OPEN Foundation

Day: 30 December 2015

Effects of Long-Term Ayahuasca Administration on Memory and Anxiety in Rats

Abstract

Ayahuasca is a hallucinogenic beverage that combines the action of the 5-HT2A/2C agonist N,N-dimethyltryptamine (DMT) from Psychotria viridis with the monoamine oxidase inhibitors (MAOIs) induced by beta-carbonyls from Banisteriopsis caapi. Previous investigations have highlighted the involvement of ayahuasca with the activation of brain regions known to be involved with episodic memory, contextual associations and emotional processing after ayahuasca ingestion. Moreover long term users show better performance in neuropsychological tests when tested in off-drug condition. This study evaluated the effects of long-term administration of ayahuasca on Morris water maze (MWM), fear conditioning and elevated plus maze (EPM) performance in rats. Behavior tests started 48h after the end of treatment. Freeze-dried ayahuasca doses of 120, 240 and 480 mg/kg were used, with water as the control. Long-term administration consisted of a daily oral dose for 30 days by gavage. The behavioral data indicated that long-term ayahuasca administration did not affect the performance of animals in MWM and EPM tasks. However the dose of 120 mg/kg increased the contextual conditioned fear response for both background and foreground fear conditioning. The tone conditioned response was not affected after long-term administration. In addition, the increase in the contextual fear response was maintained during the repeated sessions several weeks after training. Taken together, these data showed that long-term ayahuasca administration in rats can interfere with the contextual association of emotional events, which is in agreement with the fact that the beverage activates brain areas related to these processes.

Favaro, V. M., Yonamine, M., Soares, J. C. K., & Oliveira, M. G. M. (2015). Effects of Long-Term Ayahuasca Administration on Memory and Anxiety in Rats. PloS one, 10(12), e0145840. http://dx.doi.org/10.1371/journal.pone.0145840
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Neuroimaging in moderate MDMA use: A systematic review

Abstract

MDMA (“ecstasy”) is widely used as a recreational drug, although there has been some debate about its neurotoxic effects in humans. However, most studies have investigated subjects with heavy use patterns, and the effects of transient MDMA use are unclear. In this review, we therefore focus on subjects with moderate use patterns, in order to assess the evidence for harmful effects. We searched for studies applying neuroimaging techniques in man. Studies were included if they provided at least one group with an average of <50 lifetime episodes of ecstasy use or an average lifetime consumption of <100 ecstasy tablets. All studies published before July 2015 were included. Of the 250 studies identified in the database search, 19 were included.

There is no convincing evidence that moderate MDMA use is associated with structural or functional brain alterations in neuroimaging measures. The lack of significant results was associated with high methodological heterogeneity in terms of dosages and co-consumption of other drugs, low quality of studies and small sample sizes.

Mueller, F., Lenz, C., Steiner, M., Dolder, P. C., Walter, M., Lang, U. E., … & Borgwardt, S. (2016). Neuroimaging in moderate MDMA use: A systematic review. Neuroscience & Biobehavioral Reviews, 62, 21-34. http://dx.doi.org/10.1016/j.neubiorev.2015.12.010
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2 April - New Insights on Addiction & Psychedelic Healing Followed by a Live Q&A!

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