Norepinephrine induces growth of Desulfovibrio vulgaris in an iron dependent manner

Abstract

Desulfovibrio spp. is a commensal sulfate reducing bacterium that is present in small numbers in the gastrointestinal tract. Increased concentrations of Desulfovibrio spp. (blooms) have been reported in patients with inflammatory bowel disease and irritable bowel syndrome. Since stress has been reported to exacerbate symptoms of these chronic diseases, this study examined whether the stress catecholamine norepinephrine (NE) promotes Desulfovibrio growth. Norepinephrine-stimulated growth has been reported in other bacterial taxa, and this effect may depend on the availability of the micronutrient iron.

Objectives: This study tested whether norepinephrine exposure affects the in vitro growth of Desulfovibrio vulgaris in an iron dependent manner.

Methods: DSV was incubated in a growth medium with and without 1 μm of norepinephrine. An additional growth assay added the iron chelator deferoxamine in NE exposed DSV. Iron regulatory genes were assessed with and without the treatment of NE and Deferoxamine.

Results: We found that norepinephrine significantly increased growth of D. vulgaris. Norepinephrine also increased bacterial production of hydrogen sulfide. Additionally, norepinephrine significantly increased bacterial expression in three of the four tested iron regulatory genes. The iron chelator deferoxamine inhibited growth of D. vulgaris in a dose-dependent manner and reversed the effect of norepinephrine on proliferation of D. vulgaris and on bacterial expression of iron regulatory genes.

Conclusion: The data presented in this work suggests that promotion of D. vulgaris growth by norepinephrine is iron dependent.

Keywords: Brain gut axis; Catecholamines; Desulfovibrio; Pathobiont; Sulfate reducing bacteria.