AIMTo investigate the effect of cetirizine hydrochloride on the expression of neuropeptide substance P (SP) in IgE-dependent triphasic cutaneous reaction induced by dinitrofluorobenzene (DNFB) in the ears of BALB/c mice.

METHODSBALB/c mice were passively sensitized by intravenous infection of anti-DNP IgE monoclonal antibody 24 h before DNFB challenge. Skin reaction was elicited by applying DNFB to both sides of each ear of sensitized mice. Mice were treated with cetirizine (1 and 10 mg x kg)-1), ig). The ears were removed for pathohistological examination and immunohistochemical staining of SP at different designated times after challenge. The contents of SP in the skin of mouse ear were determined by radioimmunoassay (RIA).

RESULTSThe mice exhibited a triphasic cutaneous reaction with an immediate-phase response (IPR) at 1 h, a late-phase response (LPR) at 24 h and a very late-phase response (vLPR) at 7 days after challenge with DNFB. The expression of SP in different phases increased gradually. Cetirizine (1 and 10 mg x kg(-1)) was shown to significantly inhibit the ear swellings induced by the IPR (P < 0.01), while no obvious effect on the vLPR. The SP contents in ear skin of triphasic cutaneous reaction were decreased by cetirizine.

CONCLUSIONSP is considered to be involved in the pathogenesis of allergic dermatitis. Cetirizine hydrochloride can inhibit the expression of SP in IgE-dependent triphasic cutaneous reaction. It might be part of the mechanisms of anti-anaphylaxis of cetirizine.