Objective: 

Adolescence is the period of physical, cognitive, and social maturation between childhood and adulthood. The N-methyl-D-aspartate (NMDA) receptor plays an important role in the regulation of neuronal development, learning and memory, neurodegenerative diseases, and neurogenesis. The role of NMDA receptor blockade during the early development period on emotional behaviours and the role of NMDA-mediated glutamate transmission remain to be elucidated. The aim of the present study was to investigate the role of NMDA receptor blockade during the early development period on anxiety and response to novelty in adolescence.

Methods: 

Male Wistar rats were used. NMDA receptor blockade was performed between postnatal 7–10 days using MK-801 treatment. Rats were intraperitoneally injected with MK-801 twice a day for a period of 4 days (dizocilpine either at a dose of 0.25 mg/kg or in a volume of 0.1 ml/20 g body weight). The OF (open field) and EPM (elevated plus maze) tests were used to evaluate emotional behaviours in adolescence (30–50 days of age).

Results: 

In the OF test, the frequency of rearing in the center area (p?0.05) velocity and distance movement (p?0.01) increased in the the MK-801 group than in the saline group. In the EPM test, the time spent in the open arm of the maze (p?0.01) and headdiping (p?0.01) was incresead while the latencies to enter open arm of the maze decreased (p?0.05) in group treated with MK-801.

Conclusions: 

We propose that the NMDA receptor blockade during the early development period increased locomotor activity as detected by open field test and reduced to anxiety as measured by elevated plus maze in adolescence.