retrorsine and Necrosis

Astaxanthin (Asta), a xanthophyll carotenoid, has been reported to be a strong antioxidative agent and has anti-inflammatory, antitumor and free radical-scavenging activities. However, inadequate stability and water solubility results in its low bioavailability. This study incorporated Asta into hydrophilic hyaluronan nanoparticles (HAn) to produce Asta-HAn aggregates (AHAna) using an electrostatic field system and investigated the restorative effects of AHAna on retrorsine-CCl₄-induced liver fibrosis in rats in vivo. Transmission electron microscopy (TEM) revealed that the prepared HAn were approximately 15 ± 2.1 nm in diameter and after the incorporation of Asta into HAn, the size increased to 210-500 nm. The incorporation efficiency of Asta was approximately 93% and approximately 54% of Asta was released after incubation for 18 h. Significant reductions in alanine aminotransferase and aspartate aminotransferase levels were observed after the rats were intraperitoneally injected with AHAna. Histopathological findings revealed the greatest reduction in hepatic fibrosis and hepatocyte necrosis in the rats after 2 weeks of intraperitoneal injection with AHAna, which is consistent with the data acquired from serum biochemical analysis. The restorative effects on liver damage displayed by AHAna in vivo demonstrated that Asta aggregated through HAn incorporation exerts therapeutic effects on liver fibrosis and necrosis.

Topics: Animals; Carbon Tetrachloride; Hyaluronic Acid; Liver Cirrhosis; Liver Diseases; Male; Necrosis; Pyrrolizidine Alkaloids; Rats; Xanthophylls

Liver regeneration after partial hepatectomy (PH) in rats exposed to the pyrrolizidine alkaloid retrorsine is accomplished through the proliferation and differentiation of a population of small hepatocyte-like progenitor cells (SHPCs). The activation, emergence, and outgrowth of SHPCs in response to the liver deficit generated through surgical PH have been well characterized. However, the participation of these cells in the restoration of hepatocyte numbers and regeneration of liver tissue mass following necrotic injury has not been investigated. To investigate the capacity of SHPCs to respond to necrotizing liver injury, we combined retrorsine treatment with the centrilobular-specific toxin carbon tetrachloride (CCl(4)). Male Fischer 344 rats were treated with retrorsine (30 mg/kg ip) at 6 and 8 weeks of age, followed by CCl(4) treatment (1500 mg/kg ip) 5 weeks later. Liver tissues were harvested at 3, 7, 14, 21, and 30-days post-injection. The dose of CCl(4) employed resulted in the necrotic destruction of 59±2% of liver mass and elicited a regenerative response equivalent to that of surgical PH. Livers from retrorsine-exposed CCl(4)-treated rats exhibit SHPC proliferation similar to retrorsine-exposed rats subjected to PH (RP). SHPCs appear at 3-days post-injection, continue to expand at 7-days and 14-days post-injection, and completely regenerate/restore the liver mass and structure in these animals by 30-days post-injection. The magnitude of SHPC response observed in the undamaged periportal zone of the liver in these animals is unaffected (versus RP rats) by the loss of the centrilobular region. The results of this study show that SHPCs are capable of regenerating liver after exposure to necrotizing agents and suggest that the progenitor cell of origin of the SHPCs is not restricted to the centrilobular zone of the liver parenchyma.

Topics: Animals; Carbon Tetrachloride; Chemical and Drug Induced Liver Injury; Hepatectomy; Hepatocytes; Liver Regeneration; Male; Necrosis; Pyrrolizidine Alkaloids; Random Allocation; Rats; Rats, Inbred F344; Stem Cells

To study the effect of retrorsine on mouse hepatocyte proliferation.. Mice and rats were treated respectively with two injections of retrorsine (as retrosine-treated group) or saline (as non-treated group) at 2 wk intervals. They received a single injection of carbon tetrachloride (CCl4) 4 wk later. On d 0, 1, 2, 3, 4, 6, 15 after CCl4 administration, the animals were killed and their livers were excised. Hematoxylin and eosin (HE) staining and Ki-67 antibody immunohistochemical analysis of liver samples were used to evaluate the pathological changes and hepatocyte proliferation.. In rats treated with retrorsine and CCl4, the liver displayed obvious megalocytosis, proliferation of mild bile duct,small hepatocyte-forming nodule, which were not found in liver samples from non-treated group. However,in mice treated with retrorsine combined with CCl4, the liver displayed hepatocyte degeneration and necrosis in perivenous areas.There was no obvious difference between retrorsine-treated group and non-treated group. Ki-67 immunohistochemical analysis showed that in rats treated with retrorsine, the positive hepatocytes mainly found in small hepatocyte nodules, were obviously less than those in non-treated group. The mice treated with retrorsine showed that the number of Ki-67 positive hepatocytes was very high and more than that in non-treated group.. Retrorsine has no effect on mouse hepatocyte proliferation.

Topics: Animals; Carbon Tetrachloride; Cell Proliferation; Hepatocytes; Immunohistochemistry; Ki-67 Antigen; Liver; Male; Mice; Mice, Inbred C57BL; Necrosis; Pyrrolizidine Alkaloids; Random Allocation