The scopolamine-induced impairment of spatial cognition parallels the acetylcholine release in the ventral hippocampus in rats

K. Mishima, K. Iwasaki, H. Tsukikawa, Y. Matsumoto, N. Egashira, K. Abe, T. Egawa, M. Fujiwara

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

We investigated the relationship between the induction of spatial cognition impairment in the 8-arm radial maze task and regional changes (ventral hippocampus (VH), dorsal hippocampus, frontal cortex, and basolateral amygdala nucleus) in brain acetylcholine (ACh) release using microdialysis in rats treated with muscarinic (M) receptor antagonists. In a behavioral study, two M1 antagonists, scopolamine (0.5 mg/kg, i.p. and 20 μg, i.c.v.) and pirenzepine (80 μg, i.c.v.) but not an M2 antagonist, AF-DX116 (40 - 80 μg, i.c.v.), disrupted spatial cognition in the 8-arm radial maze task. In brain microdialysis with Ringer's solution containing 0.1 mM eserine sulfate, scopolamine and AF-DX116, but not pirenzepine, increased ACh release in the VH. Moreover, in the bilateral injection of scopolamine (2 μg/side), the VH dorsomedial thalamus nucleus were important regions for scopolamine-induced impairment of spatial cognition. A simultaneous determination of the behavioral changes revealed that scopolamine (0.5 mg/kg, i.p.) markedly decreased the ACh contents and also increased the ACh release in all regions tested. Especially, the changes in the ACh release of the VH closely paralleled the induction of the scopolamine-induced impairment of spatial cognition. These results suggest that the blocking balance between M1 and M'2 muscarinic receptor in the VH therefore plays a major role in the spatial cognition impairment induced by scopolamine in the 8-arm radial maze task.

Original languageEnglish
Pages (from-to)163-173
Number of pages11
JournalJapanese Journal of Pharmacology
Volume84
Issue number2
DOIs
Publication statusPublished - Nov 25 2000
Externally publishedYes

Keywords

  • 8-Arm radial maze task
  • Acetylcholine release
  • Scopolamine
  • Spatial cognition
  • Ventral hippocampus

ASJC Scopus subject areas

  • Pharmacology

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