Bile lipid alterations in taurine-depleted monkeys

Area of Science:

• Biochemistry
• Primate Metabolism
• Digestive Physiology

Background:

• Bile acids are crucial for digestion and are conjugated with either taurine or glycine.
• Primate species exhibit varying degrees of taurine and glycine conjugation.
• Dietary taurine availability may influence bile acid metabolism and cholesterol solubility.

Purpose of the Study:

• To investigate the impact of taurine depletion on bile acid conjugation and cholesterol solubility in cebus and cynomolgus monkeys.
• To compare the metabolic responses of obligate taurine-conjugating cebus monkeys versus facultative glycine-conjugating cynomolgus monkeys.

Main Methods:

• Newborn monkeys were fed a taurine-free formula with or without added taurine for 5 months.
• Bile was collected after interrupting enterohepatic circulation.
• Bile acid conjugation, pool size, lipid composition, and cholesterol solubility were analyzed.

Main Results:

• Taurine depletion did not affect bile acid conjugation or cholesterol solubility in cebus monkeys.
• In cynomolgus monkeys, taurine depletion reduced taurine conjugation (84% to 64%) and increased glycine conjugation (16% to 36%).
• Taurine depletion improved maximal cholesterol solubility in cynomolgus bile due to increased phospholipids and a higher taurochenodeoxycholate to taurocholate ratio.

Conclusions:

• Taurine availability significantly influences bile acid characteristics and cholesterol solubility in glycine-conjugating primates.
• Taurochenodeoxycholate plays a role in conserving taurine during depletion.
• Species-specific differences in bile acid conjugation impact metabolic adaptation to taurine deficiency.