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Induction of heat shock proteins 27 and 72 in retinal ganglion cells after acute pressure‐induced ischaemia
Author(s) -
Windisch Bettina K,
LeVatte Terry L,
Archibald Michele L,
Chauhan Balwantray C
Publication year - 2009
Publication title -
clinical and experimental ophthalmology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.3
H-Index - 74
eISSN - 1442-9071
pISSN - 1442-6404
DOI - 10.1111/j.1442-9071.2009.02032.x
Subject(s) - medicine , heat shock protein , ischemia , retina , ophthalmology , retinal , intraocular pressure , retinal ganglion cell , hsp70 , andrology , shock (circulatory) , pathology , anesthesia , biology , biochemistry , neuroscience , gene
A bstract Background: We wanted to investigate whether heat shock protein (HSP) 27 and HSP 72 are induced in retinal ganglion cells (RGCs) after acute intraocular pressure (IOP)‐induced ischaemia. Methods: Retinal ischaemia was induced by acutely increasing IOP to 100–110 mmHg for 30 or 90 min unilaterally in Sprague Dawley rats. A fluorescent tracer (fluorogold, FG) was applied to the superior colliculi to label RGCs. Twenty‐four hours, 1 week or 2 weeks after of IOP elevation, rats were killed, RGCs counted, and immunohistochemical labelling of the retina was performed. HSP‐positive RGCs were counted and normalized HSP RGC counts determined. Results: The ratio of FG‐positive labelled RGCs in the experimental to the contralateral eye as a marker of RGC survival remained unchanged after 30 min of ischaemia: 1.09 ± 0.11 at 1 week, and 0.94 ± 0.28 at 2 weeks. After 90 min of ischaemia RGC survival decreased to 0.19 ± 0.14 at 1 week, and 0.20 ± 0.14 at 2 weeks. After 30 min of ischaemia, the normalized HSP 27‐ and HSP 72‐positive RGC count was detected at highest levels (HSP 27: 5.42 ± 1.18; HSP 72: 12.23 ± 1.24) at 2 weeks compared with controls, whereas after 90 min ischaemia it was detected at higher levels at 1 week (HSP 27: 52.63 ± 3.65; HSP 72: 206.84 ± 60.38), as well as at 2 weeks (HSP 27: 89.00 ± 17.21; HSP 72: 191.00 ± 50.05). Conclusion: These results demonstrate an enhanced induction of HSP 27 and HSP 72 after 90 min acute IOP‐induced ischaemia. In contrast to 30 min ischaemia, we showed time‐dependent loss of RGCs after 90 min of ischaemia after 1 week or 2 weeks.