A Comparative Update on the Neuroendocrine Regulation of Growth Hormone in Vertebrates

Abstract

Growth hormone (GH), mainly produced from the pituitary somatotrophs is a key endocrine regulator of somatic growth. GH, a pleiotropic hormone, is also involved in regulating vital processes, including nutrition, reproduction, physical activity, neuroprotection, immunity, and osmotic pressure in vertebrates. The dysregulation of the pituitary GH and hepatic insulin-like growth factors (IGFs) affects many cellular processes associated with growth promotion, including protein synthesis, cell proliferation and metabolism, leading to growth disorders. The metabolic and growth effects of GH have interesting applications in different fields, including the livestock industry and aquaculture. The latest discoveries on new regulators of pituitary GH synthesis and secretion deserve our attention. These novel regulators include the stimulators adropin, klotho, and the fibroblast growth factors, as well as the inhibitors, nucleobindin-encoded peptides (nesfatin-1 and nesfatin-1–like peptide) and irisin. This review aims for a comparative analysis of our current understanding of the endocrine regulation of GH from the pituitary of vertebrates. In addition, we will consider useful pharmacological molecules (i.e. stimulators and inhibitors of the GH signaling pathways) that are important in studying GH and somatotroph biology. The main goal of this review is to provide an overview and update on GH regulators in 2020. While an extensive review of each of the GH regulators and an in-depth analysis of specifics are beyond its scope, we have compiled information on the main endogenous and pharmacological regulators to facilitate an easy access. Overall, this review aims to serve as a resource on GH endocrinology for a beginner to intermediate level knowledge seeker on this topic.

Nesfatin‐1 is an inhibitor of the growth hormone‐insulin‐like growth factor axis in goldfish (Carassius auratus)

“…The regulation of GH in fish pituitary is multifactorial. 38 Whether nesfatin-1 influences additional regulators of GH in fish needs to be determined. The present study did not determine whether differences exist in the abundance of endogenous NUCB2/ nesfatin-1 in the GH-IGF system tissues of male and female goldfish.…”

Somatotroph Tumors and the Epigenetic Status of the GNAS Locus

“…Surgical removal leads to normalization of GH and IGF1 in 34–74% of cases depending on the series, related mostly to tumor size [ 1 ]. GH synthesis and secretion is primarily under stimulatory control of GH-releasing hormone (GHRH), while somatostatin inhibits GH release, mainly through the subtype 2 of the somatostatin receptor (SSTR2) [ 2 ]. SSTR2 is the primary target of the somatostatin analogues (SSAs) currently used to treat these tumors.…”

Protective Effects of PACAP in a Rat Model of Diabetic Neuropathy

“…PACAP acts through G-protein-coupled receptors: its specific receptor is PAC1, while VPAC1 and VPAC2 receptors bind PACAP and VIP with the same affinity. PACAP has a widespread distribution in the body, with the highest expression levels in the nervous system and endocrine glands, where it acts as a neurotransmitter, neuromodulator, and neurohormone [ 2 , 3 , 4 , 5 , 6 ]. In addition, PACAP and its receptors are widely expressed in peripheral organs [ 1 , 7 , 8 , 9 , 10 ], and the peptide plays different roles in numerous physiological processes in the cardiovascular, respiratory, urogenital, musculoskeletal, and digestive systems [ 11 , 12 , 13 , 14 , 15 , 16 ].…”

“…PACAP acts through G-protein-coupled receptors: its specific receptor is PAC1, while VPAC1 and VPAC2 receptors bind PACAP and VIP with the same affinity. PACAP has a widespread distribution in the body, with the highest expression levels in the nervous system and endocrine glands, where it acts as a neurotransmitter, neuromodulator, and neurohormone [2][3][4][5][6]. In addition, PACAP and its receptors are widely expressed in peripheral Int.…”