OPEN Foundation

D. de Gregorio

Lysergic acid diethylamide differentially modulates the reticular thalamus, mediodorsal thalamus, and infralimbic prefrontal cortex: An in vivo electrophysiology study in male mice

February 21, 2022 / LSD, Neuroscience, Papers / Leave a Comment / By / , , , , ,

Abstract

Background: The reticular thalamus gates thalamocortical information flow via finely tuned inhibition of thalamocortical cells in the mediodorsal thalamus. Brain imaging studies in humans show that the psychedelic lysergic acid diethylamide (LSD) modulates activity and connectivity within the cortico-striato-thalamo-cortical (CSTC) circuit, altering consciousness. However, the electrophysiological effects of LSD on the neurons in these brain areas remain elusive.

Methods: We employed in vivo extracellular single-unit recordings in anesthetized adult male mice to investigate the dose-response effects of cumulative LSD doses (5-160 µg/kg, intraperitoneal) upon reticular thalamus GABAergic neurons, thalamocortical relay neurons of the mediodorsal thalamus, and pyramidal neurons of the infralimbic prefrontal cortex.

Results: LSD decreased spontaneous firing and burst-firing activity in 50% of the recorded reticular thalamus neurons in a dose-response fashion starting at 10 µg/kg. Another population of neurons (50%) increased firing and burst-firing activity starting at 40 µg/kg. This modulation was accompanied by an increase in firing and burst-firing activity of thalamocortical neurons in the mediodorsal thalamus. On the contrary, LSD excited infralimbic prefrontal cortex pyramidal neurons only at the highest dose tested (160 µg/kg). The dopamine D2 receptor (D2) antagonist haloperidol administered after LSD increased burst-firing activity in the reticular thalamus neurons inhibited by LSD, decreased firing and burst-firing activity in the mediodorsal thalamus, and showed a trend towards further increasing the firing activity of neurons of the infralimbic prefrontal cortex.

Conclusion: LSD modulates firing and burst-firing activity of reticular thalamus neurons and disinhibits mediodorsal thalamus relay neurons at least partially in a D2-mediated fashion. These effects of LSD on thalamocortical gating could explain its consciousness-altering effects in humans.

Inserra, A., De Gregorio, D., Rezai, T., Lopez-Canul, M. G., Comai, S., & Gobbi, G. (2021). Lysergic acid diethylamide differentially modulates the reticular thalamus, mediodorsal thalamus, and infralimbic prefrontal cortex: An in vivo electrophysiology study in male mice. Journal of psychopharmacology (Oxford, England), 35(4), 469–482. https://doi.org/10.1177/0269881121991569

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Lysergic acid diethylamide (LSD) promotes social behavior through mTORC1 in the excitatory neurotransmission

February 6, 2022 / LSD, Neuroscience, Papers, Psychology, Psychopharmacology / Leave a Comment / By / , , , , , , , , , , , , , ,

Abstract

Clinical studies have reported that the psychedelic lysergic acid diethylamide (LSD) enhances empathy and social behavior (SB) in humans, but its mechanism of action remains elusive. Using a multidisciplinary approach including in vivo electrophysiology, optogenetics, behavioral paradigms, and molecular biology, the effects of LSD on SB and glutamatergic neurotransmission in the medial prefrontal cortex (mPFC) were studied in male mice. Acute LSD (30 μg/kg) injection failed to increase SB. However, repeated LSD (30 μg/kg, once a day, for 7 days) administration promotes SB, without eliciting antidepressant/anxiolytic-like effects. Optogenetic inhibition of mPFC excitatory neurons dramatically inhibits social interaction and nullifies the prosocial effect of LSD. LSD potentiates the α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and 5-HT2A, but not N-methyl-D-aspartate (NMDA) and 5-HT1A, synaptic responses in the mPFC and increases the phosphorylation of the serine-threonine protein kinases Akt and mTOR. In conditional knockout mice lacking Raptor (one of the structural components of the mTORC1 complex) in excitatory glutamatergic neurons (Raptor f/f :Camk2alpha-Cre), the prosocial effects of LSD and the potentiation of 5-HT2A/AMPA synaptic responses were nullified, demonstrating that LSD requires the integrity of mTORC1 in excitatory neurons to promote SB. Conversely, in knockout mice lacking Raptor in GABAergic neurons of the mPFC (Raptor f/f :Gad2-Cre), LSD promotes SB. These results indicate that LSD selectively enhances SB by potentiating mPFC excitatory transmission through 5-HT2A/AMPA receptors and mTOR signaling. The activation of 5-HT2A/AMPA/mTORC1 in the mPFC by psychedelic drugs should be explored for the treatment of mental diseases with SB impairments such as autism spectrum disorder and social anxiety disorder.

