An EEG and behavioural study on the interactions of clonidine with phencyclidine and ketamine in rats.
Progress in neuro-psychopharmacology & biological psychiatry January 1, 1990 P Popoli, A Pezzola, A Scotti de Carolis
Clonidine, an alpha-2 adrenergic agonist, caused sedation and synchronized brain electrical activity in rats starting at 0.05 mg/kg. At low and moderate doses of the dissociative anesthetics PCP and ketamine, clonidine fully inhibited their EEG and behavioral effects, but at high doses it potentiated them. Yohimbine reversed both the inhibitory and potentiating effects of clonidine, as well as the sedation and EEG synchronization. Prazosin did not produce these effects, indicating alpha-2 adrenoceptors are involved. The interaction between dissociative anesthetics and central adrenergic receptors appears complex, with possible relevance for improving ketamine anesthesia and treating PCP intoxication.