Effect of the cyclopyrrolones suriclone and RP 59037 on body temperature in mice.

The effects of the cyclopyrrolones suriclone and RP 59037 on body temperature were investigated in male TO mice. The full agonist suriclone (3, 10, 30 mg/kg i.p.) produced significant hypothermia which was inhibited by concurrent administration of benzodiazepine receptor antagonists of both benzodiazepine (flumazenil; 10 mg/kg i.p.) and beta-carboline (ZK 93426; 3 mg/kg i.p.) structure. The response to suriclone (10 mg/kg i.p.) was also attenuated by benzodiazepine (Ro 17-1812; 10 mg/kg i.p.) and beta-carboline (ZK 91296; 30 mg/kg i.p.) partial agonists - which have no effect on body temperature per se. In contrast with these compounds, the cyclopyrrolone partial agonist RP 59037 (10, 30 mg/kg i.p.) produced significant hypothermia itself (although it was much less efficacious in this respect than the full agonist) and at a dose of 30 mg/kg failed to block the decrease in body temperature induced by suriclone (10 mg/kg i.p.). Thus suriclone acts as a full agonist at benzodiazepine receptors in the body temperature paradigm. RP 59037 possesses some partial agonist properties in this model, however, it appears to have greater intrinsic activity than other partial agonists tested previously.