Abstract WP327: Modulation of Microvascular Blood Flow and Stroke Outcome via GPR39

Abstract

Background: Ischemic stroke is a leading cause of morbidity and mortality. Efficacy of current thrombolytic and endovascular therapies are not uniform in all patients, and depends on age, stroke severity and diabetic status. This is in part attributed to impaired microvascular reperfusion, which limits the benefit from large-vessel recanalization. Microvascular blood flow is regulated by a number of molecules including the P450 eicosanoids which are arachidonic acid-derived lipid signaling molecules whose levels are known to be altered during stroke. We have recently identified GPR39 as a dual sensor for two vasoactive P450 eicosanoids: the dilator 14,15-epoxyeicosatrienoate (EET) and constrictor 15-hydroxyeicosatetranoate (HETE). GPR39 is expressed in arteriolar vascular smooth muscle cells and peri-capillary pericytes. Thus, GPR39 is uniquely positioned to sense the balance of vasoactive eicosanoids and modulate microvascular blood flow during and following stroke. To investigate the role of GPR39 in stroke, we have generated a global GPR39 knock-out (KO) mouse via CRISPR/Cas9 deletion of the receptor’s first exon, eliminating expression of GPR39. We tested the hypothesis that GPR39 KO mice sustain larger infarcts after transient focal cerebral ischemia compared to wild-type (WT) littermates with intact GPR39. Methods: A 60-min middle cerebral artery occlusion (MCAO) was induced in 3-month old male and female mice using a silicone coated filament introduced through an external carotid stump under isoflurane anesthesia. A total of 15 KO (8 males, 7 females) and 8 WT (4 males and 4 females) mice were used for the study. Brains were harvested at 24 hours of reperfusion, sliced coronally in 2-mm segments, sections stained with triphenyltetrazolium chloride ( TTC ), and infarcted areas measured after accounting for edema. Results: Hemispheric infarct was 44.7% ± 3.31% in male GPR39 KO mice compared to 34.7% ± 5.23% in WT male littermates (mean ± sem, p=0.07). In females, infarct size was 30.3% ± 5.58% in GPR39 KO mice compared to 33.9% ± 1.45% in WT littermates (p = 0.34). Conclusions: Our preliminary results suggest that GPR39 plays a sexually-dimorphic protective role in ischemic stroke, and that GPR39 may serve as a therapeutic target in stroke.