Injected vs. smoked cannabis had different effects on inflammation in pregnant rats
In pregnant rats, injected THC and CBD increased pro-inflammatory markers in placental and fetal brain tissue, while smoked cannabis generally reduced them, highlighting how the route of administration changes outcomes.
Quick Facts
What This Study Found
Pregnant rats exposed to high-THC or high-CBD cannabis smoke from gestational day 6-20 showed different inflammatory profiles than those receiving injected THC or CBD. Injected cannabinoids upregulated pro-inflammatory cytokines in placental and fetal brain tissue, while smoke exposure reduced cytokine and chemokine concentrations. Injection also led to fewer offspring and more uterine reabsorption events.
Key Numbers
High-THC smoke: 18% THC, 0.1% CBD; high-CBD smoke: 0.7% THC, 13% CBD; injected doses: 3 mg/kg THC, 10 mg/kg CBD; treatment period: gestational day 6-20
How They Did This
Pregnant Sprague-Dawley rats were treated daily from gestational day 6-20 with room air, vehicle, high-THC smoke (18% THC, 0.1% CBD), high-CBD smoke (0.7% THC, 13% CBD), injected THC (3 mg/kg), or injected CBD (10 mg/kg). Plasma cannabinoid levels, cytokine profiles, and reproductive outcomes were assessed.
Why This Research Matters
Most preclinical cannabis-pregnancy research uses injected pure cannabinoids, but most human use involves smoking. This study shows these routes produce opposite inflammatory effects, calling into question how well injection studies translate to real-world exposures.
The Bigger Picture
The divergent effects by route of administration suggest that the large body of preclinical research using injected cannabinoids may not accurately predict what happens when pregnant people smoke cannabis.
What This Study Doesn't Tell Us
Rat model may not translate directly to human pregnancy. Smoke exposure involves combustion products beyond cannabinoids. Specific cannabinoid doses delivered via smoke are harder to control than injections.
Questions This Raises
- ?What drives the opposite inflammatory responses between smoked and injected cannabinoids?
- ?Do these route-dependent differences persist in offspring developmental outcomes?
Trust & Context
- Key Stat:
- Injected vs. smoked cannabinoids produced opposite inflammatory effects in fetal tissue
- Evidence Grade:
- Well-controlled animal study with multiple exposure routes, but rat model and combustion variables limit direct human translation.
- Study Age:
- Published 2023
- Original Title:
- Characterization of cannabinoid plasma concentration, maternal health, and cytokine levels in a rat model of prenatal Cannabis smoke exposure.
- Published In:
- Scientific reports, 13(1), 21070 (2023)
- Authors:
- Black, Tallan(6), Baccetto, Sarah L(3), Barnard, Ilne L(4), Finch, Emma, McElroy, Dan L, Austin-Scott, Faith V L, Greba, Quentin, Michel, Deborah, Zagzoog, Ayat, Howland, John G, Laprairie, Robert B
- Database ID:
- RTHC-04420
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Does the way cannabis is consumed matter during pregnancy?
In this rat study, yes. Injected THC and CBD increased pro-inflammatory markers in placental and fetal brain tissue, while smoked cannabis generally reduced them, producing opposite effects from the same compounds.
Did cannabis smoke or injection cause more reproductive harm in rats?
Injected THC and CBD were associated with fewer offspring and more uterine reabsorption events compared to smoke exposure, though both routes affected fetal development.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-04420APA
Black, Tallan; Baccetto, Sarah L; Barnard, Ilne L; Finch, Emma; McElroy, Dan L; Austin-Scott, Faith V L; Greba, Quentin; Michel, Deborah; Zagzoog, Ayat; Howland, John G; Laprairie, Robert B. (2023). Characterization of cannabinoid plasma concentration, maternal health, and cytokine levels in a rat model of prenatal Cannabis smoke exposure.. Scientific reports, 13(1), 21070. https://doi.org/10.1038/s41598-023-47861-8
MLA
Black, Tallan, et al. "Characterization of cannabinoid plasma concentration, maternal health, and cytokine levels in a rat model of prenatal Cannabis smoke exposure.." Scientific reports, 2023. https://doi.org/10.1038/s41598-023-47861-8
RethinkTHC
RethinkTHC Research Database. "Characterization of cannabinoid plasma concentration, matern..." RTHC-04420. Retrieved from https://rethinkthc.com/research/black-2023-characterization-of-cannabinoid-plasma
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.