title: DNA fragmentation characteristic of apoptosis and cell loss induced by kainic acid in rabbit retinas.
abstract: We have examined whether in vivo exposure to the glutamate analogue, kainic acid, induces cell loss through apoptosis and/or through necrosis. The vulnerability of rabbit retinal cells was evaluated by routine histopathology. The DNA fragmentation was examined using an in situ method (TUNEL: TdT-mediated biotin-dUTP nick-end labelling) and agarose gel electrophoresis of extracted retinal DNA. Retinas were examined at 30 min, and 4, 16, 24 and 36 h, and 2-5 days following the intraocular administration of 140 nmol kainic acid. Although pyknotic cells could be seen already at 30 min post-injection, TUNEL-labelled nuclei were first observed 4 h after the injection. A relatively large number of pyknotic cells and of TUNEL-labelled nuclei were still seen at 5 days post-injection. Pyknotic cells were seen throughout the inner nuclear layer (mostly in the proximal half of the layer) and in the ganglion cell layer. The TUNEL-labelled nuclei were almost only seen in the proximal inner nuclear layer. Analysis of DNA by electrophoresis revealed the presence of large molecular weight fragments 4 h after the injection, and of oligonucleosome-size fragments between 16 h and 2 days after the injection. The present study thus presents evidence that, in our model, the retinal cell loss induced by kainic acid is preceded, probably in most cells, by a fragmentation of DNA characteristic of apoptotic cell death. The process of cell loss following kainic acid administration was found to be relatively slow, further suggesting that a programmed type of cell death, which eventually induces apoptosis, is involved. No indication that cells were lost also through necrosis was obtained.
authors.affiliation: Department of Ophthalmology, University Hospital of Lund, Sweden. maria_thereza.perez@oft.lu.se
authors.forename: M T
authors.initials: MT
authors.lastname: Perez
authors.forename: K
authors.initials: K
authors.lastname: Arnér
authors.forename: A
authors.initials: A
authors.lastname: Håkansson
mesh_terms: D000818:Animals; D017209:Apoptosis; D053938:DNA Fragmentation; D004587:Electrophoresis, Agar Gel; D005260:Female; D005821:Genetic Techniques; D007608:Kainic Acid / Q000494:pharmacology*; D008297:Male; D011817:Rabbits; D012160:Retina / Q000187:drug effects* / Q000473:pathology / Q000502:physiology*
chemical_list: D007608:Kainic Acid