Bifidobacterium supplementation attenuates hypercholesterolemia induced gut-brain-testis dysfunction in a rat model
Authors: Kim Jae Young , Seo Eun Jin , Kim Sae Hun 
Published: May 2023

Hypercholesterolemia is the state of high LDL blood cholesterol levels. This may lead to cholesterol accumulation in organs and cause diseases such as male infertility and NAFLD. Recent studies have shown strong correlations between Bifidobacterium strains and plasma cholesterol reduction. Bifidobacterium species are gram positive bacteria known to colonize the human gastrointestinal tract. Studies suggest that Bifidobacterium may reduce serum cholesterol levels by increasing bile salt hydrolase (BSH) activity. BSH increases fecal excretion of bile salt, and to compensate the loss of circulating bile acids, productions of bile acids using cholesterol are promoted. Currently, medications such as statins are commonly used. However, long term consumption could cause adverse effects on male reproductive organs. Bifidobacterium strains are known to regulate the hypothalamus-pituitary-gonadal (HPG) axis by modulating gut microbiota . Gut microbial bacteria such as Bifidobacterium contribute to the host metabolism by enhancing gut barrier integrity, reducing inflammation cytokine expressions, and increasing metabolite productions such as short chain fatty acids (SCFAs). Particularly, SCFAs like butyrate can cross the blood-brain barrier, and consequently affect the HPG axis. This suggests that Bifidobacterium strains may lower serum cholesterol while protecting reproductive organs. Therefore, this study aimed to evaluate and compare the serum cholesterol lowering and HPG axis protecting effects of Bifidobacterium strains with statin in the gut-brain-testis axis of a high cholesterol diet (HCD) induced hypercholesterolemia rat model. 6-week oral gavage of Bifidobacterium strains known to have BSH activity effectively reduced serum total cholesterol and LDL cholesterol levels in rats given HCD for the same period. Moreover, serum inflammatory cytokine IL-1β was reduced by Bifidobacterium treatment. Bifidobacterium also exerted protective effects against intestinal, testicular, and cerebral damage by attenuating disruption of histology and modulating transcript levels of inflammation markers. Notably, Bifidobacterium alleviated the HCD-induced reduction of male sex hormone synthesis markers in the testis, which statin had no effect. Fecal analysis revealed that Bifidobacterium treatment modulates gut microbiota compositions and metabolite levels such as SCFAs. Particularly, 16s rRNA genomic annotation showed that Bifidobacterium strains may have specific functions related to cholesterol reduction. Altogether, Bifidobacterium supplementation may reduce serum cholesterol levels by altering gut microbiota compositions, which affect gut metabolite compositions, inflammatory markers, and sex hormone synthesis markers. In conclusion, Bifidobacterium supplementation is a potential therapeutic approach for hypercholesterolemia-induced intestine, brain, and testis dysfunction. This work was supported by Cellbiotech Co., Ltd. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.