Non-hallucinogenic Psychedelic Analog Design: A Promising Direction for Depression Treatment

Psilocybin as a lead candidate molecule in preclinical therapeutic studies of psychiatric disorders: A systematic review

Psilocybin is the main psychoactive compound found in hallucinogenic/magic mushrooms and can bind to both serotonergic and tropomyosin receptor kinase b (TrkB) receptors. Psilocybin has begun to show efficacy for a range of neuropsychiatric conditions, including treatment-resistant depression and anxiety disorders; however, neurobiological mechanisms are still being elucidated. Clinical research has found that psilocybin can alter functional connectivity patterns in human brains, which is often associated with therapeutic outcomes. However, preclinical research affords the opportunity to assess the potential cellular mechanisms by which psilocybin may exert its therapeutic effects. Preclinical rodent models can also facilitate a more tightly controlled experimental context and minimise placebo effects. Furthermore, where there is a rationale, preclinical researchers can investigate psilocybin administration in neuropsychiatric conditions that have not yet been researched clinically. As a result, we have systematically reviewed the knowledge base, identifying 82 preclinical studies which were screened based on specific criteria. This resulted in the exclusion of 44 articles, with 34 articles being included in the main review and another 2 articles included as Supporting Information materials. We found that psilocybin shows promise as a lead candidate molecule for treating a variety of neuropsychiatric conditions, albeit showing the most efficacy for depression. We discuss the experimental findings, and identify possible mechanisms whereby psilocybin could invoke therapeutic changes. Furthermore, we critically evaluate the between-study heterogeneity and possible future research avenues. Our review suggests that preclinical rodent models can provide valid and translatable tools for researching novel psilocybin-induced molecular and cellular mechanisms, and therapeutic outcomes.

Intranasal Delivery of Near-Infrared and Magnetic Dual-Response Nanospheres to Rapidly Produce Antidepressant-Like and Cognitive Enhancement Effects

Restricted by synaptic plasticity, dopamine receptor (DR) upregulation takes a long time to work. Moreover, the impact of the blood-brain barrier (BBB) on delivery efficiency restricts the development of drugs. Taking inspiration from snuff bottles, a convenient, fast-acting, and nonaddictive nasal drug delivery system has been developed to rapidly reshape the balance of synaptic transmitters. This optical and magnetic response system called CFs@DP, comprised of carbonized MIL-100 (Fe) frameworks (CFs) and domperidone (DP), which can enter the brain via nasal administration. Under dual stimulation of near-infrared (NIR) irradiation and catecholamine-induced complexation, CFs@DP disintegrates to release iron ions and DP, causing upregulation of the dopamine type 1 (D1), type 2 (D2) receptors, and brain-derived neurotrophic factor (BDNF) to achieve a therapeutic effect. In vivo experiments demonstrate that the DR density of mice (postnatal day 50-60) increased in the prefrontal cortex (PFC) and the hippocampus (HPC) after 10 days of therapy, resulting in antidepressant-like and cognitive enhancement effects. Interestingly, the cognitive enhancement effect of CFs@DP is even working in noniron deficiency (normal fed) mice, making it a promising candidate for application in enhancing learning ability.

Ethopharmacological evaluation of antidepressant-like effect of serotonergic psychedelics in C57BL/6J male mice

Serotonergic psychedelics such as psilocybin, lysergic acid diethylamide, and DOI exert a hallucinatory effect through serotonin 5-HT2A receptor (5-HT2A) activation. Recent studies have revealed that serotonergic psychedelics have therapeutic potential for neuropsychiatric disorders, including major depressive and anxiety-related disorders. However, the involvement of 5-HT2A in mediating the therapeutic effects of these drugs remains unclear. In this study, we ethopharmacologically analyzed the role of 5-HT2A in the occurrence of anxiolytic- and antidepressant-like effects of serotonergic psychedelics such as psilocin, an active metabolite of psilocybin, DOI, and TCB-2 in mice 24 h post-treatment. Mice with acute intraperitoneal psychedelic treatment exhibited significantly shorter immobility times in the forced swimming test (FST) and tail-suspension test (TST) than vehicle-treated control mice. These effects were eliminated by pretreatment with volinanserin, a 5-HT2A antagonist. Surprisingly, the decreasing immobility time in the FST in response to acute psilocin treatment was sustained for at least three weeks. In the novelty-suppressed feeding test (NSFT), the latency to feed, an indicator of anxiety-like behavior, was decreased by acute administration of psilocin; however, pretreatment with volinanserin did not diminish this effect. In contrast, DOI and TCB-2 did not affect the NSFT performance in mice. Furthermore, psilocin, DOI, and TCB-2 treatment did not affect the spontaneous locomotor activity or head-twitch response, a hallucination-like behavior in rodents. These results suggest that 5-HT2A contributes to the antidepressant effects of serotonergic psychedelics rather than anxiolytic effects.

