Cannabinoids 101 — THC, CBD, CBG, CBN, CBC and the receptors they hit

A cannabinoid is any compound that interacts with the body's endocannabinoid system. The plant Cannabis sativa produces a family of >100 phytocannabinoids — molecules with a shared 21-carbon terpenophenolic skeleton — but the body itself produces endocannabinoids (anandamide, 2-AG), and chemists synthesize synthetic cannabinoids in the lab. All three categories converge on the same receptors.

The two best-characterized cannabinoid receptors are CB1 and CB2:

• CB1 is densely expressed in the central nervous system — particularly the basal ganglia, hippocampus, cerebellum, and prefrontal cortex. Activating CB1 in those regions produces the psychoactive effects associated with THC.
• CB2 is mostly peripheral — found on immune cells, in the spleen, and in some peripheral tissues. CB2 activation modulates immune signaling without psychoactive effect.

Cannabinoids also interact with non-cannabinoid targets — TRPV1 (the capsaicin receptor), GPR55, 5-HT1A serotonin, and PPARγ. This polypharmacology is why cannabinoids produce such a wide range of effects, and why "the cannabis system" doesn't reduce to a single mechanism.

THC is the principal psychoactive cannabinoid in cannabis. It's a partial agonist at CB1 and CB2, with about 4x higher affinity for CB1. The euphoric, time-distorting, and appetite-stimulating effects most associated with cannabis use come from CB1 activation in cortical and limbic brain regions.

Documented effects in clinical research:

• Analgesia (mild-to-moderate, dose-dependent)
• Antiemetic activity — FDA-approved as dronabinol (synthetic THC) for chemotherapy-induced nausea
• Appetite stimulation — clinically meaningful in HIV-wasting syndrome
• Sleep onset shortening at low-to-moderate doses; sleep architecture disruption at higher doses
• Anxiety reduction at low doses; anxiety induction at higher doses (the inverted-U dose-response is well-documented in the literature)

The "high" most consumers describe at 5-15 mg oral or 5-20 mg inhaled is largely CB1-driven. At doses above 20-30 mg in inhaled form (proportionately higher orally), users with low tolerance experience adverse effects: tachycardia, anxiety, paranoia, perceptual distortion. These effects are also CB1-mediated — same receptor, different intensity.

Federal status: THC is Schedule I in the U.S., though dronabinol (synthetic THC) is Schedule III as Marinol. Δ8-THC and Δ10-THC, increasingly common in retail, are isomers with similar CB1 activity but legal status that varies by state and is currently in flux.

CBD is the most-studied non-psychoactive cannabinoid. It does not bind CB1 with appreciable affinity at consumer doses. Its mechanism is more diffuse: negative allosteric modulation at CB1, partial agonism at 5-HT1A serotonin receptors, TRPV1 desensitization, and inhibition of fatty-acid amide hydrolase (FAAH, the enzyme that breaks down anandamide).

The FAAH inhibition mechanism is significant — by slowing anandamide breakdown, CBD effectively increases endogenous endocannabinoid signaling, producing what appears to be CB1-like effect without direct receptor binding.

Clinical evidence:

• Epilepsy — Epidiolex (purified CBD) is FDA-approved for Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex. The doses are high (10-25 mg/kg/day) compared to typical wellness use.
• Anxiety — multiple RCTs (Bergamaschi 2011, Linares 2019) show acute anxiolytic effect at 300-600 mg in healthy adults under stress conditions.
• Sleep — emerging evidence (Shannon 2019) for sleep-onset improvement, particularly when comorbid with anxiety.
• Inflammation — preclinical strong; clinical evidence inconsistent.

Most consumer-grade CBD products are dosed at 10-50 mg per serving, well below the doses used in published trials. Whether wellness-dose CBD produces clinically meaningful effects in healthy adults is genuinely contested in the literature.

CBG is sometimes called "the mother cannabinoid" because the plant biosynthesizes most other cannabinoids from CBGA (its acidic precursor) via specific synthase enzymes. Most cannabis cultivars contain <1% CBG by dry weight; specialized "high-CBG" cultivars reach 4-9%.

