Anxiolytic-Like Effects and Increase in Locomotor Activity Induced by Infusions of NMDA into the Ventral Hippocampus in Rat: Interaction with GABAergic System.
BACKGROUND
In this study, we investigated the role of N-Methyl-D-Aspartate (NMDA) receptors in the ventral hippocampus (VH) and their possible interactions with GABAA system on anxiety-like behaviors.


METHODS
We used an elevated-plus maze test (EPM) to assess anxiety-like behaviors and locomotor activity in male Wistar rats.


RESULTS
The results showed that intra-VH infusions of different doses of NMDA (0.25 and 0.5 μg/rat) increased locomotor activity, and also induced anxiolytic-like behaviors, as revealed by a tendency to increase percentage of open arm time (%OAT), and a significant increase in percentage of open arm entries (%OAE). The results also showed that intra-VH infusions of muscimol (0.5 and 1 μg/rat) or bicuculline (0.5 and 1 μg/rat) did not significantly affect anxiety-like behaviors, but bicuculline at dose of 1 μg/rat increased locomotor activity. Intra-VH co-infusions of muscimol (0.5 μg/rat) along with low doses of NMDA (0.0625 and 0.125 μg/rat) showed a tendency to increase %OAT, %OAE and locomotor activity; however, no interaction was observed between the drugs. Interestingly, intra-VH co-infusions of bicuculline (0.5 μg/rat) along with effective doses of NMDA (0.25 and 0.5 μg/rat) decreased %OAT, %OAE and locomotor activity, and a significant interaction between two drugs was observed.


CONCLUSIONS
It can be concluded that GABAergic system may mediate the anxiolytic-like effects and increase in locomotor activity induced by NMDA in the VH.
Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Payvand
P
Bina
Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Mehrnaz
M
Rezvanfard
Department of Biological Science and Biotechnology, Faculty of Science, University of Kurdistan, Sanandaj, Iran.
Shamseddin
S
Ahmadi
Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.; Department of Pharmacology, Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran.
Mohammad Reza
MR
Zarrindast
Anxiety-like behavior; Bicuculline; Elevated-plus maze; Muscimol; NMDA