Calycosin alleviates hyperbilirubin nerve injury in Ugt1-/- mice by inhibiting oxidative stress, apoptosis, and mitochondrial function

Abstract

Background and purposeHyperbilirubinemia is a common condition in neonates that is associated with poor neurodevelopmental outcomes. Although studies have proposed that calycosin has a neuroprotective effect, the exact molecular mechanism underlying calycosin treatment of hyperbilirubinemia remains elusive. To fill this gap, we analyzed the mechanism of calycosin treatment in hyperbilirubinemia model mice. MethodThirty neonatal mice were randomly divided into wide type (WT), Ugt1-/- and calycosin treatment group. Neuronal damage was observed with Nissl staining. Immunofluorescence staining were carried out to determine DNA damage repair and neurodegeneration. Oxidative stress was investigated by immunostaining with 4-hydroxynonenal (4-HNE). Western blot (WB) and Qpcr were used to detect relative protein and mRNA expression levels. Mitochondrial CI/CII activity of mitochondria was analyzed with a spectrophotometer. ResultThe total bilirubin concentration was significantly higher in Ugt1-/- group compared with WT, but calycosin treatment reduced concentration of bilirubin. The total bilirubin and bilirubin/albumin ratio were significantly higher at postnatal day 4 compared with day 2. Calycosin treatment reduced serum bilirubin concentration and bilirubin/albumin ratio. After calycosin treatment, Nissl body count increased, apoptosis-related protein was downregulated and 4-HNE level decreased.Compared with Ugt-/- group, calycosin treatment increased neurons (NeuN+) and calbindin positive cells and decreased fluorojade C(FJC)positive neurons in WT group. In mitochondria, calycosin alleviated mitochondrial electron transport chain dysfunction in Ugt1-/- mice. ConclusionWe demonstrated that the mechanism of calycosin treatment on hyperbilirubinemia-induced Ugt1-/- was associated mainly with antioxidant effects, antiapoptosis and inhibition of normal mitochondrial function.