Effects of Ceruletide, Administered Singly and in Combination with Central-Acting Drugs, on Discrete Shuttle Avoidance Response in Mice

The single administration of ceruletide at 10-300 micrograms/kg, i.p., slightly but significantly decreased the response rate (frequency of shuttles) under a discrete avoidance task in mice. Over 10 micrograms/kg of ceruletide attenuated the increase in the response rate induced by methamphetamine (0.5 mg/kg, s.c.). However, ceruletide, at 1-300 micrograms/kg, did not significantly enhance the response- and/or avoidance-decreasing effects of chlorpromazine (1 mg/kg, s.c.), haloperidol (0.1 mg/kg, s.c.), pilocarpine (4 mg/kg, s.c.) and N6-(L-2-phenylisopropyl)-adenosine (0.1 mg/kg, s.c.), but rather tended to reduce the avoidance-decreasing effect of chlorpromazine and pilocarpine at 1-100 micrograms/kg.