The effects of quinine and 4-aminopyridine on conditioned place preference and changes in motor activity induced by morphine in rats.
1. The effects of two unselective potassium (K(+)-) channel blockers, quinine (12.5, 25 and 50 mg/kg) and 4-aminopyridine (1 and 2 mg/kg), on conditioned place preference and biphasic changes in motor activity induced by morphine (10 mg/kg) were tested in Wistar rats. Quinine is known to block voltage-, calcium- and ATP-sensitive K(+)-channels while 4-aminopyridine is known to block voltage-sensitive K(+)-channels. 2. In the counterbalanced method, quinine attenuated morphine-induced place preference, whereas 4-aminopyridine was ineffective. In the motor activity test measured with an Animex-activity meter neither of the K(+)-channel blockers affected morphine-induced hypoactivity, but both K(+)-channel blockers prevented morphine-induced secondary hyperactivity. 3. These results suggest the involvement of quinine-sensitive but not 4-aminopyridine-sensitive K(+)-channels in morphine reward. It is also suggested that the blockade of K(+)-channels sensitive to these blockers is not sufficient to prevent morphine-induced hypoactivity whereas morphine-induced hyperactivity seems to be connected to both quinine- and 4-aminopyridine-sensitive K(+)-channels.
Meririnne
E
E
Department of Mental Health and Alcohol Research, Laboratory of Substance Abuse, Helsinki, Finland.
Kankaanpää
A
A
Vanakoski
J
J
Lillsunde
P
P
Seppälä
T
T
D015761:4-Aminopyridine / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D026902:Potassium Channel Blockers; D011803:Quinine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D026902:Potassium Channel Blockers; D009020:Morphine; D011803:Quinine; D015761:4-Aminopyridine