Abstract
Purpose:
To characterize long-term bilateral retinal microglia responses after unilateral optic nerve (ON) transection.
Methods:
Unilateral optic nerve transections were performed intraorbitally on the right side 0.5mm behind the eyeballs of adult Fischer rats. After allowed to survive for various periods of time from 3 days to 12 weeks, retinas from both eyes of the animals were obtained for immunohistochemistry to label microglial cells. Density and morphology of microglial cell were evaluated in retinal flat mounts under fluorescent microscope.
Results:
Quantitative analysis of microglia in flat mount retinas showed that, 3 days after ON transection, the average number of microglial cells in the injured side (1463±137/mm2) was similar to that of the control group (1407±134/mm2). The number was dramatically increased on day 7 (2016±122/mm2), and kept stable for at least 3 weeks before dropped to the control level by 6 weeks (1494±80/mm2). In retinas of the contralateral side, however, no obvious change of the average number of microglial cells was seen. For morphology analysis, average numbers of branch points of microglial processes in bilateral sides were shown decreased by 5 folds on day 7, and kept stable for at least 3 weeks. The numbers of branch points were seen gradually increased in 6 weeks and reached the control level by 12 weeks.
Conclusions:
Proliferation of microglial cells was seen only in the injury side after unilateral ON transection. However, morphology changes of microglial cells were shown in retinas from both eyes.
Keywords: 594 microbial pathogenesis: experimental studies