Regulation of catecholamine release and tyrosine hydroxylase in human adrenal chromaffin cells by interleukin-1β: role of neuropeptide Y and nitric oxide

Adrenal chromaffin cells synthesize and secrete catecholamines and neuropeptides that may regulate hormonal and paracrine signaling in stress and also during inflammation. The aim of our work was to study the role of the cytokine interleukin-1β (IL-1β) on catecholamine release and synthesis from primary cell cultures of human adrenal chromaffin cells. The effect of IL-1β on neuropeptide Y (NPY) release and the intracellular pathways involved in catecholamine release evoked by IL-1β and NPY were also investigated. We observed that IL-1β increases the release of NPY, norepinephrine (NE), and epinephrine (EP) from human chromaffin cells. Moreover, the immunoneutralization of released NPY inhibits catecholamine release evoked by IL-1β. Moreover, IL-1β regulates catecholamine synthesis as the inhibition of tyrosine hydroxylase decreases IL-1β-evoked catecholamine release and the cytokine induces tyrosine hydroxylase Ser40 phosphorylation. Moreover, IL-1β induces catecholamine release by a mitogen-activated protein kinase (MAPK)-dependent mechanism, and by nitric oxide synthase activation. Furthermore, MAPK, protein kinase C (PKC), protein kinase A (PKA), and nitric oxide (NO) production are involved in catecholamine release evoked by NPY. Using human chromaffin cells, our data suggest that IL-1β, NPY, and nitric oxide (NO) may contribute to a regulatory loop between the immune and the adrenal systems, and this is relevant in pathological conditions such as infection, trauma, stress, or in hypertension.