Ciliary neurotrophic factor protects rat retina cells in vitro and in vivo via PI3 kinase.
OBJECTIVE
Neurotrophic factors and neurotrophins are well-known to have neuroprotective efficacy against retinal injury. The aim of this experiment is to investigate the signal transduction pathway of ciliary neurotrophic factor (CNTF) on the upregulation of viability of retinal primary culture and retinal protection against constant light damage in vivo. CNTF is known to enhance the viability of retinal culture and provide protection under constant light exposure conditions, but little is known about how the signal transduction pathways of CNTF affect retina function.


METHODS
Primary retinal cultures were prepared from 7-day-old Wistar rats. Brain-derived neurotrophic factor (BDNF) (0.1, 1, 10 ng/ml), CNTF (0.1, 1, 10 ng/ml), PD98059 (10, 100, 1000 nM), or LY294002 (10, 100, 1000 nM) was added to these cultures at the time of cell preparation. After 3 days, the percentage of cells surviving was assessed using alamarBlue. For the in vivo experiment, inhibitors for the MAPKK (PD98059, 10 microg/eye) or PI3K (LY294002, 10 microg/eye) pathways were injected into the vitreous together with CNTF (1 microg/eye) 2 days before constant light exposure. Electroretinogram (ERG) analysis was performed to investigate which pathway was used by CNTF.


RESULTS
CNTF at 1, 10, or 100 ng/ml enhanced cell viability in retinal cultures. The cell-survival activity of CNTF was blocked by 10 ng/ml LY294002 (Dunnet's test, p < 0.05). In vivo, the neuroprotective activity of CNTF in constant-light conditions was attenuated by 10 microg/eye LY294002 (Dunnet's test, p < 0.05).


CONCLUSIONS
These data suggest that CNTF promotes cell survival via the PI3K signaling pathway in vitro and in vivo.
Ikeda
Kazuhito
K
Sumitomo Pharmaceuticals Research Division, Osaka 554-0022, Japan. ikedak@sumitomopharm.co.jp
Tatsuno
Tohru
T
Noguchi
Hiroshi
H
Nakayama
Chikao
C
D000818:Animals; D000831:Animals, Newborn; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D020934:Ciliary Neurotrophic Factor / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects; D003623:Dark Adaptation; D004596:Electroretinography / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology; D008027:Light; D008297:Male; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011833:Radiation Injuries, Experimental / Q000201:enzymology / Q000503:physiopathology / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000528:radiation effects; D012162:Retinal Degeneration / Q000201:enzymology / Q000503:physiopathology / Q000517:prevention & control*
D019208:Brain-Derived Neurotrophic Factor; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002867:Chromones; D020934:Ciliary Neurotrophic Factor; D005419:Flavonoids; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one