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Conn K, Milton LK, Huang K, Munguba H, Ruuska J, Lemus MB, Greaves E, Homman-Ludiye J, Oldfield BJ, Foldi CJ. Psilocybin restrains activity-based anorexia in female rats by enhancing cognitive flexibility: contributions from 5-HT1A and 5-HT2A receptor mechanisms. Mol Psychiatry 2024; 29:3291-3304. [PMID: 38678087 PMCID: PMC11449803 DOI: 10.1038/s41380-024-02575-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 04/16/2024] [Accepted: 04/19/2024] [Indexed: 04/29/2024]
Abstract
Psilocybin has shown promise for alleviating symptoms of depression and is currently in clinical trials for the treatment of anorexia nervosa (AN), a condition that is characterised by persistent cognitive inflexibility. Considering that enhanced cognitive flexibility after psilocybin treatment is reported to occur in individuals with depression, it is plausible that psilocybin could improve symptoms of AN by breaking down cognitive inflexibility. A mechanistic understanding of the actions of psilocybin is required to tailor the clinical application of psilocybin to individuals most likely to respond with positive outcomes. This can only be achieved using incisive neurobiological approaches in animal models. Here, we use the activity-based anorexia (ABA) rat model and comprehensively assess aspects of reinforcement learning to show that psilocybin (post-acutely) improves body weight maintenance in female rats and facilitates cognitive flexibility, specifically via improved adaptation to the initial reversal of reward contingencies. Further, we reveal the involvement of signalling through the serotonin (5-HT) 1 A and 5-HT2A receptor subtypes in specific aspects of learning, demonstrating that 5-HT1A antagonism negates the cognitive enhancing effects of psilocybin. Moreover, we show that psilocybin elicits a transient increase and decrease in cortical transcription of these receptors (Htr2a and Htr1a, respectively), and a further reduction in the abundance of Htr2a transcripts in rats exposed to the ABA model. Together, these findings support the hypothesis that psilocybin could ameliorate cognitive inflexibility in the context of AN and highlight a need to better understand the therapeutic mechanisms independent of 5-HT2A receptor binding.
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MESH Headings
- Animals
- Female
- Psilocybin/pharmacology
- Rats
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT1A/metabolism
- Receptor, Serotonin, 5-HT1A/drug effects
- Anorexia/metabolism
- Anorexia/drug therapy
- Cognition/drug effects
- Disease Models, Animal
- Anorexia Nervosa/drug therapy
- Anorexia Nervosa/metabolism
- Rats, Sprague-Dawley
- Body Weight/drug effects
- Reward
- Hallucinogens/pharmacology
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Affiliation(s)
- K Conn
- Monash University, Department of Physiology, 26 Innovation Walk, Clayton, VIC, 3800, Australia
- Monash Biomedicine Discovery Institute, 23 Innovation Walk, Clayton, VIC, 3800, Australia
| | - L K Milton
- Monash University, Department of Physiology, 26 Innovation Walk, Clayton, VIC, 3800, Australia
- Monash Biomedicine Discovery Institute, 23 Innovation Walk, Clayton, VIC, 3800, Australia
| | - K Huang
- Monash University, Department of Physiology, 26 Innovation Walk, Clayton, VIC, 3800, Australia
- Monash Biomedicine Discovery Institute, 23 Innovation Walk, Clayton, VIC, 3800, Australia
| | - H Munguba
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA
| | - J Ruuska
- University of Helsinki, Yliopistonkatu 4, 00100, Helsinki, Finland
| | - M B Lemus
- Monash University, Department of Physiology, 26 Innovation Walk, Clayton, VIC, 3800, Australia
- Monash Biomedicine Discovery Institute, 23 Innovation Walk, Clayton, VIC, 3800, Australia
| | - E Greaves
- Monash University, Department of Physiology, 26 Innovation Walk, Clayton, VIC, 3800, Australia
- Monash Biomedicine Discovery Institute, 23 Innovation Walk, Clayton, VIC, 3800, Australia
| | - J Homman-Ludiye
- Monash Micro Imaging, Monash University, 15 Innovation Walk, Clayton, VIC, 3800, Australia
| | - B J Oldfield
- Monash University, Department of Physiology, 26 Innovation Walk, Clayton, VIC, 3800, Australia
- Monash Biomedicine Discovery Institute, 23 Innovation Walk, Clayton, VIC, 3800, Australia
| | - C J Foldi
- Monash University, Department of Physiology, 26 Innovation Walk, Clayton, VIC, 3800, Australia.
