Effects of the triterpenoids oleanolic acid and ursolic acid in rat F344 submitted to the resistant hepatocyte model of hepatocarcinogenesis

Author(s)

Rogério Pietro Mazzantini

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2005-09-27

Examining board members

Fernando Salvador Moreno; Silvia Berlanga de Moraes Barros; Maria Lucia Zaidan Dagli; Sergio Britto Garcia; Helio Vannucchi

• Advisor: Fernando Salvador Moreno

Abstract

It was evaluated the effects of the oleanólico acid (OA) and ursolic acid (UA), triterpenoids present in vegetable foods and spices, when administered to rat F344 during the initiation and selection/promotion stages of the resistant hepatocyte model of hepatocarcinogenesis RH. The rat received for 8 weeks, by gavage and dissolved in com oil (CO): OA or UA (8 mg/100 g of body weight [b.w.]). The control groups just received CO (0,25 mL/100 g b.w.; CO group), or water (0,25 mL/100 g b.w.; group Water). Normal group did not receive any treatment type. The initiation agent was dietilnitrosamine (DEN, 20 mg/100 g b.w.). 2 weeks after gavage, it was applied 3 consecutive doses of 2-acetilaminofluoreno (2-AAF) (2 mg/100 g of b.w.) and it was made a 70% partial hepatectomy, added of 1 dose of 2-AAF (0,5 mg/100 9 b.w.) 4 days after the surgery. In 6 weeks after the initiation, the animals were sacrificed. Results: the macroscopic analysis demonstrated that OA did not alter and UA tended to increase the number of hepatocytes nodules, compared to the CO group. The morphometric analysis of the pre-neoplastic lesions (PNL) positive for glutatione S-transferase placentary form (GST-p), demonstrated that OA and UA did not alter the medium number of persistent LPN, however they reduced the medium number of remodeling LPN, compared to the OM group (p <0,05). OA and UA did not alter the medium area of persistent LPN, but they reduced the medium area of remodeling LPN, compared to the CO group (p <0,05). The triterpenoids did not alter the occupied area of the section for persistent LPN, but they reduced the occupied area cut for remodeling LPN, compared to the CO group (p <0,05). The Water, OM and AU groups showed increase in the plasmatic concentration of cholesterol, compared to the Normal group. OA promoted increase of the expression of the gene that codifies for the HMG-CoA reductase enzyme, compared to the Normal group (p <0,05), and AU promoted increase expression when compared to the Normal, Water, OM and AU groups (p <0,05). OA and UA did not alter the indexes of cellular proliferation (imunoistochemistry for bromodeoxiuridine [BrdU)) in persistent LPN. AU promoted increase (p <0,05) in the cellular proliferation in remodeling LPN when compared to the CO group. OA and UA did not alter the apoptosis in persistent LPN, but they increased the medium number of apoptotics bodies in remodeling LPN (p <0,05). The Adjusted Index Growth (cellular apoptosis/proliferation) of the groups demonstrated that, in persistent LPN, the cellular proliferation has predominance on the apoptosis. In remodeling LPN, the apoptosis has preponderance over the cellular proliferation. The damages in hepatic DNA (method of the \"comet\") were larger in the group OA (p <0,05) and AU (p <0,061), compared to the CO group. The analysis for imunoblot revealed that the RH model increased the expression and the activation of the NF-&#954;B transcription factor (p <0,05). OA and UA increased the expression and the activation of NF-&#954;B, compared to the CO group (p> 0,05). It was observed that the p53 tumor suppresser protein is accumulated in the hepatocytes cytoplasm of 77,2% (Water), 66,5% (CO), 69,6% (OA) and 69,7% (UA) of persistent LPN, and of 22,8% (Water), 33,5% (CO), 30,4% (OA) and 30,3% (UA) of remodeling LPN marked for p53. The bcl-2 anti-apoptotic protein presented increase expression in 78,4% (Water), 72,6% (CO), 73,0% (OA) and 70,4% (UA) of persistent LPN, and of 21,6% (Water), 27,4% (CO), 27,0% (OA) and 29,6% (UA) of remodeling LPN marked for bcl-2. Conclusions: AO and AU did not present chemopreventive activity in the study conditions, but they reduced remodeling PNL. The apoptosis increase and cellular proliferation decrease are involved with the remodeling. The transcription factor NF-&#954;B is involved with the hepatocarcinogenesis. AO and AU increased the expression and the activation of NF-&#954;B. The p53 accumulation in the cytoplasm, as well as the increased expression of bcl-2 is related to the phenotype of persistent PNL. (AU)