Influence of the neuropeptides vasoactive intestinal peptide and substance P on sudomotor functions

• Published in: Klinische Neurophysiologie
• Main Authors: Schlereth, T, Seewald, B, Birklein, F
• Format: Conference Proceeding
• Language: English
• Published: 24.03.2006
• ISSN: 1434-0275; 1439-4081
• DOI: 10.1055/s-2006-939278

Neuropeptides are the mediators of neurogenic inflammation. Some neuropathic pain states, e.g. complex regional pain syndromes, are characterized by increased neurogenic inflammation and by exaggerated sudomotor function. We have shown that the neuropeptide calcitonin gene related peptide (CGRP), which is enhanced in complex regional pain syndrome, enhances sweating (Schlereth 2004). The aim of the present study was to explore, whether the neuropeptides vasoactive intestinal peptide (VIP) and substance P (SP), which are involved in neurogenic inflammation, influence human sweating. In previous studies VIP and SP reduced cholinergic induces sweating (Kumazawa 1994, Berg 1995). We investigated the effects of different concentrations of VIP and SP on acetylcholine (ACh) induced axon-reflex sweating in healthy subjects (n=6, age: 26 +/- 1; 3 female, 3 male), n=4 were tested with each concentration of VIP and SP. All substances were applied via dermal microdialysis using fibers with a cut-off of 3000 kDalton. With this technique all substances were applied without time related skin trauma. For measuring of the sweating response two sweat capsules were attached to the skin of the lower leg surrounded by two microdialysis membranes each, which were either perfused with ACh alone or ACh combined with VIP or SP in various concentrations. Acetylcholine 10–2 M always elicited a sweating response, the neuropeptides VIP or SP alone did not. VIP at any concentration had no significant effect on axon reflex sweating (absolute humidity with 1.4+/-0.4g/m 3 and without VIP 1.2+/-0.3g/m 3 , p=0.4; sweat amount: 188+/-52 AUC vs. 122+/-29 AUC, p=0.2; duration of sweating response: 538+/-52s vs. 472+/-73s, p=0.3). SP reduced only the duration of the sweating response significantly (499+/-150s vs. 704+/-170s, p<0.01), whereas the amount of sweat was not significantly affected (absolute humidity with 0.69+/-0.16g/m 3 and without SP 0.73+/-0.17g/m 3 , p=0.8; sweat amount 78+/-28 AUC vs. 105+/-37 AUC, p=0.2), indicating reduced sweating with SP. Accordingly ACh-induced skin blood flow was not affected by VIP and SP. The results indicate that the neuropeptide VIP in contrast to CGRP has no effect on axon-reflex sweating, whereas substance P shows a tendency to reduce axon-reflex sweating. Supported by DFG Bi 579–1/1–3