Abstract
Massive bubble formation after diving can lead to decompression sickness (DCS), which can result in neurological disorders. We demonstrated that hydrogen production from intestinal fermentation could exacerbate DCS in rats fed with a standard diet. The aim of this study is to identify a fecal metabolomic signature that may result from the effects of a provocative hyperbaric exposure. The fecal metabolome was studied in two groups of rats previously fed with maize or soy in order to account for diet effects. 64 animals, weighing 379.0_20.2 g on the day of the dive, were exposed to the hyperbaric protocol. The rats were separated into two groups: 32 fed with maize (Div MAIZE) and 32 fed with soy (Div SOY). Gut fermentation before the dive was estimated by measuring exhaled hydrogen. Following hyperbaric exposure, we assessed for signs of DCS. Blood was analyzed to assay inflammatory cytokines. Conventional and ChemRICH approaches helped the metabolomic interpretation of the cecal content. The effect of the diet is very marked at the metabolomic level, a little less in the blood tests, without this appearing strictly in the clinic status. Nevertheless, 37 of the 184 metabolites analyzed are linked to clinical status. 35 over-expressed compounds let suggest less intestinal absorption, possibly accompanied by an alteration of the gut microbial community, in DCS. The decrease in another metabolite suggests hepatic impairment. This spectral difference of the ceca metabolomes deserves to be studied in order to check if it corresponds to functional microbial particularities.
Highlights
Massive bubble formation after diving can lead to decompression sickness (DCS), which can result in neurological disorders
The incidence of clinical signs of neurological DCS (Fig. 1) is not significantly different between the groups of rats fed on maize and those fed on soy (n = 32/32, Levene median p = 0.806), with 44% and 47% of rats symptomatic respectively (Fig. 1). 8 and 7 rats succumbed to the sequelae of their DCS (MAIZE n = 8; SOY n = 7)
As the purpose of our study was principally to understand better the mechanisms of decompression sickness, using two different diets has enabled us to spotlight the metabolites which seem to be an indication for DCS
Summary
Massive bubble formation after diving can lead to decompression sickness (DCS), which can result in neurological disorders. We demonstrated that hydrogen production from intestinal fermentation could exacerbate DCS in rats fed with a standard diet. 35 over-expressed compounds let suggest less intestinal absorption, possibly accompanied by an alteration of the gut microbial community, in DCS The decrease in another metabolite suggests hepatic impairment. When bubbles form in excessive quantities in the blood and tissues, symptoms of decompression sickness (DCS) may appear[1]. It could contribute to a direct increase in the inert gas burden during hyperbaric exposure, and be excreted in the form of bubbles during the decompression phase. Less intuitively, increased fermentation over the long term with production of hydrogen before the dive would limit the risk of DCS due to the possible antioxidant and neuroprotective properties of the h ydrogen[10]. The metabolic pathways for the hydrogen by the intestinal microbiota, and more generally, the fecal metabolome in the risk of DCS must, be specified
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