Nicotine and electronic cigarette (E‐Cig) exposure decreases brain glucose utilization in ischemic stroke

Abstract

Previous studies in our laboratory have shown that nicotine exposure decreases glucose transport across the blood-brain barrier in ischemia-reperfusion conditions. We hypothesize that nicotine can also dysregulate brain parenchymal glucose utilization by altering glucose transporters with effects on sensitivity to ischemic stroke. In this study, we investigated the effects of nicotine exposure on neuronal glucose utilization using an in vitro ischemic stroke model. We also tested the effects of e-Cig vaping on ischemic brain glucose utilization using an acute brain slice technique. Primary cortical neurons and brain slices were subjected to oxygen-glucose deprivation followed by reoxygenation to mimic ischemia-reperfusion injury. We estimated brain cell glucose utilization by measuring the uptake of [ H] deoxy-d-glucose. Immunofluorescence and western blotting were done to characterize glucose transporters (GLUTs) and α7 nicotinic acetylcholine receptor (nAChR) expression. Furthermore, we used a glycolytic stress test to measure the effects of nicotine exposure on neuronal glucose metabolism. We observed that short- and long-term nicotine/cotinine exposure significantly decreased neuronal glucose utilization in ischemic conditions and the non-specific nAChR antagonist, mecamylamine reversed this effect. Nicotine/cotinine exposure also decreased neuronal GLUT1 and up-regulated α7 nAChR expression and decreased glycolysis. Exposure of mice to e-Cig vapor for 7 days likewise decreases brain glucose uptake under normoxic and ischemic conditions along with down-regulation of GLUT1 and GLUT3 expressions. These data support, from a cerebrovascular perspective, that nicotine and/or e-Cig vaping induce a state of glucose deprivation at the neurovascular unit which could lead to enhanced ischemic brain injury and/or stroke risk. OPEN PRACTICES: Open Science: This manuscript was awarded with the Open Materials Badge. For more information see: https://cos.io/our-services/open-science-badges/.

Prenatal electronic cigarette exposure decreases brain glucose utilization and worsens outcome in offspring hypoxic–ischemic brain injury

“…There have been reports of adverse health effects of e‐Cig use including enhanced carcinogenic potential (Lee et al, ), oxidative stress and inflammatory activity (Muthumalage et al, ), as well as altered BBB permeability and worsened ischemic brain injury (Kaisar, Villalba, et al, ). We have previously published that e‐Cig exposure can also decrease brain glucose utilization in ischemic stroke (Sifat et al, ). Among the general population, a group of people who can be drastically affected by the e‐Cig are pregnant women.…”

“…The severity of neonatal HI brain injury was found to be inversely correlated with total brain glucose metabolism in a clinical study (Thorngren‐Jerneck et al, ). Previously we have reported that nicotine and e‐Cig exposure decreases brain glucose utilization in ischemic stroke (Sifat et al, ). But, till date, no study has been done to investigate the effects of prenatal e‐Cig exposure on offspring brain glucose utilization and the glucose transporters expression after neonatal HI brain injury.…”

“…This exposure model was adopted following a partial modification of the study by Li et al who investigated effects of perinatal nicotine exposure on offspring HI brain injury in rats (Li, Xiao, et al, ). We used Blu™ as this is a popular e‐Cig brand, the cig‐a‐like structure is convenient to use in the smoking apparatus, and there have been previously reported studies using Blu™ (Kaisar, Villalba, et al, ; Sifat et al, ). A modified CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco) standard smoking protocol adapted to study e‐Cig exposure (27.5 ml puff depth volume, 3 s puff duration, 2 puffs per 60 s, 32 puffs/session) was followed in the laboratory.…”

“…A modified CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco) standard smoking protocol adapted to study e‐Cig exposure (27.5 ml puff depth volume, 3 s puff duration, 2 puffs per 60 s, 32 puffs/session) was followed in the laboratory. E‐Cig vapor was generated using a Single Cigarette Smoking Machines (SCSM, CH Technologies Inc.) following a previously published method (Kaisar, Villalba, et al, ; Sifat et al, ). This method was followed to mimic the smoking behavior of a human chronic and heavy smoker and yields plasma levels of cotinine (111 ng/ml) which is in the range of blood cotinine level (30–250 ng/ml) found in other preclinical rodent models of chronic e‐Cig exposure (McGrath‐Morrow et al, ; Shi et al, ).…”

“…The sample size for the animal study was estimated based on published literature (Li, Xiao, et al, ; Shah, Boreddy, & Abbruscato, ; Sifat et al, ). No sample size calculation was performed and there were no sample size differences between the beginning and end of the experiments.…”