TY - JOUR
T1 - Peripheral κ-opioid modulation of the formalin response
T2 - An electrophysiological study in the rat
AU - Haley, J.
AU - Ketchum, S.
AU - Dickenson, A.
PY - 1990/1/1
Y1 - 1990/1/1
N2 - The activity of single dorsal horn nociceptive neurones was recorded in the spinal cord of halothane anaesthetized rats. S.c. injection of a 5% formalin solution into the receptive field of these neurones resulted in two peaks of neuronal firing over a period of 60 min. Prior administration of the κ-opioid receptor agonist U50488H directly into the site of formalin injection caused a dose-dependent decrease in the size of both the first and second peaks of the response which was naloxone reversible. Injection of U50488H into the contralateral paw had no effect on either peak of the formalin response. Injection of the top dose (100 μg) of U50488H had no effect on the electrically evoked Aβ- or C-fibre responses of the neurone. Neither morphine nor Tyr-D-Ser(Otbu)-Gly-Phe-Leu-Thr (DSTBULET), administered into the receptive field, had any significant effect on either peak of the formalin response. Plasma extravasation in the skin, measured using Evans blue, produced by the formalin injection was not blocked by U50488H. Thus, whilst the spinal responses of this peripheral model of inflammation can be inhibited by peripheral κ-opioid activation, but not μ- or δ-, plasma extravasation associated with this inflammation is not reduced.
AB - The activity of single dorsal horn nociceptive neurones was recorded in the spinal cord of halothane anaesthetized rats. S.c. injection of a 5% formalin solution into the receptive field of these neurones resulted in two peaks of neuronal firing over a period of 60 min. Prior administration of the κ-opioid receptor agonist U50488H directly into the site of formalin injection caused a dose-dependent decrease in the size of both the first and second peaks of the response which was naloxone reversible. Injection of U50488H into the contralateral paw had no effect on either peak of the formalin response. Injection of the top dose (100 μg) of U50488H had no effect on the electrically evoked Aβ- or C-fibre responses of the neurone. Neither morphine nor Tyr-D-Ser(Otbu)-Gly-Phe-Leu-Thr (DSTBULET), administered into the receptive field, had any significant effect on either peak of the formalin response. Plasma extravasation in the skin, measured using Evans blue, produced by the formalin injection was not blocked by U50488H. Thus, whilst the spinal responses of this peripheral model of inflammation can be inhibited by peripheral κ-opioid activation, but not μ- or δ-, plasma extravasation associated with this inflammation is not reduced.
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0025606037&partnerID=8YFLogxK
U2 - 10.1016/0014-2999(90)94178-Z
DO - 10.1016/0014-2999(90)94178-Z
M3 - Article
AN - SCOPUS:0025606037
SN - 0014-2999
VL - 191
SP - 437
EP - 446
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 3
ER -