Selective enhancement of lipid peroxidation in plasma membrane in two experimental models of liver regeneration: Partial hepatectomy and acute CCl₄administration

Abstract

with the rate of mitosis in several tissues, which has been It has been proposed that lipid peroxidation (LP) supported by the decreased LP found in subcellular fractions might be a modulator of cell division, influencing initiaof liver tumor cells. [2][3][4] However, some discrepancies have been tion and cessation of mitosis in regenerating liver. Howraised concerning the LP status during the characteristic acever, the understanding of the participating role of this tive cell proliferation following partial hepatectomy (PH). Acevent in the onset of liver proliferation has been hamtually, it was reported that both nicotinamide-adenine dinupered by the fact that both higher or lower LP have been cleotide phosphate-and tert-butyl hydroperoxide-induced reported after two-thirds partial hepatectomy (PH).LP were diminished after PH. [5][6][7] However, other research Therefore, the present study deals with the extent of LP groups have found an early increase of LP in homogenates in the main subcellular fractions from rat liver at early of regenerating liver. 8,9 Moreover, a transient enhancement stages of regeneration, induced by either PH of 70% or of mitochondrial LP has been reported to occur in preparaacute CCl 4 administration. Our results, using several tions obtained from hepatectomized rats. 10 methods to monitor LP, indicate a differential effect inThe present study was aimed at providing additional data the peroxidative pattern of specific subcellular fractions to settle the controversy about LP status during liver regenerfrom regenerating liver after 24 hours of PH: a decrease ation. We used two models to induce liver cell proliferation: in microsomes and an increase confined to plasma memtwo-thirds hepatectomy and acute intoxication with CCl 4 ; brane and cytosolic fractions, peaking after 24 hours of assessing LP by three different methods. The results show PH. In CCl 4 -treated rats, higher LP was also noted in that, in both models, an increased amount of LP activity is plasma membrane and cytosol, being maximal at the confined to the plasma membrane and cytosolic fractions, replicative stage in this experimental model (48 hours).whereas microsomes had a lower LP rate only in PH rats. In addition, increased LP was found in microsomal andThe changes in LP pattern, associated to liver regeneration, nuclear fractions, declining before the 48 hours. In hepashowed an organ specificity and correlated with the magnitectomized rats, changes in LP seem to be an organ-spetude of the loss of hepatic mass. The overall data suggest that cific event and related to only PHs capable of triggering controlled peroxidative modifications of membranes could be a synchronized proliferative response, namely above playing a role in the early steps of liver regeneration. fed ad libitum, and maintained under a 12-hour light/dark period. Surgical procedures were performed between 9 and 10 AM. Shamoperated animals were laparotomized under ether anesthesia to proThe liver is capable of recovering from damage or loss up vide a cont...

Effects of Bicyclol on Liver Regeneration After Partial Hepatectomy in Rats

“…It has been found that LP began to occur in a very early phase in regenerating liver [32,33]. Actually, some discrepancies still exist concerning the role of LP during typical cell proliferation following PH [34]. It has been reported that diminished LP contributes to cell division after PH [35, Bicyclol (300 mg/kg) was administrated three times before operation.…”

The response of liver lipid peroxidative and antioxidant defense systems of protein undernourished rats to liver regeneration

“…Variable levels of LP in the various subcellular fractions have also been reported (19). For example, there is decreased lipid peroxidation in microsomes and increase in the plasma membrane and cytosolic fractions of normal (well-fed) rats following Partial hepactectomy (19).…”

“…For example, there is decreased lipid peroxidation in microsomes and increase in the plasma membrane and cytosolic fractions of normal (well-fed) rats following Partial hepactectomy (19). There are, however, little or no reports in the literature concerning changes in the levels …”

Effect of retinoic acid on transglutaminase and ornithine decarboxylase activities during liver regeneration

“…On the other hand, it is reported that PUT promotes DNA synthesis in regenerating liver after PH through the suppression of lipid peroxidation in subcellular fractions. 34 The lipid peroxidation is found at early stages of regeneration after PH, and inversely correlates with the rate of DNA synthesis. [34][35][36] Therefore, Gln-PUT increase after PH may also be involved in the regulation of DNA synthesis.…”

“…34 The lipid peroxidation is found at early stages of regeneration after PH, and inversely correlates with the rate of DNA synthesis. [34][35][36] Therefore, Gln-PUT increase after PH may also be involved in the regulation of DNA synthesis. Shortly after PH, the EGF plasma level becomes elevated two to three-fold, 37 therefore, the activation of EGF receptors is likely to be involved in G1 phase progression during liver regenerative growth.…”