Growth Hormone (GH) Questions
-What is growth hormone?
-How does growth hormone work?
-How is natural growth hormone released?
What is growth hormone?
Synthetic Growth Hormone (Somatropin) is an artificially created hormone (made up of a sequence of 191 amino acids) that is identical to the one found in humans. Some common names of synthetic growth hormone include: Genotropin by Genentech, Humatrope by Eli Lilly, Nutropin by Genentech and Saizen by Serono. While many companies are capable of generating growth hormone not all of the companies are capable of creating the correct structure that is identical to naturally occurring growth hormone. The structure determines the strength with which the growth hormone molecule binds to a receptor which will in turn affect the "strength" of the events leading to protein transcription, metabolism, IGF-1 creation, etc. It is this inconsistency that accounts in part for the differences in effectiveness of various produced synthetic growth hormone. Synthetic growth hormone is not really true or natural growth hormone. It was manufactured in a laboratory and not by your pituitary.
Naturally produced Growth Hormone is produced in the anterior pituitary. It is made up of a blend of amino acids with the majority of them being the 191 amino acid variety.
How does growth hormone work?
Growth hormone in the body is released in a pulsating fashion. It has been demonstrated that this pattern promotes growth. The pituitary is capable of rather quickly synthesizing very large amounts of growth hormone which it stores in both a finished and unfinished form. Adults rarely experience growth hormone pulses that completely deplete these stores. As we get older we do not lose the ability to create and store large amounts of growth hormone, rather we experience a diminished capacity to instruct their release. The growth hormone pulse is measured in a wave with the trough being the "off" or non-secretion of growth hormone and the crest being the "on" or highest point during growth hormone secretion.
The volume of growth hormone that is released in the body cannot be properly compared to the administration of synthetic growth hormone for the reason that a set of behavioral characteristics associated with natural growth hormone differ from those of synthetic growth hormone. Therefore attempting to find a natural growth hormone to a synthetic growth hormone equivalency is not very productive because in the end what is probably most important is: The quantity and quality of intracellular signaling events and the degree to which growth hormone stimulates autocrine/paracrine (locally produced/locally used) muscle IGF-1 & post-exercise its splice variant MGF.
How is natural growth hormone released?
Growth hormone release in the pituitary depends on 3 factors:
1. Somatostatin which is the inhibitory hormone and responsible in large part for the creation of pulsation.
2. Growth Hormone Releasing Hormone (GHRH) which is the stimulatory hormone responsible for initiating growth hormone release.
3. Growth Hormone Releasing Peptides (GHRP) which is a modulating hormone and in essence optimizes the balance between the "on" and the "off" periods of growth hormone.