Long-term in vivo imaging and measurement of dendritic shrinkage of retinal ganglion cells.
OBJECTIVE
To monitor and measure dendritic shrinkage of retinal ganglion cells (RGCs) in a strain of transgenic mice (Thy-1 YFP) that expresses yellow fluorescent proteins in neurons under the control of a Thy-1 promoter.


METHODS
A total of 125 RGCs from 16 eyes of Thy-1 YFP transgenic mice were serially imaged with a confocal scanning laser ophthalmoscope for 6 months after optic nerve crush. Quantitative analysis of cell body area, axon diameter, dendritic field, number of terminal branches, total dendritic branch length, branching complexity, symmetry, and distance from the optic disc was used to characterize the morphology of RGCs, describe the patterns of axonal and dendritic degeneration, identify the morphologic predictors for cell survival, and estimate the rate of dendritic shrinkage.


RESULTS
RGC damage was observed prospectively to begin with progressive dendritic shrinkage, followed by loss of the axon and the cell body. In a small proportion of RGCs, progressive axonal changes including fragmentation, beading, retraction, and bulb formation were also observed. RGCs with a larger dendritic field and a longer total dendritic branch length in general have a better survival probability. The rate of dendritic shrinkage was variable with a slower rate observed in cells having a larger dendritic field, a longer total dendritic branch length, and a greater distance from the optic disc.


CONCLUSIONS
Estimating the probability of RGC survival and measuring the rate of dendritic shrinkage could become a new paradigm for investigating neuronal degeneration and evaluating the response of neuroprotective treatment.
Department of Ophthalmology and Visual Sciences, Chinese University of Hong Kong, Kowloon, Hong Kong, Peoples Republic of China. tlims00@hotmail.com
Christopher Kai-shun
CK
Leung
Robert N
RN
Weinreb
Zhi Wei
ZW
Li
Shu
S
Liu
James D
JD
Lindsey
Nathan
N
Choi
Lan
L
Liu
Carol Yim-lui
CY
Cheung
Cong
C
Ye
Kunliang
K
Qiu
Li Jia
LJ
Chen
Wing Ho
WH
Yung
Jonathan G
JG
Crowston
Mingliang
M
Pu
Kwok Fai
KF
So
Chi Pui
CP
Pang
Dennis Shun Chiu
DS
Lam
D000818:Animals; D001369:Axons / Q000473:pathology*; D001426:Bacterial Proteins / Q000235:genetics; D002452:Cell Count; D002470:Cell Survival; D003712:Dendrites / Q000473:pathology*; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D007091:Image Processing, Computer-Assisted; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009409:Nerve Crush; D009410:Nerve Degeneration / Q000175:diagnosis*; D009887:Ophthalmoscopy; D020221:Optic Nerve Injuries / Q000175:diagnosis*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D018800:Thy-1 Antigens / Q000235:genetics
D001426:Bacterial Proteins; D008164:Luminescent Proteins; D018800:Thy-1 Antigens; C054562:yellow fluorescent protein, Bacteria