Effects of rat growth hormone (rGH)-releasing factor and somatostatin on the release and synthesis of rGH in dispersed pituitary cells

Journal Article · Thu Aug 01 00:00:00 EDT 1985 · Endocrinology; (United States)

DOI:https://doi.org/10.1210/endo-117-2-457· OSTI ID:6181175

Fukata, J; Diamond, D J; Martin, J B

The effects of rat hypothalamic GH-releasing factor (GRF) and somatostatin (SRIF) on the release and biosynthesis of rat GH were studied by RIA and quantitative immunoprecipitation using monolayer cultures of rat anterior pituitary cells. In kinetic studies, GRF stimulation of GH release appeared at the first sampling time (20-min incubation) and the effect began to diminish after 2-h incubation with GRF. On the other hand, total (cell plus medium) content of GH significantly increased only after 24-h incubation. To examine the GH-synthesizing effect of GRF more directly, newly synthesized GH labeled by (TVS)methionine during incubation with GRF was quantified by immunoprecipitation. The amount of immunoprecipitable GH increased significantly and specifically also only after 24-h incubation. When GH pools were labeled with (TVS)methionine under different schedules, the basal release of newly synthesized GH, which was labeled for 1 h immediately before chase incubation was lower during the first 15 min than stored GH which had been labeled earlier. Basal newly synthesized GH secretion exceeded stored GH secretion after 30 min. In this system, SRIF suppressed both the basal and stimulated release of GH but did not modify GH biosynthesis under either condition. Newly synthesized GH showed significant degradation during 24-h incubation; neither GRF nor SRIF affected the rate of GH degradation during the same incubation period.

• Research Organization: Massachusetts General Hospital, Boston
• OSTI ID: 6181175
• Journal Information: Endocrinology; (United States), Vol. 2
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
LIBERINS
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IODINE ISOTOPES
METHIONINE
PITUITARY GLAND
RATS
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ANIMALS
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ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
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ORGANS
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