A proposed autacoid mechanism controlling mastocyte behaviour.

Evidence is provided here supporting the existence of a novel autacoid mechanism negatively modulating mast cell behaviour in response to noxious stimuli in vivo; hence, the denomination "autacoid local inflammation antagonism" (ALIA). In particular, as lipid amides of the N-acylethanolamine type have been reported to accumulate in tissues in degenerative inflammatory conditions, we examined whether these N-acylated lipids could exert regulatory effects on mast cell activation in vivo. The results reported show that both long- and short-chain N-acylethanolamines, when systemically administered, are effective in reducing mast cell degranulation induced by local injection of substance P in the ear pinna of developing rats. These and other data suggest that the endogenous production of N-acylethanolamines may constitute a local autocrine/paracrine response for the negative feedback control of mast cell responses to various activating signals. Such a process may be of physio-pathological relevance in the regulation of functional neuro-immune-mast cell interactions.