Many skin disorders, such as atopic dermatitis and psoriasis, worsen during stress and are associated with increased numbers and activation of mast cells which release vasoactive, nociceptive, and proinflammatory mediators. Nontraumatic acute psychological stress by immobilization has been shown to induce mast cell degranulation in the rat dura and colon. Moreover, intradermal injection of corticotropin-releasing hormone (CRH) or its analogue urocortin (10(-5)-10(-7) M) induced skin mast cell degranulation and increased vascular permeability. Here, we investigated the effect of acute immobilization stress on skin mast cell degranulation by light microscopy and electron microscopy. Immobilization for 30 min resulted (P < 0.05) in degranulation of 40.7 +/- 9.1% of skin mast cells compared to 22.2 +/- 7.3% in controls killed by CO(2) or 17.8 +/- 2.4% in controls killed by pentobarbital. Pretreatment intraperitoneally (ip) with antiserum to CRH for 60 min prior to stress reduced (P < 0.05) skin mast cell degranulation to 21.0 +/- 3. 3%. Pretreatment with the neurotensin (NT) receptor antagonist SR48692 reduced (P < 0.05) mast cell degranulation to 12.5 +/- 3.4%, which was significantly (P < 0.05) below control levels. In animals treated neonatally with capsaicin to deplete their sensory neurons of their neuropeptides, such as substance P (SP), mast cell degranulation due to immobilization stress was reduced to about 15%. This is the first time that stress has been shown to trigger skin mast cell degranulation, an action not only dependent on CRH, but apparently also involving NT and SP. These findings may have implications for the pathophysiology and possible therapy of neuroinflammatory skin disorders such as atopic dermatitis, neurogenic pruritus, or psoriasis, which are induced or exacerbated by stress.
Copyright 1999 Academic Press.