Basic fibroblast growth factor (basic FGF) in isolated ovine thyroid follicles: thyrotropin stimulation and effects of basic FGF on DNA synthesis, iodine uptake and organification, and the release of insulin-like growth factors (IGFs) and IGF-binding proteins.
Hill. D J DJ; Phillips. I D ID; Wang. J F JF; Becks. G P GP
Key Findings
- TSH (10‑50 µU/mL) increased basic FGF mRNA levels 2‑3‑fold in cultured ovine thyroid follicles.
- Basic FGF protein rose in both the cytoplasm and extracellular matrix after TSH exposure, with significant increases at 50‑100 µU/mL.
- Higher TSH concentrations (250 µU/mL) were less effective at boosting basic FGF levels.
Practical Outcomes
- The findings are of interest to thyroid cell researchers but offer no actionable guidance for GHK‑Cu supplementation, longevity, or performance optimization. Biohackers looking for practical protocols should consider this study irrelevant to their goals.
Summary
This study looked at how thyroid‑stimulating hormone (TSH) makes thyroid cells in sheep produce more of a protein called basic fibroblast growth factor (FGF). It found that moderate levels of TSH raise the amount of basic FGF mRNA and protein inside the cells and in the surrounding matrix, but very high TSH levels are less effective. The work is purely basic science about thyroid cell biology and does not involve the peptide GHK‑Cu or suggest any practical health protocol.
Abstract
We examined the effects of thyroid-stimulating hormone (TSH) on basic fibroblast growth factor (basic FGF) expression in isolated ovine thyroid follicles in vitro, and the effects of exogenous basic FGF on thyroid growth and function, to elucidate the significance of increased basic FGF expression during TSH-induced rat thyroid hyperplasia in vivo. Primary cultures of ovine thyroid follicles were maintained in serum-free Ham's modified F-12M medium containing transferrin, somatostatin, and glycyl-histidyl-lysine (designated 3H) with or without basic FGF alone, or in combination with TSH (100 microU/mL) and cortisol (10 nM). Following 48 h incubation, cells were harvested and total RNA prepared for the detection of basic FGF mRNA using Northern blot analysis and ribonuclease protection assay. Basic FGF in the cytoplasm and extracellular matrix fractions was quantified by radioimmunoassay. Basic FGF mRNA transcripts of 3.7, 3.0, and 2.2 kb, respectively, were found in thyroid follicles cultured in 3H medium, and the abundance of each increased between 2- and 3-fold following incubation with 10-50 microU/mL TSH, although higher concentrations of TSH were less effective. Similar results were seen using a more sensitive ribonuclease protection assay. Cells cultured in control, 3H medium contained 2.4 +/- 0.5 fmol immunoreactive basic FGF/micrograms cell DNA within the cytoplasm and 21.1 +/- 1.5 fmol/micrograms DNA within the extracellular matrix (mean +/- SD, n = 6). A significant increase (p < 0.05) in basic FGF content was seen in both cell compartments following incubation with 50 or 100 microU/mL TSH, while 250 microU/mL was less effective.(ABSTRACT TRUNCATED AT 250 WORDS)
Study Information
pubmed
1994
10.1089/thy.1994.4.77