The Belgian Blue breed of cows is famous for its striking muscular appearance. This is a result of a mutation related to myostatin.
What is YK11?
It is a partial androgen receptor agonist and it functions as a myostatin inhibitor. Most SARMs stimulate muscle growth by attaching to and activating androgen receptors. The vast majority of SARMs are full androgen receptor agonists, as they elicit a maximal response of the AR upon occupation. On the other hand, partial agonists activate the androgen receptor with only partial efficacy and may even display some antagonistic activity. What makes YK11 unusual is its effect on myostatin. Myostatin is a myokine, a protein produced and released by myocytes that acts on muscle cells’ autocrine function to inhibit myogenesis: muscle cell growth and differentiation.
How does YK11 work?
YK11 works by increasing production of Follistatin. Follistatin is a potent antagonist of myostatin. In the presence of Follistatin, myostatin cannot inhibit muscle growth. This effect actually isn’t unique, as many steroids function as myostatin inhibitors to one degree or another. However, what is unique is the potency with which YK11 works to combat this muscle destroying molecule. In one study, YK11 was shown to increase Follistatin production several times higher than DHT, which is itself a potent inhibitor of myostatin.
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