Neuronostatin alters gene expression in rat anterior pituitary cells: a possible role in energy balance and glucose homeostasis

Abstract

Neuronostatin is a recently discovered peptide hormone derived from the somatostain preprohormone (JBC 287:4572, 2008). We now have identified that the orphan G protein‐coupled receptor, GPR107, is a potential cognate receptor for neuronostatin (AJP 303:R941, 2012). Because of the abundant expression of GPR107 in anterior pituitary cells, and because neuronostatin is present in somatostatin‐producing neurons of the hypothalamus that project to median eminence, we hypothesized that neuronostatin would alter hormone production in anterior pituitary. The ability of neuronostatin to activate early gene expression in pituitary gland further suggested trophic effects; however, we were initially unable to detect acute effects of the peptide on basal, stimulated or inhibited hormone secretion in cells in culture. Therefore, anterior pituitary cells were isolated from male rats, treated for longer time periods with neuronostatin, and changes in hormone gene expression were examined using real‐time polymerase chain reaction. We found that neuronostatin activated early gene expression and induced an increase in growth hormone mRNA levels, suggesting that neuronostatin may regulate growth hormone production, which could have important implications for energy homeostasis and glucose metabolism in addition to possible direct effects in the pancreas where the peptide also activates early gene expression. (NIH HL066023)