Suckling reduces allergic skin responses and plasma levels of neuropeptide and neurotrophin in lactating women with atopic eczema/dermatitis syndrome

BACKGROUND: Lactation is associated with an inhibited hypothalamic-pituitary-adrenal axis response to physical and psychological stress in women and female rats. However, suckling also improved mood and calmness in nonatopic lactating women. Relaxation by humor reduced allergen-induced skin wheal responses, while various forms of stress enhanced those responses in allergic patients. Moreover, enhancement and reduction in allergen-induced skin wheal responses are associated with up- and down-regulation of plasma levels of substance P (SP) and vasoactive intestinal peptide (VIP), respectively. In addition, plasma levels of SP, VIP and nerve growth factor (NGF), but not neurotrophin-3 (NT-3), are elevated in allergic patients. Therefore, the effects of suckling on allergic responses and plasma levels of neuropeptides and neurotrophins were studied in lactating women with atopic eczema/dermatitis syndrome (AEDS). METHODS: Before and after suckling, allergic skin responses to allergens were studied by skin prick test; simultaneously plasma levels of substance P, vasoactive intestinal peptide, nerve growth factor and neurotrophin-3 were measured in lactating women with atopic eczema/dermatitis syndrome. RESULTS: Suckling reduces allergen-induced, but not histamine-induced, skin wheal responses, while holding infants without suckling failed to do so. Suckling also reduced plasma levels of SP, VIP and NGF, but not NT-3 in these patients, while holding infants without suckling failed to do so. CONCLUSIONS: These results indicate that suckling reduces allergic responses with a concomitant reduction in plasma levels of SP, VIP and NGF. Collectively, suckling may have some implication in the study of maternal allergy in atopic patients.