Inhibitory effect of clonidine on ketamine-induced norepinephrine release from the medial prefrontal cortex in rats.
We have investigated the effect of clonidine on ketamine-induced norepinephrine release from the medial prefrontal cortex in rats using microdialysis. Twenty-one male Wistar rats weighing 200-300 g were allocated randomly to one of four groups: i.p. injection of ketamine 100 mg kg-1 with clonidine 0 (saline: group C0, n = 6), 3 (group C3, n = 5), 30 (group C30, n = 5) and 300 micrograms kg-1 (group C300, n = 5). As reported previously, ketamine increases norepinephrine release. In groups C0 and C3, marked increases in norepinephrine release were observed with maximum values of mean 483 (SEM 55)% and 412 (53)% compared with basal values, respectively. Although significant increases in norepinephrine release were also observed (276 (43)%) in group C30, they were significantly lower than those in groups C0 and C3 (P < 0.01 and P < 0.05, respectively). In group C300, there was a significant reduction in norepinephrine release (62 (13)%) compared with basal and the three other groups (P < 0.01). This inhibitory effect of clonidine on norepinephrine may be related to reduction in undesirable emergence reactions after ketamine anaesthesia.
Kubota
T
T
Department of Anaesthesiology, University of Hirosaki School of Medicine, Japan.
Hirota
K
K
Yoshida
H
H
Takahashi
S
S
Ohkawa
H
H
Anzawa
N
N
Kushikata
T
T
Matsuki
A
A
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D018686:Anesthetics, Intravenous; D000818:Animals; D002490:Central Nervous System / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology*; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000187:drug effects* / Q000378:metabolism; D051381:Rats
D000316:Adrenergic alpha-Agonists; D018686:Anesthetics, Intravenous; D007649:Ketamine; D003000:Clonidine; D009638:Norepinephrine