February 2026
Serotonin
What February 2026's 15 new studies found, synthesized from the papers below. All Serotonin research →
The synthesis
Synthesized from 15 studies in the library · AI-generated, grounded in the abstracts below
Found by searching the library for Serotonin, 5-HT, serotonergic, 5-HT2A receptor, then ranked by relevance.
In February 2026, serotonin research focused on the mechanisms and therapeutic potential of serotonergic psychedelics. Studies found that psilocybin's cognitive benefits in a rat model of Fragile X Syndrome depend on BDNF/TrkB signaling rather than classical serotonin receptors, and that the 5-HT1B receptor contributes to some of psilocybin's behavioral effects in mice. Additionally, research showed that MDMA's effects on cortical plasticity are stereoselective and sex-dependent, and that ayahuasca can modulate traumatic fear memories via BDNF-dependent mechanisms in the infralimbic cortex. A key caveat is that most findings are from preclinical models, with limited human data.
Confidence in the evidence
Low-Moderate- The evidence consists primarily of preclinical studies (rat and mouse models) with small sample sizes, limiting direct human applicability.
- Study designs include controlled experiments and reviews, but no large-scale human RCTs were reported for the specific findings.
- Results are generally consistent in supporting serotonergic involvement in psychedelic effects, but mechanisms vary across compounds and models.
- Some studies have conflicting or nuanced findings, such as psilocybin's effects being independent of 5-HT2A/5-HT1A receptors in one model but involving 5-HT1B in another.
How we rate confidence
Confidence reflects the strength of the underlying evidence, not whether the result is favorable. It weighs the number and size of studies, their design (randomized trials count for more than observational or single-case work), how consistently they point the same way, and their risk of bias.
Tiers run from Insufficient to High. High is rare in this field: small, early, or open-label studies land lower even when their direction is encouraging.
Evidence by study
Direction is each study's finding relative to your question: Supports, Opposes, No effect, Mixed, or Unclear.
| Study | Design | Sample size | Direction | Finding |
|---|---|---|---|---|
| Psilocybin improves novel object recognition in a rat model of Fragile X Syndrome through the modulation of the BDNF/TrkB signaling pathway 2026 | preclinical (rat model) | Supports | Psilocybin microdosing rescued novel object recognition deficits in a rat model of Fragile X Syndrome via BDNF/TrkB signaling, independent of 5-HT2A or 5-HT1A receptor activation. | |
| Correction: The serotonin 1B receptor is required for some of the behavioral effects of psilocybin in mice 2026 | correction (preclinical mouse study) | Supports | The 5-HT1B receptor is required for some behavioral and neural effects of psilocybin in mice, including its enduring antidepressant-like effects. | |
| Stereoselective, sex-dependent 5-HT2A receptor modulation of cortical plasticity by MDMA in mice. 2026 | preclinical (mouse study) | Mixed | MDMA's effects on 5-HT2A receptor signaling and dendritic spine density are stereoselective and sex-dependent, with S(+)-MDMA showing partial agonism and spine remodeling in males only. | |
| Ayahuasca modulation of traumatic-like fear memories requires infralimbic cortex BDNF-dependent mechanisms in rats. 2026 | preclinical (rat study) | Supports | Ayahuasca enhanced fear extinction and reduced fear generalization in rats via BDNF-dependent mechanisms in the infralimbic cortex, with sex differences in BDNF dependence for fear generalization. | |
| Spatiotemporal mapping of brain organisation following the administration of 2C-B and psilocybin 2026 | within-subjects, double-blind, placebo-controlled crossover | 22 | Mixed | 2C-B and psilocybin both altered functional brain connectivity, with 2C-B showing less reduction in between-network dynamic connectivity but greater increases in transmodal static connectivity compared to psilocybin. |
