In addition to its IOP lowering properties, many studies on preclinical models have illustrated the neuroprotective effect of brimonidine in protecting neurons from damage [17, 22, 23]. A low-tension glaucoma clinical trial was conducted recently to compare the efficacy of
brimonidine versus timolol in preserving visual function. Patients were randomly assigned to receive monotherapy with either topical brimonidine tartrate (0.2%) or timolol maleate (0.5%), and the visual field progression was studied. Visual field loss was preserved in patients treated with brimonidine despite similar IOP-lowering effect by the two drugs . Inhibitors,research,lifescience,medical These results are consistent with brimonidine’s known neuroprotective properties of enhancing RGC survival and blocking axonal degeneration [17, 24]. Neurotrophic factors have shown promise as potential drugs for treating neurodegenerative conditions since they are responsible Inhibitors,research,lifescience,medical for the growth and maintenance of neurons. Ji et al. evaluated the neuroprotective effect of ciliary neurotropic factor (CNTF) on RGCs in a rat glaucoma Inhibitors,research,lifescience,medical model. The investigators also studied the CNTF-mediated activation of Janus Kinase (JAK)/signal transducer and activation of transcription (JAK-STAT) signaling pathway to identify the potential correlation neuroprotection of RGCs by CNTF. While it is not known how the signaling pathway mediates the protection
of RGCs, it was reported that JAK-STAT signaling plays an important role in halting EGFR inhibitors cancer apoptotic neuronal death [25, 26]. The intravitreal injection of CNTF in rat glaucoma models improved the survival rate of RGCs . It was observed that phosphorylated STAT3 (pSTAT3) and endogenous CNTF concentrations were not sufficient enough to protect the damaged RGCs in hypertensive glaucomatous conditions. Inhibitors,research,lifescience,medical Thus, the injection of exogenous CNTF provided further neuroprotection by increasing pSTAT3 phosphorylation. Although there is a possibility that other signaling pathways could have been activated, experimental
results published by Ji et al., substantiated the importance of CNTF as a promising therapeutic agent for glaucoma treatment. Another neurotrophic Inhibitors,research,lifescience,medical factor that has been investigated in glaucoma treatment is the nerve first growth factor (NGF). Topical administration of NGF in patients with severe retinal dysfunction showed promising improvement after 3 consecutive months of treatment . The study exploited the high permeability properties of NGF when administered topically. This is the first human study reported using this neuroprotective agent, and topical application of NGF demonstrated inhibition of apoptosis of RGCs. Even after discontinuing NGF therapy, neuronal function was maintained for 3 months signifying reduced risk of vision loss in advanced glaucoma . In general, deprivation of neurotrophins in glaucomatous optic nerve coupled with increase in vitreal glutamate concentrations have been implicated in RGCs loss.