Protection of regenerating liver after partial hepatectomy from carbon tetrachloride hepatotoxicity in rats: role of hepatic stimulator substance.
BACKGROUND
In the present study, we examined the effect of hepatic stimulator substance (HSS) on modulating hepatotoxicity induced by carbon tetrachloride (CCl4) in the regenerating rat liver.


METHODS
Hepatotoxicity was induced in vivo by administering CCl4 to rats that had undergone a 68% partial hepatectomy (PH). In vitro studies were also performed in hepatocytes isolated from PH rats.


RESULTS
Hepatic stimulator substance was extracted from regenerating rat liver 96 h after PH and its activity, as determined according to the method of LaBrecque, reached its maximum 96 h after PH. At this time, the mortality induced by CCl4 was significantly decreased in PH rats compared with sham-operated rats (18 vs 59%, P < 0.01). Likewise, changes in serum alanine aminotransferase (ALT) or bilirubin induced by CCl4 were less in rats after 96 h PH. The resistance of regenerating hepatocytes to CCl4 was retained in in vitro samples. Thus, leakage of intracellular ALT or aspartate aminotransferase induced by CCl4 in hepatocytes from 96 h hepatectomised rats was less than in control hepatocytes. HSS demonstrated a protective effect on hepatocytes against CCl4 both in vivo and in vitro. In additional studies, regenerating liver showed increased mitochondrial respiratory activity and enhanced plasma membrane fluidity. The HSS was also shown to increase hepatic mitochondrial respiratory activity and enhance plasma membrane fluidity. Further, the protective effect induced by HSS was correlated with the restoration of mitochondrial respiratory activity and plasma membrane fluidity induced by CCl4.


CONCLUSIONS
Regenerating rat liver exhibits resistance to CCl4-induced hepatotoxicity, and the protection afforded by the regenerating state can be attributed, at least in part, to HSS-induced increases in mitochondrial respiratory activity and plasma membrane fluidity.
Zhang
B H
BH
Department of Medicine, The University of Sydney at Westmead Hospital, New South Wales, Australia. zhangb@westmed.wh.usyd.edu.au
Gong
D Z
DZ
Mei
M H
MH
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001663:Bilirubin / Q000097:blood; D002251:Carbon Tetrachloride / Q000037:antagonists & inhibitors / Q000633:toxicity*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D019069:Cell Respiration / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005454:Fluorescence Polarization; D006133:Growth Substances / Q000494:pharmacology / Q000502:physiology*; D006498:Hepatectomy; D036341:Intercellular Signaling Peptides and Proteins; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008115:Liver Regeneration / Q000187:drug effects*; D008297:Male; D008560:Membrane Fluidity / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014783:Viscosity / Q000187:drug effects
D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; C073456:hepatic stimulator substance; D002251:Carbon Tetrachloride; D000410:Alanine Transaminase; D001663:Bilirubin