Future psychedelic treatments may depend on understanding what separates individual compounds. A new study in Nature Communications found that psilocybin, LSD, and 2C-B produced distinct patterns of brain glucose metabolism in rats, despite acting on the same central serotonin receptor.
The findings support investigating psychedelics individually rather than assuming that a shared receptor target produces interchangeable effects. They do not establish which compound works best for any psychiatric condition.
A Shared Receptor Does Not Explain Everything
Serotonergic psychedelics are commonly grouped by their activity at serotonin 2A receptors, which help mediate their acute effects. However, individual compounds differ in chemical structure and interactions with other receptors.
There are currently no established criteria for matching these drugs to particular psychiatric disorders based on brain circuit effects. Understanding their biological differences could help researchers design more targeted clinical comparisons.
Comparing Different Psychedelics Across Brain Networks
Researchers used positron emission tomography, or PET, with a radioactive glucose tracer to examine brain metabolism before treatment, during acute drug effects, and one week later. Separate groups received psilocybin, LSD, 2C-B, or saline.
The experiment began with 48 rats, including males and females. Final drug analyses included 12 animals each for psilocybin and 2C-B and 11 for LSD.
The team focused on two interconnected systems: one involved in action selection, habits, and cognitive control, and another involved in emotion, memory, and stress regulation.
Repeated measurements allowed each animal’s later scans to be compared with its own baseline. Saline controls helped distinguish drug effects from changes associated with repeated testing.
Three Compounds Produced Distinct Metabolic Patterns
During acute exposure, psilocybin increased relative glucose uptake in the dorsal striatum, nucleus accumbens, and insula. These regions contribute to action selection, motivation, and processing internal bodily signals.
LSD reduced relative metabolism in anterior cingulate and orbitofrontal regions while increasing it in the amygdala, hypothalamus, and midbrain regions containing dopamine-producing neurons.
2C-B also reduced relative metabolism in several frontal regions, but increased it in the thalamus, ventral hippocampus, hypothalamus, and dopamine-associated midbrain.
These measurements were normalized against whole-brain uptake. An increase therefore describes a regional change relative to the brain overall, rather than necessarily indicating an absolute increase in energy consumption.
Lasting Changes Require Careful Interpretation
One week later, some regional metabolic differences remained. Psilocybin showed increased relative insula metabolism, while 2C-B showed changes in the nucleus accumbens and midbrain.
Broader analyses also suggested modest persistent reductions involving contributions from psilocybin and LSD. However, individual drug comparisons did not produce significant whole-brain clusters at that time point.
Researchers additionally examined whether metabolism in different regions varied together across animals. Most apparent changes in these relationships did not survive correction for multiple comparisons. The evidence is consequently stronger for distinct regional metabolic patterns than for widespread changes in network coordination.
Similar Receptor Engagement, Different Downstream Effects
Separate receptor imaging suggested that the selected doses occupied approximately 50% to 70% of serotonin 2A receptors. Different metabolic patterns emerged despite this broadly comparable engagement.
That finding suggests receptor occupancy alone cannot explain the drugs’ effects. Broader receptor interactions and downstream signaling may contribute, although this experiment did not isolate their individual roles.
Glucose imaging measures energy use indirectly. It does not demonstrate new synapse formation or prove that a metabolic change represents therapeutic improvement.
Toward More Precise Clinical Questions
The study’s contribution is its comparison of three compounds using the same imaging framework. Human research has separately documented acute and persistent network changes following psilocybin, but those findings do not establish equivalent effects across psychedelics.
For clinical research, the next step is testing whether these biological differences predict meaningful differences in symptoms, tolerability, or treatment durability. Distinct brain signatures offer hypotheses for future trials, not a prescribing guide.
Citations
- Gudmundsen, F., et al. (2026). Serotonergic Psychedelics Induce Distinct Patterns Of Metabolic Activity And Covariance Within Biologically Informed Rat Brain Networks. Nature Communications, 17, 9340.
- Siegel, J. S., et al. (2024). Psilocybin Desynchronizes The Human Brain. Nature, 632, 131–138.
Explore more at https://www.interventionalpsychiatry.org/
