Neuropeptide Y (NPY) is highly abundant in the brain and is released as a co-transmitter with plasticity-related neurotransmitters such as glutamate, GABA and noradrenaline. Functionally, its release is associated with appetite, anxiety, and stress regulation. NPY acting on Y2 receptors (Y2R), facilitates fear extinction, suggesting a role in associative memory. Here, we explored to what extent NPY action at Y2R contributes to hippocampus-dependent spatial memory and found that dorsal intrahippocampal receptor antagonism improved spatial reference memory acquired in a water maze in rats, without affecting anxiety levels, or spontaneous motor activity. Water maze training resulted in an increase of Y2R, but not Y1R expression in the hippocampus. By contrast, in the prefrontal cortex there was a decrease in Y2R, and an increase of Y1R expression. Our results indicate that neuropeptide Y2R are significantly involved in hippocampus-dependent spatial memory and that receptor expression is dynamically regulated by this learning experience. Effects are consistent with a metaplastic contribution of NPY receptors to cumulative spatial learning.
Keywords: Extinction learning; Hippocampus; Morris water maze; NPY Y(2)R antagonist; Prefrontal cortex.
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