The distinct mechanism regulating taurine homeostasis in mice: Nutrient availability affects taurine levels in the liver and energy restriction influences it in the intestine

Aims: Our previous findings indicate that caloric restriction (CR) stimulates the production and secretion of taurine-conjugated bile acids in mice. Subsequent processing by gut microbiota leads to increased levels of deconjugated bile acids, taurine, and various taurine conjugates in the intestine. Furthermore, we demonstrated that carbohydrate restriction and protein restriction, to a smaller extent, mirror the impact of CR in terms of hepatic production of bile acids but not their secretion. We hypothesized that modulating dietary macronutrient levels would influence taurine homeostasis in the liver and intestine of ad libitum-fed and CR animals.

Materials and methods: Ad libitum-fed male mice were allocated to receive either a control, low-protein (LP), low-fat (LF), or low-carbohydrate (LC) diet. Meanwhile, CR groups were given 80 % of their regular voluntary food intake as a control, high-protein (HP), high-fat (HF), or high-carbohydrate (HC) diet.

Key findings: While CR did not affect the taurine levels and its conjugates in the liver, alteration in carbohydrates and protein intake impacted it. Conversely, in the intestine, CR increased the amount of free and conjugated taurine, whereas the various diets did not affect it or disrupt the CR-specific phenotype. Notably, variations in diet composition impacted the expression of the taurine transporter (Slc6a6) and glutathione-S transferases (GST) in the intestine as well as cysteine dioxygenase (Cdo) in the liver.

Significance: The liver and the intestine show distinct responses to dietary interventions, with hepatic taurine being affected by the diet composition, while intestinal taurine is governed by energy availability.