Cholecystokinin and GABA interaction in the dorsal hippocampus of rats in the elevated plus-maze test of anxiety

In the present study, we have investigated the effects and interaction of CCK and GABAergic systems in the dorsal hippocampus of rats using the elevated plus-maze test of anxiety. Bilateral injection of different doses of CCK8s (0.01, 0.05 and 0.1 mu g/rat) into the dorsal hippocampus (infra-CA1) decreased percentage of open arm time (%OAT) and open arm entries (%OAE) that are representative of anxiogenic-like behavior. The bilateral injection of three doses of LY225910, a selective CCKZ receptor antagonist (0.01, 0.1 and 0.5 mu g/rat) produced significant anxiolytic behavior. Although muscimol (GABA(A)(+)) (0.1, 0.5 and 1 mu g/rat, intra-CA1) produced dose dependent increase in %OAT and a slight increase in %OAE, bicuculline (GABA(A)(-)), (1, 2 and 4 mu g/rat, infra-CA1) failed to change the anxiety profile. Both muscimol (0.1 mu g/rat) and bicuculline (1 mu g/rat), when co-administered with LY225910, reversed the effect of latter drug on anxiety but when co-administered with CCK8s (0.05 mu g/rat) showed no effect on anxiety profile. In conclusion, it seems that both CCK and GABAergic systems not only play a part in the modulation of anxiety in the dorsal hippocampus of rats but also have demonstrated a complex interaction as well. (c) 2005 Published by Elsevier Inc.