Third-Generation Synthetic Cannabinoids Were Up to 30 Times More Potent Than Earlier Versions
Four third-generation Spice/K2 compounds showed CB1 receptor binding affinities up to 30 times higher than JWH-018, with greater dopamine-stimulating properties in the brain's reward center.
Quick Facts
What This Study Found
Researchers characterized four third-generation synthetic cannabinoids (BB-22, 5F-PB-22, 5F-AKB-48, STS-135) and compared them to the earlier compound JWH-018.
BB-22 and 5F-PB-22 had CB1 receptor binding affinities 30 and 26 times higher than JWH-018 respectively, with higher potency and efficacy as CB1 agonists. All four compounds stimulated dopamine release specifically in the nucleus accumbens shell (the brain's reward center) but not in other nearby regions.
The dopamine-stimulating effect was completely blocked by the CB1 antagonist AM251 and showed a bell-shaped dose-response curve. The compounds did not activate G-proteins in CB1 knockout mice, confirming CB1 receptor specificity.
Key Numbers
BB-22 Ki: 0.11 nM (vs. JWH-018: 3.38 nM). 5F-PB-22 Ki: 0.13 nM. BB-22 Emax: 217% (vs. JWH-018: 163%). All four stimulated nucleus accumbens shell dopamine release at doses consistent with their CB1 affinity.
How They Did This
In vitro receptor binding and GTPgammaS assays on rat and mouse CB1/CB2 receptors. In vivo brain microdialysis in freely moving mice measuring dopamine release in nucleus accumbens shell, core, and medial prefrontal cortex. CB1 knockout mice used for specificity.
Why This Research Matters
The escalating potency of successive synthetic cannabinoid generations helps explain the increasing severity of clinical toxicity reports. Compounds 30 times more potent than earlier versions pose correspondingly greater risks of overdose and adverse effects.
The Bigger Picture
This study documents a dangerous trend in the synthetic cannabinoid market: each generation of compounds is more potent than the last. The selective dopamine release in the reward center, combined with super-high potency, helps explain both the addictive potential and the severe toxicity of these substances.
What This Study Doesn't Tell Us
In vitro binding does not perfectly predict in vivo effects. Mouse dopamine studies may not directly translate to human reward processing. Only acute effects were studied. The specific compounds may have been replaced by even newer variants in the illicit market.
Questions This Raises
- ?Is there a ceiling to how potent synthetic cannabinoids can become?
- ?Does the bell-shaped dose-response curve for dopamine explain some of the paradoxical effects reported by users?
Trust & Context
- Key Stat:
- BB-22 had 30x higher CB1 receptor affinity than the earlier synthetic cannabinoid JWH-018
- Evidence Grade:
- This is a well-designed pharmacological study combining in vitro and in vivo approaches with appropriate controls, providing strong preclinical characterization.
- Study Age:
- Published in 2016. The synthetic cannabinoid market has continued to evolve with potentially even more potent compounds.
- Original Title:
- Native CB1 receptor affinity, intrinsic activity and accumbens shell dopamine stimulant properties of third generation SPICE/K2 cannabinoids: BB-22, 5F-PB-22, 5F-AKB-48 and STS-135.
- Published In:
- Neuropharmacology, 105, 630-638 (2016)
- Authors:
- De Luca, Maria Antonietta(7), Castelli, M Paola(3), Loi, Barbara, Porcu, Alessandra, Martorelli, Mariella, Miliano, Cristina, Kellett, Kathryn, Davidson, Colin, Stair, Jacqueline L, Schifano, Fabrizio, Di Chiara, Gaetano
- Database ID:
- RTHC-01137
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Why are newer synthetic cannabinoids more dangerous?
Each generation has been designed with higher potency at CB1 receptors. This study showed third-generation compounds with up to 30x higher receptor binding than earlier versions, meaning less material is needed for an effect, which makes overdose more likely and effects less predictable.
Why do synthetic cannabinoids release dopamine in the reward center?
All cannabinoid CB1 agonists, including THC, can stimulate dopamine release in reward circuits. However, the super-high potency of these synthetic compounds means they produce much stronger dopamine signals, which may contribute to both their addictive potential and acute toxicity.
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Cite This Study
https://rethinkthc.com/research/RTHC-01137APA
De Luca, Maria Antonietta; Castelli, M Paola; Loi, Barbara; Porcu, Alessandra; Martorelli, Mariella; Miliano, Cristina; Kellett, Kathryn; Davidson, Colin; Stair, Jacqueline L; Schifano, Fabrizio; Di Chiara, Gaetano. (2016). Native CB1 receptor affinity, intrinsic activity and accumbens shell dopamine stimulant properties of third generation SPICE/K2 cannabinoids: BB-22, 5F-PB-22, 5F-AKB-48 and STS-135.. Neuropharmacology, 105, 630-638. https://doi.org/10.1016/j.neuropharm.2015.11.017
MLA
De Luca, Maria Antonietta, et al. "Native CB1 receptor affinity, intrinsic activity and accumbens shell dopamine stimulant properties of third generation SPICE/K2 cannabinoids: BB-22, 5F-PB-22, 5F-AKB-48 and STS-135.." Neuropharmacology, 2016. https://doi.org/10.1016/j.neuropharm.2015.11.017
RethinkTHC
RethinkTHC Research Database. "Native CB1 receptor affinity, intrinsic activity and accumbe..." RTHC-01137. Retrieved from https://rethinkthc.com/research/de-2016-native-cb1-receptor-affinity
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.