Harmine Impairs Memory Performance of Treated Rats and Nontreated Cagemates

• Published in: Experimental and clinical psychopharmacology Vol. 30; no. 6; pp. 751 - 759
• Main Authors: Libânio, Tânia C., Eufrásio, Raí A., Niigaki, Suzy S., Peres, Fernanda F., Silva, Regina H., Zuardi, Antônio W., Hallak, Jaime E. C., Crippa, José A. S., Calzavara, Mariana B., Abílio, Vanessa C.
• Format: Journal Article
• Language: English
• Published: United States American Psychological Association 01-12-2022
• Subjects: Animal; Animal Emotionality; Animal Models; Animals; Cognition; Contagion; Emotions; Fear; Harmine - pharmacology; Male; Medicinal Herbs and Plants; Memory; Memory Disorders; Monoamine Oxidase Inhibitors; Psychedelic Drugs; Rats; emotional contagion; animal models; harmine; learning/memory; Ayahuasca
• ISSN: 1064-1297; 1936-2293
• DOI: 10.1037/pha0000525

The interest in psychedelic substances as potential treatments for psychiatric disorders is increasing. The β-carboline harmine, an Ayahuasca component, presents hallucinogenic and antidepressant effects. Although Ayuahuasca-and consequently harmine-is usually consumed in rituals, the role of social contexts in the behavioral effects of harmine has not been investigated yet. In this sense, affective states may modulate cohabitants' behavior, including learning/memory. This work investigates the effects of harmine on the learning/memory performance of rats evaluated on the contextual and tone fear conditioning (CFC and TFC) and on the plus-maze discriminative avoidance (PMDAT) tasks. The possible influence of a harmine-treated cohabitant was assessed by evaluating rats housed in homogeneous cages-where all the animals were acutely administered with the same treatment (vehicle, 5, 10, or 15 mg/kg harmine), and in heterogeneous cages-where each animal received a different drug treatment. The main results are: (a) harmine impaired CFC (10 mg/kg) and PMDAT discrimination (all doses); and (b) harmine caused a memory deficit in CFC, TFC, and PMDAT of untreated rats kept in heterogeneous cages. Our results show that harmine induces a memory deficit in tasks with emotional contexts. Further, the cohabitation with animals treated with this drug also seems to impair memory performance of untreated animals.
Public Health Significance
Harmine, one of the components of the Ayahuasca beverage, presents hallucinogenic and antidepressant effects. Here, we demonstrate that harmine induces memory deficits, and the cohabitation with harmine-treated animals impairs memory performance of untreated animals. The investigation of the effects of harmine per se and on the emotions/behaviors of others is of great importance considering the potential of psychedelic agents as an alternative for the treatment of psychiatric disorders.