- Monash Biomedicine Discovery Institute, 23 Innovation Walk, Clayton, VIC, 3800, Australia.
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Fisher EL, Smith R, Conn K, Corcoran AW, Milton LK, Hohwy J, Foldi CJ. Psilocybin increases optimistic engagement over time: computational modelling of behaviour in rats. Transl Psychiatry 2024; 14:394. [PMID: 39349428 PMCID: PMC11442808 DOI: 10.1038/s41398-024-03103-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2024] [Revised: 09/18/2024] [Accepted: 09/19/2024] [Indexed: 10/02/2024] Open
Abstract
Psilocybin has shown promise as a novel pharmacological intervention for treatment of depression, where post-acute effects of psilocybin treatment have been associated with increased positive mood and decreased pessimism. Although psilocybin is proving to be effective in clinical trials for treatment of psychiatric disorders, the information processing mechanisms affected by psilocybin are not well understood. Here, we fit active inference and reinforcement learning computational models to a novel two-armed bandit reversal learning task capable of capturing engagement behaviour in rats. The model revealed that after receiving psilocybin, rats achieve more rewards through increased task engagement, mediated by modification of forgetting rates and reduced loss aversion. These findings suggest that psilocybin may afford an optimism bias that arises through altered belief updating, with translational potential for clinical populations characterised by lack of optimism.
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Affiliation(s)
- Elizabeth L Fisher
- Monash Centre for Consciousness and Contemplative Studies, Monash University, Melbourne, VIC, Australia.
| | - Ryan Smith
- Laureate Institute for Brain Research, University of Tulsa, Tulsa Oklahoma, OK, USA
| | - Kyna Conn
- Anorexia and Feeding Disorders Laboratory, Department of Physiology, Monash University, Melbourne, VIC, Australia
- Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Andrew W Corcoran
- Monash Centre for Consciousness and Contemplative Studies, Monash University, Melbourne, VIC, Australia
| | - Laura K Milton
- Anorexia and Feeding Disorders Laboratory, Department of Physiology, Monash University, Melbourne, VIC, Australia
- Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Jakob Hohwy
- Monash Centre for Consciousness and Contemplative Studies, Monash University, Melbourne, VIC, Australia
| | - Claire J Foldi
- Anorexia and Feeding Disorders Laboratory, Department of Physiology, Monash University, Melbourne, VIC, Australia
- Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
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Xu M, Kiss AJ, Jones JA, McMurray MS, Shi H. Effect of oral tryptamines on the gut microbiome of rats-a preliminary study. PeerJ 2024; 12:e17517. [PMID: 38846751 PMCID: PMC11155674 DOI: 10.7717/peerj.17517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Accepted: 05/15/2024] [Indexed: 06/09/2024] Open
Abstract
Background Psilocybin and related tryptamines have come into the spotlight in recent years as potential therapeutics for depression. Research on the mechanisms of these effects has historically focused on the direct effects of these drugs on neural processes. However, in addition to such neural effects, alterations in peripheral physiology may also contribute to their therapeutic effects. In particular, substantial support exists for a gut microbiome-mediated pathway for the antidepressant efficacy of other drug classes, but no prior studies have determined the effects of tryptamines on microbiota. Methods To address this gap, in this preliminary study, male Long Evans rats were treated with varying dosages of oral psilocybin (0.2 or 2 mg/kg), norbaeocystin (0.25 or 2.52 mg/kg), or vehicle and their fecal samples were collected 1 week and 3 weeks after exposure for microbiome analysis using integrated 16S ribosomal DNA sequencing to determine gut microbiome composition. Results We found that although treatment with neither psilocybin nor norbaeocystin significantly affected overall microbiome diversity, it did cause significant dose- and time-dependent changes in bacterial abundance at the phylum level, including increases in Verrucomicrobia and Actinobacteria, and decreases in Proteobacteria. Conclusion and Implications These preliminary findings support the idea that psilocybin and other tryptamines may act on the gut microbiome in a dose- and time-dependent manner, potentially identifying a novel peripheral mechanism for their antidepressant activity. The results from this preliminary study also suggest that norbaeocystin may warrant further investigation as a potential antidepressant, given the similarity of its effects to psilocybin.
