Sensitization of nociceptive C-fibers in zinc-deficient rats.
A marked decrease in zinc concentration was observed in plasma (P < 0.001), hindpaw skin (P < 0.01), and dorsal skin (P < 0.01) in zinc-deficient rats (rats fed a zinc-deficient diet for 3 wk), compared with the control rats fed the same zinc-deficient diet supplemented with ZnCO3 (50 mg/kg diet). The threshold intensity needed to elicit vasodilatation in the hindpaw skin of the zinc-deficient rats on electrical stimulation of the saphenous nerve in a peripheral direction was markedly lower (P < 0.01) than that in the control rats. No difference was observed between control (n = 5) and zinc-deficient rats (n = 5) in the magnitude of the plasma extravasation evoked by either histamine or substance P. There was no difference between control and zinc-deficient rats in terms of the dose-response curve for release of histamine by substance P. Prostaglandin E2 (PGE2) concentration in the hindpaw skin of the zinc-deficient rats was nearly fourfold higher (P < 0.01) than that of the control rats, whereas no difference in the leukotriene B4 level in the hindpaw skin was observed between control and zinc-deficient rats. From the present study, it seems likely that an increased level of PGE2 in the vicinity of the nociceptive C-fiber terminals in the hindpaw skin of zinc-deficient rats may sensitize the terminals of the nociceptive C-fibers of the saphenous afferent nerve in the hindpaw and thus facilitate the production of antidromic vasodilatation.
Izumi
H
H
Department of Physiology, Tohoku University School of Dentistry, Sendai, Japan.
Mori
H
H
Uchiyama
T
T
Kuwazuru
S
S
Ozima
Y
Y
Nakamura
I
I
Taguchi
S
S
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D002254:Carbonates / Q000494:pharmacology*; D015232:Dinoprostone / Q000378:metabolism; D004558:Electric Stimulation; D006614:Hindlimb; D006632:Histamine / Q000494:pharmacology; D007975:Leukotriene B4 / Q000378:metabolism; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology*; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology*; D010525:Peripheral Nerves / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply / Q000294:innervation / Q000378:metabolism; D013373:Substance P / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D015032:Zinc / Q000172:deficiency* / Q000378:metabolism; D017967:Zinc Compounds / Q000494:pharmacology*
D002254:Carbonates; D017967:Zinc Compounds; D007975:Leukotriene B4; D013373:Substance P; D006632:Histamine; C036650:zinc carbonate; D015032:Zinc; D015232:Dinoprostone