Involvement of the σ- receptor in passive-avoidance learning in the day-old chick during the second wave of neuronal activity

The specific o-receptor agonist (+)-SKF 10047 and antagonist BD 1047 were used to investigate whether this receptor was involved in passive-avoidance training in the day-old chick. We found 300 μM (+)-SKF 10047 to be amnesic when injected into the lobus parolfactorius 5 h after training (p < .01). Higher or lower concentrations of (+)-SKF 10047 did not disrupt memory formation. The amnesia produced by the efficacious dose of (+)-SKF 10047 was reversed by the specific antagonist, BD 1047. It is suggested that the σ-receptor may exert its effect on passive-avoidance memory consolidation during the later stages of long-term memory formation by modulation of memory-related neurotransmission.