Fast hyperbaric decompression after heliox saturation altered the brain proteome in rats

Abstract

Better understanding of the physiological mechanisms and neurological symptoms involved in the development of decompression sickness could contribute to improvements of diving procedures. The main objective of the present study was to determine effects on the brain proteome of fast decompression (1 bar/20 s) compared to controls (1 bar/10 min) after heliox saturation diving, using rats in a model system. The protein S100B, considered a biomarker for brain injury, was not significantly different in serum samples from one week before, immediately after, and one week after the dive. Alterations in the rat brain proteome due to fast decompression were investigated using both iontrap and orbitrap LC-MS, and 967 and 1062 proteins were quantified, respectively. Based on the significantly regulated proteins in the iontrap (56) and orbitrap (128) datasets, the networks “synaptic vesicle fusion and recycling in nerve terminals” and “translation initiation” were significantly enriched in a system biological database analysis (Metacore). Ribosomal proteins (RLA2, RS10) and the proteins hippocalcin-like protein 4 and proteasome subunit beta type-7 were significantly upregulated in both datasets. The heat shock protein 105 kDa, Rho-associated protein kinase 2 and Dynamin-1 were significantly downregulated in both datasets. Another main effect of hyperbaric fast decompression in our experiment is inhibition of endocytosis and stimulation of exocytosis of vesicles in the presynaptic nerve terminal. In addition, fast decompression affected several proteins taking parts in these two main mechanisms of synaptic strength, especially alteration in CDK5/calcineurin are associated with a broad range of neurological disorders. In summary, fast decompression after heliox saturation affected the brain proteome in a rat model for diving, potentially disturbing protein homeostasis, e.g. in synaptic vesicles, and destabilizing cytoskeletal components. Data are available via ProteomeXchange with identifier PXD006349

A Single Simulated Heliox Dive Modifies Endothelial Function in the Vascular Wall of ApoE Knockout Male Rats More Than Females

“…This suggests endothelial dysfunction at early age of ApoE KO rats although this was not studied yet. In comparative studies that simulate human diving, rats have been used more than any other species (Lillo et al, 1985; Lillo and Parker, 2000; Bjorkum et al, 2017). In compressed gas diving, the pulmonary vasculature is exposed to oxidative stress and oxygen toxicity due to high partial pressure of oxygen and inert gas bubbles that develop during the decompression (ascent) phase (Butler and Hills, 1979; Wingelaar et al, 2017).…”

Proteasome and Neuroprotective Effect of Hyperbaric Oxygen Preconditioning in Experimental Global Cerebral Ischemia in Rats

“…While a prolonged exposure to hyperoxia may decrease 20S proteasome activity and increase levels of apoptotic proteins ( 32 ), short repetitive hyperbaric oxygenation might generate opposite results, leading to a conditioning effect. It has been also shown that modulating pressure conditions may affect proteasome expression as hyperbaric decompression upregulates proteasome subunit beta type-7 in the rat brain ( 33 ). Future studies will examine whether and how HBO preferentially targets the apoptotic protein for degradation as suggested by this present study.…”