Effects of ischemic preconditioning on cyclinD1 expression during early ischemic reperfusion in rats.

AIM: To observe the effect of ischemic preconditioning on cyclinD1 expression in rat liver cells during early ischemic reperfusion. METHODS: Fifty-four SD rats were randomly divided into ischemic preconditioning group (IP), ischemia/reperfusion group (IR) and sham operation group (SO). The IP and IR groups were further divided into four sub-groups (n = 6). Sham operation group (SO) served as the control group (n = 6). A model of partial liver ischemia/reperfusion was used, in which rats were subjected to liver ischemia for 60 min prior to reperfusion. The animals in the IP group underwent ischemic preconditioning twice for 5 min each time prior to the ischemia/reperfusion challenge. After 0, 1, 2, and 4 h of reperfusion, serum and liver tissue in each group were collected to detect the level of serum ALT, liver histopathology and expression of cyclinD1 mRNA and protein. Flow cytometry was used to detect cell cycle as the quantity indicator of cell regeneration. RESULTS: Compared with IR group, IP group showed a significantly lower ALT level in 1 h to 4 h sub-groups (P < 0.05). Proliferation index (PI) indicated by the S-phase and G2/M-phase ratio [(S+G2/M)/(G0/G1+S+G2/M)] was significantly increased in IP group at 0 and 1 h (26.44 +/- 7.60% vs 18.56 +/- 6.40%, 41.87 +/- 7.27% vs 20.25 +/- 6.70%, P < 0.05). Meanwhile, cyclinD1 protein expression could be detected in IP group. But in IR group, cyclinD1 protein expression occurred 2 h after reperfusion. The expression of cyclinD1 mRNA increased significantly in IP group at 0 and 1 h (0.568 +/- 0.112 vs 0.274 +/- 0.069, 0.762 +/- 0.164 vs 0.348 +/- 0.093, P < 0.05). CONCLUSION: Ischemic preconditioning can protect liver cells against ischemia/reperfusion injury, which may be related to cell proliferation and expression of cyclinD1 during early ischemic reperfusion.

Preconditioning effects on expression of proto-oncogenes c-fos and c-jun after hepatic ischemia/reperfusion in rats.

BACKGROUND: Ischemia/reperfusion is the main cause of hepatic damage in liver transplantation. Immediate early genes (IEGs) encode proteins can regulate expression of cellular response genes after injury, and is associated with tissue repair and cell apoptosis. The purpose of this research was to investigate the effects of preconditioning on expression of immediate early genes c-fos and c-jun following hepatic ischemia/reperfusion (IR) and its roles in cellular regeneration and apoptosis. METHODS: Ninety-six Wistar rats were randomly divided into IR group and hepatic ischemic preconditioning (IPC) group, and each group was further divided into eight sub-groups (n=6). The model of partial liver ischemia/reperfusion was used. The rats were subjected to 60-minute liver ischemia, preceded by 10-minute preconditioning. After 0-, 0.5-, 1-, 2-, 4-, 8-, 12-, 24-hour reperfusion, the serum and liver tissue in each group were collected to detect the level of serum ALT/AST, liver histopathology, expression of c-fos, and c-jun mRNA. Flow cytometer was used to detect Ki67 and Sub-G1 as the quantity indicators of cell regeneration and apoptosis respectively. RESULTS: Compared with IR group, IPC group showed a significantly lower ALT/AST level in 0.5-hour sub-group to 8-hour sub-group (P<0.05). Ki67 elevated significantly at 0.5, 1, 2 hours, but decreased significantly at 24 hours (P<0.05). Ap index decreased significantly after 1-hour reperfusion (P<0.05). Expressions of c-fos and c-jun mRNA were low, especially c-jun at 0.5, 1 and 2 hours after reperfusion. CONCLUSION: Ischemic preconditioning can protect liver cells against ischemia/reperfusion injury, and this protective effect may be related to influence transcription levels of c-fos and c-jun.