Mechanism: CBG is a partial agonist at CB1 and CB2 (lower potency than THC), an α2-adrenergic receptor agonist, and a 5-HT1A serotonin antagonist. The α2-adrenergic activity is unusual among cannabinoids and may underlie CBG's reported alerting effects.

Published research:

• Antibacterial activity, particularly against MRSA (Appendino 2008, Farha 2020)
• Neuroprotective effects in Huntington's disease models (Valdeolivas 2015)
• Appetite stimulation (Brierley 2016)
• Possible anti-inflammatory bowel disease activity (Borrelli 2013)

Clinical human data is sparse. CBG is sold in the supplement market but the dose-response in humans has not been characterized in published trials. This is a place where consumer marketing has run ahead of the evidence base — claims of "focused energy" or "anxiety relief" from CBG are plausible based on mechanism but not yet validated in human RCTs.

CBN forms when THC oxidizes — it's not a primary biosynthetic product of the plant; it's a degradation product. Aged cannabis flower contains substantially more CBN than fresh flower. Concentrations in cured product range 0.1-1.5%.

CBN is a weak CB1 agonist (about 10% of THC's affinity) and slightly stronger at CB2. The folk reputation as "the sleep cannabinoid" is poorly supported — controlled studies in humans are very limited and the available data is mixed (Karniol 1975 found no significant sleep effect at modest oral doses).

What is well-established about CBN:

• Antibacterial activity (similar to other cannabinoids)
• Mild appetite stimulation
• Minor sedative effect, but possibly mostly because CBN is often paired with THC in "sleep blends" — meaning the THC may be doing the sedation work

Honest summary: CBN-only products at consumer doses (3-10 mg) lack robust evidence for sleep effect. Products combining CBN with THC and CBD are likely deriving most effect from the other two. We mention CBN here for completeness, not as a recommendation.

CBC is structurally distinct from THC and CBD — it doesn't share their characteristic phenol ring orientation. As a result, it interacts with cannabinoid receptors only weakly and reaches its primary targets (TRPV1, TRPA1, anandamide breakdown enzymes) instead.

Most cannabis cultivars contain 0.1-0.5% CBC. Specialized cultivars reach 2-3%. The compound is most studied for:

• Antinociception (animal models)
• Anti-inflammatory effect via TRPA1 modulation
• Possible neurogenesis effects (Shinjyo 2013) — particularly relevant given the broader interest in neuroplasticity-modulating compounds

Like CBG, CBC suffers from a thin human research base relative to the marketing claims. We include it here because the mechanism (TRPV1/TRPA1, FAAH inhibition) is genuinely interesting, and CBC may turn out to be clinically meaningful when finally studied — but as of today the human evidence is preclinical-stage.

The "entourage effect" hypothesis holds that whole-plant cannabis extracts produce different effects than purified single cannabinoids at the same dose, because of synergistic interaction between cannabinoids and terpenes. This idea (Ben-Shabat 1998, Russo 2011) has become so embedded in the wellness industry that it's often treated as fact — but the evidence is mixed.

What is well-supported:

• CBD modulates the subjective effects of THC. At THC:CBD ratios near 1:1, the perceived intensity and adverse effects (anxiety, paranoia) of THC are reduced compared to THC alone (Englund 2013). This is the strongest entourage-style finding.
• Terpenes affect the sensory experience (smell, taste) and may modulate effects via mechanisms unrelated to cannabinoid receptors (LaVigne 2021 — though this paper has been critiqued).

What is less supported:

• The specific "indica vs sativa" effect-prediction framework (more on this in the strain selection guide)
• Strong claims that low-dose minor cannabinoids (CBG, CBC, CBN) materially shift effects of accompanying THC and CBD

The honest summary: full-spectrum vs broad-spectrum vs isolate genuinely matters for some users, and there's reasonable mechanistic basis for caring about the THC:CBD ratio specifically. The deeper claims about minor cannabinoids and terpenes shifting effects are scientifically plausible but under-evidenced in humans.