Suppression of Methamphetamine Self-Administration by Ketamine Pre-treatment Is Absent in the Methylazoxymethanol (MAM) Rat Model of Schizophrenia
Jana Ruda-Kucerova, Zuzana Babinska, Tibor Stark, Vincenzo Micale
Neurotoxicity Research July 1, 2017 DOI: 10.1007/s12640-017-9718-9 via Springer Nature
Summary
In a rat model of schizophrenia (MAM-treated rats), ketamine reduced methamphetamine self-administration in control animals but not in MAM-treated animals. MAM rats showed a lack of habituation in locomotor activity but maintained stable methamphetamine intake similar to controls. Ketamine's effect may stem from increased glutamatergic signaling in the prefrontal cortex via NMDA receptor antagonism and disinhibition of GABA interneurons, a mechanism impaired in MAM rats. This suggests ketamine's anti-craving potential in clinical settings, though it may be ineffective in schizophrenia.
Study at a glance
| Characteristics | Controlled laboratory experiment Peer reviewed |
|---|---|
| Population | Male Sprague-Dawley rats (MAM-treated and control) |
| Topics | Ketamine |
| Keywords | Mam model Methamphetamine Self-administration Sprague-dawley rats |
| Citations | 26 |
| Key finding | Ketamine (5 mg/kg) significantly reduced methamphetamine intake in control rats but not in MAM-treated rats, indicating a differential effect in the schizophrenia model. |
Abstract
Ketamine may prove to be a potential candidate in treating the widespread drug addiction/substance abuse epidemic among patients with schizophrenia. Clinical studies have shown ketamine to reduce cocaine and heroin cravings. However, the use of ketamine remains controversial as it may exacerbate the symptoms of schizophrenia. Therefore, the aim of this study is to characterize the effects of ketamine on drug addiction in schizophrenia using the methylazoxymethanol (MAM) acetate rat model on operant IV methamphetamine (METH) self-administration. MAM was administered intraperitoneally (22 mg/kg) on gestational day 17. Locomotor activity test and later IV self-administration (IVSA) were then performed in the male offspring followed by a period of forced abstinence and relapse of METH taking. After reaching stable intakes in the relapse phase, ketamine (5 mg/kg) was administered intraperitoneally 30 min prior to the self-administration session. As documented previously, the MAM rats showed a lack of habituation in the locomotor activity test but developed stable maintenance of METH self-administration with no difference in operant behaviour to control animals. Results show that ketamine treatment significantly reduced the METH intake in the control animals but not in MAM animals. Ketamine effect on METH self-administration may be explained by increased glutamatergic signalling in the prefrontal cortex caused by the N-methyl-D-aspartate antagonism and disinhibition of GABA interneurons which was shown to be impaired in the MAM rats. This mechanism may at least partly explain the clinically proven anti-craving potential of ketamine and allow development of more specific anti-craving medications with fewer risks.