[Solved] Psilocybin and the serotonin receptors

Psilocybin has relatively little effect on the receptors. It is a prodrug that must first be converted into psilocin before it becomes active. Psilocin shares strong structural similarities with serotonin, a neurotransmitter essential for mood, perception, and consciousness. As a result, psilocin can bind to various serotonin receptors in the brain and trigger a cascade of neurological processes. A detailed overview of how this works follows below.

1. Psilocybin as a prodrug of psilocin

After oral ingestion of psilocybin, this substance is rapidly converted into psilocin in the liver by phosphatase enzymes. Only then can the substance cross the blood-brain barrier and bind to serotonin receptors in the central nervous system. Psilocybin itself has a low affinity for these receptors and is barely active on its own.

2. Binding to serotonin receptors

Psilocin binds to multiple types of serotonin receptors., each with a specific role in the psychedelic experience and the therapeutic effects:

1. 5-HT2A receptor
   Psilocin has a high affinity for this receptor, which is located primarily in the prefrontal cortex. Activation of this receptor is responsible for the core of the psychedelic experience: visual hallucinations, distortion of time- and space perception, ego dissolution, heightened introspection, and spiritual insights. Activation occurs via Gq/11 proteins, which initiate intracellular signaling pathways such as mTOR, ERK, and BDNF-related routes.

2. 5-HT1A receptor
   The binding of psilocin to this receptor plays an important role in regulating mood and anxiety. This explains why psilocybin experiences are often accompanied by a feeling of emotional calm and safety. This receptor activation has an anxiety-reducing effect and prevents panic reactions during intense phases of the trip.

3. 5-HT2C receptor
   Psilocin also has a moderate affinity for this receptor, which is involved in regulating mood, appetite, and anxiety. In some users, activation of this receptor can cause mild side effects such as nausea or temporary restlessness, particularly at higher doses.

4. SERT (serotonin transporter)
   Psilocin inhibits the reuptake of serotonin by the serotonin transporter protein (SERT) to a limited extent, thereby increasing the amount of available serotonin in the synaptic cleft. This contributes to a sense of connectedness, well-being, and emotional openness.

3. Activation of neuroplasticity via BDNF and TrkB

The activation of 5-HT2A receptors by psilocin not only influences conscious experience but also triggers a biological process that leads to lasting changes in the brain. This occurs through the production of Brain-Derived Neurotrophic Factor (BDNF), a growth factor that supports the survival, growth, and reconnection of brain cells. The elevated BDNF is subsequently bound to the TrkB receptor. In addition to this indirect receptor affiliation, psilocin also appears to bind directly to these receptors, activating a number of important signaling pathways:

1. PI3K/Akt route, which promotes cell survival.
2. MAPK/ERK route, which stimulates gene expression and neuronal growth.
3. PLCγ-route, which drives calcium-dependent processes such as synaptic plasticity.

These pathways lead to increased neuroplasticity, improvement of cognitive functions, and repair of neuronal networks affected in conditions such as depression, anxiety disorders, and PTSD.

4. Rearrangement of brain networks

Psilocin influences functional connectivity in the brain. During the experience, activity decreases in the Default Mode Network (DMN), a network active in self-reflection, rumination, and ego-related processes. Simultaneously, connectivity between other brain regions is strengthened, such as the salience network (which detects important stimuli) and the central executive network (involved in attention and memory). This brain activity supports the emotional and spiritual insights that often emerge from a psilocybin session.

5. Therapeutic implications

Due to the combined effects on serotonin receptors, BDNF production, and brain networks, psilocin offers powerful therapeutic potential for a wide range of mental disorders. The experience is not only perceived as insightful but also leads to measurable structural changes in the brain that can contribute to long-term improvement in mental health.

Conclusion

Psilocybin acts indirectly by activating the serotonergic systems in the brain via conversion to psilocin. Psilocin binds primarily to the 5-HT2A receptor, which triggers the psychedelic experience and associated neurobiological processes. Through activation of BDNF and TrkB, profound changes in the brain are stimulated, contributing to the therapeutic effect. This combined action makes for a psilocybin session or truffle session under professional guidance to a valuable option for people seeking healing, insight, and transformation.