Changes in liver fatty acid unsaturation after partial hepatectomy in the rat

The purpose of this study was to assess changes in the degree of fatty acid unsaturation in rat liver after partial hepatectomy. This is the first stu dy in which liver fatty acid unsaturation has been analyzed over a long per iod of regeneration until day 28 after operation. The relationship between changes in unsaturation and fatty acid composition in the regenerating live r were also investigated in this study. Proton nuclear magnetic resonance s pectroscopy revealed significantly elevated levels of unsaturation with a m aximum on day 5 after partial hepatectomy, compared with untreated controls (11.72 +/- 0.55 vs. 11.05 +/- 0.26%, P < 0.05). No significant changes in unsaturation were found in day 1 regenerating liver, which is rich in absol ute amounts of fatty acids. Based on gas-liquid chromatography, the relativ e amounts of oleic acid (18:1n-9) and linoleic acid (LA; 18:2n-6) were incr eased, while polyunsaturated fatty acids such as arachidonic acid (20:4n-6) and docosahexaenoic acid (DHA; 22:6n-3) were decreased on day 1. On the ot her hand, on day 5 of regeneration, while most fatty acids were returning t o their preoperative control levels, only DHA was higher than the control v alue (7.69 +/- 0.58 vs. 5.57 +/- 0.37%, P < 0.001). The high levels of unsa turation on day 5 were found to be partly due to the increase in DHA. The f indings suggest that some significant signals are transmitted during the re generation process owing to alterations in the membrane structure by the hi gh levels of fatty acid unsaturation and the increase in DHA levels on day 5 after partial hepatectomy.