s To observe the synthesis of Toll like receptor (TLR) 4 protein and its mRNA exp ression in Kupffer cells (KCs) and evaluate the role of TLR 4 in liver injury to rats through alcohol induced liver disease Methods Twenty eight Wistar rats were divided into two groups: ethanol fed (group E) a nd control (group C) Group E rats were given ethanol at a dose of 5-12 g·kg 1 ·d 1 , while group C received dextrose Animals from bot h groups were killed at 4 and 8 weeks The KCs were isolated and synthesis of T LR 4 protein was determined by laser scanning confocal microscopy TLR 4 mRNA e xpression in KCs was determined by reverse transcription polymerase chain reacti on (RT PCR) analysis The levels of endotoxin, tumor necrosis factor α (TN F α) and interleukin 6 (IL 6) in plasma were determined Changes in liver pathology were observed Results Laser scanning confocal microscopy showed that the intensity of fluorescence of TLR 4 protein in group E was stronger than group C Ethanol administration led to a significant increase in TLR 4 mRNA expression in group E compared with grou p C ( P <0 05) The concentrations of plasma endotoxin, TNF α and IL 6 were higher in group E than in group C ( P <0 05) Liver sections from rat s in group E demonstrated marked pathological changes Conclusion Ethanol administration can lead to the synthesis of TLR 4 protein and its gene e xpression in KCs, indicating that TLR 4 may play a major role in the development of alcohol induced liver injury s To observe the synthesis of Toll like receptor (TLR) 4 protein and its mRNA exp ression in Kupffer cells (KCs) and evaluate the role of TLR 4 in liver injury to rats through alcohol induced liver disease Methods Twenty eight Wistar rats were divided into two groups: ethanol fed (group E) a nd control (group C) Group E rats were given ethanol at a dose of 5-12 g · kg 1 · d 1 while group C received dextrose Animals from bot h groups were killed at 4 and 8 weeks The KCs were isolated and synthesized of T LR 4 protein was determined by laser scanning confocal microscopy TLR 4 mRNA expression in KCs was determined by reverse transcription polymerase chain reacti on (RT PCR) analysis The levels of endotoxin, tumor necrosis factor α (TN F α) and interleukin 6 (IL 6) in plasma were determined changes in liver pathology were observed Results Laser scanning confocal microscopy showed that the intensity of fluorescence of TLR 4 protein in group E was stronger than group C Ethanol administration led to a significant increase in TLR4 mRNA expression in group E compared with grou p C (P <0 05) The concentrations of plasma endotoxin, TNFα and IL 6 were higher in group E than in group C (P <0 05) Liver sections from rat s in group E indicated marked pathological changes Conclusion Ethanol administration can lead to the synthesis of TLR 4 protein and its gene e xpression in KCs, indicating that TLR 4 may play a major role in the development of alcohol induced liver injury