title: Potent mitogenic effects of parathyroid hormone (PTH) on embryonic chick and rabbit chondrocytes. Differential effects of age on growth, proteoglycan, and cyclic AMP responses of chondrocytes to PTH.
abstract: The effect of PTH on chondrocyte proliferation as a function of cartilage age was examined. PTH[1-34] induced a 12- to 15-fold increase in the efficiency of colony formation in soft agar by chondrocytes from embryonic 13- to 19-d-old chickens and fetal 25-d-old rabbits with a 10-fold increase in their DNA content. It also caused a 2.5-fold increase in [3H]thymidine incorporation into DNA in fetal 25-d-old rabbit chondrocytes. No mitogenic responses to PTH were observed, however, in postnatal 7- to 21-d-old chick chondrocytes or postnatal 21-d-old rabbit chondrocytes. This age dependency was observed only with PTH: fibroblast growth factor, epidermal growth factor, and insulin stimulated chondrocyte proliferation irrespective of cartilage age. The absence of a mitogenic effect in postnatal chondrocytes was not due to a decrease in number or a reduction in affinity of receptors for PTH. PTH also increased [35S]sulfate incorporation into proteoglycans and the cyclic AMP level in fetal and postnatal chondrocytes, but at 100-fold higher concentrations (10(-8)-10(-7) M) than those (10(-10)-10(-9) M) required for the stimulation of cell division. These results suggest that PTH is a potent mitogen for embryonic chondrocytes, and that its mitogenic effect disappears selectively after birth.
authors.affiliation: Department of Biochemistry, Faculty of Dentistry, Osaka University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Koike
authors.forename: M
authors.initials: M
authors.lastname: Iwamoto
authors.forename: A
authors.initials: A
authors.lastname: Shimazu
authors.forename: K
authors.initials: K
authors.lastname: Nakashima
authors.forename: F
authors.initials: F
authors.lastname: Suzuki
authors.forename: Y
authors.initials: Y
authors.lastname: Kato
mesh_terms: D000367:Age Factors; D000818:Animals; D002356:Cartilage / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002642:Chick Embryo; D000242:Cyclic AMP / Q000096:biosynthesis*; D004247:DNA / Q000096:biosynthesis; D005333:Fetus / Q000187:drug effects; D010281:Parathyroid Hormone / Q000494:pharmacology*; D011509:Proteoglycans / Q000096:biosynthesis*; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000032:analysis; D018016:Receptors, Parathyroid Hormone
chemical_list: D010281:Parathyroid Hormone; D011509:Proteoglycans; D011956:Receptors, Cell Surface; D018016:Receptors, Parathyroid Hormone; D004247:DNA; D000242:Cyclic AMP