Sexually Dimorphic Responses Reveal Multifaceted Benefits of Glibenclamide in Traumatic Brain Injury.

Abstract

Sex disparities in traumatic brain injury (TBI) remain poorly understood. Previous data suggest that males are more susceptible to acute secondary injury processes and cell death, whereas females are more vulnerable chronically. Additional sex-based differences have been reported depending on injury model/severity and post-traumatic neurodegeneration. This gap in understanding limits therapy translation. We previously demonstrated sex-based differences in genetic modulation of a key pathway of secondary injury in TBI, sulfonylurea-receptor 1 (SUR1). Glibenclamide (GLI, SUR1-inhibitor) has shown promise in pre-clinical and early clinical studies of TBI and stroke. Here, we evaluated GLI's modulation of multifaceted TBI outcomes across sex for the first time. In total, 120 mice were randomized to controlled cortical impact (CCI) ± GLI or vehicle (dimethyl sulfoxide, DMSO). Either vehicle or GLI treatment was administered post-CCI using an intraperitoneal (IP) loading dose (10 µg/mouse, 10 min post-TBI), followed by a 7-day subcutaneous maintenance infusion at 0.5 µL/h using ALZET mini-osmotic pumps (1007D, Durect Corp.). Mice were tested for cognitive function (Morris water maze, MWM), motor function (rotarod), anxiety (elevated plus maze, EPM), immunofluorescence markers of neurodegeneration (TAU, TDP43), neurogenesis (SOX2, Ki67), angiogenesis (VEGFA), and cerebral blood flow (CBF) to interrogate behavioral, molecular, and physiological effects of TBI and therapy. Different measures within behavioral, immunofluorescence, and CBF outcomes varied across sex, either post-CCI and/or in response to GLI. Motor impairment had baseline differences across sex post-CCI. In both sexes, behavioral deficits were improved by GLI. The effect of GLI on behavior was moderated by sex, with greater benefit in males versus females, including improved MWM latency (p_{treatment*sex_interaction} < 0.0001) and rotarod latency (p_{treatment*sex_interaction} = 0.016, revolutions per minute, p_{treatment*sex_interaction} = 0.03). Males had increased anxiety post-CCI (EPM); GLI was beneficial across sexes. TDP43 and TAU in several brain regions were increased 72 h post-CCI (males>females, all p < 0.0001). These remained markedly elevated only in females by 21 days, whereas TAU in males decreased without treatment. GLI downregulated TDP43 and TAU across sex and brain region (all p < 0.01-0.0001). In females only, DMSO had similar effects as GLI on TDP43 and TAU. SOX2 was increased in the dentate gyrus (DG) only in males post-CCI (p_72h < 0.01, p_21d < 0.001). GLI increased DG SOX2 in females (p_72h < 0.05, p_21d < 0.001). GLI increased VEGFA at 72 h across sexes. CCI reduced CBF acutely in both sexes; in males, GLI improved this by 21 days (p = 0.031). In females, both GLI and DMSO-vehicle benefited CBF versus untreated-CCI. We demonstrate novel sex-based differences post-CCI and GLI-response across several metrics. TAU was chronically elevated (and responsive to treatment) in females, not males, potentially providing a sex-specific target. DMSO may have previously unrecognized benefits on certain pathways (TAU, CBF) in females. Although GLI has multifaceted benefits across sexes, effects are more pronounced in males. This may have important implications for clinical trial study design and analysis.