Daily THC in Adolescent Mice Disrupted Immune Cells in the Brain Until Young Adulthood
Adolescent THC exposure in mice caused persistent dysfunction in brain immune cells (microglia) that lasted into young adulthood but resolved with further aging.
Quick Facts
What This Study Found
Daily THC from postnatal day 30 to 44 produced microglia dysfunction in both male and female mice that persisted to young adulthood (PND70) but receded by PND120. The effects were prevented by a CB1 receptor antagonist and were not replicated when THC was given to adult mice.
Key Numbers
THC dose: 5 mg/kg daily for 14 days; dysfunction persisted to PND70 (young adulthood); resolved by PND120; effects blocked by CB1 antagonist
How They Did This
Mice received daily THC (5 mg/kg) during adolescence (PND30-44). Researchers examined microglia transcriptomes at PND70 and PND120, tested responses to immune challenge (LPS) and social stress (repeated social defeat), and used mass cytometry to map brain immune populations.
Why This Research Matters
Microglia play critical roles in brain development during adolescence. If THC disrupts their function during this window, it could impair the brain's ability to respond to infections and stress during a vulnerable developmental period.
The Bigger Picture
This study provides a biological mechanism for why adolescent cannabis use may carry different risks than adult use. The finding that effects were adolescent-specific and reversible with aging adds nuance to the debate.
What This Study Doesn't Tell Us
Animal study using injected THC at a single dose, which does not replicate human cannabis use patterns. Translating mouse developmental timelines to human adolescence is imprecise.
Questions This Raises
- ?Do lower THC doses or less frequent exposure produce similar microglial effects?
- ?Does this dysfunction contribute to the increased psychiatric risk observed in adolescent cannabis users?
Trust & Context
- Key Stat:
- Effects lasted to young adulthood but resolved by later adulthood
- Evidence Grade:
- Well-designed animal study with multiple verification methods and controls, but findings need human confirmation.
- Study Age:
- Published in 2022
- Original Title:
- Frequent Low-Dose Δ9-Tetrahydrocannabinol in Adolescence Disrupts Microglia Homeostasis and Disables Responses to Microbial Infection and Social Stress in Young Adulthood.
- Published In:
- Biological psychiatry, 92(11), 845-860 (2022)
- Authors:
- Lee, Hye-Lim, Jung, Kwang-Mook(3), Fotio, Yannick(3), Squire, Erica, Palese, Francesca, Lin, Lin, Torrens, Alexa, Ahmed, Faizy, Mabou Tagne, Alex, Ramirez, Jade, Su, Shiqi, Wong, Christina Renee, Jung, Daniel Hojin, Scarfone, Vanessa M, Nguyen, Pauline U, Wood, Marcelo, Green, Kim, Piomelli, Daniele
- Database ID:
- RTHC-03994
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
What are microglia and why do they matter?
Microglia are the brain's resident immune cells. During adolescence, they actively participate in brain maturation by pruning synapses and responding to threats. Disrupting their function could impair normal brain development.
Was the THC effect permanent?
No. The microglial dysfunction persisted into young adulthood (PND70) but had resolved by PND120, suggesting the effects were temporary, though they covered a significant developmental window.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-03994APA
Lee, Hye-Lim; Jung, Kwang-Mook; Fotio, Yannick; Squire, Erica; Palese, Francesca; Lin, Lin; Torrens, Alexa; Ahmed, Faizy; Mabou Tagne, Alex; Ramirez, Jade; Su, Shiqi; Wong, Christina Renee; Jung, Daniel Hojin; Scarfone, Vanessa M; Nguyen, Pauline U; Wood, Marcelo; Green, Kim; Piomelli, Daniele. (2022). Frequent Low-Dose Δ9-Tetrahydrocannabinol in Adolescence Disrupts Microglia Homeostasis and Disables Responses to Microbial Infection and Social Stress in Young Adulthood.. Biological psychiatry, 92(11), 845-860. https://doi.org/10.1016/j.biopsych.2022.04.017
MLA
Lee, Hye-Lim, et al. "Frequent Low-Dose Δ9-Tetrahydrocannabinol in Adolescence Disrupts Microglia Homeostasis and Disables Responses to Microbial Infection and Social Stress in Young Adulthood.." Biological psychiatry, 2022. https://doi.org/10.1016/j.biopsych.2022.04.017
RethinkTHC
RethinkTHC Research Database. "Frequent Low-Dose Δ9-Tetrahydrocannabinol in Adolescence Dis..." RTHC-03994. Retrieved from https://rethinkthc.com/research/lee-2022-frequent-lowdose-9tetrahydrocannabinol-in
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.