Pharmacological hypothermia induced neurovascular protection after severe stroke of transient middle cerebral artery occlusion in mice.
HPI-201-induced hypothermia shows potential for neurovascular protection in mice after severe stroke, but human applicability is unclear.
Where it sits
this study against the rest of the abs-201 corpusSummary and findings
The study assessed the neurovascular protective effects of pharmacological hypothermia induced by HPI-201 in mice after severe ischemic stroke. Mice underwent middle cerebral artery occlusion and were treated with HPI-201 to maintain hypothermia. The treatment reduced infarct volume, neuronal cell death, and inflammation while improving blood-brain barrier integrity.
Abstract
Therapeutic hypothermia is a potential protective strategy after stroke. The present study evaluated the neurovascular protective potential of pharmacological hypothermia induced by the neurotensin receptor 1 agonist HPI-201 after severe ischemic stroke. Adult C57BL/6 mice were subjected to filament insertion-induced occlusion of the middle cerebral artery (60 min MCAO). HPI-201 was i.p. injected 120 min after the onset of MCAO to initiate and maintain the body temperature at 32-33°C for 6 hrs. The infarct volume, cell death, integrity of the blood brain barrier (BBB) and neurovascular unit (NVU), inflammation, and functional outcomes were evaluated. The hypothermic treatment significantly suppressed the infarct volume and neuronal cell death, accompanied with reduced caspase-3 activation and BAX expression while Bcl-2 increased in the peri-infarct region. The cellular integrity of the BBB and NVU was significantly improved and brain edema was attenuated in HPI-201-treated mice compared to stroke controls. The hypothermic treatment decreased the expression of inflammatory factors including tumor necrosis factor-α (TNF-α), MMP-9, interleukin-1β (IL-1β), the M1 microglia markers IL-12 and inducible nitric oxide synthase (iNOS), while increased the M2 marker arginase-1 (Arg-1). Stroke mice received the hypothermic treatment showed lower neurological severity score (NSS), performed significantly better in functional tests, the mortality rate in the hypothermic group was noticeably lower compared with stroke controls. Taken together, HPI-201 induced pharmacological hypothermia is protective for different neurovascular cells after a severely injured brain, mediated by multiple mechanisms.
Background
Stroke is a leading cause of disability and death, and therapeutic hypothermia has been proposed as a protective strategy to mitigate damage. Previous research has suggested that lowering body temperature can reduce neuronal injury and improve outcomes after stroke. This study explores the potential of HPI-201, a neurotensin receptor 1 agonist, to induce hypothermia and provide neurovascular protection in a mouse model of severe ischemic stroke.
Methods
The study used adult C57BL/6 mice subjected to a 60-minute middle cerebral artery occlusion to simulate severe ischemic stroke. HPI-201 was administered intraperitoneally 120 minutes post-occlusion to induce and maintain hypothermia at 32-33°C for 6 hours. Outcomes measured included infarct volume, neuronal cell death, blood-brain barrier integrity, inflammation, and functional performance.
Results
Pharmacological hypothermia significantly reduced infarct volume and neuronal cell death, with decreased caspase-3 activation and BAX expression, and increased Bcl-2 in the peri-infarct region. Blood-brain barrier and neurovascular unit integrity were improved, and brain edema was reduced. Inflammatory markers such as TNF-α, MMP-9, IL-1β, IL-12, and iNOS were decreased, while the M2 microglia marker Arg-1 was increased. Treated mice showed better functional outcomes and lower mortality rates compared to controls.
Interpretation
The findings suggest that HPI-201-induced hypothermia may offer neurovascular protection by reducing inflammation and preserving cellular integrity in a mouse model of severe stroke. While the results are promising, the clinical relevance remains uncertain due to the study's animal model and lack of long-term outcome data. Further research is needed to determine if these effects can be replicated in humans.
Key findings
- Infarct volume and neuronal cell death were significantly suppressed.
- Caspase-3 activation and BAX expression were reduced, while Bcl-2 increased.
- Blood-brain barrier and neurovascular unit integrity improved.
- Inflammatory markers TNF-α, MMP-9, IL-1β, IL-12, and iNOS decreased.
- M2 microglia marker Arg-1 increased.
Limitations
- Animal study, not human.
- Short-term follow-up.
- Single species model.
- No long-term outcome data.