In 1992, researchers in Jerusalem isolated a molecule from pig brains that binds the same receptor as THC — proving the brain makes its own version of cannabis, a finding that transformed neuroscience.
Anyone interested in how the brain works, why cannabis affects the body the way it does, or the discovery of the endocannabinoid system — one of the most important biological systems identified in the 20th century.
#1ranked paper in bibliometric analyses of endocannabinoid and cannabinoid research — the most impactful publication in the field
The Backstory
By 1990, neuroscientists had a problem they couldn't ignore. The cannabinoid receptor — CB1 — had been cloned, mapped, and shown to be one of the most abundant receptors in the human brain. More common than receptors for serotonin, dopamine, or opioids. Clearly, evolution had gone to enormous trouble to build this system.
But the brain didn't evolve cannabinoid receptors so that humans could smoke marijuana. Something inside the body had to be making its own version of THC. Nobody had ever seen it. But it had to exist.
The Question That Demanded an Answer
The logic was inescapable, and it followed directly from the isolation of THC twenty-eight years earlier.
Biological Mechanism
From Plant Molecule to Brain Mystery
THC Structure Identified (1964)
Mechoulam and Gaoni determine the exact molecular structure of the psychoactive compound in cannabis.
THC Binds Specific Receptors (1988)
Allyn Howlett and William Devane at St. Louis University prove THC doesn't just dissolve into brain membranes — it binds to precise, dedicated receptor sites.
CB1 Receptor Cloned (1990)
Tom Bonner's lab at the NIH sequences the gene for the cannabinoid receptor. It's a G-protein-coupled receptor — the same family as receptors for dozens of known neurotransmitters.
CB1 Is Wildly Abundant
Mapping studies reveal CB1 is one of the most abundant receptors in the brain — dense in the hippocampus, cerebellum, basal ganglia, and cortex.
The Inevitable Question
Why would the brain build the most abundant receptor system in the nervous system for a plant molecule? It wouldn't. There must be an endogenous ligand — the brain's own cannabinoid.
Howlett et al. (1988), Mol Pharmacol; Matsuda et al. (1990), Nature
This wasn't speculative. In pharmacology, every receptor discovered to date had turned out to have an endogenous ligand — a molecule the body makes to activate it. Opioid receptors had endorphins. Benzodiazepine receptors had neurosteroids. The cannabinoid receptor had to have something.
Finding it became the most important open question in cannabinoid science.
Three Countries, One Lab
The team that answered the question converged in Raphael Mechoulam's laboratory at the Hebrew University of Jerusalem — the same lab where THC had been characterized nearly three decades earlier.
William Devane was an American molecular pharmacologist who had already made his mark. In 1988, working in Allyn Howlett's lab at St. Louis University, he had co-discovered the cannabinoid receptor binding site — proving that THC acts through specific receptors rather than simply disrupting cell membranes. Having found the lock, Devane moved to Jerusalem specifically to find the key.
Lumír Hanuš was a Czech analytical chemist with the technical skills to isolate vanishingly small quantities of lipid compounds from biological tissue. He would perform the actual hands-on isolation work.
Raphael Mechoulam — now sixty-two, twenty-eight years past his THC breakthrough — orchestrated the project. He had spent three decades building the knowledge base that made this hunt possible.
“It was me who then isolated the compound in the brain, but he was running various tests to assess its activity, and I wouldn't have been able to do that without him, so it was our teamwork.”
— Lumír Hanuš
Hebrew University of Jerusalem
On his collaboration with William Devane
Searching Pig Brains
The method was conceptually simple but technically brutal. Take brain tissue, extract every lipid in it, and test each fraction for the ability to bind the cannabinoid receptor. Whatever sticks is your candidate.
How They Did It
How They Found the Brain's Own Cannabinoid
Lipid Extraction
Porcine (pig) brain tissue was chosen as starting material — large, readily available, and biochemically similar to human brain for lipid signaling. All lipids were extracted from the tissue using organic solvents.
Pig brains are standard in neurochemistry — they yield more material than rodent brains
Receptor Binding Screen
Each lipid fraction was tested for its ability to displace a radiolabeled cannabinoid probe from brain synaptosomal membranes. Fractions that competed for binding were flagged for further purification.
