Investigation of the mechanism of dexmedetomidine-induced hyperthermy in the rat hypothhalamus by proteomics analysis

AIM: In this study it was aimed to invastigate the changing proteome profiles in rat hypothalamus cells via proteomics and bioinformatic analysis to elucidate the detailed central mechanism of body temperature rise due to dexmedetomidine which is a highly selective α2 adrenergic receptor agonist. MATERIALS AND METHODS: After obtaining the ethical approval from Experimental Animals Ethics Committee, 10 adult male rats aged 8-10 weeks were divided into 2 separate groups. 0.15 µg/gr dexmedetomidine was administered intraperitoneally to the experimental group and the same volume of physiological saline was administered intraperitoneally to the control group, for four times in 24 hours. According to the sedation scale hourly scoring was done alongside heart rate, saturation and body temperatures were recorded hourly during sedation. At the end of 24 hours, all subjects were sacrificed using 70% carbon dioxide inhalation followed by guillotine. The hypothalamus were dissected and stored at -80°C in the freezer. High resolution proteomics analysis was performed with Liquid Chromatography-Mass Spectrometer (LC-MS/MS) on the tissue separated by FASP (Filter-Aided Sample Preparation) protocol. Protein identification was performed using PLGS Threshold Inspector and PLGS 3.0.1 bioinformatics tools. For mass comparative analysis of large numbers of samples The Progenesis QIP software was used. Obtained proteins from rat tissue were translated into human orthologs by Gene Set Enrichment Analysis (GSEA), and prominent pathways were determined according to normalized enrichment scores (NES). FINDINGS: Between the two groups of hypothalamus samples, 49 out of 866 proteins identified according to proteomics analysis were statistically significant (p ≤0.05), and 9 protein fold changes (≥1.4-fold change) were found to be statistically significant. STIP 1 (Stress-induced-phosphoprotein 1) and MTCO2 (Cytochrome c oxidase subunit 2) came to presence as the two most important proteins in terms of both statistical significance and fold change. Biological Oxidations, Fatty Acid Metabolism, Gene And Protein Expression By JAK STAT Signalıng After Interleukın 12 Stımulatıon, Proteasome, Cross Presentation Of Soluble Exogenous Antigen Endosomes, Metabolism of Poliamins, IL12 Signaling, IL12 Family Signaling, Cellular Responses To External Stimuli, Cellular Responses of Stress were the pathways that are up-regulated according to NES. G Alpha I Signalling Events, Regulation Of Insulin Secretion, Ion Channel Transport, Opioid Signaling, Signaling By GPCR, Iron Uptake And Transport, Signaling By Receptor Tyrosine Kinases, Neurotransmitter Receptors And Postsynaptic Signal Transmission, Oxidative Phosphorylation, Transmission Across Chemical Synapses, Neuronal System, Transport Of Small Molecules were the pathways that are down-regulated according to NES. CONCLUSION: In our study, pathways that are showing up- and down-regulation and significant proteins were compared with the pathways and significant proteins that were prominently studied in relation to hyperthermia-hypothalamus in articles published previously. STIP 1 (Stress-induced-phosphoprotein 1) and MTCO2 (Cytochrome c oxidase subunit 2), PSMC6 (26S proteasome subunit) and the Cellular Responses To External Stimuli Biological Oxidations they represent, up-regulation of proteasome pathways, down-regulation of Oxidative Phosphorylation pathway are proves the existence of a physiological stress such as fever.