Inhibition of brain NOS activity impair spatial learning acquisition in fish

•Spatial learning in fish are dependent of telencephalic NO.•NO synthesis has scarcely any effect on retrieval process of information in fish.•Inhibition of NO production produced a selective deficit in place learning. Nitric oxide plays a role in the long term potentiation mechanisms produced in the mammalian hippocampus during spatial learning. A great deal of data has demonstrated that the dorsolateral telencephalon of fish could be homologous to the mammalian hippocampus sharing functional similarities. In the present study, we analyzed the role of nitric oxide in spatial learning in teleost fish. In Experiment 1, we studied the effects of the inhibition of telencephalic nitric oxide in goldfish during the acquisition of a spatial task. The results showed that nitric oxide is involved in the learning of a spatial task. Experiment 2 evaluated the effects of the inhibition of telencephalic nitric oxide in goldfish for the retrieval of a learned spatial response. The results indicated that the retrieval of the information previously stored is not dependent of the nitric oxide. The last experiment analyzed the role of the telencephalic nitric oxide in place and cue learning. Results showed a clear impairment in place but not in cue learning. As a whole, these results indicate that fish and mammals, could have a relational memory system mediated by similar biochemical mechanisms.