Effects of Interleukin-1-Beta, Interleukin-6 and Tumor Necrosis Factor-Alpha, Alone or in Association with Hexarelin or Galanin, on Growth Hormone Gene Expression and Growth Hormone Release from Pig Pituitary Cells

Abstract

Objective: We studied the effects of IL-1β, IL-6 and TNF-α on GH gene expression and secretion with or without galanin and hexarelin. Methods: Pituitary cells from adult pigs were treated with IL-1β, IL-6 or TNF-α (1, 10 and 100 ng/ml), alone or in association with galanin or hexarelin (10^–8M): GH mRNA was measured by RT-PCR and GH secretion by ELISA. Results: IL-1β (1, 10 and 100 ng/ml) and IL-6 (1 and 10 ng/ml) significantly (p < 0.05) enhanced GH output. IL-1β and TNF-α (1 and 10 ng/ml) reduced (p < 0.05) the galanin-induced GH secretion and IL-6 (10 ng/ml) potentiated the effect of both GH releasers (p < 0.05). GH gene expression was increased only by IL-6 at the concentrations of 1 and 10 ng/ml, either alone or in association with both galanin and hexarelin. Conclusions: We hypothesize that cytokines may play a paracrine/autocrine role in GH regulation in the pituitary independently from the intracellular pathways of the GH secretagogues.