This is competitive binding — if a fraction pushes the labeled probe off the receptor, something in that fraction fits the receptor
Structural Identification
The active compound was analyzed by mass spectrometry (to determine molecular weight) and nuclear magnetic resonance spectroscopy (to determine atomic structure). It was an arachidonic acid derivative — a fatty acid amide.
Nobody expected a lipid — most known neurotransmitters are amino acids or amines
Synthetic Confirmation
The proposed compound was synthesized from scratch in the laboratory. The synthetic version was identical to the natural isolate in every measurable property.
Gold standard confirmation — if you can build it and it matches, the structure is correct
Functional Validation
The compound was tested in the mouse vas deferens preparation — a classic cannabinoid bioassay. It produced concentration-dependent inhibition of electrically evoked muscle contractions, exactly as THC and other cannabinoids do.
This proved the compound doesn't just bind the receptor — it activates it
Devane et al. (1992), Science 258(5090):1946-9
The compound they isolated was unlike any known neurotransmitter. It wasn't an amino acid like glutamate or GABA. It wasn't an amine like dopamine or serotonin. It was a fatty acid amide — a lipid. This was unexpected. The idea that a greasy lipid molecule could transmit signals between brain cells struck many neuroscientists as implausible.
It would take years for the field to fully accept it.
Ananda — Bliss
On March 24, 1992, Hanuš isolated the compound. It needed a name.
Mechoulam wanted something fitting. The molecule was produced by the brain, bound the same receptor as the plant compound that had fascinated humanity for millennia, and appeared to be involved in pleasure and reward. He considered a Hebrew name.
"We looked for a Hebrew name," he later recalled, "but as you may well be aware, Jews are not very happy. We have a lot of words for being down and so on, but not so many words for extreme joy."
They turned to Sanskrit instead. Ananda — bliss, joy, delight. The compound became anandamide: the bliss amide.
Molecular Profile
Anandamide (N-arachidonoylethanolamine)
Anandamide
The first discovered endocannabinoid — a fatty acid amide produced in the brain that binds the same CB1 receptor as THC. Structurally, it is nothing like THC. It is derived from arachidonic acid (an omega-6 fatty acid) conjugated with ethanolamine. Unlike most neurotransmitters, it is a lipid — synthesized on demand from membrane phospholipids rather than stored in vesicles.
Formula
C₂₂H₃₇NO₂
Molecular Weight
347.53 g/mol
Class
Fatty acid amide
Receptors
CB1, CB2, TRPV1
Half-life
Seconds to minutes
Degraded by
FAAH enzyme
Devane et al. (1992), Science; PubChem CID 5281969
A Two-Sentence Answer to a 28-Year Question
The paper was published December 18, 1992, in Science — one of the two most prestigious scientific journals in the world. Four pages. Ten authors from Israel, the United States, and the United Kingdom.
#1
ranked paper in bibliometric analyses of endocannabinoid and cannabinoid research. The keyword 'anandamide' appears in 17 of the 100 most-cited papers in the field.
This single discovery — that the brain makes its own cannabinoid — launched more subsequent research than any other finding in cannabis science.
PMC7815052, Bibliometric analysis of cannabinoid research (2021)
The paper's conclusion, stripped to its essence: your brain makes its own cannabis. Not THC exactly — something structurally different that fits the same receptor. But the implication was staggering. The entire cannabinoid receptor system — the most abundant receptor family in the brain — existed not for marijuana but for the body's own signaling network.
The endocannabinoid system had been found.
Not Quite THC
The "bliss molecule" label caught on with the public. But it oversells what anandamide actually is, and confuses how it works.
Myth vs. Reality
Anandamide is the brain's version of THC — a bliss molecule that makes you feel high.
Anandamide binds the same receptor as THC but is structurally completely different, much weaker, and disappears from the brain in seconds. It's a regulatory signal, not a euphoria switch.
