To identify genes responding to the cholesterol-rich diet, differentially expressed hepatic genes have been searched from a diet-induced hypercholesterolemic rabbit by differential display reverse transcription-polymerase chain reaction (DDRT-PCR). Among the many screened genes, Rab7 gene was shown to be distinctively up-regulated in response to the cholesterol-loading into the rabbit. To visualize the location of elevated Rab7 expression in tissues, patterns of the gene expression were monitored within hepatic and aortic tissues by in situ hybridization and immunohistochemistry. The expression of Rab7 was obviously increased in the hepatic tissues, especially in the endothelial cells and hepatocytes around central veins of the high cholesterol-fed rabbit, compared to the tissues from rabbit fed a normal diet. To find out a potential relationship between the Rab7 and the atherogenesis, the same experiments were conducted with the atherosclerotic plaques obtained from rabbit and human. The elevated expression of Rab7 gene was clearly evident in both tissues, suggesting that the Rab7 may be involved in the process of atherogenesis. (C) 2002 Elsevier Science (USA). All rights reserved.