Neurotrophins and nerve regeneration-associated genes are expressed in the cornea after lamellar flap surgery.
OBJECTIVE
To determine the in vivo expression of neurotrophins (NTs) and nerve regeneration-associated genes (RAGs) after surgically creating a hinged lamellar corneal flap in thy1-YFP mice.


METHODS
Lamellar corneal flaps with multiple hinges were created in thy1-YFP mice. Mice were killed at weeks 2, 4, and 8. Quantitative polymerase chain reaction was performed to determine the expression of NTs and RAGs in the corneas after lamellar transection. Nerve growth factor (Ngf), brain-derived neurotrophic factor (Bdnf), glial cell-derived neurotrophic factor (Gdnf), neurotrophin 3, neurotrophin 5, small proline-rich repeat protein 1A (Sprr1a), growth-associated protein 43 (Gap43), and beta III tubulin (Tubb3) gene expressions were analyzed. Whole-mount confocal immunofluorescence and Western analyses were performed for localization and abundance of robustly expressed genes.


RESULTS
Sprouts of fine YFP-positive fronds emanating from transected (injured) nerve bundles were seen in the flap area at 2 weeks onward. Bdnf and Sprr1a were robustly and significantly expressed at 2 weeks postoperatively (>2-fold increase in expression; P<0.05). Bdnf localized to thy1-YFP+ cells in operated corneas. Sprr1a localized to corneal epithelial cell membranes. At 8 weeks, none of the NTs and RAGs had increased expression. Bdnf (ρ=0.73, P=0.001) and Sprr1a (ρ=0.76, P=0.001) showed a significant positive correlation with beta III tubulin.


CONCLUSIONS
The neurotrophin Bdnf and RAG Sprr1a are robustly and significantly expressed during corneal nerve regeneration in vivo.
Corneal Neurobiology Laboratory, Department of Ophthalmology and Visual Sciences, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
Shweta
S
Chaudhary
Abed
A
Namavari
Lisette
L
Yco
Jin-Hong
JH
Chang
Snehal
S
Sonawane
Vishakha
V
Khanolkar
Joy
J
Sarkar
Sandeep
S
Jain
D000818:Animals; D015153:Blotting, Western; D003315:Cornea / Q000294:innervation* / Q000601:surgery; D005786:Gene Expression Regulation / Q000502:physiology*; D051379:Mice; D018613:Microscopy, Confocal; D009414:Nerve Growth Factors / Q000235:genetics*; D009416:Nerve Regeneration / Q000235:genetics*; D016133:Polymerase Chain Reaction; D013524:Surgical Flaps; D012668:Trigeminal Ganglion / Q000502:physiology*
D009414:Nerve Growth Factors