The Evidence
THC is a terpenophenolic compound from the cannabis plant. Anandamide is a fatty acid amide made from cell membrane components. At the receptor, anandamide is a partial agonist (weak activator) while THC produces stronger activation. Anandamide's half-life is seconds to minutes due to rapid breakdown by the enzyme FAAH — compared to THC, which persists for hours. Calling anandamide a 'bliss molecule' is like calling insulin a 'sugar molecule' because it's involved in blood sugar regulation.
Sagheddu et al. (2019), PMC6460372; Devane et al. (1992), Science
The differences matter. When you consume cannabis, you flood your brain with a potent, long-lasting CB1 agonist. When your brain releases anandamide, it's a brief, precisely targeted signal — more like a whisper than a shout. This is why daily cannabis use can disrupt the endocannabinoid system: chronic THC overwhelms the subtle signaling that anandamide provides. It's also why withdrawal symptoms occur — the brain has downregulated its response to both THC and its own anandamide.
The Day Anandamide Almost Died
The discovery was not universally celebrated. In 1996, anandamide came dangerously close to being discredited.
The problem was conceptual and technical. The idea that a lipid — essentially a fat molecule — could function as a neurotransmitter was deeply counterintuitive to many neuroscientists. Classical neurotransmitters are stored in vesicles and released into synapses. Lipids don't behave that way. They're part of cell membranes. How could a membrane component also be a signaling molecule?
Replication was difficult. Anandamide is produced in tiny quantities and destroyed almost instantly by FAAH. Measuring it accurately required techniques that were still being developed. Some labs couldn't reproduce key findings. Questions swirled about whether measured anandamide levels were genuine signals or extraction artifacts.
What rescued anandamide's reputation was partly the discovery of 2-arachidonoylglycerol (2-AG) in 1995 — a second endocannabinoid that was more abundant and easier to detect — and partly the development of FAAH inhibitors that allowed researchers to study what happens when anandamide levels rise in a controlled way. Both confirmed the core insight: the brain really does produce cannabinoid receptor ligands.
Two Endocannabinoids, Two Roles
The discovery of 2-AG three years later revealed that anandamide was only half the picture. The two molecules were initially treated as interchangeable, but they turned out to be fundamentally different.
Anandamide (AEA)
- Partial agonist at CB1 — weaker activation
- 10–100× less abundant in the brain than 2-AG
- Uniquely binds TRPV1 vanilloid receptors (pain/heat sensing)
- Broken down by FAAH enzyme
- More 'tonic' — involved in baseline mood and stress regulation
- Discovered 1992
The subtle regulator
2-AG (2-Arachidonoylglycerol)
- Full agonist at CB1 — stronger activation
- 10–100× more abundant in the brain
- Does not bind TRPV1
- Broken down by MAGL enzyme
- More 'phasic' — the primary retrograde messenger at synapses
- Discovered 1995
The workhorse signal
Sagheddu et al. (2019), PMC6460372; Mechoulam & Parker (2013)
They're not competitors — they're complementary. 2-AG handles most of the moment-to-moment synaptic signaling. Anandamide appears to play a more modulatory role, setting baseline tone for mood, stress resilience, and pain perception. Both are essential. Both are disrupted by chronic cannabis use.
What Anandamide Unlocked
The 1992 paper didn't just identify a molecule. It proved a system exists. And that system turned out to be everywhere.
Research Timeline
From One Molecule to an Entire Regulatory System
Mechoulam & Gaoni identify the structure of THC
The starting point — you can't find a receptor without knowing the molecule
Howlett & Devane discover cannabinoid receptor binding sites
Proof that THC works through specific receptors, not membrane disruption
CB1 receptor gene cloned (Bonner, NIH)
The receptor is a real, sequenced gene — most abundant GPCR in the brain
Anandamide discovered (Devane, Hanuš, Mechoulam)
The brain makes its own cannabinoid — the endocannabinoid system exists
CB2 receptor cloned (Munro, Cambridge)
A second cannabinoid receptor, primarily in immune cells
Anandamide biosynthesis and inactivation pathways mapped (Di Marzo)
Understanding how anandamide is made and destroyed
2-AG discovered (Mechoulam, Sugiura — independently)
A second, more abundant endocannabinoid identified
FAAH identified (Cravatt)
The enzyme that degrades anandamide — a key drug target
Clinical endocannabinoid deficiency proposed (Russo)
Low endocannabinoid tone as a disease mechanism for migraine, fibromyalgia, IBS
Runner's high attributed to endocannabinoids, not endorphins
Anandamide crosses the blood-brain barrier; endorphins don't
Pertwee (2006), Br J Pharmacol; Russo (2004), Neuroendocrinol Lett; Raichlen et al. (2012)
From Pig Brains to Runner's High
Thirty years after its discovery, anandamide has gone from an obscure lipid isolated from pig brain tissue to a molecule at the center of multiple lines of medical research.
