When it comes to stimulating cell
growth and promoting normal and balanced growth and development of
muscle, cartilage, bone, liver, kidney, skin tissue, lungs, and
nerves, there is hardly anything as potent as Insulin-like Growth
Factor 1 or IGF-1.
The fact that use of IGF-1 is
closely
associated with burning of fat as a source of energy and it has the
ability to inhibit insulin from transporting glucose across cell
membranes means that it is an exceptional choice for sportsmen and
bodybuilders who bridge between cycles. Since injected IGF-1 (also
known as somatomedin C) does not enter the bloodstream,[1]
it cannot be
detected by both blood and urine testing. This is something every
sportsman would like to hear about a drug he or she is about to use
or using.

Insulin-like growth factor 1 is
commonly used as a diagnostic marker of the deficiency of growth
hormone and for monitoring growth hormone replacement therapy.[2]
Locally administered IGF-1 has the potential of promoting wound
repair in an estrogen-deprived animal model by dampening the local
inflammatory response and promoting re-epithelialization. In addition
to that, Insulin-like growth factor-I (IGF-I) functions as a mediator
of GH-independent anabolic responses in many cells and tissues and
the major mediator of growth hormone (GH)-stimulated somatic growth.
It exerts its effects via activation of the IGF-I receptor that is
widely distributed and enables blood-transported IGF-I to coordinate
balanced growth among multiple tissues and organs. At physiologically
relevant levels, IGF-1 blocks the cytotoxic action(s) of the
antiestrogens 4-hydroxytamoxifen (4-OHT) and tamoxifen (TAM) when
used as single agents or in a combination with the antiprogestin
mifepristone (MIF) for treating estrogen receptor positive (ER+)
breast cancer cells.[3]

It is also known to promote cell
survival by activating phosphatidylinositol 3-kinase (PI3K)/Akt
kinase pathway and inducing the phosphorylation of endogenous FKHRL1
(a member of the Forkhead family of transcription factors possibly
involved in cell cycle and apoptosis) in hippocampal neurons.[4]
It also
tends to block the nuclear translocation of FKHRL1 in hippocampal
neurons and promoted survival in parallel to the phosphorylation of
Akt and FKHRL1. If that was not all, IGF-1 use is associated with
providing extra glucose for the nervous system, preventing the signs
of aging such as wrinkles, promoting the growth of new tissue, and
supporting sexual performance. When used in dosages of 20-120 mcg per
day, with or without meals for a period of fifty days of more and
followed with a gap of thirty or forty days and then restarted again
in the same doses, IGF-1 minimizes body fat, promotes lean muscle
mass, improves skin tone, treats stunted growth or growth hormone
deficiencies, improves the production of white blood cells, and
repair nerve tissues besides promoting restful sleep and the sense of
well being.[5]

When produced and secreted, IGF-1
can
circulate back to the hypothalamus and the pituitary to initiate the
release of somatostain that completes the negative feedback loop and
reduces the release of human growth hormone. It is found to be
neuroprotective in animal models of focal brain ischemia and has the
ability to improve neurological outcomes besides stimulating the
regeneration of neural tissue. Moreover, it stimulates
5alpha-reductase, adrenal and gonadal androgen synthesis, androgen
receptor signal transduction, lipogenesis, and sebocyte
proliferation. IGF-1 is also well known for its ability to increase
satellite cell activity, protein translation, and gene transcription
and each of these processes prove beneficial to local and general
muscle growth and can produce divergent effects on the hypertrophy
response.[6]

Mechano-growth factor (MGF), on
the
other hand, is a splice-variant of IGF-I sharing an identical mature
region. It can produce rapid increases in strength and muscles to
give it significant therapeutic and doping potential. MGF has the
unique potential of activating the muscle stem cells and to start the
process of tissue repair and hypertrophy processes. Studies in the
past have indicated that Mechano-growth factor, an alternatively
spliced variant of insulin-like growth factor 1 (IGF-1), is found to
function independently from the rest of the molecule and demonstrated
a neuroprotective effect in vivo and in vitro and the C-terminal
peptide (MGF) has the potential to be developed into a therapeutic
modality for the prevention of neuronal damage. Unlike mature
Insulin-like growth factor-1, Mechano-growth factor inhibits terminal
differentiation whilst increasing myoblast proliferation.

MGF can up-regulate heme
oxygenase-1
(HO-1), which is an important cell defense mediator, and protects
dopamine cells that could be beneficial in offering neuroprotection
in Parkinson's disease. It was recently been identified as one of the
most important insulin-like growth isoforms with regard to
hypertrophy in response to a mechanical overload stimulus and plays
an important role in skeletal muscle regeneration, as part of a
cascade, in response to externally induced muscle damage. In addition
to that, Mechano-growth factor also has the potential of activating
muscle progenitor cells that provide the extra nuclei required for
muscle hypertrophy, repair, and maintenance. It responds to changes
in physiological conditions or environmental stimuli and expression
of MGF is significantly increased in muscle, bone, and tendon after
damage resulting from mechanical stimuli and in the heart and brain
following ischemia.

The difference between IGF-1 and
Mechano-growth factor is that MGF stimulates myoblasts division
through stimulation of different receptors. MGF is used by
professional sportsmen, especially those into bodybuilding, to
accelerate growth of muscles, reducing fat mass of the body, increase
endurance, strengthening bones, reducing levels of cholesterol,
improving immune defense and skin, and accelerating recovery.
Moreover, use of MGF has been associated with improvements in the
context of hind limb muscle strength, motoneuron survival, and
increase in motor unit. It also has the ability to stimulate
localized muscle growth by leading to a response in the skeletal
muscle when administered in an injectable form. It is expressed by
mechanically overloaded muscles and its sequence differs from the
systemic insulin-like growth factor-1 produced by the liver. The
C-terminal peptide MGF is important for muscle repair and new cell
growth, on the lines of IGF-1. This is the reason why sportsmen have
been admiring it as it helps them with incredible body fat loss,
fullness, increased pumps, and vascularity besides helping them gain
5-7 pounds of lean mass and losing 4-6 percent of body fat with just
four weeks of MGF use.