Acclimation to decompression: stress and cytokine gene expression in rat lungs

• Published in: Journal of applied physiology (1985) 2011-10, Vol.111 (4), p.1007-1013
• Main Authors: YE CHEN, MONTCALM-SMITH, Elizabeth, SCHLAERTH, Christine, AUKER, Charles, MCCARRON, Richard M
• Format: Article
• Language: English
• Subjects: Acclimatization - genetics; Acclimatization - physiology; Animals; Biological and medical sciences; Cells; Cytokines; Cytokines - biosynthesis; Cytokines - genetics; Decompression - methods; Decompression Sickness - genetics; Decompression Sickness - metabolism; Down-Regulation; Early Growth Response Protein 1 - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression; Inflammation - genetics; Inflammation - metabolism; Interleukins - genetics; Interleukins - metabolism; Lung - metabolism; Lung - physiology; Male; MAP Kinase Signaling System - genetics; Mitogen-Activated Protein Kinase Kinases - genetics; Mitogen-Activated Protein Kinase Kinases - metabolism; Oncogene Protein v-akt - genetics; Oncogene Protein v-akt - metabolism; Oxidative Stress - genetics; Oxidative Stress - physiology; Phosphorylation; Phosphorylation - genetics; Rats; Rats, Sprague-Dawley; Signal transduction; Signal Transduction - genetics; Stress, Physiological - genetics; Stress, Physiological - physiology; Tumor Necrosis Factor-alpha - genetics; Tumor Necrosis Factor-alpha - metabolism; Up-Regulation
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01402.2010

Previous studies demonstrated that animals exposed to repeated compression-decompression stress acclimated (i.e., developed reduced susceptibility) to rapid decompression. This study endeavored to characterize inflammatory and stress-related gene expression and signal transduction associated with acclimation to rapid decompression. Rats were divided into four groups: 1) control-sham: pressure naïve rats; 2) acclimation-sham: nine acclimation dives [70 feet seawater (fsw), 30 min]; 3) control-dive: test dive only (175 fsw, 60 min); and 4) acclimation-dive: nine acclimation dives and a test dive. After the test dive, rats were observed for decompression sickness (DCS). Expression of 13 inflammatory and stress-related genes and Akt (or PKB, a serine/threonine protein kinase) and MAPK phosphorylation of lung tissue were examined. The expression of immediate early gene/transcription factor early growth response gene 1 (Egr-1) was observed in both control and acclimation animals with DCS but not in animals without DCS. Increased Egr-1 in control-dive animals with DCS was significantly greater than in acclimation-dive animals with DCS. TNF-α, IL-1β, IL-6, and IL-10 were significantly elevated in control-DCS animals. Acclimation-DCS animals had increased TNF-α, but there was no change in IL-1β, IL-6, and IL-10. High levels of Akt phosphorylation were observed in lungs of acclimation-sham, acclimation-dive, and control-dive animals; phosphorylated ERK1/2 was only observed in animals with DCS. This study suggests that activation of ERK1/2 and upregulation of Egr-1 and its target cytokine genes by rapid decompression may play a role in the initiation and progression of DCS. It may be that the downregulated expression of these genes in animals with DCS is associated with previous exposure to repeated compression-decompression cycles. This study represents an initial step toward understanding the molecular mechanisms associated with acclimation to decompression.