Hepatic carbohydrate metabolism in rats after laparotomy and laparoscopy

Portal venous and mesenteric blood flow are reduced by 40-60% in humans and animals during laparoscopic surgery compared to laparotomy. Little is known about whether these intraabdominal micro- and macrocirculatory changes are associated with alterations in the hepatic energy metabolism.

We operated on male Sprague-Dawley rats, performing either laparoscopy (CO2, 6 mmHg; n = 27) or laparotomy (n = 28), and compared the results with two control groups: intraperitoneal (i.p.) endotoxin administration (n = 28, positive control) and anesthesia only (n = 28, negative control). We investigated the impact of the two different surgical techniques on daily food intake, body weight gain, glycogen content in the liver, levels of blood glucose, and liver function tests (LFTs) on postoperative days 1, 2, 4, and 8. Local (hepatic) and systemic inflammatory responses (interleukin-6 and tumor necrosis factor-alpha) during the postoperative time course were also determined. Data were analyzed using the Kruskal-Wallis test or univariate analysis of variance.

Body weight gain, food intake, liver and spleen weights, as well as LFTs [except aspartate aminotransferase (AST)] did not differ among the four groups. The significant increase in the AST level following laparoscopy compared to the anesthesia-only group was found on postoperative days 1 and 2; however, a similar difference was not detected after laparotomy or i.p. endotoxin injection. Laparoscopy showed no alterations in the hepatic glycogen stores compared to anesthesia only, whereas laparotomy and endotoxinemia significantly reduced the hepatic glycogen stores on postoperative days 2 and 4. The systemic postoperative inflammatory response did not differ between laparotomy and laparoscopy, but it was higher in both groups than in anesthesia only. In rats treated with endotoxin, the systemic inflammatory response was even higher than in the two surgical groups. The hepatic inflammatory response did not differ between the four groups.

This study shows a significant postoperative decrease in the hepatic glycogen content after laparotomy and i.p. endotoxin injection but not after laparoscopy. Food intake and inflammatory response cannot explain this difference between the two surgical groups, which suggests that alterations in the postsurgical hormonal stress response are the most likely explanation for these findings.