The serotonergic hallucinogen 5-Methoxy-N,N-dimethyltryptamine disrupts cortical activity in a regionally-selective manner

Authored by: Maurizio S. Riga, Bc, Analia Bortolozzi, PhD, Letizia Campa, Bc, Francesc Artigas, PhD, Pau Celada, PhD

Abstract
5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a natural hallucinogen, acting as a non-selective serotonin 5-HT 1A /5-HT 2A -R agonist. Psychotomimetic agents such as the non-competitive NMDA-R antagonist phencyclidine and serotonergic hallucinogens (DOI and 5-MeO-DMT) disrupt cortical synchrony in the low frequency range (<4 Hz) in rat prefrontal cortex (PFC), an effect reversed by antipsychotic drugs. Here we extend these observations by examining the effect of 5-MeO-DMT on low frequency cortical oscillations (LFCO, <4 Hz) in PFC, visual (V1), somatosensory (S1) and auditory (Au1) cortices, as well as the dependence of these effects on 5-HT 1A -R and 5-HT 2A -R, using wild type (WT) and 5-HT 2A -R knockout (KO2A) anesthetized mice. 5-MeO-DMT reduced LFCO in the PFC of WT and KO2A mice. The effect in KO2A mice was fully prevented by the 5-HT 1A -R antagonist WAY-100635. Systemic and local 5-MeO-DMT reduced 5-HTU release in PFC mainly via 5-HT 1A -R. Moreover, 5-MeO-DMT reduced LFCO in S1, Au1 and V1 of WT mice and only in V1 of KO2A mice, suggesting the involvement of 5-HT 1A -R activation in the 5-MeO-DMT-induced disruption of V1 activity. In addition, antipsychotic drugs reversed 5-MeO-DMT effects in WT mice. The present results suggest that the hallucinogen action of 5-MeO-DMT is mediated by simultaneous alterations of the activity of sensory (S1, Au1, V1) and associative (PFC) cortical areas, also supporting a role of 5-HT 1A -R stimulation in V1 and PFC, in addition to the well-known action on 5-HT 2A -R. Moreover, the reversal by antipsychotic drugs of 5-MeO-DMT effects adds to previous literature supporting the usefulness of the present model in antipsychotic drug development.

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Posted by Rafael Lancelotta