Microglia/macrophages responses to kainate-induced injury in the rat retina

Min Lin Chang, Ching Hsiang Wu, Hsiung Fen Chien, Ya Fen Jiang-Shieh, Jeng Yung Shieh, Chen Yuan Wen*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

25 Scopus citations


The present study was aimed to elucidate how retinal microglia/macrophages would respond to neuronal death after intravitreal kainate injection. An increased expression of the complement receptor type 3 (CR3) and an induction of the major histocompatibility complex (MHC) class II and ED-1 antigens were mainly observed in the inner retina after kainate injection. Prominent cell death revealed by Fluoro Jade B (FJB) staining and ultrastructural examination appeared at the inner border of the inner nuclear layer (INL) at 1 day post-injection. Interestingly, some immunoreactive cells appeared at the outer segment of photoreceptor layer (OSPRL) at different time intervals. Our quantitative analysis further showed that CR3 immunoreactivity was drastically increased peaking at 7 days but subsided thereafter. MHC class II and ED-1 immunoreactivities showed a moderate but steady increase peaking at 3 days and declined thereafter. Double labeling study further revealed that retinal microglia/macrophages expressed concurrently CR3 and ED-1 antigens (OX-42 +/ED-1+) or MHC class II molecules (OX-42 +/OX-6+) and remained branched in shape at early stage of kainate challenge. By electron microscopy, microglia/macrophages with CR3 immunoreactivity displayed abundant cytoplasm containing a few vesicles and phagosomes. Other cells ultrastructurally similar to Müller cells or astrocytes could also engulf exogenous substances. In conclusion, retinal microglia/macrophages responded vigorously to kainate-induced neuronal cell death that may also trigger the recruitment of macrophages from neighboring tissues and induce the phagocytotic activity of cells other than retinal microglia/macrophages.

Original languageEnglish
Pages (from-to)202-212
Number of pages11
JournalNeuroscience Research
Issue number3
StatePublished - 03 2006
Externally publishedYes


  • Intravitreal injection
  • Kainate
  • Microglia/macrophages
  • Retina


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