Fatty acid synthesis in the regenerating liver of the rat

Abstract

1. Synthesis de novo of fatty acids in the rat liver, measured per g wet wt. of tissue, was increased by a factor of about two, between 1 and 4 days after partial hepatectomy, compared with rates in sham-operated control rat livers. 2. There were no associated changes in the rates ofliver cholesterol synthesis or of adipose-tissue fatty acid synthesis in rats after partial hepatectomy, compared with rates in sham-operated rats. 3. In regenerating livers, perfused under three different conditions, there was no alteration in the capacity for fatty acid synthesis compared with that of control rats. 4. The increased synthesis of fatty acids in regenerating liver was associated with insignificant increases in plasma concentrations oftriacylglycerols and free fatty acids, with a decrease in content of liver glycogen, and with no change in hepatic activity of acetyl-CoA carboxylase. 5. The accelerated rate ofsynthesis offatty acids in regenerating liver appears not to be due to any intrinsic alteration in hepatic capacity for fatty acid synthesis, but it may be caused by the continuous action on liver of unidentified circulating factors.

Hyperactivation of anandamide synthesis and regulation of cell-cycle progression via cannabinoid type 1 (CB 1 ) receptors in the regenerating liver

“…These proteins include the transcription factor forkhead box protein M1 (FoxM1) and its targets cyclin B2 (Ccnb2) (15) and cyclin-dependent kinase 1 (CDK1), with additional proteins involved in DNA replication and centrosome organization, including kinesin-like 1 (Knsl1) (16), proliferating nuclear cell antigen (PCNA) (17), and Rad21 (18). In addition, the lipogenic transcription factor sterol regularity element-binding protein 1c (SREBP-1c) showed the same pattern of activation, in agreement with evidence that its hepatic expression is regulated by CB 1 R (5) and that lipogenesis is increased in the regenerating liver (8)(9)(10). These targets were validated at the mRNA and protein levels by real-time PCR and Western blotting, respectively (Figs.…”

“…CB 1 R and endocannabinoids also are present in the liver (5) where they promote de novo lipogenesis (5-7), a process also activated during regeneration (8)(9)(10). The ability of endocannabinoids to promote cell proliferation and to stimulate hepatic lipogenesis suggests that they may contribute to the early stages of the regenerative response of the liver.…”

Evidence that CTP:choline‐phosphate cytidylyltransferase is regulated at a pretranslational level in rat liver after partial hepatectomy

“…The animals, which had free access to water and pelleted standard diet in both pre-and post-surgical periods, had been kept under an inverted lighddark cycle (dark between 06.00 and 18.00 h) for at least two weeks. In accordance with observations by Gove and Hems [23], feed intake of sham-operated and partially hepatectomized rats was approximately the same.…”

Ketone-body metabolism after surgical stress or partial hepatectomy. Evidence for decreased ketogenesis and a site of control distal to carnitine palmitoyltransferase I

“…Rates of lipogenesis [4] and esterification [5] are increased, suggesting possible restriction of ketogenesis by mitochondrial substrate supply. These changes, possibly accompanied by increased oxidation of acetyl-CoA to CO2 [3,6], may be responsible for the decreased ketone-body concentrations.…”

“…Rats were then subjected to functional hepatectomy (by isolating the liver from the general circulation) as described in [11]. The decrease in blood ketone bodies after functional hepatectomy was monitored from 4 to 30 min, with sampling from the vena cava at 4, 7.5, 15 and 30 min. Rates of ketone-body disappearance were linear for the first 7.5 min after functional hepatectomy (see below).…”