MDMA (ecstasy) and nicotine activate shared neuronal pathways. In male Swiss mice, a single injection of MDMA (1 mg/kg) or MDMA combined with nicotine (0.05 mg/kg) improved memory consolidation in a passive avoidance test. MDMA also increased locomotor activity in mice that had developed behavioral sensitization to nicotine. The study reports for the first time strong behavioral and biochemical interactions between the two drugs, including effects on oxidative stress and α7 nicotinic acetylcholine receptor expression in the prefrontal cortex and hippocampus. These findings may help explain why people often co-use MDMA and nicotine.
Acute exposure to MDMA reduces anxiety-like behavior and increases social preference in 3-week-old zebrafish. These effects are biphasic: the lowest dose (0.5 μM) increases anxiety while also increasing social preference, and as concentration rises the effects reverse, peaking at 2.5 μM. MDMA suppresses expression of serotonin receptor and transporter genes, increases oxytocin receptor genes, decreases a vasopressin receptor gene, and reduces AKT phosphorylation. An oxytocin receptor agonist mimics MDMA's effects, while an antagonist has no significant effect on anxiety or social behavior. The findings suggest MDMA has therapeutic potential for anxiety disorders and social impairments, and that young zebrafish are a useful model for neurobehavioral research.