Intracerebral microinjections of Δ9-tetrahydrocannabinol: Search for the impairment of spatial memory in the eight-arm radial maze in rats

Nobuaki Egashira, Kenichi Mishima, Katsunori Iwasaki, Michihiro Fujiwara

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74 Citations (Scopus)


The purpose of this study was to identify brain sites that contribute to the Δ9-tetrahydrocannabinol (Δ9-THC)-induced impairment of spatial memory in rats. Rats were tested in the eight-arm radial maze after microinjections of Δ9-THC into one of 14 different brain regions. The bilateral microinjection of Δ9-THC (20 μg/side) impaired spatial memory when injected into the dorsal hippocampus (DH), ventral hippocampus (VH) or dorsomedial thalamus nucleus (DMT). However, rats treated with Δ9-THC into DMT produced perseverative behavior which has not been observed by systemic administration of Δ9-THC. On the other hand, spatial memory was unaffected by microinjections of Δ9-THC into the other 11 areas examined: frontal (FC) and frontoparietal (FPC) cortex, central (ACE) and basolateral (ABL) amygdaloid nucleus, medial caudate putamen (CPM), lateral hypothalamus (LH), mammillary body (MB), basal forebrain (BF), medial septal nucleus (SEP) and dorsal (DR) and median (MR) raphe nucleus. These results suggest that DH and VH may be important brain sites for the Δ9-THC-induced impairment of spatial memory.

Original languageEnglish
Pages (from-to)239-245
Number of pages7
JournalBrain Research
Issue number2
Publication statusPublished - Oct 18 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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