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Influence of insulin on growth hormone secretion, level and growth hormone signalling

QIU Han¹, YANG Jin-Kui², Chen Chen^3,*

¹Department of Forensic Medicine, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China；²Endocrinology Department, Tongren Hospital, Capital Medical University, Beijing 100730, China；³School of Biomedical Science, University of Queensland, Brisbane, Qld 4072, Australia

Abstract

Growth hormone (GH), as a vital hormone, has to experience a series of processes to fulfill its function including secretion, entering the circulation to reach target tissues (pre-receptor process), binding on the GH receptor (GHR) and triggering signaling inside cells (post-GHR process). Insulin can directly or indirectly influence part of these processes. GH secretion from pituitary somatotropes is regulated by GH-releasing hormone (GHRH) and somatostatin (SS) from hypothalamus. Insulin may exert positive or negative effects on the neurons expressing GHRH and SS and somatotropes under healthy and pathological conditions including obesity and diabetes. Glucose and lipid levels in circulation and dietary habits may influence the effect of insulin on GH secretion. Insulin may also affect GHR sensitivity and the level of insulin-like growth factor 1 (IGF-1), thus influence the level of GH. The GH signaling is also important for GH to play its role. GH signaling involves GHR/JAK2/STATs, GHR/JAK2/SHC/MAPK and GH/ insulin receptor substrate (IRS)/PI3K/Akt pathways. These pathways may be shared by insulin, which is the basis for the interaction between insulin and GH, and insulin may attenuate or facilitate the GH signal by influencing molecules in the pathways. Many factors are related to the effect of insulin, among them the most important ones are duration of action and amount of insulin. The tendency of insulin-reduced GH signaling becomes obvious with increased dose and acting time of insulin. The participation of suppressor of cytokine signaling (SOCS), the interaction between JAK2 and IRS, and GHR sensitivity should also be considered when discovering GH signal. The involvement of SS in response to insulin is not clear yet. The details of how GH secretion, level and signaling change in response to time and dose of insulin treatment warrant further studies.

Key words: Insulin; growth hormone ; somatostatin ; obesity ; diabetes ; signal pathway

Received: 2017-02-20　　Accepted: 2017-06-10

Corresponding author: 陈晨　　E-mail: chen.chen@uq.edu.au

DOI: 10.13294/j.aps.2017.0062

Citing This Article：

QIU Han, YANG Jin-Kui, Chen Chen. Influence of insulin on growth hormone secretion, level and growth hormone signalling. Acta Physiol Sin 2017; 69 (5): 541-556