Influence of epidermal growth factor on liver regeneration after partial hepatectomy in mice

The role of epidermal growth factor (EGF) in liver regeneration was studied in mice after partial hepatectomy. Two weeks before partial hepatectomy, mice were sham-operated (control) or sialoadenectomized (removal of submandibular glands) to reduce plasma EGF levels. Sialoadenectomized mice showed low plasma EGF levels (29.7 +/- 6.6 pmol/l; mean +/- S.E.M.) compared with controls (66.0 +/- 8.3 pmol/l). After partial hepatectomy, sialoadenectomized mice were treated with or without a daily s.c. injection of 5 micrograms EGF and the rate of DNA synthesis in the regenerating liver was monitored by [125I]iododeoxyuridine uptake. Control mice showed a sharp peak of DNA synthesis at 48 h after partial hepatectomy while sialoadenectomized mice showed a delayed and broad peak at 84 h. Treatment of sialoadenectomized mice with EGF (5 micrograms/mouse per day) completely restored the pattern of DNA synthesis so that a sharp peak appeared at 48 h. The total liver DNA content of the control mice (79.1 +/- 2.5% of the preoperative level; mean +/- S.E.M.) was significantly (P less than 0.01) higher than that of the sialoadenectomized mice (65.2 +/- 3.0%) 3 days after partial hepatectomy, but this difference disappeared on day 7 when liver regeneration was almost completed in both groups. Treatment of sialoadenectomized mice with EGF increased total liver DNA content (78.2 +/- 2.9%) to that of control mice on day 3 after partial hepatectomy. In addition, normal mice showed a rapid increase in plasma EGF levels at 1-8 h after partial hepatectomy, whereas sialoadenectomized mice showed low plasma EGF levels throughout the course of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)