Sex Differences in Neuroprotection Provided by Inhibition of TRPM2 Channels following Experimental Stroke

Abstract

The calcium-permeable transient receptor potential M2 (TRPM2) ion channel is activated following oxidative stress and has been implicated in ischemic damage; however, little experimental evidence exists linking TRPM2 channel activation to damage following cerebral ischemia. We directly assessed the involvement of TRPM2 channels in ischemic brain injury using pharmacological inhibitors and short-hairpin RNA (shRNA)-mediated knockdown of TRPM2 expression. Each of the four TRPM2 inhibitors tested provided significant protection to male neurons following in vitro ischemia (oxygen-glucose deprivation, OGD), while having no effect in female neurons. Similarly, TRPM2 knockdown by TRPM2 shRNA resulted in significantly reduced neuronal cell death following OGD only in male neurons. The TRPM2 inhibitor clotrimazole reduced infarct volume in male mice, while having no effect on female infarct volume. Finally, intrastriatal injection of lentivirus expressing shRNA against TRPM2 resulted in significantly smaller striatal infarcts only in male mice following middle cerebral artery occlusion, having no significant effect in female mice. Data presented in the current study demonstrate that TRPM2 inhibition and knockdown preferentially protects male neurons and brain against ischemia in vitro and in vivo, indicating that TRPM2 inhibitors may provide a new therapeutic approach to the treatment of stroke in men.

Androgen and PARP-1 Regulation of TRPM2 Channels after Ischemic Injury

“…14 We confirm that important observation in this study using TRPM2 KO mice and neurons. Similarly, there is extensive evidence that inhibition of PARP-1 activity reduces ischemic injury in the male mouse brain specifically.…”

“…Indeed, we recently demonstrated that genetic knockdown (shRNA) or TRPM2 inhibition with clotrimazole (CTZ) reduced neuronal damage after middle cerebral artery occlusion (MCAO) or in vitro ischemia in male brain while having no effect in the female brain. 14,15 The aim of the current study is to determine the mechanism of TRPM2 regulation in the male brain.…”

Transient Receptor Potential Melastatin Subfamily Member 2 Cation Channel Regulates Detrimental Immune Cell Invasion in Ischemic Stroke

“…Of note, Trpm2 deficiency in ischemic stroke has been suggested to preferentially protect neurons of male mice because of TRPM2 regulation by androgen signaling. 5,7,8 Although in vitro experiments point toward a central role of TRPM2 in neuronal injury, 6,9 its relative contribution to ischemic tissue injury in vivo by controlling immune cell activation has not been investigated. Notably, TRPM2 signaling controls specific functions in immune cells including production of cytokines and chemokines, chemotaxis of immune cells, and inflammasome activation.…”

“…Therefore, TRPM2 might be involved in early ischemic neuronal cell death but also in the subsequent detrimental sterile inflammation. Involvement of TRPM2 in cerebral ischemic injury has recently been investigated, [5][6][7][8] showing a pathogenetic contribution of TRPM2 to ischemic stroke. However, these analyses focused on the role of TRPM2 in neuronal injury during ischemia.…”

Role of the ubiquitin–proteasome system in brain ischemia: Friend or foe?

“…The activation of transient receptor potential melastatin (TRPM) channels, primarily the Ca 2+ -permeable TRPM2 (Lipski et al, 2006;Jia et al, 2011) and TRPM7 channels (Aarts et al, 2003;Sun et al, 2009), has been associated to oxidative stress, in addition to anoxic and ischemic cell death. Another key event during stroke is acidosis, caused by the decrease in the supply of oxygen to the brain, which leads to calcium influx, and failure of oxidative phosphorylation, with an increase in lactate production and the switch to glycolytic metabolism, with the final decrease in tissue pH (Xiong et al, 2004;Gu et al, 2010).…”