OPEN Foundation

L. Campa

Involvement of NMDA receptors containing the GluN2C subunit in the psychotomimetic and antidepressant-like effects of ketamine

Abstract

Acute ketamine administration evokes rapid and sustained antidepressant effects in treatment-resistant patients. However, ketamine also produces transient perceptual disturbances similarly to those evoked by other non-competitive NMDA-R antagonists like phencyclidine (PCP). Although the brain networks involved in both ketamine actions are not fully understood, PCP and ketamine activate thalamo-cortical networks after NMDA-R blockade in GABAergic neurons of the reticular thalamic nucleus (RtN). Given the involvement of thalamo-cortical networks in processing sensory information, these networks may underlie psychotomimetic action. Since the GluN2C subunit is densely expressed in the thalamus, including the RtN, we examined the dependence of psychotomimetic and antidepressant-like actions of ketamine on the presence of GluN2C subunits, using wild-type and GluN2C knockout (GluN2CKO) mice. Likewise, since few studies have investigated ketamine’s effects in females, we used mice of both sexes. GluN2C deletion dramatically reduced stereotyped (circling) behavior induced by ketamine in male and female mice, while the antidepressant-like effect was fully preserved in both genotypes and sexes. Despite ketamine appeared to induce similar effects in both sexes, some neurobiological differences were observed between male and female mice regarding c-fos expression in thalamic nuclei and cerebellum, and glutamate surge in prefrontal cortex. In conclusion, the GluN2C subunit may discriminate between antidepressant-like and psychotomimetic actions of ketamine. Further, the abundant presence of GluN2C subunits in the cerebellum and the improved motor coordination of GluN2CKO mice after ketamine treatment suggest the involvement of cerebellar NMDA-Rs in some behavioral actions of ketamine.

Tarrés-Gatius, M., Miquel-Rio, L., Campa, L., Artigas, F., & Castañé, A. (2020). Involvement of NMDA receptors containing the GluN2C subunit in the psychotomimetic and antidepressant-like effects of ketamine. Translational psychiatry, 10(1), 427. https://doi.org/10.1038/s41398-020-01110-y

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The serotonergic hallucinogen 5-methoxy-N,N-dimethyltryptamine disrupts cortical activity in a regionally-selective manner via 5-HT1A and 5-HT2A receptors.

Abstract

5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a natural hallucinogen, acting as a non-selective serotonin 5-HT1A/5-HT2A-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-HT1A-R and 5-HT2A-R, using wild type (WT) and 5-HT2A-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-HT1A-R antagonist WAY-100635. Systemic and local 5-MeO-DMT reduced 5-HT release in PFC mainly via 5-HT1A-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-HT1A-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-HT1A-R stimulation in V1 and PFC, in addition to the well-known action on 5-HT2A-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.

Riga, M. S., Bortolozzi, A., Campa, L., Artigas, F., & Celada, P. (2015). The serotonergic hallucinogen 5-Methoxy-N, N-dimethyltryptamine disrupts cortical activity in a regionally-selective manner via 5-HT 1A and 5-HT 2A receptors. Neuropharmacology. http://dx.doi.org/10.1016/j.neuropharm.2015.10.016
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