The endocannabinoid system runs on two main molecules — 2-AG and anandamide — that regulate everything from synaptic plasticity to stress response, and THC hijacks this machinery.
Anyone who wants to understand the biology behind how cannabis actually works in the brain.
What the researchers found
The endocannabinoid system (ECS) is one of the most widespread signaling networks in the brain. It operates through two primary endocannabinoids — 2-arachidonoyl glycerol (2-AG) and anandamide — that act as retrograde messengers, meaning they signal backward across synapses to regulate how much neurotransmitter gets released. CB1 receptors, the main targets, are among the most abundant receptors in the brain.
Despite their structural similarities, 2-AG and anandamide are made and broken down by entirely different enzyme pathways, giving them distinct biological roles. THC from cannabis mimics these molecules, binding to the same receptors but without the precise timing and location control that endocannabinoids use. The review also examines how this system appears disrupted in schizophrenia, where altered endocannabinoid signaling may contribute to the condition.
Why it matters
You can't understand what cannabis does to the brain without understanding the system it acts on. This review lays out the machinery: the receptors, the molecules, the enzymes, and the feedback loops. When someone uses cannabis, THC doesn't create new effects from scratch — it takes over an existing system that normally regulates neural communication with precise timing. Cannabis essentially floods a signaling network designed for brief, targeted bursts.
The distinction between 2-AG and anandamide matters because it means the endocannabinoid system isn't one thing — it's at least two overlapping systems with different jobs. Drugs that target one pathway may have very different effects than drugs targeting the other.
The numbers in context
• CB1 receptors are among the most abundant G protein-coupled receptors in the central nervous system
• Two primary endocannabinoids: 2-AG and anandamide, with distinct synthesis/degradation pathways
• The ECS modulates glutamate and GABA release through retrograde signaling
How the study worked
Narrative review of preclinical and clinical literature on the endocannabinoid system, covering receptor pharmacology, synthesis and degradation pathways, synaptic plasticity mechanisms, and relevance to schizophrenia. Published in Biological Psychiatry as part of a themed issue on cannabinoids.
Who was studied
This is a review of the endocannabinoid system, summarizing existing knowledge.
What this study cannot tell us
As a narrative review, this paper summarizes existing knowledge rather than presenting new data. The schizophrenia connection, while biologically plausible, relies heavily on preclinical models that may not fully translate to human disease. The review was published in 2016 and the field has advanced since.
How to read the evidence
Narrative review synthesizing preclinical and clinical literature. Provides framework for understanding, not new experimental evidence.
When this study was published
Published in 2016. Core ECS biology remains current, though specific therapeutic targets have advanced since.
The bigger picture
This is foundational biology. Every study about cannabis and the brain — whether it's about psychosis, pain relief, appetite, or addiction — ultimately comes back to the endocannabinoid system described here. Understanding that THC works by hijacking an existing regulatory system, not by creating novel effects, changes how you think about both the benefits and risks of cannabis use.
Replication
Not stated in abstract.
Funding
Not reported in abstract.
Conflicts of interest
Not reported in abstract.
Questions still open
- Could drugs targeting specific endocannabinoid enzymes provide cannabis-like benefits without the psychoactive effects?
- Why do some people seem more sensitive to THC than others — is it variation in their endocannabinoid system?
- How does chronic cannabis use change endocannabinoid system function over time?
Common questions
What is the endocannabinoid system?
How does THC relate to endocannabinoids?
Read the original research
An introduction to the endogenous cannabinoid system
Biological Psychiatry, 79(7), 516-525
Biological Psychiatry is a well-respected journal focusing on the intersection of psychiatry and biological sciences.
Citation
Lu, Hui-Chen; Mackie, Ken. (2016). An introduction to the endogenous cannabinoid system. Biological Psychiatry, 79(7), 516-525.
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