. The objective of this study is to investigate lutein as a possible pharmacological adjunct to surgery.


METHODS
Subretinal injections of 1.4 % sodium hyaluronate were used to induce RD in Sprague-Dawley rats until their retinae were approximately 70 % detached. Daily injections of corn oil (control group) or 0.5 mg/kg lutein in corn oil (treatment group) were given intraperitoneally starting 4 h after RD induction. Animals were euthanized 3 days and 30 days after RD and their retinae were analyzed for photoreceptor apoptosis and cell survival at the outer nuclear layer (ONL) using TUNEL staining and cell counting on retinal sections. Glial fibrillary acidic protein (GFAP) and rhodopsin (RHO) expression were evaluated with immunohistochemistry. Western blotting was done with antibodies against cleaved caspase-3, cleaved caspase-8 and cleaved caspase-9 to delineate lutein's mechanism of action in the apoptotic cascade. To seek a possible therapeutic time window, the same set of experiments was repeated with treatment commencing 36 h after RD.


RESULTS
When lutein was given 4 h after RD, there were significantly fewer TUNEL-positive cells in ONL 3 days after RD when compared with the vehicle group. Cell counting showed that there were significantly more nuclei in ONL in lutein-treated retinae by day 30. Treatment groups also showed significantly reduced GFAP immunoreactivity and preserved RHO expression. At day 3 after RD, Western blotting showed reduced expression of cleaved caspase-3 and cleaved caspase-8 in the treatment group. No difference was found for cleaved caspase-9. When lutein was given 36 h after RD similar results were observed.


CONCLUSIONS
Our results suggest that lutein is a potent neuroprotective agent that can salvage photoreceptors in rats with RD, with a therapeutic window of at least 36 h. The use of lutein in patients with RD may serve as an adjunct to surgery to improve visual outcomes.
Eye Institute, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
Tiffany T Y
TT
Woo
Suk-Yee
SY
Li
Wico W K
WW
Lai
David
D
Wong
Amy C Y
AC
Lo
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D002452:Cell Count; D002470:Cell Survival; D004195:Disease Models, Animal; D019084:Fluorescent Antibody Technique, Indirect; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D007274:Injections, Intraperitoneal; D014975:Lutein / Q000627:therapeutic use*; D008297:Male; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012163:Retinal Detachment / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D012243:Rhodopsin / Q000378:metabolism
D005904:Glial Fibrillary Acidic Protein; D018696:Neuroprotective Agents; D012243:Rhodopsin; C505528:Casp8 protein, rat; D053148:Caspase 3; D053181:Caspase 8; D014975:Lutein