Smoking-derived nicotine (N) and oral contraceptive (OC) synergistically exacerbate ischemic brain damage in females, and the underlying mechanisms remain elusive. In a previous study, we showed that N + OC exposure altered brain glucose metabolism in females. Since lipid metabolism complements glycolysis, the current study aims to examine the metabolic fingerprint of fatty acids in the brain of female rats exposed to N+/−OC. Adolescent and adult Sprague–Dawley female rats were randomly (n = 8 per group) exposed to either saline or N (4.5 mg/kg) +/−OC (combined OC or placebo delivered via oral gavage) for 16–21 days. Following exposure, brain tissue was harvested for unbiased metabolomic analysis (performed by Metabolon Inc., Morrisville, NC, USA) and the metabolomic profile changes were complemented with Western blot analysis of key enzymes in the lipid pathway. Metabolomic data showed significant accumulation of fatty acids and phosphatidylcholine (PC) metabolites in the brain. Adolescent, more so than adult females, exposed to N + OC showed significant increases in carnitine-conjugated fatty acid metabolites compared to saline control animals. These changes in fatty acyl carnitines were accompanied by an increase in a subset of free fatty acids, suggesting elevated fatty acid β-oxidation in the mitochondria to meet energy demand. In support, β-hydroxybutyrate was significantly lower in N + OC exposure groups in adolescent animals, implying a complete shunting of acetyl CoA for energy production via the TCA cycle. The reported changes in fatty acids and PC metabolism due to N + OC could inhibit post-translational palmitoylation of membrane proteins and synaptic vesicle formation, respectively, thus exacerbating ischemic brain damage in female rats.
Introduction: Smoking is a preventable risk factor for stroke and battery-operated nicotine delivery systems known as electronic cigarettes (EC) are popular. EC vapes aerosolize a mix of nicotine and chemicals forming harmful toxicants such as formaldehyde hemiacetal. Our understanding about effects of EC vaping on stroke outcome is limited. This study investigated effects of EC on global metabolic signature and stroke outcome in animals of both sexes. Methods: Sprague-Dawley rats (2-3 months old; n=8) of both sexes were randomly assigned either to air or EC vapor (5% nicotine Juul pods) exposure using the EcigAero-TM Aerosol Exposure Apparatus. Rats were exposed to air/EC for 16 nights. Per night, rats were exposed to 16 episodes of EC vapor. Each episode consisted of 2 seconds of Juul puffs followed by 8 seconds of air over the period of 8 minutes. After 16 days, the rats were divided into two cohorts. The first cohort of rats exposed to EC/Air was tested for cognitive capacities using the Morris water maze (WM) followed by brain collection for unbiased metabolomic (Metabolon Inc.) or Western blot analysis. The second cohort of rats exposed to EC/Air was subjected to transient middle cerebral artery occlusion (tMCAO; 90 min) or sham surgery and survived for 15-21 days. During the post-tMCAO survival, rats were tested for cognition using WM followed by brain collection for histopathological analysis. Results: Metabolomic analysis indicated that EC exposure resulted in significant increases (p≤0.05) in phenylalanine and tryptophan metabolites, and both increases (p≤0.05) and decreases (p≤0.05) in histamine and tyrosine metabolites in the brains of female and male rats. Western blotting of rate-limiting enzymes in respective NT pathways corroborated the metabolomic data. Behavioral testing indicated worsened cognitive outcome in EC groups compared to air groups in rats of both sexes. Conclusion: EC vape exposure, even for as short as 2 weeks, impacts the metabolism of NT, induces cognitive deficits and worsens stroke outcomes in young male and female rats. Future studies investigating the impact of EC withdrawal on NT metabolism are needed to understand how long the deleterious effects of EC vaping persist in the brain.
Glioblastoma (GBM) remains the most common adult brain cancer, with a dismal average patient survival of less than two years. No new treatments have been approved for GBM since the introduction of the alkylating agent temozolomide in 2005. Even then, temozolomide treatment only increases the average survival of GBM patients by a few months. Thus, novel therapeutic options are direly needed. The aurora kinases A and B are targetable and overexpressed in GBM, and their expression is highly correlated with patient survival outcomes. Our lab has found that small molecule aurora kinase inhibition reduces GBM tumor growth in vitro and in vivo, however, eventually tumors still grow. Computational analysis integrating compound transcriptional response signatures from the LINCS L1000 dataset with the single-cell RNA-sequencing data of patient GBM tumors resected at the University of Miami predicts that aurora inhibition targets a subset of cells present within any GBM tumor. Results of in vivo single-cell perturbation experiments with the aurora kinase inhibitor alisertib coincide with our predictions and reveal a cellular transcriptional phenotype resistant to aurora kinase inhibition, characterized by a mesenchymal expression program. We find that small molecules that are predicted to target different cell populations from alisertib, including this resistant mesenchymal population, synergize with alisertib to kill GBM cells. As a whole, we have identified the cellular population resistant to aurora kinase inhibition and have developed an analytical framework that identifies synergistic small molecule combinations by identifying compounds that target transcriptionally distinct cellular populations within GBM tumors.
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