PD135158, A CCK-B ANTAGONIST, REDUCES STATE, BUT NOT TRAIT ANXIETY INMICE

It has recently been proposed that Balb/c neophobic responses in a fre e exploratory paradigm are related to ''trait'' anxiety, while the beh avior of mice in the light/dark choice test paradigm is related to ''s tate'' anxiety. The purpose of this study was to assess the action of the CCK-B receptor antagonist PD135158 in both models. Results show th at PD135158 was effective in the light/dark choice test but not on the Balb/c neophobic reactions in the free exploratory situation. It is s uggested that PD135158 is specially effective in state anxiety induced by fear provoking situations.