THE MEMORY-ENHANCING EFFECTS OF CHOLECYSTOKININ-OCTAPEPTIDE ARE DEPENDENT ON AN INTACT STRIA TERMINALIS

Cholecystokinin is a gastrointestinal peptide which is released from t he duodenum during eating. Cholecystokinin octapeptide (CCK-8) has bee n found to improve retention when administered intraperitoneally in in tact mice but not in vagotomized mice. This suggested that CCK-8 impro ves retention by stimulating vagal afferents to the nucleus of the sol itary tract in the brainstem. In this study, we tested whether nerve f ibers in the stria terminalis which project from the NTS to the amygda la need to be intact for CCK-8 to enhance retention. Three groups of m ice were used: nonoperated, bilateral cortical control lesioned, and b ilateral stria terminalis lesioned. The lesions were performed 1 week prior to footshock avoidance training in a T-maze. Saline, CCK-8 (0.5 mu g/kg, ip), epinephrine (100 mu g/kg, sc), or arecoline (1.5 mg/kg, sc) were administered immediately after training. Retention was tested 1 week later. Neither bilateral stria terminalis lesions nor cortical control lesions significantly altered acquisition of the task compare d to the nonoperated group. Whether the groups received a saline injec tion after training or received no injection did not affect retention test performance. CCK-8 and epinephrine enhanced retention in the mice with cortical lesions but not in mice with stria terminalis lesions. Arecoline enhanced retention in both groups. Possible pathways and neu rotransmitters mediating the effect are discussed. (C) 1995 Academic P ress, Inc.