The runner's high — that feeling of euphoria and reduced pain during sustained exercise — was long attributed to endorphins. But endorphin molecules are too large to cross the blood-brain barrier. In 2012, researchers showed that exercise dramatically increases circulating anandamide levels, and that anandamide can cross into the brain. The bliss of running is, at least partly, the bliss of anandamide.
Anandamide has even been found in chocolate — cocoa contains both anandamide itself and two compounds that slow its degradation by FAAH. (Before you get excited: the quantities are far too small to produce any meaningful cannabinoid receptor activation. Chocolate does not get you high via anandamide.)
More consequentially, drugs that boost anandamide by inhibiting FAAH — the enzyme that destroys it — are being developed for anxiety, depression, PTSD, and chronic pain. Rather than flooding the brain with an external cannabinoid like THC, these drugs amplify the brain's own signaling. It's a precision approach that traces directly back to knowing anandamide exists.
“I have spent most of my life decoding the mysteries to be found within this incredible plant.”
— Raphael Mechoulam
Hebrew University of Jerusalem
Reflecting on the journey from THC in 1964 to the endocannabinoid system — a journey that passed through this paper
Related Research
The Studies That Made This Possible — and Those It Made Possible
Anandamide's discovery sits at the center of a chain — preceded by the identification of THC and its receptor, followed by the expansion of the endocannabinoid system.
Isolation, Structure, and Partial Synthesis of an Active Constituent of Hashish
Gaoni & Mechoulam (1964)
The key — identifying THC made it possible to find the receptor it binds
Cloning the CB1 receptor
Matsuda et al. (1990)
The lock — cloning the receptor proved the system was real and raised the question anandamide answered
Discovery of 2-AG (second endocannabinoid)
Stella et al. (1997)
The sibling — a more abundant endocannabinoid that validated and expanded the system
FAAH discovery (enzyme that breaks down anandamide)
Cravatt et al. (1996)
The off-switch — identifying how anandamide is destroyed opened a therapeutic target
What is anandamide and why is it called the bliss molecule?
Anandamide is a fatty acid molecule naturally produced in the brain that binds to the same receptors as THC. It was named from the Sanskrit word "ananda" meaning bliss or joy. However, the "bliss molecule" label oversimplifies its role — anandamide is a regulatory signal involved in mood, pain, appetite, and memory, not simply a happiness chemical. It works more like a thermostat than a pleasure button.
Is anandamide the same as THC?
No. They bind the same receptor (CB1) but are structurally completely different — anandamide is a fatty acid amide while THC is a terpenophenolic compound from the cannabis plant. Anandamide is also a weaker partial agonist with a very short half-life (seconds to minutes), while THC is more potent and lasts hours. This difference is why chronic cannabis use can disrupt the endocannabinoid system — THC overwhelms the subtle signaling that anandamide normally provides.
What the researchers found
Arachidonylethanolamide (anandamide), an arachidonic acid derivative, was isolated from porcine brain tissue by screening lipid extracts for compounds that bind the cannabinoid receptor. Its structure was determined by mass spectrometry and NMR spectroscopy, confirmed by chemical synthesis. Functionally, anandamide competitively displaced a radiolabeled cannabinoid probe from synaptosomal membranes and produced concentration-dependent inhibition of the electrically evoked twitch response in mouse vas deferens — a classic cannabinoid bioassay. These results identified anandamide as the first known endogenous ligand for the cannabinoid receptor.
