Local application of capsaicin to one sciatic nerve of the adult rat induces a marked depletion in the peptide content of the lumbar dorsal horn

摘要: In an earlier study we have shown that local application of capsaicin directly to one sciatic nerve induces a decrease substance P and cholecystokinin octapeptide (CCK8)-like peptide from the dorsal spinal cord using immunocytochemical analysis.1 Here effect locally applied on seven peptides known be present in L4 segment was assessed by radioimmunoassay immunocytochemistry. The investigated were P, somatostatin CCK8-like (which are small diameter primary afferent fibres), neurotensin, enkephalin intrinsic cord), neurophysin (of supraspinal origin) bombesin (whose origin is unknown). Fourteen days after single 49 mM solution significant depletion detected. These results confirmed parallel analysis which localised dramatic decreases lamina 1 2. addition immunoreactivity observed immunocytochemistry this area, but quantitative did not detect depletion. capsaicin-induced changes dose-dependent reversible. Small noted with concentrations as low 0.1 mM. apparent day 9 onwards, maximal seen 14. By 200 post-operatively, recovery normal levels ipsilateral horn observed. addition, cutaneous area skin innervated capsaicin-treated nerve. accompanied increase noxious thermal response (hind paw immersion test, T = 49°C, leg 9.11 ± 1.3 seconds, contralateral leg: 5.1 < 0.005). enkephalin, affected treatment. These findings suggest indiscriminate peptide-containing sensory fibres dose-dependent, long-lasting,