Chronic Unpredictable Stress Impairs Vascular Reactivity in Male and Female Mice

Abstract

Background: Chronic stress is known to induce vascular inflammation causing endothelial and vascular smooth muscle dysfunction. Changes in the hypothalamic-pituitary-adrenal axis lead to increased sympathetic and decreased parasympathetic drive, causing the release of inflammatory cytokines in the vasculature, by mechanisms that are unclear. Hypothesis: We hypothesize that chronic unpredictable stress (CUS) increases reactive oxygen species and induces gasdermin pore formation and voltage-dependent anion channel (VDAC) oligomerization in the membrane of the mitochondria, which releases mitochondrial DNA (mtDNA) to the cytosol and induces TNF-α, IL-1β and IL-18 production through activation of the NLRP-3 inflammasome pathway. Methods: Adult male and female C57Bl6/J mice were exposed to 28 consecutive days of chronic unpredictable stress (CUS) or handling (CTL). Systolic blood pressure (SBP) was measured at the end of the stress period by tail cuff plethysmography. Vascular function using myographs was assessed on isolated mesenteric resistance arteries (MRAs), pudendal artery (PA) and aorta from male and female CUS and CTL mice. The arterial rings were kept in physiological salt solution at 37°C, constantly aerated with 95%O2/5%CO2. Concentration-response curves to phenylephrine (PE; 1nM-30μM) and acetylcholine (ACh; 1nM-30μM) were performed. Expression of gasderminD was measured in the MRA by western blot. Concentration-response curves were analyzed using non-linear regression analysis. Data are presented as mean ± S.E.M. Statistical significance set at p<0.05. Data were analyzed with GraphPad Prism 9.2.0. Results: SBP was increased by 12.1±4.9% in CUS mice. In CUS mice, compared to the CTL, the potency of ACh-induced relaxation was decreased in the MRA (pEC50 CUS 6.17±0.09 vs CTL 6.81±0.11; p=0.003) and PA (pEC50 CUS 6.65±0.07 vs CTL 6.31±0.09; p=0.008) but not in the aorta of male mice. In females, the potency to ACh was decreased only in the MRA (pEC50 CUS 5.94±0.30 vs CTL 6.98±0.15; p=0.041). There were no differences in the contractile responses to PE between controls and mice exposed to CUS in the MRA and PA of both males and females, while in the aorta of CUS males, there was a significant reduction in maximal response (EMAX CTL: 4.70±0.48 mN vs CUS 3.01± 0.23mN; p=0.007). The expression of gasderminD was increased in MRA of female mice only. Conclusion: Our results show that, in both sexes, CUS increased SBP and induced vascular dysfunction observed by impaired reactivity to ACh and PE, with increased expression of gasderminD in MRA of female mice only. These results suggest that the vascular adaptations to CUS are sex-dependent. This work was supported by NIH grants P20GM109091 (F.H.), R01HL130972-01A1 (F.G.S.), R01HL5949 (F.G.S.), RO1DK132948 (C.W. & F.P.) and R01 MH129798 (SKW); VA grants: VISN7 RDA (F.H.), Merit awards: BX000168-10A1 (F.G.S.), BX005320 (F.G.S.), and BX002604 (M.J.R.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the abstract. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.