Neuropeptide Y prolongs non-social memory and differentially affects acquisition, consolidation, and retrieval of non-social and social memory in male mice

Johannes Kornhuber,Iulia Zoicas

doi:10.1038/s41598-017-07273-x

Abstract

Neuropeptide Y (NPY) and its receptors (especially Y1, Y2, and Y5) are highly expressed in brain regions involved in learning and memory processes. Accordingly, NPY was shown to modulate cognitive functions in rodents. Here, we investigated possible memory-enhancing effects of NPY and determined the role of the NPY system in the acquisition, consolidation, and retrieval of non-social and social memory in mice, using the object and social discrimination tests, respectively. Intracerebroventricular (icv) infusion of NPY (1 nmol/2 µl) prolonged retention of non-social (object) memory, but not of social memory. This effect was blocked by the Y1 receptor antagonist BIBO3304 trifluoroacetate (2 nmol/2 µl), but not by the Y2 receptor antagonist BIIE0246 (2 nmol/2 µl). While icv infusion of NPY did not affect the acquisition, consolidation, and retrieval of non-social and social memory, icv infusion of BIBO3304 trifluoroacetate and BIIE0246 blocked the consolidation of non-social memory and the retrieval of both non-social and social memory. This study suggests that NPY has memory-enhancing effects in a non-social context by specifically acting on Y1 receptors. It further suggests that the central NPY system exerts differential effects on the sequential phases of non-social and social memory.

Highlights

IntroductionMemory is defined as the ability of the brain to encode, store, retain, and subsequently recall information and past experiences and can be classified according to function (working or reference memory), content (implicit or explicit memory), duration (short- or long-term memory), and nature (associative or non-associative memory)[1, 2]
Memory is defined as the ability of the brain to encode, store, retain, and subsequently recall information and past experiences and can be classified according to function, content, duration, and nature[1, 2]
The effects of neuropeptide Y (NPY) on memory retention appear to be region-dependent since NPY enhanced retention when infused into the rostral hippocampus and septum, impaired retention when infused into the amygdala and caudal hippocampus, and was ineffective when infused into the thalamus, caudate, or cortical regions above the rostral hippocampus and septum[24]

Summary

Introduction

Memory is defined as the ability of the brain to encode, store, retain, and subsequently recall information and past experiences and can be classified according to function (working or reference memory), content (implicit or explicit memory), duration (short- or long-term memory), and nature (associative or non-associative memory)[1, 2]. Memory can be classified according to the sequential phases involved, including acquisition, consolidation, retention, and retrieval of information. An increasing number of studies indicate a role of NPY in learning and memory and have shown that NPY exerts both inhibitory and stimulatory effects depending on the type of memory, sequential phase, dose applied, receptor subtype, and brain region. In operant conditioning tasks, such as passive and active avoidance tests, NPY was shown to enhance memory consolidation, retention, and retrieval[21, 22], but did not affect acquisition[23]. We investigated whether NPY and its Y1 and Y2 receptors (given their role in social behavior, learning, and memory) are involved in the acquisition, consolidation, and retrieval of non-social and social memory

Methods

Results

Conclusion