[Met5]enkephalin and delta2-opioid receptors in the spinal cord are involved in the cold water swimming-induced antinociception in the mouse.
Mice made cold water swimming (CWS: 4 degrees C, 3 min) produced an opioid-mediated antinociception. Experiments were designed to determine what types of opioid receptors and endogenous opioid peptides in the spinal cord are involved in the CWS-induced antinociception in male ICR mice. Antinociception was measured by the tail-flick test. CWS-induced antinociception was blocked by intrathecal (i.t.) pretreatment with antiserum to [Met5]enkephalin (100 microg, 1 hr), but not by antiserum (100 microg, 1 hr) to [Leu5]enkephalin, beta-endorphin or dynorphin A (1-17). Moreover, i.t. pretreatment with delta2-opioid receptor antagonist naltriben (NTB: 10 microg, 10 min) blocked the antinociception induced by CWS or i.t.-administered [Met5]enkephalin (10 microg). However, the antinociception induced by CWS or i.t.-administered [Met5]enkephalin was not blocked by i.t. pretreatment with delta1-opioid receptor antagonist 7-benzylidene naltrexone (BNTX: 1 microg, 10 min), mu-opioid receptor antagonist D-Phe-Cys-Try-D-Try-Om-Thr-Phe-Thr-NH2 (CTOP: 50 ng, 10 min), or kappa-opioid receptor antagonist norbinaltorphimine (norBNI: 5 microg, 24 hr). These data indicate that [Met5]enkephalin and delta2-opioid receptor in the spinal cord are involved in antinociception induced by CWS.
Mizoguchi
H
H
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226, USA.
Narita
M
M
Kampine
J P
JP
Tseng
L F
LF
D000818:Animals; D003080:Cold Temperature; D004399:Dynorphins / Q000276:immunology; D004743:Enkephalin, Leucine / Q000276:immunology; D004744:Enkephalin, Methionine / Q000276:immunology / Q000502:physiology*; D007106:Immune Sera; D007278:Injections, Spinal; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010146:Pain / Q000503:physiopathology*; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors / Q000502:physiology*; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D001615:beta-Endorphin / Q000276:immunology
D007106:Immune Sera; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; D004399:Dynorphins