These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Rat hepatocyte insulin-like growth factor I and binding protein: effect of growth hormone in vitro and in vivo.
    Author: Scott CD, Martin JL, Baxter RC.
    Journal: Endocrinology; 1985 Mar; 116(3):1102-7. PubMed ID: 2982573.
    Abstract:
    This study examines the regulation of insulin-like growth factor I (IGF I) and binding protein (BP) release by adult rat hepatocytes in primary culture. Increasing the density of plating of cells had a marked positive effect on the IGF I production rate per mg cell protein, with the highest rate, approximately 4 pmol/mg cell protein X 24 h, seen at densities of 1 X 10(5) cells/cm2 or higher. Cycloheximide (15 micrograms/ml) inhibited both IGF I and BP production by more than 90%, while actinomycin D (0.1 microgram/ml) caused less marked, but still significant, inhibition. Over the insulin range 30 pM-300 nM there was a 45% increase in IGF I production, but no effect on BP production. Bovine GH stimulated production of both peptides, significant effects (up to 50% stimulation) being seen at concentrations from 20-500 ng/ml. Cells from hypophysectomized rats, with serum IGF I and GH levels reduced more than 90% from normal, had IGF I and BP production rates only 7% of normal, measured after 48 h in culture. In vivo replacement with rat GH, 150 micrograms/day for 5 days by osmotic minipump, significantly restored the production of both peptides by hepatocytes. Cells isolated from rats bearing the GH-secreting tumor, MtT/W15, had IGF I and BP production rates approximately twice as high as normal. A significant stimulatory effect of bovine GH (200 ng/ml) in vitro was seen on cells from normal and hypophysectomized, GH-replaced rats, but not from unreplaced hypophysectomized, or tumor-bearing rats. The results in hypophysectomized, animals are consistent with known changes in hepatic GH receptors, while the lack of GH responsiveness in tumor-bearing rats indicates a persistence of maximal stimulation in culture. The reflection of in vivo GH status by hepatocytes cultured for 48 h suggests that messenger RNA turnover for IGF I and BP must be slow. The close parallel in the regulation of the two peptides under most conditions might be indicative of coordinated synthesis.
    [Abstract] [Full Text] [Related] [New Search]