Why it matters
This paper answered one of the most important questions in neuropharmacology: why does the brain have receptors for a plant molecule? The answer — because the brain makes its own cannabinoid — established the existence of the endocannabinoid system, now recognized as one of the most important regulatory systems in human physiology. It governs mood, pain, appetite, memory, immune function, and dozens of other processes. Every subsequent discovery in endocannabinoid research traces back to this paper.
The numbers in context
- 1992: first report of an endogenous cannabinoid receptor ligand isolated from mammalian brain
- Source tissue: porcine brain synaptosomal membranes used for receptor binding assays
- Functional assay: concentration-dependent inhibition of mouse vas deferens twitch, a hallmark cannabinoid effect
- Binding mode: competitive displacement of a radiolabeled cannabinoid probe from receptor sites
How the study worked
Lipid extracts from porcine (pig) brain tissue were screened for compounds that bind the cannabinoid receptor using a radiolabeled probe displacement assay. A compound that competitively bound the receptor was isolated and its structure was determined using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. The proposed structure was confirmed by synthesizing the compound from scratch and showing the synthetic version had identical properties. Biological activity was validated using the mouse vas deferens preparation, a standard cannabinoid bioassay where cannabinoid receptor agonists inhibit electrically stimulated muscle contractions in a concentration-dependent manner.
Who was studied
Porcine brain and mouse vas deferens, Country not specified
What this study cannot tell us
This was an animal study using pig brain tissue, not human tissue. The paper demonstrated receptor binding and one functional bioassay (vas deferens) but did not characterize anandamide's effects in living animals or determine its physiological role. No potency values, receptor subtype selectivity data, or in vivo outcomes were reported. The initial characterization as a cannabinoid receptor ligand was correct but incomplete — anandamide was later found to also bind TRPV1 vanilloid receptors and PPARα/γ nuclear receptors.
How to read the evidence
Rated strong because this is a definitive biochemical discovery confirmed by multiple independent methods (mass spectrometry, NMR, chemical synthesis, receptor binding, functional bioassay). The identification of anandamide has been replicated thousands of times and the compound is now one of the most studied lipid signaling molecules in neuroscience.
When this study was published
Published in 1992, this 34-year-old paper is the founding document of endocannabinoid research. Its core finding — that the brain produces cannabinoid receptor ligands — has been massively expanded but never contradicted. The field it created now encompasses thousands of papers annually.
The bigger picture
The discovery of anandamide proved that the endocannabinoid system is a fundamental part of mammalian biology, not just a quirk of cannabis pharmacology. It triggered a cascade of discoveries: 2-AG (1995), FAAH (1996), MAGL, and dozens of other components. The clinical implications are vast — clinical endocannabinoid deficiency is now hypothesized to underlie conditions from migraine to fibromyalgia to IBS. FAAH inhibitors (drugs that boost anandamide by blocking its breakdown) are in clinical development for anxiety and pain. The runner's high, once attributed to endorphins, is now understood to be mediated by anandamide.
Replication
Not stated in abstract.
Funding
Not reported in abstract.
Conflicts of interest
Not reported in abstract.
Questions still open
- If the brain makes its own cannabinoid, what happens to this system when someone uses cannabis regularly?
- Are there other endogenous cannabinoids beyond anandamide?
- Could boosting anandamide levels therapeutically treat conditions involving the endocannabinoid system?
Common questions
What is anandamide and why is it called the bliss molecule?
Is anandamide the same as THC?
Read the original research
Isolation and structure of a brain constituent that binds to the cannabinoid receptor
Science, 258(5090), 1946-1949
Science is a highly prestigious and credible peer-reviewed journal.
Citation
Devane, William A.; Hanus, Lumir; Breuer, Aviva; Pertwee, Roger G.; Stevenson, Lesley A.; Griffin, Graeme; Gibson, Dale; Mandelbaum, Arnon; Etinger, Alexander; Mechoulam, Raphael. (1992). Isolation and structure of a brain constituent that binds to the cannabinoid receptor. Science, 258(5090), 1946-1949. https://doi.org/10.1126/science.1470919
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