De Gregorio, D., Popic, J., Enns, J. P., Inserra, A., Skalecka, A., Markopoulos, A., Posa, L., Lopez-Canul, M., Qianzi, H., Lafferty, C. K., Britt, J. P., Comai, S., Aguilar-Valles, A., Sonenberg, N., & Gobbi, G. (2021). Lysergic acid diethylamide (LSD) promotes social behavior through mTORC1 in the excitatory neurotransmission. Proceedings of the National Academy of Sciences of the United States of America, 118(5), e2020705118. https://doi.org/10.1073/pnas.2020705118

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Psychedelics in Psychiatry: Neuroplastic, Immunomodulatory, and Neurotransmitter Mechanisms

January 27, 2022 / Neuroscience, Other substances, Papers, Psychopharmacology / Leave a Comment / By / , ,

Abstract

Mounting evidence suggests safety and efficacy of psychedelic compounds as potential novel therapeutics in psychiatry. Ketamine has been approved by the Food and Drug Administration in a new class of antidepressants, and 3,4-methylenedioxymethamphetamine (MDMA) is undergoing phase III clinical trials for post-traumatic stress disorder. Psilocybin and lysergic acid diethylamide (LSD) are being investigated in several phase II and phase I clinical trials. Hence, the concept of psychedelics as therapeutics may be incorporated into modern society. Here, we discuss the main known neurobiological therapeutic mechanisms of psychedelics, which are thought to be mediated by the effects of these compounds on the serotonergic (via 5-HT2A and 5-HT1A receptors) and glutamatergic [via N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] systems. We focus on 1) neuroplasticity mediated by the modulation of mammalian target of rapamycin-, brain-derived neurotrophic factor-, and early growth response-related pathways; 2) immunomodulation via effects on the hypothalamic-pituitary-adrenal axis, nuclear factor ĸB, and cytokines such as tumor necrosis factor-α and interleukin 1, 6, and 10 production and release; and 3) modulation of serotonergic, dopaminergic, glutamatergic, GABAergic, and norepinephrinergic receptors, transporters, and turnover systems. We discuss arising concerns and ways to assess potential neurobiological changes, dependence, and immunosuppression. Although larger cohorts are required to corroborate preliminary findings, the results obtained so far are promising and represent a critical opportunity for improvement of pharmacotherapies in psychiatry, an area that has seen limited therapeutic advancement in the last 20 years. Studies are underway that are trying to decouple the psychedelic effects from the therapeutic effects of these compounds. SIGNIFICANCE STATEMENT: Psychedelic compounds are emerging as potential novel therapeutics in psychiatry. However, understanding of molecular mechanisms mediating improvement remains limited. This paper reviews the available evidence concerning the effects of psychedelic compounds on pathways that modulate neuroplasticity, immunity, and neurotransmitter systems. This work aims to be a reference for psychiatrists who may soon be faced with the possibility of prescribing psychedelic compounds as medications, helping them assess which compound(s) and regimen could be most useful for decreasing specific psychiatric symptoms.

Inserra, A., De Gregorio, D., & Gobbi, G. (2021). Psychedelics in Psychiatry: Neuroplastic, Immunomodulatory, and Neurotransmitter Mechanisms. Pharmacological reviews, 73(1), 202–277. https://doi.org/10.1124/pharmrev.120.000056

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Hallucinogens in Mental Health: Preclinical and Clinical Studies on LSD, Psilocybin, MDMA, and Ketamine

January 7, 2022 / Ketamine, LSD, MDMA, Mushrooms / Psilocybin, Papers, Psychiatry, Psychopharmacology, Psychotherapy / Leave a Comment / By / , , , , , ,

Abstract

A revamped interest in the study of hallucinogens has recently emerged, especially with regard to their potential application in the treatment of psychiatric disorders. In the last decade, a plethora of preclinical and clinical studies have confirmed the efficacy of ketamine in the treatment of depression. More recently, emerging evidence has pointed out the potential therapeutic properties of psilocybin and LSD, as well as their ability to modulate functional brain connectivity. Moreover, MDMA, a compound belonging to the family of entactogens, has been demonstrated to be useful to treat post-traumatic stress disorders. In this review, the pharmacology of hallucinogenic compounds is summarized by underscoring the differences between psychedelic and nonpsychedelic hallucinogens as well as entactogens, and their behavioral effects in both animals and humans are described. Together, these data substantiate the potentials of these compounds in treating mental diseases.

