TRPM4 inhibition promotes angiogenesis after ischemic stroke.

Transient receptor potential melastatin 4 (TRPM4) is a voltage-dependent, nonselective cation channel. Under pathological conditions, sustained activation of TRPM4 leads to oncotic cell death. Here, we report the upregulation of TRPM4 in vascular endothelium following hypoxia/ischemia in vitro and in vivo. In human umbilical vein endothelial cells, TRPM4 expression was increased at both the mRNA and protein levels following oxygen-glucose deprivation. Blocking TRPM4 with 9-phenanthrol greatly enhanced tube formation on Matrigel. In a rat permanent middle cerebral artery occlusion model, TRPM4 was upregulated in the vascular endothelium within the penumbra region after stroke. TRPM4 expression peaked 1 day post-occlusion and gradually decreased. In vivo siRNA-mediated TRPM4 silencing enhanced angiogenesis and improved capillary integrity. A twofold reduction in infarct volume and a substantial recovery of motor function were observed in animals receiving the siRNA treatment. Interestingly, the protective effect of TRPM4 suppression disappeared 5 days after stroke induction, indicating that TRPM4 upregulation is critical for cerebral damage during the acute phase of stroke. TRPM4 could be a potential therapeutic target for ischemic stroke.

Leonurine protects middle cerebral artery occluded rats through antioxidant effect and regulation of mitochondrial function.

BACKGROUND AND PURPOSE: Oxidative stress is known to be involved in ischemic stroke. Intense interest is drawn to the therapeutic potential of Chinese herbs on ischemic stroke because many of them contain antioxidant properties. Leonurine, 1 of the active compounds from purified Herba Leonuri, was studied to evaluate its possible therapeutic effects on ischemic stroke. Method-Middle cerebral artery occlusion was selected as our model of study. The animals were pretreated with Leonurine orally for 7 days and the surgery was done. One day after surgery, 2,3,5-triphenyltetrazolium chloride staining and neurological deficit score were carried out to evaluate the functional outcome of animals, whereas levels of superoxide dismutase, glutathione peroxidase, and malondialdehyde were analyzed for oxidative stress analysis. For mitochondrial studies, 3 hours after surgery, mitochondria were isolated for analysis of reactive oxygen species production, adenosine triphosphate biosynthesis, oxygen consumption, and respiratory control ratio value. Result-In in vivo experiments, Leonurine pretreatment reduced infarct volume, improved neurological deficit in stroke groups, increased activities of antioxidant enzymes superoxide dismutase and glutathione peroxidase, and decreased levels from the lipid peroxidation marker malondialdehyde. In terms of mitochondrial modulation, Leonurine inhibited mitochondrial reactive oxygen species production and adenosine triphosphate biosynthesis. Animal studies also demonstrated that the mitochondrial function and redox state were restored by Leonurine treatment. CONCLUSIONS: Leonurine has neuroprotective effects and carries a therapeutic potential of stroke prevention.

Oxidative stress: apoptosis in neuronal injury.

Apoptosis has been well documented to play a significant role in cell loss during neurodegenerative disorders, such as stroke, Parkinson disease, and Alzheimer's disease. In addition, reactive oxygen species (ROS) has been implicated in the cellular damage during these neurodegenerative disorders. These ROS can react with cellular macromolecular through oxidation and cause the cells undergo necrosis or apoptosis. The control of the redox environment of the cell provides addition regulation in the signal transduction pathways which are redox sensitive. Recently, many researches focus on the relationship between apoptosis and oxidative stress. However, till now, there is no clear and defined mechanisms that how oxidative stress could contribute to the apoptosis. This review hopes to make clear that generation of ROS during brain injury, particularly in ischemic stroke and Alzheimer's Disease, and the fact that oxidative state plays a key role in the regulation and control of the cell survival and cell death through its interaction with cellular macromolecules and signal transduction pathway, and ultimately helps in developing an unique therapy for the treatment of these neurodegenerative disorders.

Cerebral protection of purified Herba Leonuri extract on middle cerebral artery occluded rats.

AIM OF STUDY: Oxidative stress is involved in stroke. In particular, Chinese Herbal Medicine with antioxidant properties is believed to have potential therapeutic effect. In this study, neuroprotective effects of purified Herba Leonuri (pHL) were evaluated in Wistar rats undergone middle cerebral artery occlusion (MCAO). MATERIALS AND METHODS: The rats were treated with their respective treatments for 2 weeks prior to the MCAO, continually treated for another 7 days after MCAO. During the post-surgery treatment period, neurological deficit score was measured. At the end of treatment, animals were sacrificed and samples were collected for analysis of infarct volume, apoptosis and antioxidant analysis. RESULTS: Under the treatment of pHL, the infarct volume was reduced significantly from 20.75+/-0.03% to 15.19+/-0.02% (p<0.05). The neurological impairment was alleviated to 1.82 as compared to vehicle (2.43). Plasma antioxidant concentration was increased from 0.31+/-0.03 mM to 0.42+/-0.05 mM (p<0.05). DNA oxidative damage was reduced to 1.19+/-0.03 in stroke pHL treated group (p<0.05 as compared to vehicle group, 1.78+/-0.03). pHL could reduce the level of apoptosis and also the pro-apoptotic proteins, but increase the level of anti-apoptotic proteins. CONCLUSION: pHL is believed to have promising therapeutic effect for stroke treatment through antioxidant mechanisms.