Measurement of retinal injury in the rat after optic nerve transection: an RT-PCR study.
OBJECTIVE
In the current study, a non-histological approach, namely semi-quantitative RT-PCR, was used to provide information on retinal ganglion cell (RGC) injury and survival after optic nerve transection (ONT). The levels of mRNAs synthesized by RGCs and glial components were initially measured at defined time points after ONT. Subsequently, a comparison was made between the levels of these mRNAs in the ONT retinas of rats treated with the neuroprotectant BDNF and in rats which received vehicle.


METHODS
Wistar rats received an ONT in one eye, while the fellow eye served as a control. ONT was performed 1-2 mm from the optic disc without damaging the retinal blood supply. In the first experiment, rats were killed at 1, 3, 5, 7, and 21 days after ONT. In the second experiment, brain derived neurotrophic factor (BDNF; 5 microg) or vehicle was injected intravitreally at the same time as the ONT and animals were killed after 7 days.


RESULTS
After ONT, mRNA levels of RGC markers (NF-L and Thy-1) decreased substantially, while levels of GFAP and certain trophic factors mRNAs increased significantly. Administration of BDNF resulted in a substantial, but not complete, preservation of the levels of the RGC specific mRNAs, while ONT induced increases in GFAP and trophic factor mRNAs were not reduced to any great extent by BDNF.


CONCLUSIONS
The present studies show that measurement of NF-L and Thy-1 mRNAs provides a sensitive and reliable index of RGC injury after ONT, while measurement of GFAP and trophic factors mRNAs provides more general information on the effect of the injury on the retina.
Chidlow
Glyn
G
Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK. glyn.chidlow@eye.ox.ac.uk
Casson
Robert
R
Sobrado-Calvo
Paloma
P
Vidal-Sanz
Manuel
M
Osborne
Neville N
NN
D000818:Animals; D019771:Axotomy; D019208:Brain-Derived Neurotrophic Factor / Q000627:therapeutic use; D002470:Cell Survival; D017931:DNA Primers / Q000737:chemistry; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D007124:Immunoenzyme Techniques; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism; D016900:Neurofilament Proteins / Q000235:genetics* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000627:therapeutic use; D020221:Optic Nerve Injuries / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism; D018800:Thy-1 Antigens / Q000235:genetics* / Q000378:metabolism
D019208:Brain-Derived Neurotrophic Factor; D017931:DNA Primers; D005904:Glial Fibrillary Acidic Protein; D009414:Nerve Growth Factors; D016900:Neurofilament Proteins; D018696:Neuroprotective Agents; D012333:RNA, Messenger; D018800:Thy-1 Antigens; C044882:neurofilament protein L; D012243:Rhodopsin