The effects of
Ro 15-1788 and
ethyl-beta-carboline-3-carboxylate (
beta-CCE) were studied alone and in combination on the behavioral performances of squirrel monkeys. Under one procedure, performances maintained by food were suppressed by electric
shock presentation (punishment or "conflict" procedure). Under a second procedure, responding was maintained either by food or electric
shock delivery under a 5-min fixed-interval schedule. Doses of
beta-CCE between 0.1 and 3.0 mg/kg, i.m., produced graded decreases in punished responding which were reversed by pretreatment with
Ro 15-1788 (1.0 - 10.0 mg/kg, i.m.). Low doses of
beta-CCE (0.03 - 0.3 mg/kg, i.m.) increased responding of monkeys maintained by
shock presentation, but did not affect food-maintained responding; higher doses of
beta-CCE decreased responding under both schedules. These effects of
beta-CCE are opposite those produced by the
benzodiazepines under this procedure.
Ro 15-1788 (1.0 mg/kg i.m.) antagonized the effects of
beta-CCE, producing a shift to the right in the dose-response curves. These findings provide further support for the view that
beta-CCE and
Ro 15-1788 produce effects mediated by the same
benzodiazepine receptor recognition site.