Anyone who’s used steroids is probably familiar with the role of androgen receptors—Uncle Beast has mentioned them in various previous articles—but I suspect many of you know very little about how they actually work. Today, let’s take a detailed look at their mechanism of action. Warning: This content is dry and boring!
We often say that testosterone has an anabolic effect. This is because testosterone carries a biological signal to “accelerate protein synthesis.” For testosterone to transmit this signal to the muscles, it must go through a complex “process”—
to put it in less technical terms, something a bit easier to understand: “pairing” with DNA.
For example, when testosterone or other androgenic steroids (which we’ll collectively refer to here as “ligands”) bind to the androgen receptor (hereafter simply “receptor”), they form a “ligand-receptor complex.” This “ligand-receptor complex” enters the cell nucleus, where it encounters a region of DNA called the “androgen response element”— — the Androgen Response Element, abbreviated as “ARE” (as the name suggests, this region is specifically designed for androgens to exert their effects; it encodes everything androgens can do and transcribes different information depending on the specific androgen). The “ligand-receptor complex” will accurately recognize and bind to the nucleotide sequence composed of the ARE on the DNA. Afterward, using this “ARE” as a template, the signal carried by testosterone to “synthesize and retain proteins” is transmitted to an mRNA (messenger RNA). The mRNA leaves the cell nucleus and enters the cytoplasm, where it binds to RNA (ribonucleic acid) and transmits the signal to “synthesize and retain proteins” to that RNA. Subsequently, the RNA in the cytoplasm directs the cell to “follow the instructions,” resulting in an increasing amount of protein within the cell. The cell swells, and the entire muscle consequently becomes larger.
To use an analogy, muscle growth is like a construction project, and androgens are the project managers behind the scenes. The manager has his own “ideas” (i.e., protein synthesis), and the receptor acts as a secretary. Once the two come together, they enter the cell nucleus—the “office.” In the filing cabinet (DNA) within the office, they locate the correct “format” (the ARE segment in DNA) for drafting a document. Following this “format,” the leader writes his “idea” into a “document” (mRNA, messenger RNA). The “document” is then handed over to the “engineers” (the ribosomes in the cytoplasm), who use this idea to specifically direct the “construction” (protein synthesis).
It’s worth noting that testosterone, this “leader,” sometimes “oversteps its authority.” It can bind to glucocorticoid receptors, thereby hindering the glucocorticoids from exerting their effects (after glucocorticoids bind to their receptors, they send signals to break down proteins)—because testosterone has “stolen” the glucocorticoids’ “secretary”….
From this entire process, it is evident that the mechanism by which androgens promote muscle growth is to encourage muscle cells to retain protein, thereby increasing cell volume. This approach to muscle growth clearly follows the “hypertrophy” mechanism—that is, “enlargement” rather than “proliferation.”