Increased anxiety behavior in OLETF rats without cholecystokinin-A receptor.

Cholecystokinin (CCK) may have a role in the mediation of human panic disorder and anxiogenic (anxiolytic)-like activity in an animal model of anxiety. Otsuka Long Evans Tokushima Fatty (OLETF) rats lacked CCK A receptors (CCKAR) because of a genetic abnormality. In order to elucidate the involvement of CCKAR in the regulation of anxiety, we investigated the exploratory behavior on elevated plus-maze test, the black and white box test, and open field test with OLETF rats in comparison with normal [Long-Evans Tokushima Otsuka (LETO)] rats. And OLETF rats increased the number of stretched attend postures and decreased open arm entry and the % time of open arm in an elevated plus-maze test. Time spent in the white box decreased significantly in OLETF rats than LETO rats. The total line crossing decreased significantly in OLETF rats compared to LETO rats. The missing CCKAR had a significant anxiogenic-like effect. These data support the involvement of the CCKAR in the neurobiological mechanism of anxiety.