Characterization of intraocular pressure pattern and changes of retinal ganglion cells in DBA2J glaucoma mice

To characterize the pattern of intraocular pressure (IOP) change and the deficit of retinal ganglion cells (RGCs) in DBA2J, which is most well-characterized chronic glaucoma mouse model and wild type (WT) C57bl/6 mice, and to study the relationship between IOP change and RGCs deficit.

IOP was monitored with a rebound tonometer in WT C57bl/6 and DBA2J mice from 3 to 15-month-old. Retinal function was evaluated by dark-adapted electroretinogram (ERG) in DBA2J and WT mice of 15-month-old. A dye (Neurobiotin) was applied to optic nerve stump to retrograde label RGCs. TO-PRO-3 visualized all nuclei of cells in the RGC layer.

The IOP in WT mice was 9.03±0.6 mm Hg on average and did not increase significantly as aging. The IOP in DBA2J mice, arranging from 7.2 to 28 mm Hg, was increasing significantly as aging, and it was normal at 3-month-old compared with WT mice, slightly increased from 7-month-old and increased in 50% animals at 11-month-old and in 38% animals at 15-month-old. The RGCs density in DBA2J mice started reducing by 7-month-old, continuously decreased until reached about 20% of RGC in WT retina by 15-month-old. RGC density was not linearly correlated with IOP in 15-month-old DBA2J mice. The amplitude of positive scotopic threshold response, and negative scotopic threshold response of ERG were significantly reduced in DBA2J mice of 15-month-old than that in age-paired WT mice.

The present study found that DBA2J mice display pathological and functional deficits of the retina that was not linearly correlated with IOP.