ANTIDEPRESSANT-LIKE EFFECTS OF CCKB ANTAGONISTS IN MICE - ANTAGONISM BY NALTRINDOLE

1 The effects of selective CCKB agonists, BC 264 and BC 197 were inves tigated in the conditioned suppression of motility test in mice, an an imal model used to select antidepressant drugs. The results showed tha t both CCKB agonists at doses of 3 and 30 mu g kg(-1), accentuated the suppression of motility in shocked mice and did not modify the behavi our of non-shocked mice. The effects of BC 264 were suppressed by L-36 5,260. 2 L-365,260 alone, at doses of 0.2 and 2 mg kg(-1) decreased mo tor inhibition in shocked mice and had no effect in non-shocked mice. 3 The effects of L-365,260 observed in shocked mice were suppressed by naltrindole, a selective antagonist for delta-opioid receptors, sugge sting the occurrence of physiological adverse interactions between CCK and opioid systems. 4 Together, these results suggest that CCKB antag onists could block centrally located CCKB receptors to produce antidep ressant-like effects which could indirectly involve delta-opioid recep tor stimulation.