HGH injectable Human Growth Hormone: Forms of hgh Human Growth Hormone by David P. Leonardi, MD

Introduction | Nomenclature | History | Use | Somatopause | Treatment | Benefits | Side-Effects | Summary

INTRODUCTION

HGH Human Growth Hormone is a polypeptide hormone. This means it is composed of a long chain of amino acids, 191 to be exact. Under normal physiologic conditions, HGH Growth Hormone is secreted by the anterior pituitary gland. This is a gland that lies at the base of the brain in a bony cavity called the Sella Turcica. In addition to growth hormone, the anterior pituitary also secretes prolactin, thyroid stimulating hormone, luteinizing hormone, follicle stimulating hormone, and adrenal corticotropic hormone.

The secretion of growth hormone by the pituitary gland is initiated by the hypothalamus, another gland in the brain that lies right next to the pituitary. The hypothalamus initiates growth hormone secretion by secreting growth hormone releasing hormone (GHRH); at the same time it stops secreting a growth hormone inhibitory hormone called somatostatin. When somatostatin is turned off and GHRH is turned on, the pituitary will release growth hormone in bursts of activity. These bursts of growth hormone release occur primarily during deep stages of sleep, such as stage 3 and stage 4.

Once released in the blood, growth hormone is very short lived. It is generally completely metabolized and gone within a half-hour. During that time, however, it manages to reach the liver and many other cells in the body, and induce them to make another polypeptide hormone called Insulin-like Growth Factor One (IGF-1). It is really IGF-1 that travels around to the various tissues of the body to effect most of the benefits that we attribute to growth hormone.

The secretion of hgh growth hormone itself is regulated by a classic biofeedback loop. This means when levels of growth hormone in the blood reach a certain threshold, growth hormone stimulates receptors in the pituitary to stop further growth hormone secretion.

It also stimulates receptors in the hypothalamus to stop GHRH and turn on somatostatin. IGF-1, which goes up in response to human growth hormone, also feeds back on the pituitary and hypothalamus to help control growth hormone secretion. This is nature's system of checks and balances to assure we don't have too much of any one hormone.