Background: Epidemiology links noise to increased risk of metabolic diseases like diabetes and obesity. Translational studies in humans and experimental animals showed that noise causes reactive oxygen species (ROS)-mediated cardiovascular damage. The interaction between noise and diabetes, specifically potential additive adverse effects, remains to be determined.
Methods and results: C57BL/6 mice were treated with streptozotocin (i.p. injections, 50 mg/kg/d for 5d) to induce type-1 diabetes, with S961 (subcutaneous osmotic minipumps, 0.57 mg/kg/d for 7d) or fed a high-fat diet (HFD, 20 weeks) to induce type-2 diabetes. Control and diabetic mice were exposed to aircraft noise to an average sound pressure level of 72 dB(A) for 4d. While body weight was unaffected, noise reduced insulin production in all diabetes models. The oral glucose tolerance test showed only an additive aggravation by noise in the HFD model. Noise increased blood pressure and aggravated diabetes-induced aortic, mesenteric, and cerebral arterioles endothelial dysfunction. ROS formation in cerebral arterioles, the aorta, the heart, and isolated mitochondria was consistently increased by noise in all models of diabetes. Mitochondrial respiration was impaired by diabetes and noise, however without additive effects. Noise increased ROS and caused inflammation in adipose tissue in the HFD model. RNA sequencing data and alteration of gene pathway clusters also supported additive damage by noise in the setting of diabetes.
Conclusion: In all three models of diabetes, aircraft noise exacerbates oxidative stress, inflammation, and endothelial dysfunction in mice with pre-existing diabetes. Thus, noise may potentiate the already increased cardiovascular risk in diabetic patients.
Keywords: Noise exposure; cardiovascular complications; diabetes; oxidative stress.
Traffic noise significantly contributes to an increased risk of cardiometabolic diseases (including diabetes and obesity) in the general population via stress hormones, inflammation and oxidative stress, all of which contribute to impaired vascular function and high blood pressure. However, the extent to which noise affects pre-existing diabetes is not sufficiently explained, which prompted us to investigate the molecular mechanisms responsible for noise-mediated exacerbation of cardiometabolic complications in three different animal models with diabetes mellitus: Noise exposure in diabetic mice caused further impairment of insulin signalling, increased blood pressure, and damage of small and large blood vessels as well as oxidative stress in the aorta, brain, and heart.Our functional observations were supported by gene analyses indicating combined effects of noise and diabetes on gene groups related to inflammation and metabolism, suggesting a need for further studies in humans to investigate how noise impacts cardiovascular risk in vulnerable groups such as patients with diabetes.
© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.