Ceramide production associated with retinal apoptosis after retinal detachment.
BACKGROUND
During retinal detachment, premature apoptosis of photoreceptors and a loss of optimally corrected visual acuity occur. We hypothesized that retinal cell death and generation of ceramide, a pro-apoptotic lipid, would progress as a function of time following experimental retinal detachment, and undertook to define the appropriate temporal window.


METHODS
Unilateral retinal detachment was induced in white New Zealand rabbits by subretinal injection of sodium hyaluronate. In experimental animals, we injected sphingosine-1-P into the vitreous 2 hours before retinal detachment. Both eyes were removed on days 1, 3 and 6 for histological and biochemical examination. The number of photoreceptors was counted in section, the level of apoptosis was assessed using the TUNEL assay, and the production of ceramide was analyzed in situ with immunohistochemistry. The concentration of ceramide was also determined on retinal homogenates using a diacylglycerol kinase assay.


RESULTS
We confirmed that the average number of live photoreceptors decreased gradually after retinal detachment. In eyes pre-treated with sphingosine-1-P the number of apoptotic photoreceptors was significantly lower. The proportion of apoptotic photoreceptors (14%) remained constant as a function of time in the window studied. As compared to controls, the detached retina showed intense ceramide immunostaining that was prominent in the photoreceptors, but also present to a lesser extent in other retinal layers. The total concentration of intra-retinal ceramide increased by 40% on the first day and continued augmenting through the sixth day after retinal detachment.


CONCLUSIONS
Retinal apoptosis during experimental retinal detachment is associated with in vivo production of ceramide.
Ranty
Marie-Laure
ML
Service d'Anatomie Pathologique, CHU Rangueil, Toulouse, 31000, France.
Carpentier
Stéphane
S
Cournot
Maxime
M
Rico-Lattes
Isabelle
I
Malecaze
François
F
Levade
Thierry
T
Delisle
Marie-Bernadette
MB
Quintyn
Jean-Claude
JC
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002452:Cell Count; D002518:Ceramides / Q000378:metabolism*; D004195:Disease Models, Animal; D006820:Hyaluronic Acid; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008246:Lysophospholipids / Q000494:pharmacology; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000473:pathology; D011817:Rabbits; D012163:Retinal Detachment / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D055675:Viscosupplements
D002518:Ceramides; D008246:Lysophospholipids; D055675:Viscosupplements; C060506:sphingosine 1-phosphate; D006820:Hyaluronic Acid; D013110:Sphingosine