The effect of insulin-like growth factor I on proteoglycan metabolism in immature and adult bovine articular cartilage
Explants of articular cartilage from calf (15 weeks old) and steer (18-24 months old) were cultured for up to 19 days in medium containing either insulin-like growth factor (IGF-I) or 20% fetal bovine serum (FBS). Explants cultured in medium alone were controls. {sup 35}S-proteoglycans (PGs) synthesized on day 7 of culture during a 5-hour pulse with {sup 35}S-sulfate were isolated, quantified and characterized. Lower concentrations of IGF-I were required for maximal stimulation of PG synthesis in calf than in steer (10 vs 20 ng/ml). In calf, IGF-I was as effective as 20% FABS in stimulating PG synthesis. In steer, PG synthesis in the presence of IGF-I reached its maximum at a rate that was half that obtained with 20% FBS. The stimulation by IGF-I or FBS was not accompanied at either age by alterations in the size and composition of the aggregating PGs nor by changes in the relative proportions of the CS-rich and CS-poor PG subpopulations. Importantly, the newly synthesized calf and steer PGs retained marked age-related differences in composition regardless of the culture conditions. The effects of exogenously added IGF-I and FBS on the rate of turnover of cartilage PGs was also studied. In calf, IGF-I and FBS did not significantly alter the rate of turnover of either the {sup 35}S-PGs synthesized in vitro or of the unlabeled PGs representing mostly molecules synthesize and organized into the matrix in vivo. In steer, explants cultured in the absence of IGF-I or FBS exhibited very fast rates of turnover which resulted in severe depletion of matrix PG with time. Importantly, IGF-I and FBS were equally effective in reducing the turnover rate of {sup 35}S-PGs and unlabeled PGs and in preventing PG depletion. These results demonstrate age-related differences in the effect of IGF-I on PG synthesis by articular chondrocytes.
- Research Organization:
- Rush Univ., Chicago, IL (USA). Graduate Coll. of Nursing
- OSTI ID:
- 5526811
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Stimulation of DNA synthesis by ascorbate in cultures of articular chondrocytes
Decreased synthesis of extracellular matrix components by chondrocytes cultured in scorbutic guinea pig serum plus vitamin C
Related Subjects
GLYCOPROTEINS
METABOLISM
GROWTH FACTORS
BIOCHEMICAL REACTION KINETICS
AGE DEPENDENCE
CARTILAGE
CATTLE
CHEMICAL COMPOSITION
INSULIN
SULFUR 35
TRACER TECHNIQUES
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CONNECTIVE TISSUE
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
EVEN-ODD NUCLEI
HORMONES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAMMALS
MITOGENS
NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RUMINANTS
SULFUR ISOTOPES
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques
550501 - Metabolism- Tracer Techniques