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Anti-exploratory effect of N-methyl-d-aspartate in elevated plus-maze. Involvement of NMDA and CCK receptors

Vasar, E., Harro, J., Lang, A., Soosaar, A., Ööpik, T., Kõks, S., Sihver, S. and Volke, V. (1993) Anti-exploratory effect of N-methyl-d-aspartate in elevated plus-maze. Involvement of NMDA and CCK receptors. European Neuropsychopharmacology, 3 (1). pp. 63-73.

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(NMDA, 20 mg/kg) produced a clear decrease in mouse exploration in open parts of an elevated plus-maze. Paradoxically, 40 mg/kg NMDA did not modify the behavior of the mice in the plus-maze. NMDA at a dose of 80 mg/kg again depressed the exploratory activity of mice, but this effect was accompanied with tremor and compulsive tail biting. The ‘anti-exploratory’ dose of NMDA (20 mg/kg) increased, whereas the ‘tremorigenic’ dose (80 mg/kg) significantly decreased the number of cholecystokinin (CCK) binding sites in the mouse cerebral cortex. The competitive NMDA antagonist (±)-CPP (2.5–5 mg/kg) and the non-competitive antagonist MK-801 (0.25 mg/kg) antagonized the anti-exploratory effect of NMDA (20 mg/kg). The tricyclic antidepressant imipramine (5 mg/kg, but not 1 or 10 mg/kg) also attenuated the inhibition of exploratory activity induced by NMDA. Of three CCK receptor antagonists tested, the unselective CCK antagonist proglumide (1 mg/kg, but not 0.1 and 10 mg/kg) significantly opposed the anti-exploratory action of NMDA. The selective CCK antagonists L-365,260 (1 μg/kg) and devazepide (1 μg/kg) were evidently weaker antagonists of NMDA. Furthermore, 10 μg/kg of L-365,260, a CCK-B receptor antagonist, and 1 mg/kg of devazepide, a CCK-A receptor antagonist, even tended to augment the effect of NMDA in the plus-maze. The results of the present study seem to give some support to the notion that not only NMDA receptors, but also CCK-ergic mechanisms are involved in the modulation of anti-exploratory action of NMDA in the elevated plus-maze.

Item Type: Journal Article
Publisher: Elsevier
Copyright: © 1993 Elsevier B.V.
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