Autocrine-paracrine inhibition of growth hormone and prolactin production by GH3 cell-conditioned medium |
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Authors: | C A Lapp J M Tyler Y S Lee M E Stachura |
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Institution: | (1) Department of Medicine, Medical College of Georgia, 30910 Augusta, Georgia;(2) Endocrine Section (111B), VA Medical Center, 30910 Augusta, Georgia |
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Abstract: | Summary In previous work we have shown that perifused GH3 cells exhibit spontaneously accelerating growth hormone (GH) and prolactin (PRL) secretory rates. This behavior contrasts
with GH and PRL secretion rates that are decreasing or stable over the same 3-d period in static cell culture. We now report
that GH3 cells maintained in serum-supplemented medium produce an autocrine-paracrine factor(s) which inhibits GH secretion in plate
culture; PRL release is frequently reduced as well. The inhibitory effect of conditioned medium on GH secretion was concentration
dependent, whereas PRL release was stimulated at low and inhibited at high concentrations over the same range. Extensive dialysis
of conditioned medium using membranes with a molecular weight cut-off of 12 000–14 000 did not remove GH inhibition but produced
a retentate that stimulated PRL secretion. Heat-inactivation of conditioned medium did not abolish inhibition of GH release
but did remove the PRL-stimulatory effect. IGF-I added to fresh culture medium did not reproduce the GH-inhibitory effects
of conditioned medium. We conclude that GH3 cell secretory behavior in perifusion and plate culture systems may be partially explained by the production of an autocrine-paracrine
factor: its accumulation in plate culture inhibits GH and PRL secretion whereas its removal, by perifusing medium, allows
GH and PRL secretion to accelerate.
Supported by grant DK33388 to M. E. S. from the National Institute of Health, Bethesda, MD, and in part by the Medical Research
Service of the Veterans Administration, Washington, DC. |
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Keywords: | growth hormone (GH) prolactin (PRL) autocrine paracrine perifusion conditioned medium GH3 cells |
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