Abstract
Purpose: :
Royal jelly (RJ), which is fed to the queen honey-bee, has been reported to possess variety of biological activities toward various types of cells and tissues. Increasing evidence recently suggests that RJ may induce neurite outgrowth and play neuroprotective roles in the adult brain. However, nothing is known about its effect on retinal ganglion cell (RGC). This study examined whether Royal jelly peptide (RJP) prevents RGCs loss in an experimental model of glaucoma.
Methods: :
Intraocular pressure (IOP) elevation in adult male Norwegian Brown rats was induced by anterior chamber injection of paramagnetic polystyrene microspheres. Soluble RJP were intravitreally injected to examine its effects on RGC survival after ocular hypertension by the counting of retrograde FG-labeled RGCs. The loss of nerve fibers and RGC were also evaluated in paraffin-fixed retinal cross sections. The possible mechanisms of neuroprotective effects mediated by RJP were further characterized by determining BDNF and GDNF expressions in retina using Western blotting and Real-time quantitative PCR, respectively.
Results: :
RJP significantly reduced RGC loss 2 and 4 weeks after ocular hypertension. The loss of RGC in PBS-(used as a negative control) and RJP-treated retinas was approximately 34.6% and 19.2% respectively at 4weeks (p<0.01), compared with control. Thus RJP preserved 32.1% of cells that were destined to die in glaucomatous retinas. Western blot and qPCR results showed that RJP obviously up-regulated protein and mRNA expressions of GDNF and BDNF in retinas.
Conclusions: :
The present results first demonstrate that RJP treatment reduced the loss of RGC and neurofibers in an experimental model of glaucoma. RJP may exert neuroprotective effects by up-regulating BDNF and GDNF in retina.
Keywords: ganglion cells • neuroprotection • nutritional factors