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Affiliation(s)
- Mengyang Xu
- Biology, Miami University, Oxford, OH, United States
| | - Andor J. Kiss
- Center for Bioinformatics and Functional Genomics, Miami University, Oxford, OH, United States
| | - J. Andrew Jones
- Chemical, Paper, and Biomedical Engineering, Miami University, Oxford, OH, United States
| | | | - Haifei Shi
- Biology, Miami University, Oxford, OH, United States
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Aaronson ST, van der Vaart A, Miller T, LaPratt J, Swartz K, Shoultz A, Lauterbach M, Sackeim HA, Suppes T. Single-Dose Synthetic Psilocybin With Psychotherapy for Treatment-Resistant Bipolar Type II Major Depressive Episodes: A Nonrandomized Open-Label Trial. JAMA Psychiatry 2024; 81:555-562. [PMID: 38055270 PMCID: PMC10701666 DOI: 10.1001/jamapsychiatry.2023.4685] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 09/20/2023] [Indexed: 12/07/2023]
Abstract
Importance Bipolar II disorder (BDII) is a debilitating condition frequently associated with difficult-to-treat depressive episodes. Psilocybin has evidence for rapid-acting antidepressant effects but has not been investigated in bipolar depression. Objective To establish the safety and efficacy of psilocybin in patients with BDII in a current depressive episode. Design, Setting, and Participants This was a 12-week, open-label nonrandomized open-label trial conducted at Sheppard Pratt Hospital. Participants aged 18 to 65 years with BDII, a current depressive episode longer than 3 months, and documented insufficient benefit with at least 2 pharmacologic treatments during the current episode were invited to participate. Of 70 approached, 19 met inclusion criteria and were enrolled. The trial was conducted between April 14, 2021, and January 5, 2023. Interventions A single dose of synthetic psilocybin, 25 mg, was administered. Psychotropic medications were discontinued at least 2 weeks prior to dosing. Therapists met with patients for 3 sessions during pretreatment, during the 8-hour dosing day, and for 3 integration sessions posttreatment. Main Outcomes and Measures The primary outcome measure was change in Montgomery-Åsberg Depression Rating scale (MADRS) at 3 weeks posttreatment. Secondary measures included MADRS scores 12 weeks posttreatment, the self-rated Quick Inventory of Depression Symptoms-Self Rating (QIDS-SR), and the self-rated Quality of Life Enjoyment and Satisfaction Questionnaire-Short Form (Q-LES-Q-SF), each completed at baseline and all subsequent visits. Safety measures included the Columbia Suicide Severity Rating Scale (CSSRS) and the Young Mania Rating Scale (YMRS) completed at each visit. Results Of the 15 participants in this study (6 male and 9 female; mean [SD] age, 37.8 [11.6] years), all had lower scores at week 3, with a mean (SD) change of -24.00 (9.23) points on the MADRS, (Cohen d = 4.08; 95% CI, -29.11 to -18.89; P < .001). Repeat measures analysis of variance showed lower MADRS scores at all tested posttreatment time points, including the end point (Cohen d = 3.39; 95% CI, -33.19 to -16.95; adjusted P < .001). At week 3, 12 participants met the response criterion (50% decrease in MADRS), and 11 met remission criterion (MADRS score ≤10). At the study end point, 12 patients met both response and remission criteria. QIDS-SR scores and Q-LES-Q-SF scores demonstrated similar improvements. YMRS and CSSRS scores did not change significantly at posttreatment compared to baseline. Conclusions and Relevance The findings in this open-label nonrandomized open-label trial suggest efficacy and safety of psilocybin with psychotherapy in BDII depression and supports further study of psychedelics in this population.
