N-arachidonoyl dopamine (NADA), an endocannabinoid, inhibited fat cell differentiation in human stem cells through CB1 receptor activation, while anandamide promoted fat cell formation through a different pathway.
Read this if you want to understand how different endocannabinoids affect fat cell development.
AEA promotes fat cell formation via PPARg; NADA inhibits it via CB1 receptors
What the researchers found
Three endocannabinoids were tested for their effects on fat cell (adipocyte) development from human bone marrow stem cells. Anandamide (AEA) promoted adipocyte differentiation, while NADA inhibited it. 2-AG had no significant effect at non-toxic concentrations.
The difference between AEA and NADA was traced to their effects on PPARg, a nuclear receptor critical for fat cell formation. AEA directly activated PPARg, promoting fat storage. NADA did not affect PPARg but inhibited adipogenesis through CB1 receptor activation, an effect blocked by the CB1 antagonist rimonabant.
Interestingly, rimonabant itself promoted fat cell formation when given alone, suggesting that baseline CB1 receptor activity normally suppresses adipocyte differentiation in these stem cells. This finding provides a molecular explanation for some metabolic effects of cannabinoid system modulation.
Why it matters
Understanding how different endocannabinoids regulate fat cell formation could lead to new approaches for treating obesity and metabolic disorders. The finding that CB1 activation suppresses rather than promotes fat cell development adds nuance to the complex relationship between the cannabinoid system and metabolism.
The numbers in context
AEA promoted adipogenesis via PPARg activation. NADA inhibited adipogenesis via CB1. 2-AG had no effect at non-toxic doses. Rimonabant (CB1 inverse agonist) promoted adipogenesis, suggesting constitutive CB1 activity suppresses fat cell formation.
How the study worked
Human bone marrow mesenchymal stem cells (hBM-MSCs) were induced to differentiate into adipocytes in the presence of three endocannabinoids: AEA, NADA, and 2-AG. PPARg transactivation assays determined direct receptor activation. CB1 and TRPV1 antagonists were used to identify the receptor pathways involved.
What this study cannot tell us
This was an in vitro study using cultured human stem cells, which may not fully reflect in vivo fat tissue development. The concentrations used may not be physiologically relevant. The study did not assess whether these effects translate to changes in body fat in animals or humans.
How to read the evidence
This is an in vitro study using human cells. While mechanistically informative, translation to in vivo metabolism requires further research.
When this study was published
Published in 2015. Research on cannabinoid system involvement in metabolic regulation continues.
The bigger picture
The cannabinoid system's role in metabolism extends beyond appetite regulation to include direct effects on fat cell development. The opposing effects of different endocannabinoids (AEA promoting and NADA inhibiting fat cell formation) reveal a complex regulatory system that could be therapeutically exploited.
Questions still open
- Do circulating NADA levels affect body fat distribution in vivo? Could selective CB1 agonists that lack PPARg activity be developed as anti-obesity agents? How do these in vitro findings relate to the known weight gain effects of cannabis use?
Common questions
What is NADA?
If CB1 activation blocks fat cells, why do cannabis users sometimes gain weight?
Read the original research
A cannabinoid receptor agonist N-arachidonoyl dopamine inhibits adipocyte differentiation in human mesenchymal stem cells.
Biomolecules & therapeutics, 23(3), 218-24
Citation
Ahn, Seyeon; Yi, Sodam; Seo, Won Jong; Lee, Myeong Jung; Song, Young Keun; Baek, Seung Yong; Yu, Jinha; Hong, Soo Hyun; Lee, Jinyoung; Shin, Dong Wook; Jeong, Lak Shin; Noh, Minsoo. (2015). A cannabinoid receptor agonist N-arachidonoyl dopamine inhibits adipocyte differentiation in human mesenchymal stem cells.. Biomolecules & therapeutics, 23(3), 218-24. https://doi.org/10.4062/biomolther.2014.137
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