Abstract: AIM: To investigate the role of leukotriene B4 (LTB4) and the expression of 5-lipoxygenase (5-LO) in ovalbumin-induced asthmatic mice and study the effect of arsenolite on LTB4 and the expression of 5-LO in those mice as well as the mechanism of arsenolite inhibiting asthma.METHODS: The mice were challenged with saline or OVA and ig with saline, mung bean, dexamethasone or arsenolite (0.625, 1.25, 2.50, 5.00mg·kg^-1) twice daily for 3 days.The LTB4 of BALF was measured by ELISA and RT-PCR was used to detect the mRNA expression of 5-LO in pulmonary tissue.RESULTS: The levels of LTB4 in BALF and 5-LO mRNA expression in pulmonary tissue of asthmatic group significantly increased compared with normal group.The levels of LTB4 in BALF and 5-LO mRNA expression in lung tissue in groups treated with 4 doses arsenolite were significantly lower than those in asthmatic group.Moreover, the 5-LO mRNA in group As 5.00 was significantly lower than that in group As 0.625.CONCLUSION: The high level of LTB4 in BALF, up-regulation of 5-LO mRNA in pulmonary tissue play very important roles in bronchial asthma.Arsenolite can efficiently treat asthma.Its mechanism maybe partly relates to the decrease of LTB4 in airway and the inhibitions of the mRNA expression of 5-Lo in pulmonary tissue.

Key words: asthma, arsenolite, arsenic trioxide, leukotriene B4, 5-lipoxygenase, mouse