Involvement of Dorsal Hippocampal NMDA-Glutamatergic
System in Anxiety-Related Behaviors of Rats¹

J. Solati^a,2 and A. A. Salari^b

^aDepartment of Biology, Islamic Azad University, Karaj Branch, Karaj, Iran

^bDepartment of Biology, north Tehran Branch, Islamic Azal University, Tehran, Iran

Received February 05, 2011

Abstract—Dorsal hippocampus is one of the brain regions which plays an important role in anxiety. In the
present study we investigated the effects of Intra-dorsal hippocampus (CA1) microinjection of NMDA-
glutamatergic receptor agonist, NMDA and its antagonist, MK-801 on anxiety-related behavior in rats. Elevated
plus-maze (EPM) which is one of the common methods employed for testing of anxiety was used in this study.
Rats were anaesthetized with a mixture of ketamine and xylazine and special cannulas were inserted stereotaxi-
cally into the CA1 region of the dorsal hippocampus. After a one-week recovery, the effects of intra-CA1
administration of NMDA receptor agents were studied. Bilateral Intra-dorsal hippocampus microinjection of
different doses of NMDA (0.25, 0.5, 0.75 and 1 g/rat) increased the percentage of open arm time (%OAT) and
open arm entries (%OAE), indicating an anxiolytic-like behavior. On the other hand, administration of MK-801
(60, 125, 250 and 500 ng/rat) decreased %OAT and %OAE significantly. Pre-treatment administration of MK-
801(60, 125, 250 and 500 ng/rat) reversed the anxiolytic effect of NMDA (0.5 g/rat) microinjection into the
dorsal hippocampus in a dose-dependent manner. From the findings of the present study, it can be concluded
that the NMDA-glutamatergic system in the dorsal hippocampus is involved in anxiety-related behaviors.

Keywords: anxiety, dorsal hippocampus, MK-801, NMDA

DOI: 10.1134/S1819712411030081

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