The Effect And Molecular Mechanism Of Sulforaphane In Bladder Remodeling Induced By Bladder Outlet Obstruction

Purpose: Oxidative stress plays an important role in the pathogenesis of partial bladder outlet obstruction(PBOO).This research aims to investigate whether sulforaphane regulates the level of oxidative stress by Nrf2-ARE signal pathway ameliorates the change of structure and function of bladder in rats with PBOO in vitro and in vivo studies,and then clarify the protective effect and molecular mechanism of sulforaphane in ameliorating bladder dysfunction in BOO model.Methods:(1)A total of 24 male Sprague-Dawley rats,rats were randomly divided into four groups: the sham-operated group(n = 6),the 2-week BOO group(n = 6),the 4-week BOO group(n = 6)and the BOO+SFN group(n = 6).After the designated experimental period,urodynamics and histomorphology were performed to observe the change of bladder structure and function.(2)Biochemical and molecular biological measurement were carried out to observe the change of oxidative stress level,the bladder smooth muscle cell proliferation,apoptosis and Nrf2-ARE signaling pathway molecule expression in the bladder specimens of experimental groups.(3)The Nrf2-ARE signaling pathway was investigated in BSMCs by cyclic stretch in a time-and tension-dependent manner,to achieve an improved understanding of the underlying cellular and molecular mechanisms and to find out the most effective cyclic mechanical stretching parameters.(4)To study the effect of sulforaphane,a Nrf2 agonist,on oxidative stress and the protein expression of Nrf2-ARE signaling pathway in BSMCs,clarifying the molecular mechanism aganist oxidative stress.Results:(1)The histological staining showed that muscle bundles were severely damaged and collagen deposition was increased in a time-dependent manner in BOO rats.SFN treatment ameliorated the increase of collagen fibers induced by obstruction.Additionally,SFN treatment attenuated the decreased expression of PCNA,and rescued BOO-induced apoptosis.In addition,SFN treatment inhibited BOO-induced malondialdehyde(MDA) accumulation,and resulted in an increased level of total superoxide dismutase(SOD).Immunohistochemical and Western blot analysis illustrated that SFN increased the expression of Nrf2,HO-1,NQO1.(2)The protein expression of Nrf2-ARE signaling pathway were upregulated to the maximum extent at 20% stretch for 6h,and then the levels began to decline.We selected the degree of 25% stretch for 8h as the point that BSMCs entered into the decompensated stage by cyclic mechanical stretching for the following research.(3)Sulforaphane,a Nrf2 agonist,relieved the level of oxidative stress caused by cell stretching,and decreased the expression of apoptosis protein through the activation of Nrf2-ARE signaling pathways.Conclusions: The increased level of oxidative stress was associated with bladder structural and functional alterations following partial bladder outlet obstruction.Sulforaphane may play an important role in protection against bladder dysfunction in partial bladder outlet obstruction model by activating the Nrf2-ARE pathway.