Background. The importance of bile in liver regeneration after hepatectomy is unknown, although we have recently shown that preoperative internal biliary drainage is superior to external biliary drainage for liver regeneration in obstructive jaundiced rats. This study examined the hypothesis that the presence or absence of bile in the intestinal tract modulates cyclins and cyclin-dependent kinases after hepatectomy in rats. Methods. In male Wistar rats, bile was drained externally (ED group) or into the duodenum (ID group) for 7 days before 70% hepatectomy. Relative liver weight, DNA synthesis rate, and proliferating cell nuclear antigen labeling index were determined at the time of hepatectomy (day 0) and on days 1, 3, and 7 after hepatectomy. Posthepatectomy expressions of cyclin D1 and E and of cyclin D1-and E-associated kinases were serially analyzed. Hepatic function tests were performed. Results. No significant difference in liver function was found between the 2 groups at hepatectomy except for the lower albumin level in the ED group. The relative liver weight was lower in the ED group than in the ID group on day 3 after hepatectomy (ED, 2.58% ± 0.06%; ID, 2.84% ± 0.08%; P < .05). Both the DNA synthesis rate and proliferating cell nuclear antigen labeling index in the ED group (77 ± 36 disintegrations per minute/μg DNA and 8.3% ± 1.9%, respectively) were lower than those in the ID group (262 ± 50 disintegrations per minute/μg DNA and 21.6% ± 5.6%, respectively) on day 1 after hepatectomy (P < .05, respectively), Cyclin D1-associated kinase activity and cyclin D1 expression were not significantly different between the 2 groups. Cyclin E-associated kinase activity was lower in the ED group than in the ID group at 18 hours after hepatectomy (ED, 84% ± 17%; ID, 146% ± 28% of the value at 0 hour in the ID group; P < .05), although expressions of cyclin E and p27 binding to cyclin E were not significantly different between the 2 groups. Conclusions. These results suggest that the absence of bile in the intestine delays liver regeneration associated with cyclin E-associated kinase inactivation after hepatectomy.
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