Nitric Oxide Scavenger Carboxy-PTIO Impaired Memory of Avoidance Conditioning in Goldfish

The long-term potentiation (LTP), an activity-induced increase in the efficacy of neurotransmission, has long been conceived to be a physiological correlate of learning and memory. Investigations of synaptic transmission suggest that the postsynaptic N-methyl-D-aspartate (NMDA) receptor is the upstream mediator of LTP, while nitric oxide (NO), a retrograde messenger from postsynaptic neurons to presynaptic neuron, is the downstream mediator of LTP. Our previous studies showed that microinjections of NMDA receptor antagonist D-AP5 to the goldfish telencephalon prior to trainings impaired learning of avoidance conditioning in goldfish. However, microinjections of D-AP5 to the goldfish telencephalon immediately following trainings did not impair memory of avoidance conditioning. Carboxy-PTIO is a NO scavenger that prevents NO from reaching the presynaptic neurons. The present study investigated the effects of microinjections of carboxyPTIO to the goldfish telencephalon immediately following trainings on avoidance conditioning. The results showed that microinjections of carboxy-PTIO to the goldfish telencephalon immediately following trainings impaired memory of avoidance conditioning.