Mechanisms of adrenaline-induced antinociception in mice.
Infusion of adrenaline into the upper lumbar subarachnoid space in lightly anesthetized mice produced a significant elevation of the nociceptive threshold as quantitated by tail flick test. The antinociceptive effect of adrenaline was dose-dependent and antagonized equally by pretreatment with either alpha-1 selective antagonist prazosin or alpha-2 selective antagonist yohimbine at a dose of 0.05 microgram/5 microliter/mouse. This antinociceptive effect of adrenaline was also blocked by pretreatment with beta antagonist propranolol or opiate antagonist naloxone at higher doses, i.e., 0.5 microgram and 1.0 microgram/5 microliter/mouse, respectively. These results suggest that the antinociceptive mechanisms of adrenaline at the lumbar spinal level in the mouse seem to be mediated not only through alpha- and beta-adrenergic pathways but also through opiate system.
Peng
Y I
YI
Department of Physiology, College of Medicine, National Taiwan University, Taipei, R.O.C.
Liu
H J
HJ
Guo
L
L
Fu
T C
TC
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D007278:Injections, Spinal; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology / Q000517:prevention & control*; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D012684:Sensory Thresholds / Q000187:drug effects; D015016:Yohimbine / Q000494:pharmacology
D000700:Analgesics; D015016:Yohimbine; D009270:Naloxone; D011433:Propranolol; D011224:Prazosin; D004837:Epinephrine