| Computational Analysis of Psilocybin Effects on Three-Choice Touchscreen Reversal Learning in Rats: A Pilot Study 2026 | preclinical (rat pilot study) | 5 | Opposes | Psilocybin administration impaired learning and unlearning rates in a three-choice reversal learning task in rats, suggesting a negative effect on cognitive flexibility in this paradigm. |
| Predicting drug–drug interactions between ayahuasca alkaloids and SSRIs using physiologically based pharmacokinetic modeling 2026 | modeling study | Supports | Physiologically based pharmacokinetic modeling predicted a clinically relevant drug-drug interaction between ayahuasca alkaloids and SSRIs, with increased DMT exposure potentially intensifying serotonergic effects. | |
| N,N-dimethyltryptamine (DMT) is neither formed nor retained in serotonin terminals in the rat brain. 2026 | preclinical (rat study) | Opposes | Endogenous DMT was not detected in rat brain even after monoamine oxidase inhibition, and exogenous DMT was not retained in serotonin terminals, challenging the hypothesis that DMT acts as a co-transmitter with serotonin. | |
| N,N-dimethyltryptamine (DMT) is neither formed nor retained in serotonin terminals in the rat brain 2026 | preclinical (rat study) | Opposes | Endogenous DMT was not detected in rat brain after pargyline pretreatment, and exogenous DMT disposition was not altered by serotonin transporter inhibition, indicating DMT is neither formed nor retained in serotonin terminals. | |
| Neurotransmitter Mechanisms of Ketamine and Ketamine–Magnesium Sulfate-Induced Hypothermia: Evidence for Serotonergic and Adrenergic Involvement Without GABAA Contributions 2026 | preclinical (rat study) | Mixed | Serotonergic and adrenergic systems contribute to ketamine-induced hypothermia in rats, with methysergide showing bidirectional effects depending on dose, while GABAA receptors are not involved. | |
| Repeated administration of the synthetic cannabinoid AKB48 induces serotonergic neuroadaptation in male and female mice: behavioural and immunohistochemical evidence. 2026 | preclinical (mouse study) | Supports | Repeated administration of the synthetic cannabinoid AKB48 induced serotonergic neuroadaptation, including changes in 5-HT2A receptors and serotonin transporter in cerebellum and cortex, with sex-dependent effects. | |
| MDMA-Assisted Therapy for PTSD: Neuroplastic Change or Psychotherapeutic Catalyst? 2026 | review | Supports | MDMA-assisted therapy for PTSD may work through a synergistic model combining neurobiological effects (fear extinction, neuroplasticity) and relational effects (enhanced therapeutic alliance), both involving serotonergic and oxytocinergic signaling. | |
| The effects of acute and repeated adolescent MDMA exposure on behavior, cognition, and the monoamine neurotransmitter systems: A review of human and pre-clinical research 2026 | review | Mixed | Acute high-dose MDMA in adolescents impairs the serotonin system and increases locomotor activity, but repeated exposure shows conflicting results depending on dosing and timing; there is a lack of data on females. | |
| Psychedelic Therapy: A Primer for Primary Care Clinicians—Mescaline 2026 | review | Supports | Mescaline shows preliminary safety in healthy humans with dose-dependent subjective effects and transient autonomic stimulation, but remains understudied in clinical populations. | |
| Opioid Receptors in Psychedelia: Indirect Serotonergic Modulation of Direct KOR Activation by Salvinorin A 2026 | review | Unclear | Salvinorin A acts via kappa opioid receptor agonism independent of serotonin, while classical serotonergic psychedelics indirectly engage opioid systems through downstream 5-HT2A signaling, contributing to analgesic and mood effects. |
Psilocybin microdosing rescued novel object recognition deficits in a rat model of Fragile X Syndrome via BDNF/TrkB signaling, independent of 5-HT2A or 5-HT1A receptor activation.
preclinical (rat model)
The 5-HT1B receptor is required for some behavioral and neural effects of psilocybin in mice, including its enduring antidepressant-like effects.
correction (preclinical mouse study)
MDMA's effects on 5-HT2A receptor signaling and dendritic spine density are stereoselective and sex-dependent, with S(+)-MDMA showing partial agonism and spine remodeling in males only.
