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Episode 140 Cannabis & Adaptation

Pregnenolone: Your Body's THC Brake

Your body has a built-in mechanism to prevent THC overdose—a hormone that acts as a dimmer switch on CB1 activation.

By Justin Hartfield 4:20 Cannabis & Adaptation Updated December 22, 2025
Pregnenolone: Your Body's THC Brake
Justin Hartfield

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Justin Hartfield

Founder of Weedmaps, student of Dr. Bob Melamede, and explorer of far-from-equilibrium systems. Connecting thermodynamics, consciousness, and human potential.

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Your body has a built-in mechanism to prevent you from getting too high. It's called pregnenolone, and understanding it changes how you think about cannabis tolerance and safety.

The Discovery

Researchers found that when THC activates CB1 receptors, it triggers the release of pregnenolone—a neurosteroid that then blocks further CB1 activation. It's a negative feedback loop, a built-in safety mechanism.

This is why it's virtually impossible to fatally overdose on cannabis. Your body has a brake pedal. The more THC you consume, the more pregnenolone you produce, the less effect the THC has.

Dr. Bob Melamede saw this as another example of the body's elegant self-regulation. The endocannabinoid system isn't just about activation—it's about balance.

Implications for Cannabis Use

This mechanism explains several things about cannabis use:

First, it explains tolerance. Regular cannabis users produce more pregnenolone in response to THC, which is why they need higher doses to achieve the same effect.

Infographic
Your body has a built-in safety valve for cannabis: pregnenolone, released when THC levels get too high, modulating the CB1 response.

Second, it explains why cannabis is so safe compared to other drugs. Opioids don't have this kind of brake—that's why overdoses are possible and common. Cannabis has a built-in ceiling.

Third, it suggests that the citicoline discovery might work partly by modulating this pregnenolone response.

"Your body knows how to handle cannabis. It's been preparing for millions of years."

The Bigger Picture

Pregnenolone isn't just a THC brake—it's the precursor to all steroid hormones. It's called the "mother hormone" because it can be converted into cortisol, DHEA, testosterone, estrogen, and progesterone.

This connects cannabis use to the broader hormonal system. The Forward-Looking approach recognizes that nothing in biology is isolated. Everything connects to everything else. Understanding these connections is key to using cannabis wisely.

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