Therapeutic potential of psychedelics: History, advancements, and unexplored frontiers

Psychedelics (serotonergic hallucinogens) are psychoactive substances that can alter perception and mood, and affect cognitive functions. These substances activate 5-HT2A receptors and may exert therapeutic effects. Some of the disorders for which psychedelic-assisted therapy have been studied include depression, addiction, anxiety and post-traumatic stress disorder. Despite the increasing number of studies reporting clinical effectiveness, with fewer negative symptoms and, additionally, minimal side effects, questions remain to be explored in the field of psychedelic medicine. Although progress has been achieved, there is still little understanding of the relationship among human brain and the modulation induced by these drugs. The present article aimed to describe, review and highlight the most promising findings in the literature regarding the (putative) therapeutic effects of psychedelics.

Synthesis and bioactivity of psilocybin analogues containing a stable carbon-phosphorus bond

Psilocybin analogues have been synthesized comprising a non-hydrolysable P-C bond to evaluate the biological activity and the selectivity towards 5-HT2AR, 5-HT2BR and the TNAP receptor. No activity was observed towards the phosphatase, however all compounds showed good binding affinity for 5-HT2AR and 5-HT2BR and one compound showed a higher selectivity towards 5-HT2AR than psilocin.

Serotonin 2A Receptor (5-HT2AR) Agonists: Psychedelics and Non-Hallucinogenic Analogues as Emerging Antidepressants

Psychedelics make up a group of psychoactive compounds that induce hallucinogenic effects by activating the serotonin 2A receptor (5-HT2AR). Clinical trials have demonstrated the traditional psychedelic substances like psilocybin as a class of rapid-acting and long-lasting antidepressants. However, there is a pressing need for rationally designed 5-HT2AR agonists that possess optimal pharmacological profiles in order to fully reveal the therapeutic potential of these agonists and identify safer drug candidates devoid of hallucinogenic effects. This Perspective provides an overview of the structure-activity relationships of existing 5-HT2AR agonists based on their chemical classifications and discusses recent advancements in understanding their molecular pharmacology at a structural level. The encouraging clinical outcomes of psychedelics in depression treatment have sparked drug discovery endeavors aimed at developing novel 5-HT2AR agonists with improved subtype selectivity and signaling bias properties, which could serve as safer and potentially nonhallucinogenic antidepressants. These efforts can be significantly expedited through the utilization of structure-based methods and functional selectivity-directed screening.

Ethopharmacological evaluation of antidepressant-like effect of serotonergic psychedelics in C57BL/6J male mice

Serotonergic psychedelics such as psilocybin, lysergic acid diethylamide, and DOI exert a hallucinatory effect through serotonin 5-HT 2A receptor (5-HT2A) activation. Recent studies have revealed that serotonergic psychedelics have therapeutic potential for neuropsychiatric disorders, including major depressive and anxiety-related disorders. However, the involvement of 5-HT2A in mediating the therapeutic effects of these drugs remains unclear. In this study, we ethopharmacologically analyzed the role of 5-HT2A in the occurrence of anxiolytic-and antidepressant-like effects of serotonergic psychedelics such as psilocin, an active metabolite of psilocybin, DOI, and TCB-2 in mice. Mice with acute intraperitoneal psychedelic treatment exhibited significantly shorter immobility times in the forced swimming test (FST) and tail-suspension test (TST) than vehicle-treated control mice 24 h post-treatment. These effects were eliminated by pretreatment with volinanserin, a 5-HT2A antagonist. Surprisingly, the decreasing immobility time in the FST in response to acute psilocin treatment was sustained for at least three weeks. In the novelty-suppressed feeding test (NSFT), the latency to feed, an indicator of anxiety-like behavior, was decreased by acute administration of psilocin; however, pretreatment with volinanserin did not diminish this effect. In contrast, DOI and TCB-2 did not affect the NSFT performance in mice. Furthermore, psilocin, DOI, and TCB-2 treatment did not affect the spontaneous locomotor activity or head-twitch response, a hallucination-like behavior in rodents. These results suggest that 5-HT2A contributes to the antidepressant effects of serotonergic psychedelics rather than an anxiolytic effects.