preclinical (mouse study)
Ayahuasca enhanced fear extinction and reduced fear generalization in rats via BDNF-dependent mechanisms in the infralimbic cortex, with sex differences in BDNF dependence for fear generalization.
preclinical (rat study)
2C-B and psilocybin both altered functional brain connectivity, with 2C-B showing less reduction in between-network dynamic connectivity but greater increases in transmodal static connectivity compared to psilocybin.
within-subjects, double-blind, placebo-controlled crossover Sample size: 22
Psilocybin administration impaired learning and unlearning rates in a three-choice reversal learning task in rats, suggesting a negative effect on cognitive flexibility in this paradigm.
preclinical (rat pilot study) Sample size: 5
Physiologically based pharmacokinetic modeling predicted a clinically relevant drug-drug interaction between ayahuasca alkaloids and SSRIs, with increased DMT exposure potentially intensifying serotonergic effects.
modeling study
Endogenous DMT was not detected in rat brain even after monoamine oxidase inhibition, and exogenous DMT was not retained in serotonin terminals, challenging the hypothesis that DMT acts as a co-transmitter with serotonin.
preclinical (rat study)
Endogenous DMT was not detected in rat brain after pargyline pretreatment, and exogenous DMT disposition was not altered by serotonin transporter inhibition, indicating DMT is neither formed nor retained in serotonin terminals.
preclinical (rat study)
Serotonergic and adrenergic systems contribute to ketamine-induced hypothermia in rats, with methysergide showing bidirectional effects depending on dose, while GABAA receptors are not involved.
preclinical (rat study)
Repeated administration of the synthetic cannabinoid AKB48 induced serotonergic neuroadaptation, including changes in 5-HT2A receptors and serotonin transporter in cerebellum and cortex, with sex-dependent effects.
preclinical (mouse study)
MDMA-assisted therapy for PTSD may work through a synergistic model combining neurobiological effects (fear extinction, neuroplasticity) and relational effects (enhanced therapeutic alliance), both involving serotonergic and oxytocinergic signaling.
review
Acute high-dose MDMA in adolescents impairs the serotonin system and increases locomotor activity, but repeated exposure shows conflicting results depending on dosing and timing; there is a lack of data on females.
review
Mescaline shows preliminary safety in healthy humans with dose-dependent subjective effects and transient autonomic stimulation, but remains understudied in clinical populations.
review
Salvinorin A acts via kappa opioid receptor agonism independent of serotonin, while classical serotonergic psychedelics indirectly engage opioid systems through downstream 5-HT2A signaling, contributing to analgesic and mood effects.
review
Points of agreement
- Serotonergic psychedelics (psilocybin, MDMA, ayahuasca) modulate neuroplasticity and cognitive processes through mechanisms involving BDNF/TrkB signaling and serotonin receptors.
- Preclinical studies consistently show that psychedelics can enhance fear extinction and alter brain connectivity, though effects are dose- and context-dependent.
- Sex differences are observed in the effects of MDMA and other compounds on serotonin receptor signaling and behavioral outcomes.
Conflicts
- Psilocybin improved cognitive flexibility in some paradigms but impaired learning in a rat reversal learning task, suggesting context-dependent effects.
- The role of specific serotonin receptors varies: psilocybin's effects in Fragile X rats were independent of 5-HT2A/5-HT1A, but 5-HT1B was required for some effects in mice.
- Endogenous DMT was not detected in rat brain, contradicting the hypothesis that it acts as a serotonin co-transmitter.
Gaps
- Most findings are from preclinical models; human clinical trials are lacking for many compounds, especially mescaline and 2C-B.
- Long-term safety and durability of effects are not addressed in the provided studies.
- Data on adolescent populations and sex differences are limited, particularly for MDMA in females.
- The clinical relevance of drug-drug interactions between ayahuasca and SSRIs has not been tested in controlled human studies.