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

OBJECTIVE: We studied the effects of IL-1beta, IL-6 and TNF-alpha on GH gene expression and secretion with or without galanin and hexarelin. METHODS: Pituitary cells from adult pigs were treated with IL-1beta, IL-6 or TNF-alpha (1, 10 and 100 ng/ml), alone or in association with galanin or hexarelin (10(-8) M): GH mRNA was measured by RT-PCR and GH secretion by ELISA. RESULTS: IL-1beta (1, 10 and 100 ng/ml) and IL-6 (1 and 10 ng/ml) significantly (p < 0.05) enhanced GH output. IL-1beta and TNF-alpha (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.