The synthetic GHRH agonist MR-409 reduced stroke mortality, brain damage, and hippocampal atrophy while promoting neurogenesis and functional recovery through AKT/CREB and BDNF/TrkB pathway activation in mice.
Protect + regenerateMR-409 both protected existing neurons from stroke damage AND generated new neurons — addressing the two biggest needs in stroke recovery
What the researchers found
MR-409 (5-10 μg/mouse/day SC) reduced mortality, ischemic damage, and hippocampal atrophy in tMCAO stroke mice. Enhanced endogenous neurogenesis and neuroplasticity. Protected neural stem cells from oxygen-glucose deprivation. Mechanism: AKT/CREB and BDNF/TrkB activation.
Why it matters
Stroke is the second leading cause of death and leading cause of disability worldwide. No drug currently promotes brain repair after stroke. A GHRH agonist that both protects neurons and generates new ones could be transformative.
The numbers in context
5 or 10 μg/mouse/day s.c.; reduced mortality and ischemic insult; pathways: AKT/CREB, BDNF/TrkB; tMCAO model
How the study worked
Animal study. Transient middle cerebral artery occlusion (tMCAO) stroke model in mice. MR-409 subcutaneous injection (5 or 10 μg/mouse/day). Mortality, infarct size, hippocampal volume, neurogenesis, and neurological function assessed. Neural stem cell in vitro studies. AKT/CREB and BDNF/TrkB pathway analysis.
Who was studied
C57BL/6 mice with transient middle cerebral artery occlusion (stroke model)
What this study cannot tell us
Mouse stroke model — human stroke is more complex. Long-term treatment started after stroke onset. Translation of neurogenesis findings to humans uncertain. Specific contribution of growth hormone release vs direct neuroprotection not fully separated.
How to read the evidence
Moderate evidence: animal stroke model with multiple endpoints (mortality, histology, function, neurogenesis, mechanism) showing consistent benefit.
When this study was published
Published 2021. GHRH agonists for neuroprotection are in early clinical development.
The bigger picture
GHRH agonists are being explored for multiple protective roles — from cancer cachexia to cardiac injury to now stroke. Their cell-protective and regenerative properties suggest a fundamental role in tissue survival signaling beyond just growth hormone release.
Questions still open
- Would MR-409 or similar GHRH agonists improve stroke recovery in human clinical trials?
- Is the neuroprotection mediated directly by GHRH receptor activation or indirectly through growth hormone?
- What is the optimal treatment window after stroke for GHRH agonist administration?
Common questions
Could this help stroke patients?
What is GHRH and how does it protect the brain?
Read the original research
Agonistic analog of growth hormone-releasing hormone promotes neurofunctional recovery and neural regeneration in ischemic stroke.
Proceedings of the National Academy of Sciences of the United States of America, 118(47)
Citation
Liu, Yueyang; Yang, Jingyu; Che, Xiaohang; Huang, Jianhua; Zhang, Xianyang; Fu, Xiaoxiao; Cai, Jialing; Yao, Yang; Zhang, Haotian; Cai, Ruiping; Su, Xiaomin; Xu, Qian; Ren, Fu; Cai, Renzhi; Schally, Andrew V; Zhou, Ming-Sheng. (2021). Agonistic analog of growth hormone-releasing hormone promotes neurofunctional recovery and neural regeneration in ischemic stroke.. Proceedings of the National Academy of Sciences of the United States of America, 118(47). https://doi.org/10.1073/pnas.2109600118