Effects of cholinergic system of dorsal hippocampus of rats in the MK801-induced anxiolytic-like behavior

Abstract

Introduction

Some investigations showed that the glutamate receptors have critical role for cognition such as learning and anxiety in the brain.

Objectives

The possible involvement of cholinergic system of dorsal hippocampus in the anxiolytic-like response induced by NMDA receptor antagonist, MK801 has been investigated in the present study.

Methods

The male wistar rats were used and the elevated plus maze apparatus has been used to test parameters (%OAT, %OAE, locomotor activity, grooming, rereading and defection) of anxiety-like behaviors.

Results

The data indicated that intra-CA1 administration of MK801 (2 μg/rat) increased %OAT and %OAE but did not other exploratory behaviors, indicating an anxiolytic-like response. Moreover, intra-hippocampal injection of cholinergic receptor antagonists, mecamylamine (2 μg/rat) and scopolamine (4 μg/rat) by itselves, 5 min before testing increased %OAT and %OAE, but did not alter locomotor activity and other exploratory behaviors, suggesting anxiolytic-like behavior. On the other hand, intra-CA1 co-administration of ineffective doses of scopolamine (3 μg/rat), but not mecamylamine (1 μg/rat) with ineffective dose of MK801 (1 μg/rat) increased %OAT and %OAE.

Conclusion

The data may indicate that the possible involvement of cholinergic system of CA1 on anxiolytic-like response induced by MK801.