DIFFERENT MOLECULAR-FORMS OF CHOLECYSTOKININ AND CCKB RECEPTOR-BINDING IN THE RAT-BRAIN AFTER CHRONIC ANTIDEPRESSANT TREATMENT

Cholecystokinin (CCK) is a neuropeptide recently implicated in affecti ve disorders. This study aimed at measuring the levels of different mo lecular forms of CCK and the binding characteristics of CCKB receptors in the rat brain after three weeks of treatment with four different a ntidepressants, imipramine, amitriptyline, desipramine, and citalopram (all at the dose of 10 mg/kg once per day i.p.). Chronic treatment wi th imipramine and desipramine had a significant immobility-reducing ef fect in the Porsolt's swim test. The effect of amitriptyline, albeit i n the same direction, was not significant, and citalopram had no effec t in this test. In the elevated plus-maze test of anxiety, all drugs t ended to increase the number of open aim entries and the ratio open/to tal arm entries, but only the effects of imipramine were statistically significant. None of the treatments affected the total levels of CCK or the levels of CCK-8-sulphated, CCK-8-nonsulphated, CCK-5, or CCK4 i n the frontal cortex. There was no effect of the treatments on CCKB re ceptor binding in the frontal cortex., hippocampus, or striatum. Imipr amine and amitriptyline, however, increased the affinity of CCKB recep tor binding in the hypothalamus. Thus, no consistent effect of chronic antidepressant treatment on the CCK-ergic neurotransmission in the ra ts was found.