Possible involvement of the CCK receptor in the benzodiazepine antagonism to CCK in the mouse brain.

In mice, intraperitoneally injected chlordiazepoxide and proglumide, both of which are regarded as cholecystokinin (CCK) receptor antagonists in the peripheral tissues, dose-dependently inhibited the satiety induced by 200 ng of intracisternally administered CCK octapeptide (CCK8). Intraperitoneally administered diazepam (1 mg/kg) and/or Ro 15-1788 (5 mg/kg), a benzodiazepine antagonist, both prevented the elevation in the pain threshold induced by 1 microgram of CCK8. However, Ro 15-1788 did not antagonize the effect of diazepam that reversed the CCK-induced antinociception. Ro 15-1788 also inhibited the satiety induced by CCK8. From these results, it was considered that the antagonism, which was observed in the present work, of benzodiazepines and proglumide to CCK8 seemed to occur at the CCK receptor and not at the benzodiazepine receptor in the brain.