| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Clostridium perfringens beta-toxin causes dermonecrosis and oedema in the dorsal skin of animals. In the present study, we investigated the mechanisms of oedema induced by the toxin. The toxin induced plasma extravasation in the dorsal skin of Balb/c mice. The extravasation was significantly inhibited by diphenhydramine, a histamine 1 receptor antagonist. However, the toxin did not cause the release of histamine from mouse mastocytoma cells. Tachykinin NK_<(1)> receptor antagonists, [D-Pro^<(2)>, D-Trp^<(7, 9)>]-SP, [D-pro^<(4)>, D-Trp^<(7, 9)>]-SP and spantide, inhibited the toxin-induced leakage in a dose-dependent manner. Furthermore, the non-peptide tachykinin NK_<(1)>, receptor antagonist, SR140333, markedly inhibited the toxin-induced leakage. The leakage induced by the toxin was markedly reduced in capsaicin-pretreated mouse skin but the leakage was not affected by systemic pretreatment with a calcitonin gene-related peptide receptor antagonist (CGRP_<(8-37)>). The toxin-induced leakage was significantly inhibited by the N-type Ca^<2+> channel blocker, omega-conotoxin MVIIA, and the bradykinin B_<(2)> receptor antagonist, HOE140 (D-Arg-[Hyp^<(3)>, Thi^<(5)>, D-Tic^<(7)>, Oic^<(8)>]-bradykinin), but was not affected by the selective L-type Ca^<2+> channel blocker, verapamil, the P-type Ca^<2+> channel blocker, omega-agatoxin IVA, tetrodotoxin (TTX), the TTX-resistant Na^+ channel blocker, carbamazepine, or the sensory nerve conduction blocker, lignocaine. These results suggest that plasma extravasation induced by beta-toxin in mouse skin is mediated via a mechanism involving tachykinin NK_<(1)> receptors.
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