Cell experiment:

HepG2 cells are pretreated with the inhibitors NaN3 (1 mg/mL), Genistein (50 μg/mL), MβCD (10 mM), Nystatin (50 μg/mL), Chlorpromazine (10 μg/mL), and Cholic acid (1 mg/mL) for 30 min. After removing the inhibitors, the cells are incubated with CA-LPs for 2 h, and the cellular uptake of LPs is determined in the "In vitro cellular uptake assays" section[1].

Animal experiment:

Mice[2] Tg-CYP2D6 mice are fed with normal chow (control) or 1% (w/w) Cholic acid-supplemented diet (CA) for 14 days (n=4 mice/group). Alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activities are measured in mouse serum.

Cholic acid is a major primary bile acid produced in the liver and usually conjugated with glycine or taurine. It facilitates fat absorption and cholesterol excretion.

Cholic acid competitively binds Na+/taurocholate cotransporting polypeptide (NTCP) on HepG2 cells and significantly inhibits the uptake of Cholic acid (CA)-nanoliposomes (LPs)-Doxorubicin (DOX)-HCl, which indicates that CA-LPs-DOX-HCl are also uptaken via NTCP-mediated endocytosis pathway[1].

Cholic acid feeding leads to increased CYP2D6 expression in CYP2D6-humanized mice. As a cholestasis model, Tg-CYP2D6 mice are fed a Cholic acid (CA)-supplemented diet for over 1 week. The treatment is known to increase bile acid pool size by 2-fold and to replace ~90% of bile acids with CA, recapitulating the features of cholestatic conditions in humans[2].

References:
[1]. Li Y, et al. Mechanism of hepatic targeting via oral administration of DSPE-PEG-Cholic acid-modified nanoliposomes. Int J Nanomedicine. 2017 Feb 28;12:1673-1684.
[2]. Pan X, et al. Cholic acid Feeding Leads to Increased CYP2D6 Expression in CYP2D6-Humanized Mice. Drug Metab Dispos. 2017 Apr;45(4):346-352.