Research paper Chronic subcutaneous infusion of neurosecretory protein GM increases body mass gain in chicks Kenshiro Shikano a , Shusuke Taniuchi a , Eiko Iwakoshi-Ukena a,b , Megumi Furumitsu a , George E. Bentley b , Lance J. Kriegsfeld c , Kazuyoshi Ukena a,c,⇑ a Section of Behavioral Sciences, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan b Department of Integrative Biology and The Helen Wills Neuroscience Institute, University of California at Berkeley, Berkeley, CA 94720-3140, USA c Department of Psychology and the Helen Wills Neuroscience Institute, University of California at Berkeley, Berkeley, CA 94720-3140, USA article info Article history: Received 19 September 2017 Revised 13 November 2017 Accepted 15 November 2017 Available online xxxx Keywords: Neurosecretory protein Chicken Hypothalamus Body mass gain Fat accumulation abstract Recently we discovered a small hypothalamic protein in the chicken, named neurosecretory protein GL (NPGL), which is associated with body growth and energy metabolism in birds and rodents. Genome database analysis suggested that the NPGL gene has a paralogous gene in vertebrates, named neurosecre- tory protein GM (NPGM). However, the biological action of NPGM remains unclear. In this study, we inves- tigated whether NPGM affects body growth in chicks. We found that subcutaneous infusion of NPGM for six days increased body mass gain in a dose-dependent manner. Despite the observed increase in body mass, infusion of NPGM did not alter food and water intake. Of note, we observed tendency of mass increase of several peripheral tissues, specifically. When we compared several tissue types, NPGM seemed to induce the largest growth increase in white adipose tissue mass. These results suggest that NPGM may accelerate fat accumulation and body growth. In addition, we analyzed whether NPGM increases body growth through the action of pituitary hormones. However, we observed no significant changes in mRNA expression of pituitary hormones or plasma levels of growth hormone in NPGM- treated chicks. This is the first report describing the biological action of NPGM in vertebrates. Ó 2017 Elsevier Inc. All rights reserved. 1. Introduction Body growth in animals is regulated by various hormones and genetic, nutritional, and environmental factors (Harvey, 2013). In particular, growth hormone (GH) is generally regarded as essential for body growth and development in vertebrates. GH excess results in gigantism, whereas GH deficiency results in dwarfism (Gahete et al., 2016; Hannah-Shmouni et al., 2016). Several neuropeptides, including growth hormone-releasing hormone (GHRH), ghrelin, and somatostatin (Burgus et al., 1973; Guillemin et al., 1982; Kojima et al., 1999), regulate production and secretion of GH. Growth in peripheral tissues, including liver, muscle, and adipose tissue, is mainly regulated by GH and insulin-like growth factors (IGFs) working with their respective receptors (Harvey, 2013; Hyun, 2013). However, as these tissues are associated with energy metabolism, increases in their masses are also influenced by energy state. Furthermore, various other bioactive substances can also influence body mass growth, such as neuropeptide Y (NPY), glucocorticoids, and leptin, which regulate feeding behavior and bone metabolism (Baldock et al., 2006; Engblom et al., 2007; Takeda et al., 2002). These neuropeptides, peripheral steroids, or peptide hormones are secreted from the hypothalamus, adrenal gland, and adipose tissue in response to physiological conditions. In this way, body growth is regulated by various hormones secreted from both central and peripheral tissues. Because of the complexity of growth regulation, the precise mechanism of control remains unknown and likely involves novel factors that remain to be elucidated. We recently identified a novel cDNA that encodes the precursor of a small hypothalamic secretory protein in chickens, mice, and rats (Ukena et al., 2014; Matsuura et al., 2017; Iwakoshi-Ukena et al., 2017). The precursor protein is cleaved between a signal pep- tide sequence and a dibasic amino acids cleavage site to produce the mature protein, which is then modified with C-terminus ami- dation. Because the C-terminal amino acids of the small protein are Gly-Leu-NH 2 , the small protein was named neurosecretory pro- tein GL (NPGL) (Ukena et al., 2014). Morphological analysis indi- cated that NPGL was produced in the medial mammillary nucleus (MM) and the infundibular nucleus (IN) within the https://doi.org/10.1016/j.ygcen.2017.11.010 0016-6480/Ó 2017 Elsevier Inc. All rights reserved. ⇑ Corresponding author at: Section of Behavioral Sciences, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan. E-mail address: ukena@hiroshima-u.ac.jp (K. Ukena). General and Comparative Endocrinology xxx (2017) xxx–xxx Contents lists available at ScienceDirect General and Comparative Endocrinology journal homepage: www.elsevier.com/locate/ygcen Please cite this article in press as: Shikano, K., et al. Chronic subcutaneous infusion of neurosecretory protein GM increases body mass gain in chicks. Gen. Comp. Endocrinol. (2017), https://doi.org/10.1016/j.ygcen.2017.11.010