The effects of NMDA and non-NMDA glutamate receptor antagonists were evaluated on social recognition of adult male rats. Adult animals were injected (s.c.) with drug or saline immediately after the initial exposure to a juvenile male, 21-24 days old, and re-exposed to the same or to a novel juvenile 30 min later. If the time spent by animals in social investigation during re-exposure to the same juvenile was comparable with the time measured during the initial exposure and with the time of animals re-exposed to a novel juvenile, the effect of a drug was designated as amnesia. Such an effect was found in adult animals administered 1 and 1.5 mg/kg phencyclidine, 0.1 mg/kg dizocilpine, 2.5 mg/kg CPP, and 4 mk/kg CGS 19755, Amnesic effects were observed at doses not affecting motor performance. No amnesic effect was produced by CNQX and NBQX (2.5, 5 and 10 mg/kg). These results show that while recognition capacity in adult male rats is disrupted by several NMDA antagonists, non-NMDA antagonists do not interfere with short-term retention of individual odours. This suggests that NMDA glutamate receptors may be involved in the processing of socially relevant olfactory information.
