ELECTROGRAPHIC STUDIES OF THE EFFECTS OF RP-60180, A NOVEL KAPPA-AGONIST, ON THE PHOTOSENSITIVE BABOON PAPIO-PAPIO

1. The authors describe here the effects of intravenous administration of RP 60180, a novel kappa agonist, on conscious baboons of the speci es Papio papio, which spontaneously present photically induced epilept ic responses. 2. Animals (n=2) were chronically implanted with epidura l recording electrodes and tested whilst seated in a primate chair. Th e electrocorticogram (ECoG) and electrocardiogram (EGG) were recorded during a control period of at least 30 minutes before the injection of RP 60180 (1 to 4.5 mg/kg i.v.) and immediately afterwards. 3. Qualita tively, up to the dose of 4.5 mg/kg i.v., RP60180 did not modify ECoG backgroundin term of paroxysmal activity in comparison with that obser ved during the control period. It did not cause any manifest focal or generalized seizure discharges, nor did it consistently enhance or red uce photically induced myoclonic responses. 4. From the dose of 1 mg/k g i.v., RP 60180 slowed ECG frequency. This effect, which lasted for a bout 30 minutes post-injection, was most often seen at the higher dose s. 5. In another set of experiments, one baboon received the kappa ago nist U-50488 (a benzacetamide derivative of spiradoline) at 1 and 3 mg /kg i.v. U-50488, at 3 and to a lesser degree at 1 mg/kg i.v., induced paroxysmal bursts of slow wave ECoG activity and a slowing of the EGG . These effects lasted about 1 hour post-drug administration. During t his period, we observed spontaneous vocalization, as if the animal wer e complaining, as well as shaking.