Anxiogenic effect of CCK8s in the ventral hippocampus of rats: Possible involvement of GABAA receptors

Cholecystokinin (cck) as an important neuropeptide in the brain has been implicated in the modulation of anxiety. the effects of this neurotransmitter on anxiety-like behavior in the ventral hippocampus have not been evaluated yet. moreover,some evidences show a functional interaction between gaba and cck in the nervous system. bilateral injections of three doses of cck8s (0.01,0.05 and 0.1 μg/rat) into the ventral hippocampus decreased percentage of open arm time (%oat) and open arm entries (%oae) that are representative of anxiogenic-like behavior in the elevated plus-maze test of anxiety. bilateral injections of ly225910,a selective cck2 receptor antagonist,at the doses of 0.01,0.1 and 0.5 μg/rat did not change anxiety-related parameters. administration of muscimol,a selective gabaa receptor agonist,at the doses of 0.001,0.005 and 0.01 μg/rat produced dose dependent increase in %oat and %oae indicating an anxiolytic-like effect,while administration of bicuculline,a selective gabaa receptor antagonist,at the doses of 0.1,0.2 and 0.5 μg/rat decreased %oat and %oae showing that this drug promoted anxious behavior of the rats. co-administration of bicuculline (0.2 μg/rat) with cck8s decreased the anxiogenic effects of cck8s. furthermore,coadministration of ly225910 (0.5 μg/rat) with muscimol increased the anxiolytic effect of muscimol at the dose of 0.001 μg/rat. the results of this study suggest that both cck and gabaergic system have important and opposite roles in the modulation of anxiety-like behavior in the ventral hippocampus of rats and they may have a complex interaction in the ventral hippocampus to modulate anxiety-related behavior. copyright © 2012 by institute of pharmacology polish academy of sciences.