| Hyperbilirubinemia is a very common predicament, usually requiring therapeutic intervention in early life. The significance of neonatal hyperbilirubinemia can vary from a minor nontoxic phenomenon to severe chronic neurological disability in survivors or to acute death by kernicturus. However, the mechanisms of bilirubin encephalopathy and kernicturus remain unclear, and there is little effective therapeutic intervention by now. So it is of great importance to explore the deep mechanisms of bilirubin encephalopathy and effective therapeutic drugs.In fact, several effects of unconjugated bilirubin(UCB) toxicity have been reported either in brain sections, cultured cell lines, or isolated nerve terminals. The relationship between bilirubin encephalopathy and apoptosis is the hot spot, and recent studies have demonstrated that UCBtoxicity occurs through a mitochondria! dependent pathway. NF-кB, a crucial transcription factor, anticipates the transcription regulation of many genes, which has a close relationship with neural cell apqptosis. It is of important significance to explore whether NF-кB anticipated the regulation cf bilirubin-induced neural cell apoptosis.aBaicalin (BC), which is extracted from the radix of Scutellaria baicalensis Georgi, has the inhibitory effects of inflammation and peroxidation. Since it has relatively high concentration in cerebral spinal fluid, it could be a promising therapy to brain injury. We have demonstrated that BC has the protective effects on infectious brain edema and oxidative stress brain injury, and the protective effect is closely related with NF-KB inhibition. Qingkailing, another traditional Chinese medicine, can alleviate the glutamate-induced neutoxicity. As we know, BC is one of the most important components of Qingkailing. Since the activation of excitatory amino acid acceptor and influx of Ca4* are generally accepted as the important mechanisms of bilirubin encephalopathy, we infer whether BC could play a neuroprotective role in bilirubin toxicity, whether NF-KB might anticipate the bilirubin-induced apoptosis process? In this study, we evaluate several toxic effects of UCB on cultured rat astrocytes and neurons to differentiate cell response and, therefore, better understanding the underlying mechanism leading to UCB encephalopathy and/or kernicturus. The experiments study the mechanism bilirubin-induced neurotoxicity, BC's neuroprotective effectson neural cells toxicity, and the possible regulatory effects of NF-кB on apoptosis.Section OneBilirubin induces astrocytes and neurons injury in rats [ABSTRACT] Objectives To explore the bilirubin-inducedtime-dependent and concentration-dependent neutoxicity on rats astrocytes and neurons. Methods Astrocytes and neurons from the forebrains of SD rats were cultured in vitro, incubated with UCB(12.5, 25, 50 and 100 uM) plus albumin for 6, 12, 24 respectively. Cell viability was assessed by MTT. Phenomenon of apoptosis and necrosis were evaluated by fluorescent dye of Acridine orange/Ethidium bromide (AO/EB). Results 1. Bilirubin decreased astrocytes and neurons viability in a time- and concentration-dependent manner( P < 0.05). 2. Neurons were more sensitive than astrocytes to bilirubin neutoxicity by MTT assessment, but the viability difference among groups of neurons and astrocytes was not significant statistically( P > 0.05 ). 3. Bilirubin reduced the normal astrocytes and neurons, increased apoptotic and necrotic astrocytes and neurons through AO/EB dye observation in a time-"and concentration-dependent manner. Astrocytes' death occurred both in apoptotic and in necrotic manner. 4. Apoptosis occurred more frequently than necrosis in astrocytes, and necrosis occurred more frequently than apoptosis in neurons under the condition of 50 u M, 100uM bilirubin for 12 h, 24 h, respectively. Conclusions 1. Bilirubin decreases astrocytes and neurons viability in a time- and concentration-dependent manner. 2. Bilirubin reduces the normal astrocytes and neurons, i...
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