MECHANO GROWTH FACTOR
MGF is a split variant of IGF-1 but its sequence differs from the systemic IGF-1
produced by the liver. IGF-I is spliced towards MGF which initiates hypertrophy and
repair of local muscle damage. MGF is expressed by mechanically overloaded
muscle and is involved in tissue repair and adaptation. It is expressed as a pulse
following muscle damage and is involved in the activation of muscle satellite (stem)
cells. These donate nuclei to the muscle fibers that are required for repair and for the
hypertrophy process, which may have similar regulatory mechanisms (Goldspink, G.,
2005 p22). MGF is essential for repair and therefore growth of new cells, similar to
IGF-1. If MGF is not PEGylated, the half-life is several minutes therefore PEGylated
MGF must be considered during the compounding process to ensure an appropriate
half-life, thereby increasing duration of action.
Content & Potency: 1 x 3mL at 2000mcg/ml ready-to-inject subcutaneous.
Suggested dosage: 0.10ml daily for 5 days out of 7 (1 month supply).
A.Philippou1, E. Papageorgiou1, G. Bogdanis2, A. Halapas1, A. Sourla3, m.
Maridaki, N. Pissimissis Source: Department of Experimental Physiology, Medical
School, National and Kapodistrian University of Athens.
Abstract: Different insulin-like growth factor-1 (IGF-1) isoforms, namely IGF-1Eb
and IGF-1Ec (MGF),have been proposed to have various functions in muscle repair
and growth. To gain insight into the potentially differential actions of IGF-1 isoforms
in the regulation of muscle regeneration, we assessed the time course of their
expressions at both mRNA and protein levels after exercise-induced muscle
damage in humans. In addition, we characterized mature IGF-1 and synthetic MGF
E peptide signalling in C2C12 myoblast-like cells in vitro. Ten healthy male
volunteers were subjected to exercise-induced muscle damage and biopsy
samples were taken from the exercised muscles before and 6 h, 2,5 and 16 days
post exercise. Muscle damage was documented by specific functional and
biochemical responses post exercise. PCR-based analyses of muscle biopsy
samples revealed a rapid and transient up-regulation of MGF mRNA expression
which was followed by a prolonged increase of IGF-1Ea and IGF-1Eb mRNA
expression (p<0.05). Patterns similar to those for mRNA expression were detected
for MGF and IGF-1Ea expression at the protein level. The action of synthetic MGF
E peptide differed from that of mature IGF1 since its proliferative effect on C2C12
myoblast-like cells was not blocked by an anti-IGF-1 receptor neutralizing antibody
and it did not phosphorylate Akt. Therefore, we conclude that the differential
expression profile of IGF-1 isoforms in vivo and the possible IGF-1R- independent
MGF E peptide signalling in skeletal muscle-like cells in vitro support the notion that
tissue-specific mRNA expression of MGF isoform produces mature IGF-1 and MGF
E peptides which possibly act as distinct mitogens in skeletal muscle regeneration.
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