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Effects of MK-801 on rough-and-tumble play in juvenile rats
Abstract:
Effects of the noncompetitive N-methyl-D-aspartate (NMDA) channel blocker, MK-801, on play behavior and activity were assessed in juvenile rats. A low dose (0.025 mg/kg) of MK-801 significantly increased both pinning and dorsal contacts, two indices of play behavior in the rat. Higher doses (> or = 0.1 mg/kg) significantly reduced both measures of play, with play being virtually abolished at 0.2 mg/kg. Simultaneous measurements of activity indicated that the reductions of play at the higher doses were accompanied by significant increases in horizontal activity. There was also a dose-related reduction in rearing, which was significant at all doses. When juvenile rats were tested individually for activity in an open field, MK-801 increased horizontal activity at 0.2 mg/kg and decreased rearing at all doses. So while the effects of MK-801 on play are biphasic, the effects of this compound on locomotor activity, per se, are linear. These data suggest that the effects of NMDA channel blockade on overall activity and play are mediated through independent neural systems.
Insights
The N-methyl-D-aspartate (NMDA) channel blocker MK-801 shows biphasic effects on juvenile rat play behavior. Low doses increase play, while higher doses decrease it, suggesting independent neural systems mediate play and activity.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Pharmacology
Background:
- The N-methyl-D-aspartate (NMDA) receptor is crucial for synaptic plasticity and learning.
- NMDA receptor antagonists, like MK-801, are widely used to study glutamatergic neurotransmission.
- Understanding the specific effects of NMDA receptor blockade on behavior is essential for neurological research.
Purpose of the Study:
- To investigate the dose-dependent effects of the NMDA channel blocker MK-801 on play behavior and general activity in juvenile rats.
- To determine if the effects of MK-801 on play and activity are mediated by independent neural pathways.
Main Methods:
- Juvenile rats were administered varying doses of MK-801 (0.025 to 0.2 mg/kg).
- Play behavior was assessed by measuring pinning and dorsal contacts.
- General locomotor activity was measured, including horizontal activity and rearing, in an open field test.
Main Results:
- Low-dose MK-801 (0.025 mg/kg) significantly increased play behavior.
- Higher doses of MK-801 (≥0.1 mg/kg) significantly reduced play behavior, abolishing it at 0.2 mg/kg.
- MK-801 exhibited a dose-dependent linear increase in horizontal activity and decrease in rearing, independent of its effects on play.
Conclusions:
- The effects of NMDA channel blockade by MK-801 on play behavior are biphasic.
- The effects of MK-801 on locomotor activity are linear and distinct from its effects on play.
- These findings suggest that NMDA receptor-mediated effects on play and general activity involve separate neural systems.
