Involvement of dynorphin in immobilization stress-induced antinociception in the mouse.
The effect of antiserum against [Met(5)]-enkephalin, [Leu(5)]-enkephalin, beta-endorphin, or dynorphin A-(1-13) administered intracerebroventricularly (i.c.v.) or intrathecally (i. t.) on immobilization-induced antinociception was studied in ICR mice. Antinociception was assessed by the tail-flick assay. Immobilization of the mouse increased inhibition of the tail-flick response at least 1 h. The i.c.v. or i.t. injection with antiserum against dynorphin A-(1-13) at the dose of 200 microg significantly attenuated immobilization-induced inhibition of the tail-flick response. However, antiserum against [Met(5)]-enkephalin, [Leu(5)]-enkephalin, or beta-endorphin did not affect the immobilization stress-induced antinociception. Furthermore, i.c.v. or i.t. injection with nor-binaltorphimine (Nor-BNI; from 1 to 20 microg) effectively inhibited immobilization stress-induced inhibition of the tail-flick response in a dose-dependent manner. However, beta-FNA (from 0.5 to 2 microg) or naltrindole (from 1 to 20 microg) administered i.c.v. or i.t. did not affect immobilization stress-induced antinociception. Our results suggest that supraspinally and spinally located dynorphin appears to be involved in the production of immobilization stress-induced antinociception via stimulating kappa-opioid receptors.
Suh
H W
HW
Hallym University, College of Medicine, Institute of Natural Medicine, Department of Pharmacology, Chunchon, Kangwon Do, 200-702, South Korea.hwsuh@sun.hallym.ac.kr
Song
D K
DK
Huh
S O
SO
Kim
Y H
YH
D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology; D004399:Dynorphins / Q000276:immunology / Q000502:physiology*; D004743:Enkephalin, Leucine / Q000276:immunology / Q000502:physiology*; D004744:Enkephalin, Methionine / Q000276:immunology / Q000502:physiology*; D007106:Immune Sera / Q000494:pharmacology*; D007276:Injections, Intraventricular; D007278:Injections, Spinal; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D011930:Reaction Time; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000503:physiopathology*; D001615:beta-Endorphin / Q000276:immunology / Q000502:physiology*
D007106:Immune Sera; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; D004399:Dynorphins