Clonidine analgesia: tolerance and cross-tolerance to autoanalgesia.
Clonidine induced significant antinociception in rats, as assessed by radiant-heat tail-flick procedures. Continued administration of 0 5 mg/kg and 1.0 mg/kg of the drug for 7 days induced significant analgesic tolerance in a dose-dependent manner. Significant cross-tolerance to antinociception elicited by acute footshock or classical conditioning procedures was observed, with the greatest cross-tolerance being exhibited by the 1.0 mg/kg group. These data suggest similar noradrenergic mechanisms may subserve clonidine antinociception and autoanalgesia.
D000698:Analgesia; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D004361:Drug Tolerance; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology
D011942:Receptors, Adrenergic, alpha; D003000:Clonidine; D009638:Norepinephrine