The stress hormone norepinephrine reduces the probiotic properties of Levilactobacillus: antibacterial colonization, anti-inflammation and anti-oxidation

Lingdi Niu ¹ Mingchun Gao ¹ Yifan Li ¹ Chaonan Wang ^1,2 Hai Li ¹ Chuankun Zhang ¹ Haoyuan Duan ¹ Fang Wang ^2* Junwei Ge ^1*

• ¹ Northeast Agricultural University, Harbin, China
• ² State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute (CAAS), Harbin, Heilongjiang Province, China

Probiotics as antibiotic alternatives are unstable for use under stress in the clinical. To explore the influence of catecholamine hormones on probiotic bacterial inhibition and antimicrobial activity, we tested the effects of norepinephrine on Levilactobacillus in vitro and in a mouse model. The in vitro results showed that in the presence of NE, 80% of Levilactobacillus strains showed increased growth rate and more than 80% of Levilactobacillus strains indicated lower antimicrobial activity at 22 h. Furthermore, in the mouse model, NE weakens the protective effect of L. brevis 23017 on E. coli infection, which is shown by the decreased ability of anti-bacterial colonization, anti-oxidation, antiinflammation, and downregulating the expression of antioxidant gene and intestinal mucosal barrierrelated genes. At the same time, the addition of NE modulates the intestine's bacterial microbiota richness and diversity, disrupting the balance of intestinal probiotics. These findings provide evidence that NE reduce the probiotic ability of Levilactobacillus and illustrate the plasticity of the probiotics in response to the intestinal microenvironment under stress.