Tier 3 — preclinical

Activation of AMPK by berberine induces hepatic lipid accumulation by upregulation of fatty acid translocase CD36 in mice

You-Jin Choi, Kang-Yo Lee, Seung-Hwan Jung, Hyung Sik Kim, Gayong Shim, Yu-Kyoung Oh, Mi-Gyeong Kim, Seon-Hee Oh, Dae Won Jun, Byung-Hoon Lee
Toxicology and Applied Pharmacology 2017 Volume 316, pages 74–82

Bibliography

PubMed
PMID 28038998
DOI
10.1016/j.taap.2016.12.019
Video explainer
Watch on YouTube Biohack Blueprint's video walkthrough of this study.
Funding
This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP; No. 2007-0056817) and the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (HI14C0133).
Competing interests
None listed.

Study snapshot

DesignIn vitro mechanistic experiments and an in vivo controlled animal study.
ModelHuman hepatoma cell line (HepG2), isolated primary mouse hepatocytes, and normal specific-pathogen-free male C57BL/6 mice.
Samplen=4 to 7 per mouse group; at least 3 independent experiments for in vitro assays.
InterventionBerberine (1 to 25 µM in vitro; 10 mg/kg/day intraperitoneally in vivo), alongside specific AMPK activators (AICAR, Ad-CA-AMPK), an ERK inhibitor (PD98059), and CD36 inhibition (SSO chemical inhibitor or shRNA/siRNA).
Duration24 hours for in vitro cellular treatments; 7 days of daily administration for the in vivo mouse model.
EndpointsCD36 mRNA and protein expression; plasma membrane translocation of CD36; fatty acid uptake (BODIPY-C16); intracellular lipid accumulation (Nile red); liver triglyceride levels; and phosphorylation of AMPK, ERK, and C/EBPβ.

What the study showed, in plain terms

Berberine is generally known for its beneficial metabolic effects, such as lowering blood sugar and improving insulin sensitivity in disease models. However, this study investigated an unexpected side effect: whether AMPK activation by berberine might paradoxically cause fat accumulation in the liver of normal, non-obese mice. The researchers tested this by treating human liver cells (HepG2), isolated mouse liver cells, and live mice with berberine.

They discovered that berberine activates an energy-sensing enzyme called AMPK, which triggers a chain reaction (via ERK and C/EBPβ) that increases the production and cell-surface placement of a fatty acid transporter known as CD36. As a result, the liver cells pull in excessive fatty acids from their surroundings, leading to fat buildup (steatosis) inside the cells.

In mice fed a normal diet and given berberine for seven days, liver triglycerides increased significantly. This fat accumulation was completely stopped when the researchers used genetic tools to block or silence the CD36 transporter. This suggests that while berberine is beneficial for preexisting metabolic disorders, prolonged AMPK activation by the compound can promote fatty liver in otherwise healthy individuals by over-activating fatty acid uptake.

Key findings

  • Berberine treatment (1 to 25 µM) for 24 hours dose-dependently increased intracellular lipid accumulation and fatty acid uptake in HepG2 cells and primary mouse hepatocytes.
  • In normal C57BL/6 mice, intraperitoneal administration of berberine (10 mg/kg/day) for 7 days increased liver triglyceride levels by approximately 30%.
  • Berberine significantly increased the mRNA and protein levels of the fatty acid transporter CD36 in both in vitro and in vivo models, without altering other major hepatic transporters like L-FABP, FATP2, or FATP5.
  • The observed increase in lipid accumulation and fatty acid uptake was entirely prevented when CD36 was blocked using a specific chemical inhibitor (sulfo-N-succinimidyl oleate), CD36-specific siRNA in cells, or Ad-shCD36 in live mice.
  • Mechanistically, berberine activated AMPK, which phosphorylated ERK1/2, subsequently increasing the binding of transcription factor C/EBPβ to the CD36 promoter, leading to enhanced CD36 transcription and membrane translocation.

What this study can and cannot tell us

This is a preclinical study using cell lines and normal, non-metabolically challenged mice; results may not translate directly to humans. The observed lipogenic effect occurred in healthy mice on a normal diet, which contrasts with many previous studies showing anti-steatotic effects of berberine in high-fat diet models or genetically obese/diabetic (db/db, ob/ob) mice. The preexisting metabolic state significantly influences berberine's hepatic effects, and this mechanism may be masked in metabolically challenged states.

The study used an intraperitoneal injection route for the in vivo mouse model (10 mg/kg/day), which bypasses the typical oral route and first-pass metabolism relevant to human supplementation, potentially altering bioavailability and hepatic exposure.

The study does not address the implications for human oral dosing or whether human equivalents of this dosage would induce similar CD36 upregulation in healthy individuals without preexisting metabolic syndrome.

Editorial review

Reviewed by the Biohack Blueprint research team

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability