Possible Involvement of Hallucinogenic Effects in the Aversive Effects Induced by Kappa-Opioid and 5-HT_{2A /2C}...

The regulation of new psychoactive and dangerous abused substances is very important for the prevention of drug abuse. A simple and effective evaluation method using laboratory animals is needed to regulate designated drugs with high accuracy and speed.

In the present study, we used the typical κ-opioid receptor agonist U50,488H and the typical 5-HT_2A/2C receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), which have a similar mechanism of action to hallucinogenic drugs, in a conditioned place aversion (CPA) test in mice. In addition, because hallucinogenic drugs can cause emotional abnormalities during hallucinations, we performed a marble-burying test in mice.

In the CPA test, both κ-opioid receptor and 5-HT_2A/2C receptor agonists produced significant aversive effects and abnormal behavior. These aversive effects and abnormal behavior were probably due in part to the hallucinogenic effects of these drugs.

Therefore, these tests using mice may be useful for evaluating hallucinogenic effects. We hope that these simple and rapid evaluation methods will be used to identify designated drugs.