Influência do pré-condicionamento isquêmico do fígado na concentração hepática dos ácidos graxos - estudo experimental em ratos.

Abstract

Background: The analysis proposed in this study seeks to contribute to the understanding of the role of ischemic preconditioning of the liver in the behavior of fatty acids in liver surgeries. Objective: To assess whether ischemic preconditioning of the liver interferes with the hepatic concentration of fatty acids in hepatectomies. Method: Twenty four Wistar rats were distributed into 3 groups: 8 to the SG - Sham Group, 8 to the NPCG - No Pre-Conditioning Group and 8 to the PCG - Pre-Conditioning Group. On the first day of the experiment, blood collection and median laparotomy were performed on all animals. Four rats from the SG underwent liver manipulation and completely hepatic resection, followed by death without suffering, due to anesthetic overdose, the others four only had the liver manipulated. At NPCG, a hepatectomy of 70% of the parenchyma was performed under 10 uninterrupted minutes of ischemia. The PCG was subjected to transient ischemia of the liver by clamping the hepatic hilum for 10 minutes, followed by 10 minutes of reperfusion, before 10 minutes of ischemia for resection of the surgical specimen. On the second day, all groups underwent a new blood collection and complete removal of the existing liver tissue, followed by death without suffering, due to anesthetic overdose. Biochemical analysis was performed on the blood tissue and from the liver histological preparations were obtained, in addition to the extraction, through liquid chromatography, of Palmitic, Stearic, Palmitoleic, Oleic, Alpha-Linolenic, Eicosapentaenoic, Docosahexaenoic, Linoleic, Gamma- Linolenic, Dihomo-Gamma-Linolenic, Arachidonic and Docosapentaenoic n-6 acids.. Outcomes: We observed, on D1, higher AST of NPCG when compared to PCG (699,75 ± 209,65 versus 483,00 ± 109,68; p = 0.05, SE 2.922). In the histological parameters, there was a more pronounced presence of sinusoidal congestion (12,75 ± 2,43 versus 8,38 ± 1,59; p = 0.01), neutrophilic infiltrate (3,25 ± 1,58 versus 0,38 ± 0,51; p < 0.01), hemophagocytizing Kupffer cells (9,13 ± 1,64 versus 5,50 ± 2,13; p = 0.01) and steatosis (6,38 ± 3,16 versus 2,13 ± 3,68; p = 0.02) on D0 of PCG when compared to D0 of NPCG. Comparing these two groups on D1, this difference remained significant only for the neutrophilic infiltrate (5,75 ± 1,98 versus 1,38 ± 1,18, p < 0.01). Finally, the analysis of fatty acids demonstrated a significantly lower production on D0 of PCG when compared to D0 of NPCG for the following acids: Arachidonic (423.92 ± 169.64 versus 736.92 ± 232.36; p < 0.01), Docosahexaenoic (69.96 ± 32.50 versus 128.44 ± 46.56; p = 0.01) and Dihomo-Gamma- Linolenic (12.47 ± 3.32 versus 19.97 ± 4.49; p < 0.01), which remained on D1: Arachidonic Acid (342.39 ± 115.44 versus 647.86 ± 265.93; p < 0.02), Docosahexaenoic Acid (52.36 ± 23.14 versus 115.32 ± 53.67; p < 0.01) and Dihomo-Gamma-Linolenic Acid (12.06 ± 6.39 versus 22.83 ± 7.83; p < 0.01). Finally, the enzymatic activity showed no difference between the two groups, however, NPCG exhibited, singly, an increase in the activity of SCD-1 on Palmitic Acid, on D0 and D1, and of Δ-6 desaturase, in addition to a decrease in the activity of Δ-5 desaturase. And, together with PCG, it showed an increase in the activity of SCD-1 on Stearic Acid, on D1. Conclusion: A 70% hepatectomy performed in rats under continuous ischemia for 10 minutes, with or without preconditioning, results in significant and differentiated changes in the overall and individual hepatic concentration of fatty acids. These changes, in the group submitted to ischemic preconditioning, are related to the restoration of the histological and biochemical alterations observed in animals that did not receive ischemic conditioning before hepatectomy and to the preservation of the activity of the enzymes that metabolize polyunsaturated fatty acids of the omega-3 and -6 series, thus demonstrating the hepatoprotective effect of this strategy.