De Gregorio, D., Aguilar-Valles, A., Preller, K. H., Heifets, B. D., Hibicke, M., Mitchell, J., & Gobbi, G. (2021). Hallucinogens in Mental Health: Preclinical and Clinical Studies on LSD, Psilocybin, MDMA, and Ketamine. The Journal of neuroscience : the official journal of the Society for Neuroscience, 41(5), 891–900. https://doi.org/10.1523/JNEUROSCI.1659-20.2020

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d-Lysergic Acid Diethylamide (LSD) as a Model of Psychosis: Mechanism of Action and Pharmacology

November 23, 2016 / LSD, Neuroscience, Papers, Psychiatry, Psychology, Psychopharmacology, Psychosis, Publications / By / , , ,

Abstract

d-Lysergic Acid Diethylamide (LSD) is known for its hallucinogenic properties and psychotic-like symptoms, especially at high doses. It is indeed used as a pharmacological model of psychosis in preclinical research. The goal of this review was to understand the mechanism of action of psychotic-like effects of LSD. We searched Pubmed, Web of Science, Scopus, Google Scholar and articles’ reference lists for preclinical studies regarding the mechanism of action involved in the psychotic-like effects induced by LSD. LSD’s mechanism of action is pleiotropic, primarily mediated by the serotonergic system in the Dorsal Raphe, binding the 5-HT2Areceptor as a partial agonist and 5-HT1A as an agonist. LSD also modulates the Ventral Tegmental Area, at higher doses, by stimulating dopamine D2, Trace Amine Associate receptor 1 (TAAR1) and 5-HT2A. More studies clarifying the mechanism of action of the psychotic-like symptoms or psychosis induced by LSD in humans are needed. LSD’s effects are mediated by a pleiotropic mechanism involving serotonergic, dopaminergic, and glutamatergic neurotransmission. Thus, the LSD-induced psychosis is a useful model to test the therapeutic efficacy of potential novel antipsychotic drugs, particularly drugs with dual serotonergic and dopaminergic (DA) mechanism or acting on TAAR1 receptors.

De Gregorio, D., Comai, S., Posa, L., & Gobbi, G. (2016). d-Lysergic Acid Diethylamide (LSD) as a Model of Psychosis: Mechanism of Action and Pharmacology. International Journal of Molecular Sciences, 17(11), 1953. 10.3390/ijms17111953
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The hallucinogen d-lysergic diethylamide (LSD) decreases dopamine firing activity through 5-HT1A, D2 and TAAR1 receptors

August 17, 2016 / LSD, Neuroscience, Other subjects, Papers, Psychopharmacology, Publications / By / , , , , , ,

Abstract

d-lysergic diethylamide (LSD) is a hallucinogenic drug that interacts with the serotonin (5-HT) system binding to 5-HT1 and 5-HT2 receptors. Little is known about its potential interactions with the dopamine (DA) neurons of the ventral tegmental area (VTA). Using in-vivo electrophysiology in male adult rats, we evaluated the effects of cumulative doses of LSD on VTA DA neuronal activity, compared these effects to those produced on 5-HT neurons in the dorsal raphe nucleus (DRN), and attempted to identify the mechanism of action mediating the effects of LSD on VTA DA neurons. LSD, at low doses (5–20 μg/kg, i.v.) induced a significant decrease of DRN 5-HT firing activity through 5-HT2A and D2 receptors. At these low doses, LSD did not alter VTA DA neuronal activity. On the contrary, at higher doses (30–120 μg/kg, i.v.), LSD dose-dependently decreased VTA DA firing activity. The depletion of 5-HT with p-chlorophenylalanine did not modulate the effects of LSD on DA firing activity. The inhibitory effects of LSD on VTA DA firing activity were prevented by the D2 receptor antagonist haloperidol (50 μg/kg, i.v.) and by the 5-HT1A receptor antagonist WAY-100,635 (500 μg/kg, i.v.). Notably, pretreatment with the trace amine-associate receptor 1 (TAAR1) antagonist EPPTB (5 mg/kg, i.v.) blocked the inhibitory effect of LSD on VTA DA neurons. These results suggest that LSD at high doses strongly affects DA mesolimbic neuronal activity in a 5-HT independent manner and with a pleiotropic mechanism of action involving 5-HT1A, D2 and TAAR1 receptors.

De Gregorio, D., Posa, L., Ochoa-Sanchez, R., McLaughlin, R., Maione, S., Comai, S., & Gobbi, G. (2016). The hallucinogen d-lysergic diethylamide (LSD) decreases dopamine firing activity through 5-HT 1A, D 2 and TAAR 1 receptors. Pharmacological Research, 113, 81-91. http://dx.doi.org/10.1016/j.phrs.2016.08.022
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30 April - Q&A with Rick Strassman

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