The GHRH agonist MR-409 promoted retinal ganglion cell survival after optic nerve injury in rats and enhanced the protective effects of macrophage activation, suggesting therapeutic potential for glaucoma.
Additive neuroprotectionGHRH agonist MR-409 enhanced macrophage-mediated RGC survival beyond either treatment alone
What the researchers found
GHRH agonist MR-409 protected retinal ganglion cells after optic nerve injury and additively enhanced macrophage-mediated neuroprotection, with effects mediated through Akt phosphorylation and microglial activation.
Why it matters
Glaucoma affects over 100 million people worldwide with no cure. Finding that GHRH agonists can protect retinal nerve cells and enhance existing neuroprotective mechanisms opens a new therapeutic avenue for preserving vision.
The numbers in context
GHRH-R on RGCs confirmed; MR-409 increased RGC survival; Akt phosphorylation increased; microglia activated by agonist; IL-1β, IL-6, TNF reduced by antagonist
How the study worked
Rat optic nerve crush model. Subcutaneous GHRH agonist (MR-409) or antagonist (MIA-602) treatment. RGC survival quantification, retinal Akt phosphorylation, microglial activation, inflammation gene expression, and combination with lens injury/zymosan-induced macrophage activation.
Who was studied
Adult rats with optic nerve crush injury
What this study cannot tell us
Rat model — optic nerve crush differs from the gradual nerve damage in human glaucoma. Subcutaneous administration raises questions about achieving sufficient drug levels in the eye. Long-term effects not studied.
How to read the evidence
Published in PNAS with thorough mechanistic investigation. High-quality preclinical evidence from a well-designed animal study.
When this study was published
Published in 2021, revealing a novel application for GHRH agonists in optic neuropathy.
The bigger picture
Current glaucoma treatments focus on lowering eye pressure, but nerve cell damage often continues. GHRH agonists represent a fundamentally different approach — directly protecting the nerve cells themselves — which could complement pressure-lowering treatments for better outcomes.
Questions still open
- Could GHRH agonists be delivered directly to the eye for greater effect?
- Would GHRH agonists work in chronic glaucoma models with gradual nerve damage?
- Are there systemic side effects of GHRH agonists that would limit their use for eye disease?
Common questions
Could this peptide help people with glaucoma?
What's the difference between the GHRH agonist and antagonist effects?
Read the original research
Agonist of growth hormone-releasing hormone enhances retinal ganglion cell protection induced by macrophages after optic nerve injury.
Proceedings of the National Academy of Sciences of the United States of America, 118(28)
Citation
Cen, Ling-Ping; Ng, Tsz Kin; Liang, Jia-Jian; Xu, Ciyan; Zhuang, Xi; Liu, Yu-Fen; Chen, Shao-Lang; Xu, Yanxuan; Yang, Qichen; Yuan, Xiang-Ling; Qin, Yong Jie; Chan, Sun On; Chen, Haoyu; Zhang, Mingzhi; Schally, Andrew V; Pang, Chi Pui. (2021). Agonist of growth hormone-releasing hormone enhances retinal ganglion cell protection induced by macrophages after optic nerve injury.. Proceedings of the National Academy of Sciences of the United States of America, 118(28). https://doi.org/10.1073/pnas.1920834118