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Abstract
Background: Vitiligo is one of the most common pigmentary skin disorders. Despite much research, the etiology of vitiligo and the causes of melanocyte death are not clear. High epidermal levels of acetylcholine have been reported in vitiligo. This has been attributed to almost absent epidermal AChE (acetylcholinesterase) activity due to the effect of high levels of H₂O₂. Aim of work: The aim was to elucidate the role played by members of cholinergic system of the skin & H₂O₂ in the pathogenesis of vitiligo and to evaluate the effect of NB-UVB (311 nm) on the various components of this system, namely acetylcholine (ACh), its receptors; nicotinic (nAChRs) and muscarinic (mAChRs), acetylcholinesterase enzyme (AChE) and H₂O₂. Conclusion: The skin cholinergic system appears to play an important role in vitiligo pathogenesis. H₂O₂ regulates this system through its inhibitory effect on AChE enzyme. ACh exerts its action through mAChRs leading to the development of vitiligo. These receptors are highly expressed in vitiligo skin most probably due to genetic or acquired errors or due to direct up-regulation by ACh and H₂O₂