ABSTRACT
Introduction The neuropeptide Y (NPY) is broadly distributed in the central nervous system (CNS), and it has been related to neuroprotective functions. NPY seems to be an important component to counteract brain damage and cognitive impairment mediated by drugs of abuse and neurodegenerative diseases, and both NPY and its Y2 receptor (Y2R) are highly expressed in the hippocampus, critical for learning and memory. We have recently demonstrated its influence on cognitive functions; however, the specific mechanism and involved brain regions where NPY modulates spatial memory by acting on Y2R remain unclear.
Methods Here, we examined the involvement of the hippocampal NPY Y2R in spatial memory and associated changes in brain metabolism by bilateral administration of the selective antagonist BIIE0246 into the rat dorsal hippocampus. To further evaluate the relationship between memory functions and neuronal activity, we analysed the regional expression of the mitochondrial enzyme cytochrome c oxidase (CCO) as an index of oxidative metabolic capacity in limbic and non-limbic brain regions.
Results The acute blockade of NPY Y2R significantly improved spatial memory recall in rats trained in the Morris water maze that matched metabolic activity changes in spatial memory processing regions. Specifically, CCO activity changes were found in the dentate gyrus of the dorsal hippocampus and CA1 subfield of the ventral hippocampus, the infralimbic region of the PFC and the mammillary bodies.
Conclusions These findings suggest that the NPY hippocampal system, through its Y2R receptor, influences spatial memory recall (retrieval) and exerts control over patterns of brain activation that are relevant for associative learning, probably mediated by Y2R modulation of long-term potentiation and long-term depression.
Highlights
Under hippocampal Y2R antagonism, place preference memory retrieval is enhanced
Spatial retrieval enhancement under Y2R blockade is correlated with changes in regional brain energy metabolism
Enhanced retrieval associated CCO activity increases in the dorsal DG, while decreasing in the ventral CA1, IL cortex and mammillary bodies
Y2R exert control over patterns of brain activation that are relevant for spatial memory expression
Competing Interest Statement
The authors have declared no competing interest.