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Affiliation(s)
- Scott T. Aaronson
- Institute for Advanced Diagnostics and Treatment, Sheppard Pratt Health System, Baltimore, Maryland
- Department of Psychiatry, University of Maryland, Baltimore
| | | | - Tammy Miller
- Institute for Advanced Diagnostics and Treatment, Sheppard Pratt Health System, Baltimore, Maryland
| | - Jeffrey LaPratt
- Institute for Advanced Diagnostics and Treatment, Sheppard Pratt Health System, Baltimore, Maryland
| | - Kimberly Swartz
- Institute for Advanced Diagnostics and Treatment, Sheppard Pratt Health System, Baltimore, Maryland
| | - Audrey Shoultz
- Institute for Advanced Diagnostics and Treatment, Sheppard Pratt Health System, Baltimore, Maryland
| | - Margo Lauterbach
- Institute for Advanced Diagnostics and Treatment, Sheppard Pratt Health System, Baltimore, Maryland
- Department of Psychiatry, University of Maryland, Baltimore
| | - Harold A. Sackeim
- Department of Psychiatry, Columbia University, New York
- Department of Radiology, Columbia University, New York
| | - Trisha Suppes
- VA Palo Alto Health Care System, Palo Alto, California
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California
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Ruan Y, Yuan R, He J, Jiang Y, Chu S, Chen N. New perspective on sustained antidepressant effect: focus on neurexins regulating synaptic plasticity. Cell Death Discov 2024; 10:205. [PMID: 38693106 PMCID: PMC11063156 DOI: 10.1038/s41420-024-01974-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 04/17/2024] [Accepted: 04/17/2024] [Indexed: 05/03/2024] Open
Abstract
Depression is highly prevalent globally, however, currently available medications face challenges such as low response rates and short duration of efficacy. Additionally, depression mostly accompany other psychiatric disorders, further progressing to major depressive disorder without long-term effective management. Thus, sustained antidepressant strategies are urgently needed. Recently, ketamine and psilocybin gained attention as potential sustained antidepressants. Review of recent studies highlights that synaptic plasticity changes as key events of downstream long-lasting changes in sustained antidepressant effect. This underscores the significance of synaptic plasticity in sustained antidepressant effect. Moreover, neurexins, key molecules involved in the regulation of synaptic plasticity, act as critical links between synaptic plasticity and sustained antidepressant effects, involving mechanisms including protein level, selective splicing, epigenetics, astrocytes, positional redistribution and protein structure. Based on the regulation of synaptic plasticity by neurexins, several drugs with potential for sustained antidepressant effect are also discussed. Focusing on neurexins in regulating synaptic plasticity promises much for further understanding underlying mechanisms of sustained antidepressant and the next step in new drug development. This research represents a highly promising future research direction.
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Affiliation(s)
- Yuan Ruan
- Tianjin University of Traditional Chinese Medicine, Tianjin, PR China
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, PR China
| | - Ruolan Yuan
- Tianjin University of Traditional Chinese Medicine, Tianjin, PR China
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, PR China
| | - Jiaqi He
- Tianjin University of Traditional Chinese Medicine, Tianjin, PR China
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, PR China
| | - Yutong Jiang
- Tianjin University of Traditional Chinese Medicine, Tianjin, PR China
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, PR China
| | - Shifeng Chu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, PR China.
| | - Naihong Chen
- Tianjin University of Traditional Chinese Medicine, Tianjin, PR China.
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, PR China.
