neurokinin-a and Erythema

Substance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (CGRP) coexist in nerve fibres in the skin. CGRP causes erythema upon intracutaneous injection. The erythema is independent of axon reflexes and release of mast cell histamine. SP is known to produce a flare reaction that is dependent on axon reflexes and release of mast cell histamine. The flare reaction to NKA is known to depend predominantly on axon reflexes. The purpose of the present study was to investigate possible cooperation between SP and CGRP. SP was found to shorten the duration of the reddening induced by CGRP, injected concomitantly. NKA did not shorten the duration of the CGRP response. Local elimination of mast cells in the skin by treatment with compound 48/80 had the effect that SP lost its ability to shorten CGRP-evoked erythema. These observations support the suggestion that an SP-evoked release of proteolytic enzymes from mast cells could lead to accelerated degradation of CGRP.

Topics: Adult; Calcitonin Gene-Related Peptide; Drug Combinations; Drug Interactions; Erythema; Female; Histamine; Humans; Injections, Intradermal; Male; Middle Aged; Neurokinin A; p-Methoxy-N-methylphenethylamine; Skin; Substance P; Tachykinins

The tachykinins substance P (SP) and neurokinin A are believed to be major mediators of neurogenic inflammation. To determine whether the skin reactivity to tachykinins is increased in asthmatics, we examined the erythemas and wheals induced by intradermal injections of SP, the C-terminal peptide SP6-11, the N-terminal peptide SP1-9 and neurokinin A (10(-7)-10(-5) M) in 10 allergic asthmatics and 9 normal subjects. SP and SP1-9 induced both erythemas and wheals in a concentration-dependent manner in allergic asthmatics and in normal subjects, whereas SP6-11 and neurokinin A induced only wheals in both groups. SP induced greater erythemas and wheals in allergic asthmatics than in normal subjects. However, the wheals induced by neurokinin A were not significantly different between the two groups. SP1-9 also induced greater erythemas and wheals in allergic asthmatics than in normal subjects, whereas the wheals induced by SP6-11 were not significantly different between the two groups. Therefore, the increased skin reactivity to SP was dependent on the N-terminal peptide but not on the C-terminal peptide. We conclude that the skin reactivity to SP but not to neurokinin A is increased in allergic asthmatics.

Topics: Adult; Asthma; Erythema; Female; Humans; Male; Middle Aged; Neurokinin A; Peptide Fragments; Skin; Substance P

The effects evoked by intradermal injections of substance P (SP), neurokinin A (NKA) or calcitonin gene-related peptide (CGRP) were studied in 51 non-atopic subjects. SP and NKA produced flare and weal, and CGRP produced an indurated erythema. The reactions to SP were strong, the flare being maximal 3-5 min after injection and the weal after 10-15 min. NKA evoked a much weaker flare and a slightly weaker weal than did SP. CGRP produced a prominent long-lasting, indurated erythema with pseudopodia surrounded by a pallor edge. The mode of action of the three peptides was studied by pretreatment of the skin with the histamine-releasing compound 48/80, the H1-antagonist mepyramine or the local anesthetic xylocaine. The results suggest that mast-cell histamine and an intact sensory nerve supply are essential for the flare response to both SP and NKA. The weal response to SP was somewhat reduced by pretreatment with either 48/80 or xylocaine. The weal response to NKA, however, did not seem to depend upon either mast cells or sensory nerve fibres. The erythema evoked by CGRP was not suppressed by pretreatment with xylocaine, compound 48/80 or mepyramine, suggesting a direct action of CGRP on the blood vessels. The interaction between SP and CGRP was studied in subjects receiving a low dose of CGRP and increasing doses of SP or a low dose of SP and increasing doses of CGRP. CGRP did not potentiate the SP-evoked flare and weal and SP did not seem to enhance the response to CGRP.

Topics: Adult; Calcitonin Gene-Related Peptide; Dose-Response Relationship, Drug; Drug Interactions; Erythema; Female; Humans; Male; Neurokinin A; Neurons, Afferent; Neuropeptides; Skin; Skin Tests; Substance P; Vasodilator Agents