Transient reinforcing effects of phenylisopropylamine and indolealkylamine hallucinogens in rhesus monkeys
Behavioural Pharmacology – March 01, 2004
Source: OpenAlex
Summary
Though not reliably sought, 3 out of 4 rhesus monkeys with prior MDMA self-administration experience did self-administer the hallucinogens mescaline, psilocybin, or DMT in some sessions. These animals responded between 0.75 and 3.0 times per second, appearing intoxicated. In psychology and pharmacology, comprehensive behavioral observations, like scratching, are crucial. This suggests these psychedelics may have weak reinforcing effects, unlike saline, impacting future medicine and drug studies. Forensic toxicology could further explore neurotransmitter receptor influence on behavior.
Abstract
Relatively few studies have assessed the reinforcing effects of hallucinogenic compounds, and no such studies have attempted to engender contingent responding for these compounds in animals with behavioral histories that include experience with serotonergically mediated reinforcing effects. The objectives of the present study were to investigate the capacity of several hallucinogenic compounds to maintain self-administration behavior in rhesus monkeys with a previous history of 3,4-methylenedioxymethamphetamine (MDMA) self-administration, and to compare these effects across a range of doses of drugs from two structural classes (indolealkylamines and phenylisopropylamines). The results indicate that no compound generated reliable responding and that no subject ever self-administered 4-iodo-2,5-dimethoxyphenylisopropylamine (DOI) at rates above those engendered by contingent saline. However, 3 out of 4 subjects did respond at rates between 0.75 and 3.0 responses/s in one or more sessions where N,N-dimethyltryptamine (DMT), mescaline or psilocybin were available. During some of these sessions in which self-administration was maintained, animals earned a majority of all available infusions and appeared intoxicated by the end of the session. This pattern of transient self-administration may indicate that these compounds have weak reinforcing effects, or mixed reinforcing and aversive effects.