Synergistic Effects of Testosterone and Growth Hormone - An Overview

Introduction:

Synergistic effects are produced when two or more hormones produce the same effect together. There will be an increased result because the two hormones work together and increase the functioning of each other to produce a positive outcome. Hormones are responsible for the communication of many physiological systems for modulating growth and development. The anabolic hormone in cellular growth and repair is testosterone. A growth hormone known as somatotropin is produced from the somatotropic cells by the anterior pituitary gland. The growth hormone release is regulated through feedback in response to nutrition, stress, sleep, and growth hormone. Somatostatin inhibits the release of GHRH (growth hormone releasing hormone) as well as HGH (human growth hormone) release response to GHRH stimulus and increases hypoglycemia. The synergistic action of hormones is when two hormones work together to do the same function.

What Are Growth Hormones and Their Significance?

The functions of growth hormones are as follows:

• Growth hormones are also called somatotropin. It consists of 191 amino acids produced from the anterior pituitary gland.

• Human growth hormone is responsible for the regulation of the body's functions. The functions of growth hormones are regulated by complex feedback mechanisms that are activated in response to nutrition, sleep, exercise, and stress.

• The release of growth hormone is regulated by the growth hormone-releasing hormone that is produced by the hypothalamus of the brain. Somatostatin inhibits the growth hormone-releasing hormone and GHRH stimulus during high blood glucose levels in the body.

• The growth hormone functions by acting directly or indirectly on the target site to stimulate a response.

• The insulin-like growth factor-1 is secreted by liver cells in response to high levels of growth hormones and binds to the surface receptors. The insulin-like growth factor produced by the liver cells has an impact on the metabolism and growth of the tissues.

• The growth hormone has significant growth-promoting effects on bones and cartilage. The insulin-like growth factor binds to the receptors on the tissues and activates an intracellular signaling pathway that phosphorylates various proteins to increase metabolism, cellular respiration, and anabolism. It also inhibits the apoptosis of the cells thus prolonging the lifespan of the cells.

• The main function of growth hormones is to upregulate the insulin-like growth factor and its effect on peripheral cells.

• The fat cells are processed and consumed by inducing triglyceride breakdown and oxidation of adipocytes.

What Are the Testosterones and Their Functions?

The functions of testosterone are as follows:

• Testosterone is a sex hormone produced in both males and females. It plays an important role in men’s bodies to regulate sex drive, fat distribution, bone mass, strength and muscle mass, and production of sperm and red blood cells.

• It is a primary male hormone that regulates sex differentiation, produces male sex characteristics, fertility and spermatogenesis, enlargement of the penis, and testes, and increases libido. It is also responsible for regulating male characteristics like masculinity.

• The secondary sex characteristics are vocal changes, male hair patterns, voice deepening, growth spurts, and skeletal muscle growth.

• It also increases erythropoiesis (production of red blood cells).

• With age, the production of testosterone goes down with a drop in libido, low bone density, increased fat production, and decreased erythropoiesis.

• The growth hormone-releasing hormone produced from the hypothalamus travels to the anterior pituitary gland and stimulates the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

• These two hormones act on the receptors in the gonads.

• The LH acts on the Leydig cells (cells in the testicle) to increase the production of testosterone.

• Testosterone has a negative feedback mechanism. High levels of testosterone can limit its secretion by sending signals to the hypothalamus.

• The hypothalamus suppresses the secretion of GnRH (gonadotropin-releasing hormone) so that the anterior pituitary gland is less responsive to GnRH

What Are the Synergistic Effects of Growth Hormone and Testosterone?

The effects of both growth hormone and testosterone are as follows:

• Growth hormone and testosterone have anabolic effects on protein. The muscle and liver are major sites of protein metabolism.

• Testosterone helps in the protein anabolic process only in the presence of growth hormone.

• Both hormones exhibit enhanced protein metabolism in the body. It is necessary for the normal growth of bones and tissues.

• The liver cells respond to growth hormones and trigger the production of a protein called insulin. The protein stimulates cell maturation and growth. The growth hormones play a role in the metabolic process and are involved in protein production and the breakdown of carbohydrates and fats.

• Growth hormone plays an important role in regulating proteins. It produces protein anabolism at the whole-body level by stimulating protein synthesis.

• Testosterone produces protein anabolism by decreasing oxidation and protein breakdown in the presence of growth hormone.

• Testosterone and growth hormone are anabolic hormones that interact positively to regulate protein metabolism.

• Growth hormone enhances the growth in hypogonadism (the failure of testes in men to function properly) and hypopituitarism (shortage in supply of hormones from the pituitary gland).

• The testosterone effect is low and the growth is poor in boys with hypopituitarism (short supply of hormones from the pituitary gland like growth hormone) without growth hormone treatment.

• The GH in adults stimulates the protein synthesis in muscles for energy. The release of fatty acids from adipose tissue is also stimulated by growth hormones. It inhibits the uptake of glucose by muscle while stimulating the uptake of amino acids. As it inhibits the uptake of glucose by the cells, it increases the circulating glucose level in the blood. The amino acids are used in the synthesis of proteins, and the body uses fatty acids as a source of energy.

• Testosterone stimulates the effect of GH to increase insulin-like growth factor and also exerts a protein anabolic effect that is independent of GH action.

• The effects of testosterone alone with testosterone plus growth hormone improve bone structure in men with total pituitary hormone deficiency.

• Both growth hormone and testosterone have protein anabolic effects. The major sites for protein metabolism are the muscle and liver.

What Are the Actions of Growth Hormone and Testosterone in Protein Metabolism?

Protein metabolism is the creation of proteins and amino acids known as anabolism. GH and testosterone are anabolic hormones. The protein metabolism is explained as follows:

• Growth hormone and testosterone are required by the body continuously for protein metabolism.

• Anabolic hormones like human growth hormone and testosterone increase protein synthesis and decrease protein breakdown.

• During the translation process, the ribosomes use mRNA (messenger ribonucleic acid) to synthesize proteins. The essential amino acids are produced from the diet.

• Growth hormone combined with testosterone has a greater positive effect on protein metabolism.

• Testosterone increases muscle protein synthesis.

Conclusion:

In conclusion, GH and testosterone have synergistic effects on whole-body protein anabolism and body composition. GH and testosterone both develop the full body composition and metabolic changes of the body during puberty. Apart from these, it also helps in the normal growth of bones and tissues, enhances the growth in hypogonadism, and stimulates the protein synthesis in muscles for energy.