Interleukin-1 potentiation of beta-endorphin secretion and the dynamics of interleukin-1 internalization in pituitary cells.
1. This study demonstrates that human recombinant interleukin-1 (IL-1) stimulates beta-endorphin release and potentiates the secretion of beta-endorphin in both a mouse anterior pituitary cell line AtT-20 and rat pituitary cell cultures. 2. In pituitary cell cultures, prolonged treatment with phorbol ester had no effect on IL-1-induced beta-endorphin release, but abolished the potentiating effects of IL-1 on vasopressin-induced beta-endorphin secretion. 3. The enhancement of CRF-stimulated beta-endorphin release by IL-1 was also reduced in normal pituitary cell cultures following depletion of protein kinase C. 4. The late IL-1-induced secretion of beta-endorphin does not require the continuous presence of the cytokine. 5. Incubation of monolayers with 125I-IL-1 alpha (10(-9) M) at 8 degrees C and then at 37 degrees C for various times revealed that IL-1 alpha was internalized. There was a progressive increase in the ratio of cytoplasmic to cell-surface-associated 125I-IL-1 alpha. 6. These results indicate that the IL-1-induced beta-endorphin release and its potentiation of beta-endorphin secretion involves internalization of this cytokine, perhaps via cell surface IL-1 receptors.
Fagarasan
M O
MO
Laboratory of Cellular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD.
Arora
P K
PK
Axelrod
J
J
D000818:Animals; D002460:Cell Line; D005260:Female; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011994:Recombinant Proteins / Q000494:pharmacology; D001615:beta-Endorphin / Q000378:metabolism*
D007375:Interleukin-1; D011994:Recombinant Proteins; D001615:beta-Endorphin; D011493:Protein Kinase C