Abstract:
:To study the effects of glucocorticoids and IGF-I on the modulation of growth in the tilapia Oreochromis mossambicus, we employed an epiceratobranchial cartilage radioisotope incorporation assay, wherein radiolabeled sulfate and thymidine uptakes are measured in vitro to indicate proteoglycan synthesis and cell proliferation, respectively. Cartilage explants were cultured with cortisol or dexamethasone with or without recombinant bovine insulin-like growth factor-I. Cortisol directly inhibited sulfate uptake at 100 and 1000 ng/mL concentrations in a concentration-dependent manner but inhibited thymidine uptake significantly only at the 1000 ng/mL concentration. Dexamethasone inhibited sulfate and thymidine uptake at concentrations similar to the effective concentrations of cortisol. Cortisol did not inhibit IGF-I stimulation of sulfate uptake at any of the concentrations tested. Furthermore, cortisol did not inhibit thymidine uptake when IGF-I was present in the medium. Cortisol appears to act directly on cartilage and not by interacting with the IGF-I system. However, the physiologically significant role of cortisol is mainly an inhibitory one on cartilage metabolism. The data generally indicate an inhibitory role for glucocorticoids on cartilage growth but an inability to counter the stimulation of sulfate uptake by IGF-I.
journal_name
Gen Comp Endocrinoljournal_title
General and comparative endocrinologyauthors
Datuin JP,Ng KP,Hayes TB,Bern HAdoi
10.1006/gcen.2000.7599keywords:
subject
Has Abstractpub_date
2001-03-01 00:00:00pages
289-94issue
3eissn
0016-6480issn
1095-6840pii
S0016-6480(00)97599-3journal_volume
121pub_type
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journal_title:General and comparative endocrinology
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journal_title:General and comparative endocrinology
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