POSSIBLE INVOLVEMENT OF NEUROPEPTIDERGIC SENSORY NERVES IN ALOPECIA-AREATA

ALOPECIA areata (AA) is a dermatosis involving the sudden occurrence o f bald patches on the scalp. Although the aetiology is unknown, experi mental data indicate that cutaneous microcirculation plays an importan t role. The skin is richly innervated by neuropeptidergic sensory nerv es that help regulate microvascular circulation. This study shows a re duction of cutaneous levels of substance P and calcitonin gene-related peptide (CGRP) but not of vasoactive intestinal polypeptide in scalp biopsies from patients with AA. Laser-Doppler flowmetry was used to st udy microcirculation of the scalp. Results indicate that patients with AA have lower basal blood Row and greater vasodilatation following in tradermal CGRP injection than control subjects. A vascular hyper-react ivity to vasodilatatory substances such as neuropeptides, probably bec ause of the lack of these substances, is hypothesized.