Neurointermediate pituitary lobe cells synthesize and release interleukin-6 in vitro

Effects of lipopolysaccharide and interleukin-1β

Bryan L. Spangelo, P. Douglas Deholl, L. Kalabay, Brian R. Bond, Philippe Arnaud

Research output: Contribution to journalArticle

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Abstract

The cytokine interleukin-6 (IL-6) is produced by a variety of cells, including macrophages, T-cells, and B-cells. Recent studies have confirmed a neuroendocrine role for IL-6 in the regulation of anterior pituitary (AP) hormone release. Because the neurointermediate pituitary lobe (NIL) may modulate AP hormone release, we investigated the production of IL-6 by NIL cells in vitro. NIL tissue removed from pituitary glands of male Long-Evans rats was enzymatically and mechanically dispersed, and the cells were subsequently cultured in 96-well tissue culture plates for 4-6 days in 10% serum-containing RPMI-1640. Test incubations were performed in serum-free RPMI-1640, and IL-6 concentrations were determined using the 7TD1 cell bioassay. Preliminary studies revealed a cell-dependent release of IL-6: increasing the number of NIL cells per well from 6.25 to 50 ∓ 103 revealed detectable basal release of IL-6 between 25-50 × 103 cells/well. The endotoxin lipopolysaccharide (LPS; 100 ng/ml) and IL-1β (100 ng/ml) stimulated IL-6 release at 25 and 50 × 103 cells/well. Subsequent studies used a cell density of 50 × 103 cells/well and demonstrated time-dependent 3- to 6-fold inductions of IL-6 release by 100 ng/ml IL-1β and LPS. Concentration-response studies revealed maximal stimulation of IL-6 release by 1 ng/ml and a minimally effective concentration of 1 pg/ml for both IL-1β and LPS. Treatment of NIL cells with 1-10 mM (Bu)2CAMP increased IL-6 release by 7- to 14-fold. Endotoxin and IL-1β also enhanced the accumulation of IL-6 messenger RNA in these cells. Vasopressin and oxytocin (1 μM) inhibited LPS and IL-1β stimulation of IL-6 release from NIL cells, but did not inhibit IL-6 release from AP cells. Immunofluorescent dual labeling of NIL cells for flow cytometry revealed that greater than 95% of the cells did not stain for CD11b/c (common epitope found on monocytes, granulocytes, and macrophages) or CD45 (leukocyte common antigen). These results demonstrate for the first time the synthesis and release of IL-6 from cultured NIL cells. Agents that enhance IL-6 release [LPS, IL-1β, and (Bu)2cAMP] from other cell types also increase IL-6 release from NIL cells. Vasopressin and oxytocin inhibition of IL-6 release suggests a role for these neuropeptides in feedback inhibition in vivo. Finally, the release of IL-6 is unlikely to be due to leukocytes in the NIL cultures, but is probably caused by either pituicytes (modified astroglial cells in the neural lobe) or melanotrophs of the intermediate lobe.

Original languageEnglish
Pages (from-to)556-563
Number of pages8
JournalEndocrinology
Volume135
Issue number2
Publication statusPublished - Aug 1994

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Interleukin-1
Lipopolysaccharides
Interleukin-6
Anterior Pituitary Hormones
In Vitro Techniques
Oxytocin
Vasopressins
Endotoxins
Melanotrophs
Macrophages
CD45 Antigens
Posterior Pituitary Gland
Long Evans Rats
Pituitary Gland
Neuropeptides
Serum
Granulocytes
Biological Assay

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Neurointermediate pituitary lobe cells synthesize and release interleukin-6 in vitro : Effects of lipopolysaccharide and interleukin-1β. / Spangelo, Bryan L.; Deholl, P. Douglas; Kalabay, L.; Bond, Brian R.; Arnaud, Philippe.

In: Endocrinology, Vol. 135, No. 2, 08.1994, p. 556-563.

Research output: Contribution to journalArticle

Spangelo, Bryan L. ; Deholl, P. Douglas ; Kalabay, L. ; Bond, Brian R. ; Arnaud, Philippe. / Neurointermediate pituitary lobe cells synthesize and release interleukin-6 in vitro : Effects of lipopolysaccharide and interleukin-1β. In: Endocrinology. 1994 ; Vol. 135, No. 2. pp. 556-563.
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