TRPC6 promotes daunorubicin-induced mitochondrial fission and cell death in rat cardiomyocytes with the involvement of ERK1/2-DRP1 activation.

Daunorubicin (DNR-) induced cardiotoxicity seriously restricts its clinical application. Transient receptor potential cation channel subfamily C member 6 (TRPC6) is involved in multiple cardiovascular physiological and pathophysiological processes. However, the role of TRPC6 anthracycline-induced cardiotoxicity (AIC) remains unclear. Mitochondrial fragmentation greatly promotes AIC. TRPC6-mediated ERK1/2 activation has been shown to favor mitochondrial fission in dentate granule cells. The aim of the present study was to elucidate the effects of TRPC6 on daunorubicin- induced cardiotoxicity and identify the mechanisms associated with mitochondrial dynamics. The sparkling results showed that TRPC6 was upregulated in models in vitro and in vivo. TRPC6 knockdown protected cardiomyocytes from DNR-induced cell apoptosis and death. DNR largely facilitated mitochondrial fission, boosted mitochondrial membrane potential collapse and damaged debilitated mitochondrial respiratory function in H9c2 cells，these effects were accompanied by TRPC6 upregulation. siTRPC6 effectively inhibited these mitochondrial adverse aspects showing a positive unexposed effect on mitochondrial morphology and function. Concomitantly, ERK1/2-DRP1 which is related to mitochondrial fission was significantly activated with amplified phosphorylated forms in DNR-treated H9c2 cells. siTRPC6 effectively suppressed ERK1/2-DPR1 over activation, hinting at a potential correlation between TRPC6 and ERK1/2-DRP1 by which mitochondrial dynamics are possibly modulated in AIC. TRPC6 knockdown also raised the Bcl-2/Bax ratio, which may help to block mitochondrial fragmentation-related functional impairment and apoptotic signaling. These findings suggested an essential role of TRPC6 in AIC by intensifying mitochondrial fission and cell death via ERK1/2-DPR1, which could be a potential therapeutic target for AIC.

Establishment of a Rat Model of Superior Sagittal-Sinus Occlusion and Recanalization via a Thread-Embolism Method.

There are many uncontrollable factors in the pathogenesis of cerebral venous sinus thrombosis (CVST). In order to further explore the pathophysiology and morphology of CVST, it is necessary to establish a highly compatible CVST animal model that can standardize the site and stage of venous thrombosis. The present study employed the insertion of a self-made thread embolism into the superior sagittal sinus (SSS) to establish a rat model of SSS occlusion that emulates CVST. The thread embolism was removed after 6 h of SSS occlusion in order to achieve recanalization. After successful preparation of the model, the cerebral blood flow (CBF) status and ultrastructural changes of the blood-brain barrier (BBB) were monitored. This CVST model was able to achieve continuously high occlusion of SSS. The parasagittal venous-collateral circulation underwent extensive compensation and recombination, which alleviated blood flow stasis and brain tissue hypoxia caused by restricted reflux. Removing SSS occlusion significantly improved cerebral circulation, reduced brain edema, and accelerated the receding of brain edema. This study established a new model of acute occlusion and recanalization of SSS in rats via a thread-embolism method, which standardized the ischemic site and stage of venous thrombosis. In addition, our study suggests that promoting collateral circulation may be a potential treatment for promoting brain protection.