Transient Receptor Potential Canonical 3 Inhibitor Pyr3 Improves Outcomes and Attenuates Astrogliosis After Intracerebral Hemorrhage in Mice

Abstract

Background and Purpose-Intracerebral hemorrhage (ICH) stems from the rupture of blood vessels in the brain, with the subsequent accumulation of blood in the parenchyma. Increasing evidence suggests that blood-derived factors induce excessive inflammatory responses that are involved in the progression of ICH-induced brain injury. Thrombin, a major bloodderived factor, leaks into the brain parenchyma on blood-brain barrier disruption and induces brain injury and astrogliosis. Furthermore, thrombin dynamically upregulates transient receptor potential canonical 3 channel, which contributes to pathological astrogliosis through a feed-forward upregulation of its own expression. The present study investigated whether Ethyl-1-(4-(2,3,3-trichloroacrylamide)phenyl)-5-(trifluoromethyl)-1H-pyrazole-4-carboxylate (Pyr3), a specific transient receptor potential canonical 3 inhibitor, can improve functional outcomes and attenuate astrogliosis after ICH in mice. Methods-Male C57BL6 mice received an intracerebral infusion of collagenase or autologous blood to induce ICH.Pyr3 was given both intracerebroventricularly and intraperitoneally after ICH induction. ICH-induced brain injury was evaluated by quantitative assessment of neurological deficits, brain swelling, and injury volume after ICH. Astrocyte activation was evaluated by immunohistochemical assessment of changes in S100 protein expression. Results-Neurological deficits, neuronal injury, brain edema, and astrocyte activation were all significantly improved by administration of Pyr3. Moreover, delayed administration of Pyr3 at 6 hours or 1 day after blood or collagenase infusion, respectively, also improved the symptoms. Conclusions-Pyr3, a specific inhibitor of transient receptor potential canonical 3, reduced the perihematomal accumulation of astrocytes and ameliorated ICH-induced brain injury. Therefore, transient receptor potential canonical 3 provides a new therapeutic target for the treatment of hemorrhagic brain injury.

Transient Receptor Potential Channels as Drug Targets: From the Science of Basic Research to the Art of Medicine

“…Thrombin typically upregulates TRPC3, which in turn contributes to pathologic astrogliosis (Shirakawa et al, 2010). Administration of the specific TRPC3 blocker Pyr3 in a mouse model reduced neurologic deficits, neuronal injury, brain edema, and perihematomal accumulation of astrocytes and ameliorated intracerebral hemorrhage brain injury (Munakata et al, 2013). Therefore, TRPC3 is a potential therapeutic target for the treatment of hemorrhagic brain injury (Munakata et al, 2013).…”

“…Administration of the specific TRPC3 blocker Pyr3 in a mouse model reduced neurologic deficits, neuronal injury, brain edema, and perihematomal accumulation of astrocytes and ameliorated intracerebral hemorrhage brain injury (Munakata et al, 2013). Therefore, TRPC3 is a potential therapeutic target for the treatment of hemorrhagic brain injury (Munakata et al, 2013). The TRPC6 activator hyperforin attenuated brain infarct volume in rats with middle cerebral artery occlusion in a CREB-mediated fashion .…”

Experimental animal models and inflammatory cellular changes in cerebral ischemic and hemorrhagic stroke

“…Fingolimod treatment decreases both cell types in ICH patients [200] and the total counts of T-cells in the perihematomal area of mouse models of ICH [201] , improves neurological function, and reduces edema after ICH. The number of reactive astrocytes increases significantly in the perihematomal area, and this contributes to ICH-induced injury in both autologous blood and collagenase injection ICH models [202] . Reactive astrocytes participate in edema via the induction of matrix metalloproteinase-9 in an ICH mouse model [203] .…”

Transient receptor potential-canonical 3 modulates sperm motility and capacitation-associated protein tyrosine phosphorylation via [Ca<sup>2+</sup>]<sub>i</sub> mobilization

“…Pyr3 is the most specific TRPC3 inhibitor available. As a single antagonist, Pyr3 has previously been used to investigate the function of TRPC3 [43,44]. In this study, we evaluated the effect of Pyr3 with great caution, taking care to rule out the possibility of non-specific effects or toxicity.…”