Liver regrowth and apolipoprotein B secretion by rat hepatocytes following partial hepatectomy.
Apolipoprotein (apo) B is an essential component for the assembly and secretion of lipoproteins. The current report examines apo B production using primary cultures of hepatocytes derived from rats 3 to 21 days after partial hepatectomy (PH) to determine the effects of liver regrowth on apo B. Studies indicate that hepatocytes stimulated by PH have a two-thirds reduction in net apo B production 3 to 7 days after surgery, which coincides with the period of maximum rate of liver regrowth. Both higher (apo BH)- and lower-molecular-weight (apo BL) apo B are synthesized and secreted after PH, indicating the presence of edited apo B mRNA in hepatocytes. Hepatocytes derived from PH rats are more sensitive to insulin inhibition of apo B secretion compared with controls, suggesting an enhanced effect of insulin on newly replicated hepatocytes. Epidermal growth factor (EGF), a key regulator of liver regrowth following PH, potentiates the inhibitory action of insulin on apo B secretion in control hepatocytes and those derived from rats 2 to 3 weeks after PH. However, the potentiating effect of EGF on insulin inhibition of apo B is not discernible in hepatocytes 3 to 7 days after PH. The short-term in vitro hormonal effects occurring even with decreased apo B production suggest that this pathway remains available following PH to balance lipoprotein secretion with lipid and energy requirements necessary for liver regeneration.
Sparks
J D
JD
Department of Pathology, University of Rochester School of Medicine and Dentistry, NY.
Corsetti
J P
JP
Sparks
C E
CE
D000818:Animals; D001053:Apolipoproteins / Q000032:analysis; D001055:Apolipoproteins B / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D001786:Blood Glucose / Q000032:analysis; D001798:Blood Proteins / Q000032:analysis; D003470:Culture Media / Q000737:chemistry; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006498:Hepatectomy; D007328:Insulin / Q000097:blood / Q000494:pharmacology; D008074:Lipoproteins / Q000097:blood; D008099:Liver / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D008115:Liver Regeneration / Q000502:physiology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012709:Serum Albumin / Q000032:analysis; D013963:Thyroid Hormones / Q000097:blood; D013997:Time Factors
D001053:Apolipoproteins; D001055:Apolipoproteins B; D001786:Blood Glucose; D001798:Blood Proteins; D003470:Culture Media; D007328:Insulin; D008074:Lipoproteins; D012709:Serum Albumin; D013963:Thyroid Hormones; D004815:Epidermal Growth Factor