الفهرس 
Organization of the liverOnly 14 pages are availabe for public view
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Abstract
Hepatic ischemia-reperfusion (HIR) injury is a principal pathogenic issue leading to hepatic dysfunction and hemorrhagic shock, hepatic trauma, resection, and the need for liver transplantation. Octreotide (OCT) is considered a synthetic octapeptide and resembles somatostatin in physiological actions. Melatonin (MLT) (N-acetyl-5-methoxytryptamine) and its metabolites are well-tolerated antioxidants; they scavenge radicals and prevent tissue damage. Thus, the purpose of this study was to examine whether pretreatment with OCT at doses of 50, 75, and 100 μg/kg or OCT at 75μg/kg combined with MLT can produce hepatic protection against HIR injury in rats.
Male albino rats were used and equally divided into 7 groups (8 rats in each group); (1) Sham group; (2) HIR group subjected to hepatic ischemia for 30 min by clamping portal vein and hepatic artery using a non-traumatic clamp followed by 24 h reperfusion; (3) OCT50+HIR group received 50 μg/kg of OCT (20 μg/kg, I.P. and 30 μg/kg, S.C.) 30 min before the onset of ischemia operation; (4) OCT75+HIR group received 75 μg/kg of OCT (30 μg/kg, I.P. and 45 μg/kg, S.C.) 30 min before the onset of ischemia operation; (5) OCT100+HIR group received 100 μg/kg of OCT (40 μg/kg, I.P. and 60 μg/kg, S.C.) 30 min before the onset of ischemia operation; (6) MLT+HIR group received MLT at a dose of 20 mg/kg 15 min prior to ischemia and again directly before reperfusion; (7) MLT+OCT75+HIR group.
After the reperfusion period, blood was collected for the determination of the liver function tests. After blood collection, rats were euthanized and the liver lobes were removed and divided into two parts. One part was preserved in 10% phosphate buffered formalin for histopathological and immunohistochemical examinations and the second part was either homogenized and kept in ice-cold phosphate buffer saline, RNA lysis buffer, and RIPA buffer/complete protease inhibitor for determination of enzyme-linked immunosorbent
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assays (ELISA), real-time quantitative polymerase chain reactions (qPCR), and western blot techniques, respectively.
Results of the present study showed that HIR produced a significant increase in serum markers of hepatic damage and histopathological changes accompanied by significant elevations in the hepatic keap-1, MDA, HMGB1, TLR4, MyD88, TRAF-6, p-IκBα (S32), p-NF-κBp65 (S536), NLRP3, ASC, caspase-1(p20), GSDMD-N, IL-1β, and IL-18, IL-6, TNF-𝛼, ICAM-1, VCAM-1, Bax, cytochrome c, caspase-9, TNFR1, caspase-3, and caspase-7 with significant reductions in the hepatic Nrf2, HO-1, NQO-1, CAT, SOD-1, GSH, and Bcl-2. As well, the HIR group produced a significant reduction in liver autophagy as indicated by a significant decrease in the expressions of AMPK, pS317-ULK1, beclin-1, ATG7, and LC3 accompanied by a significant elevation in AKT, mTOR, pS757-ULK1, and p62 expressions. On the other hand, OCT at doses of 50 or 75 μg/kg and MLT alone significantly reduced liver enzymes, histopathological changes, oxidative stress, inflammation, apoptosis, pyroptosis, and augmented anti-oxidant along with anti-apoptotic markers compared with the HIR group. Furthermore, liver autophagy was restored by OCT at doses of 50 or 75 μg/kg as indicated by significant elevation of the expressions of AMPK, pS317-ULK1, beclin-1, ATG7, and LC3 accompanied by a significant reduction of AKT, mTOR, pS757-ULK1, and p62 expressions. Additionally, autophagy inhibition with MLT markedly reversed the hepatoprotective effects of OCT75 after HIR injury.
Finally, OCT at dose 75 μg/kg was more effective than MLT and was sufficient to induce protective autophagy in the current HIR model, which led to the downregulation of TLR4/MyD88/NF-κB/NLRP3 inflammasome signaling pathway through induction of Nrf2-dependent AMPK/autophagy pathways.