Repeated dextromethorphan administration in adolescent rats produces long-lasting behavioral alterations.
M L Shawn Bates, Keith A Trujillo
Pharmacology, biochemistry, and behavior June 1, 2023 DOI: 10.1016/j.pbb.2023.173581 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Male rats |
| Intervention | Dextromethorphan (DXM) |
| Dose | 60 mg/kg |
| Duration | 10-day injection period, 20-day abstinence period |
| Measures | locomotor activity, reversal learning task, novel object recognition task |
| Topics | Addiction Ketamine |
| Keywords | Adolescence Cognition Dextromethorphan Locomotor Neuroadaptations Sensitization |
| Key findings | Adolescent rats treated with DXM showed greater acute locomotor response, locomotor sensitization, cross-sensitization to ketamine, and increased perseverative errors in reversal learning compared to adults. |
Abstract
Initiation of non-medical dextromethorphan (DXM) use often occurs in adolescence, yet little is known about the consequences when use begins during this developmental period. The current experiments examined the acute response and the effects of repeated exposure to DXM in adolescence on behavior in adulthood. We examined locomotor activity, locomotor sensitization, and cognitive function, in rats that received repeated administration of DXM. Groups of adolescent (PND 30) and adult (PND 60) male rats were treated with DXM (60 mg/kg) once daily for 10 days. Locomotor activity in response to DXM was assessed following the first injection, on the 10th day of injection (adolescent - PND 39; adult - PND 69), and following 20 days of abstinence (adolescent - PND 59; adult - PND 89). Acute locomotor effects and locomotor sensitization were compared in adolescents and adults; cross-sensitization to ketamine, another dissociative with abuse potential, was also examined. In a separate group of rodents cognitive deficits were assessed following a 20 day abstinence period (adolescent - PND 59; adult - PND 89) in spatial learning and novel object recognition tasks. The locomotor stimulant effect of DXM was much greater in adolescents than adults. Also, only adolescent rats that were repeatedly administered DXM demonstrated locomotor sensitization at the end of 10 days of injection. However, sensitization occurred after the abstinence period in all rats regardless of age. Nonetheless, cross-sensitization to ketamine was only evident in adolescent-treated rats. DXM also led to an increase in perseverative errors in reversal learning only in the adolescent-treated group. We conclude that repeated use of DXM produces long-lasting neuroadaptations that may contribute to addiction. Deficits in cognitive flexibility occur in adolescents, although further work is necessary to confirm these findings. The results extend the understanding of potential long-term consequences of DXM use in adolescents and adults.
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| The effects of (2R,6R)-hydroxynorketamine on oxycodone withdrawal and reinstatement. Male and female oxycodone-dependent mice | 2023 | Preclinical study | |
| Characterizing the therapeutical use of ketamine for adolescent rats of both sexes: Antidepressant-like efficacy and safety profile. Adolescent rats of both sexes, including naïve and early-life stressed (maternal... | 2025 | Preclinical study | |
| Exploring ketamine's reinforcement, cue-induced reinstatement, and nucleus accumbens cFos activation in male and female long evans rats. Long Evans rats | 2024 | Preclinical experimental study | |
| Brain acid sphingomyelinase controls addiction-related behaviours in a sex-specific way. Male and female mice with forebrain ASM overexpression | 2025 | Experimental study |