Effects of the Natural β-Carboline Alkaloid Harmine, a Main Constituent of Ayahuasca, in Memory and in the Hippocampus: A Systematic Literature Review of Preclinical Studies

ABSTRACT

Harmine is a natural β-carboline alkaloid found in several botanical species, such as the Banisteriopsis caapi vine used in the preparation of the hallucinogenic beverage ayahuasca and the seeds of Syrian rue (Peganum harmala). Preclinical studies suggest that harmine may have neuroprotective and cognitive-enhancing effects, and retrospective/observational investigations of the mental health of long-term ayahuasca users suggest that prolonged use of this harmine-rich hallucinogen is associated with better neuropsychological functioning. Thus, in order to better investigate these possibilities, we performed a systematic literature review of preclinical studies analyzing the effects of harmine on hippocampal neurons and in memory-related behavioral tasks in animal models. We found two studies involving hippocampal cell cultures and nine studies using animal models. Harmine administration was associated with neuroprotective effects such as reduced excitotoxicity, inflammation, and oxidative stress, and increased brain-derived neurotrophic factor (BDNF) levels. Harmine also improved memory/learning in several animal models. These effects seem be mediated by monoamine oxidase or acetylcholinesterase inhibition, upregulation of glutamate transporters, decreases in reactive oxygen species, increases in neurotrophic factors, and anti-inflammatory effects. The neuroprotective and cognitive-enhancing effects of harmine should be further investigated in both preclinical and human studies.

KEYWORDS:

• Harmine
• hippocampus
• learning
• memory
• neuroprotection

Funding

RGDS is Fellow of the National Post-Doctorate Program, Brazil (Programa Nacional de Pós-Doutorado/Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (PNPD/CAPES)). JECH receives a CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil) Productivity Fellowship Award. The sponsors had no role in study design, data analysis, data interpretation, or writing of the report. All authors had full access to all of the data and had final responsibility for the decision to submit for publication.

Additional information

Funding

RGDS is Fellow of the National Post-Doctorate Program, Brazil (Programa Nacional de Pós-Doutorado/Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (PNPD/CAPES)). JECH receives a CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil) Productivity Fellowship Award. The sponsors had no role in study design, data analysis, data interpretation, or writing of the report. All authors had full access to all of the data and had final responsibility for the decision to submit for publication.