A low molecular weight, heat-resistant hepatotrophic factor in an extract from the bovine intestinal mucosa was purified and identified as ethanolamine by structural analyses. The mode of action of ethanolamine in vitro and in vivo coincided with that of the crude extract of the tissue, indicating that ethanolamine is the active component. Ethanolamine synergistically elevated the stimulation of DNA synthesis in hepatocytes in primary culture when added together with a growth factor, such as epidermal growth factor, with the ED 50 being 20 M, although it showed little stimulatory effect by itself. Contrary to these in vitro results, the intraperitoneal administration of ethanolamine hydrochloride (24 mg of ethanolamine per kg of body weight) enhanced hepatocyte proliferation in regenerating rat livers after two-thirds hepatectomy without the administration of any growth factors. In the regenerating liver, hepatocyte proliferation may be initiated by an endogenous growth factor, but the supply of ethanolamine in circulation may not be sufficient for optimal hepatocyte proliferation; thus, the exogenous administration of ethanolamine may further enhance hepatocyte proliferation. Ethanolamine in circulation may be a humoral hepatotrophic factor.Previously we reported that the proliferation of hepatocytes in primary culture was synergistically stimulated by a low molecular weight (LMW, Ͻ1,000) and a high molecular weight (HMW, Ͼ10,000) factor that were derived from the bovine small intestine mucosa, separated by their solubility in methanol (1). The LMW factor synergistically enhanced the basal level of stimulation by the HMW factor, while it had little effect when added alone. Since the LMW factor could enhance the level of DNA synthesis in hepatocytes that were stimulated by epidermal growth factor (EGF) or hepatocyte growth factor (HGF), it acts by amplifying the effects of a growth factor. Contrary to the in vitro result, the LMW factor could stimulate hepatocyte proliferation in regenerating livers even when added alone. We speculate that an endogenous growth factor(s) is probably produced in the animals with the regenerating liver, but the supply of the LMW factor is below the optimal level, thus the exogenous supply of the LMW factor can further stimulate hepatocyte proliferation. The LMW factor may function as a humoral hepatotrophic factor for liver regeneration.We purified the LMW factor from the bovine small intestinal mucosa, and we identified it as ethanolamine (Etn). The commercially available Etn had effects identical to those of the LMW factor before purification; i.e., Etn synergistically stimulated the proliferation of hepatocytes in primary culture when added with the HMW factor, and it stimulated hepatocyte proliferation in the regenerating liver when administered alone. Etn can synergistically enhance DNA synthesis in hepatocytes when added with EGF, suggesting that it enhances the actions of hepatotrophic growth factors. Etn in circulation may function as a humoral hepatotrophic factor ...
A factor with a molecular weight of less than 1 kDa in the mucosa of the bovine small intestine (low molecular weight factor or LMW factor) stimulated DNA synthesis in rat hepatocytes in primary culture. This factor only showed its activity when it was added with a larger factor with a molecular weight of 30 kDa that was also found in the same tissue (high molecular weight factor or HMW factor). The LMW factor probably acts to enhance the action of a hepatotrophic growth factor, since EGF and HGF can substitute for the HMW factor. The action of the LMW factor was not due to the actions of low molecular weight substances such as norepinephrine, estradiol, triiodothyronine, and putrescine, which enhance the action of EGF or HGF, since substantial amounts of these substances were not found in the extract. When intraperitoneally administered into rats, after two-thirds hepatectomy, the LMW factor enhanced hepatocyte proliferation without the administration of the HMW factor. In the regenerating liver, a hepatotrophic growth factor(s), which acts synergistically with the LMW factor, might be properly provided, but the supply of the LMW factor might be below the level that maximally stimulates hepatocyte proliferation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.