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Wojtas A, Bysiek A, Wawrzczak-Bargiela A, Maćkowiak M, Gołembiowska K. Limbic System Response to Psilocybin and Ketamine Administration in Rats: A Neurochemical and Behavioral Study. Int J Mol Sci 2023; 25:100. [PMID: 38203271 PMCID: PMC10779066 DOI: 10.3390/ijms25010100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/15/2023] [Accepted: 12/19/2023] [Indexed: 01/12/2024] Open
Abstract
The pathophysiology of depression is related to the reduced volume of the hippocampus and amygdala and hypertrophy of the nucleus accumbens. The mechanism of these changes is not well understood; however, clinical studies have shown that the administration of the fast-acting antidepressant ketamine reversed the decrease in hippocampus and amygdala volume in depressed patients, and the magnitude of this effect correlated with the reduction in depressive symptoms. In the present study, we attempted to find out whether the psychedelic substance psilocybin affects neurotransmission in the limbic system in comparison to ketamine. Psilocybin and ketamine increased the release of dopamine (DA) and serotonin (5-HT) in the nucleus accumbens of naive rats as demonstrated using microdialysis. Both drugs influenced glutamate and GABA release in the nucleus accumbens, hippocampus and amygdala and increased ACh levels in the hippocampus. The changes in D2, 5-HT1A and 5-HT2A receptor density in the nucleus accumbens and hippocampus were observed as a long-lasting effect. A marked anxiolytic effect of psilocybin in the acute phase and 24 h post-treatment was shown in the open field test. These data provide the neurobiological background for psilocybin's effect on stress, anxiety and structural changes in the limbic system and translate into the antidepressant effect of psilocybin in depressed patients.
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Affiliation(s)
- Adam Wojtas
- Unit II, Department of Pharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 31-343 Kraków, Poland; (A.W.); (A.B.)
| | - Agnieszka Bysiek
- Unit II, Department of Pharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 31-343 Kraków, Poland; (A.W.); (A.B.)
| | - Agnieszka Wawrzczak-Bargiela
- Laboratory of Pharmacology and Brain Biostructure, Department of Pharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 31-343 Kraków, Poland; (A.W.-B.); (M.M.)
| | - Marzena Maćkowiak
- Laboratory of Pharmacology and Brain Biostructure, Department of Pharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 31-343 Kraków, Poland; (A.W.-B.); (M.M.)
| | - Krystyna Gołembiowska
- Unit II, Department of Pharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 31-343 Kraków, Poland; (A.W.); (A.B.)
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Baratta MV, Seligman MEP, Maier SF. From helplessness to controllability: toward a neuroscience of resilience. Front Psychiatry 2023; 14:1170417. [PMID: 37229393 PMCID: PMC10205144 DOI: 10.3389/fpsyt.2023.1170417] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/13/2023] [Indexed: 05/27/2023] Open
Abstract
"Learned helplessness" refers to debilitating outcomes, such as passivity and increased fear, that follow an uncontrollable adverse event, but do not when that event is controllable. The original explanation argued that when events are uncontrollable the animal learns that outcomes are independent of its behavior, and that this is the active ingredient in producing the effects. Controllable adverse events, in contrast, fail to produce these outcomes because they lack the active uncontrollability element. Recent work on the neural basis of helplessness, however, takes the opposite view. Prolonged exposure to aversive stimulation per se produces the debilitation by potent activation of serotonergic neurons in the brainstem dorsal raphe nucleus. Debilitation is prevented with an instrumental controlling response, which activates prefrontal circuitry detecting control and subsequently blunting the dorsal raphe nucleus response. Furthermore, learning control alters the prefrontal response to future adverse events, thereby preventing debilitation and producing long-term resiliency. The general implications of these neuroscience findings may apply to psychological therapy and prevention, in particular by suggesting the importance of cognitions and control, rather than habits of control.
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Affiliation(s)
- Michael V. Baratta
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, United States
| | - Martin E. P. Seligman
- Positive Psychology Center, University of Pennsylvania, Philadelphia, PA, United States
| | - Steven F. Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, United States
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Chen MH, Tu PC, Su TP. Next generation antidepressants with novel mechanisms for treatment resistant depression. PROGRESS IN BRAIN RESEARCH 2023. [DOI: 10.1016/bs.pbr.2023.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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