Growth Hormone(s), Testosterone, Insulin-Like Growth Factors, and Cortisol: Roles and Integration for Cellular Development and Growth With Exercise

Abstract

Hormones are largely responsible for the integrated communication of several physiological systems responsible for modulating cellular growth and development. Although the specific hormonal influence must be considered within the context of the entire endocrine system and its relationship with other physiological systems, three key hormones are considered the "anabolic giants" in cellular growth and repair: testosterone, the growth hormone superfamily, and the insulin-like growth factor (IGF) superfamily. In addition to these anabolic hormones, glucocorticoids, mainly cortisol must also be considered because of their profound opposing influence on human skeletal muscle anabolism in many instances. This review presents emerging research on: (1) Testosterone signaling pathways, responses, and adaptations to resistance training; (2) Growth hormone: presents new complexity with exercise stress; (3) Current perspectives on IGF-I and physiological adaptations and complexity these hormones as related to training; and (4) Glucocorticoid roles in integrated communication for anabolic/catabolic signaling. Specifically, the review describes (1) Testosterone as the primary anabolic hormone, with an anabolic influence largely dictated primarily by genomic and possible non-genomic signaling, satellite cell activation, interaction with other anabolic signaling pathways, upregulation or downregulation of the androgen receptor, and potential roles in co-activators and transcriptional activity; (2) Differential influences of growth hormones depending on the "type" of the hormone being assayed and the magnitude of the physiological stress; (3) The exquisite regulation of IGF-1 by a family of binding proteins (IGFBPs 1-6), which can either stimulate or inhibit biological action depending on binding; and (4) Circadian patterning and newly discovered variants of glucocorticoid isoforms largely dictating glucocorticoid sensitivity and catabolic, muscle sparing, or pathological influence. The downstream integrated anabolic and catabolic mechanisms of these hormones not only affect the ability of skeletal muscle to generate force; they also have Kraemer et al. Anabolic and Catabolic Hormones and Exercise implications for pharmaceutical treatments, aging, and prevalent chronic conditions such as metabolic syndrome, insulin resistance, and hypertension. Thus, advances in our understanding of hormones that impact anabolic: catabolic processes have relevance for athletes and the general population, alike.

Links Between Testosterone, Oestrogen, and the Growth Hormone/Insulin-Like Growth Factor Axis and Resistance Exercise Muscle Adaptations

“…In contrast, there are no differences observed between men and women in relation to intramuscular testosterone concentrations and steroidogenic enzymes (Vingren et al, 2008 ). Systemic testosterone is taken up by the muscle through its binding to membrane-bound or cytoplasmic androgen receptors (AR), in turn stimulating subsequent myocellular signaling (Vingren et al, 2010 ; Kraemer et al, 2020 ) and altering the expression of thousands of genes, many of which are involved in the regulation of skeletal muscle structure, fiber type (Dubois et al, 2014 ), intramyocellular metabolism (White et al, 2013 ), and mRNA transcription (MacLean et al, 2008 ) ( Figure 1 ). Once bound to the AR, testosterone is irreversibly converted to dihydrotestosterone (DHT) through the enzymatic action of 5-α reductase (Wilborn et al, 2010 ).…”

Astrocytoma: A Hormone-Sensitive Tumor?

“…Once activated by their ligands, the ARs are able to bind androgen response elements (AREs) which trigger transcription of the AR target genes. The non-genomic pathway may be activated by nuclear ARs described above, recently described transmembrane ARs (mARs) GPRC6A (g protein-coupled receptor family C group 6 member A) and ZIP9 (zinc transporter member 9), or by changes in membrane fluidity [123,124].…”

HNP-1 and HBD-1 as Biomarkers for the Immune Systems of Elite Basketball Athletes

“…These data show a perfect balance between anabolic and catabolic metabolism [41][42][43][44][45][46][47][48][49]. In fact, it is known that increased testosterone levels may induce a reduction in the transforming growth factor beta (TGF-β) signal, which in turn reduces osteoprogenitor cells and increases lean muscle mass [59][60][61][62], thereby increasing anabolic effects. In fact, testosterone is an anabolic hormone (i.e., it binds proteins), thanks to which muscle growth occurs.…”