The neuropharmacology and behavioural effects of cholecystokinin

Abstract

Studies regarding the influences of cholecystokinin on anxiety, learning and memory, are rife with inconsistency. This thesis attempts to address many of these. 1. Chlordiazepoxide decreases amplitudes in the acoustic startle chamber. Where CCK forms at specific doses increase amplitudes, a combination of CCK-4 and CCK-8s at half their effective doses exerts no effect. CCK2 antagonists CI-988 and LY-288513 alter amplitudes following an inverse bell-shaped curve. 2. A similar phenomenon is observed in the elevated plus-maze. These phenomena are explained by a hypothesis highlighting a subtle association between sub-populations of the CCK2 receptor. 3. In the two-trial plus-maze paradigm, LY-288513 exhibits a similar profile to chlordiazepoxide. Scopolamine prevents the development of chlordiazepoxide insensitivity but not for LY-288513. A similar profile was observed with acoustic startle post plus-maze exposure. 4. Experiments within this thesis also appear to refute a role for cholecystokinin in associative learning implying a fear-state underlies previous observations.