Comparisons of dose-dependent effects of systemic morphine on flexion reflex components and operant avoidance responses of awake non-human primates.
Electromyographic activity and the force of reflex and operant responses were recorded following administration of morphine. Low doses facilitated reflex responses to input from A-delta afferents but not from A-beta input. Higher doses inhibited A-delta responses but not A-beta responses. Operant avoidance responses to visual cues were unchanged. Thus, depending on the dose, nociceptive reflexes were facilitated or inhibited, without associated effects on non-nociceptive input or on motor output.
Yeomans
D C
DC
Department of Neuroscience, University of Florida College of Medicine, Gainesville 32610-0244, USA.
Cooper
B Y
BY
Vierck
C J
CJ
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D007273:Injections, Intramuscular; D008251:Macaca; D009020:Morphine / Q000494:pharmacology*; D010775:Photic Stimulation; D012026:Reflex, Stretch / Q000187:drug effects*
D009020:Morphine