Process

The birth of new neurons in the adult brain, effectively confined to the dentate gyrus. It is suppressed by sustained cortisol and by lost deep sleep, both of which these compounds produce, and it is one of the few brain processes that recovers when the insult stops.

How many androgen receptors a tissue actually has. It moves: training raises it, and sustained high-dose exposure lowers it in some tissues, which is part of why results flatten and doses creep upward.

Growing new blood vessels. It is the rate limit on healing: tissue cannot repair faster than it can be supplied, which is why so many healing peptides are described as pro-angiogenic.

Brain-derived neurotrophic factor acting at TrkB. The growth signal behind new synapses and behind the kind of memory that needs sleep to form. It is suppressed by sustained cortisol and by lost deep sleep, which is how a compound with no direct action in the brain still reaches memory.

Bile moving out of the liver and into the gut. The 17-alpha-alkyl group that lets an oral survive first pass is also what slows this, and the stall is what is felt as itching and jaundice.

Growth of the duct tissue behind the nipple, driven by oestrogen and progesterone signalling. Once it has laid down glandular tissue it does not reliably regress.

Cells moving to where the damage is. Wound closure depends on it, and it is how the actin-binding healing peptides are described as working.

Building the protein that tendon, ligament, joint surface and skin are made of. It moves slower than muscle does, and not every androgen supports it equally.

How many connection points a neuron carries. Spines appear and disappear over hours, and their number is the physical substrate of how much a circuit can currently hold. Estradiol raises spine density in hippocampal CA1, and the effect tracks the hormone.

How strongly dopamine is signalling, mostly in the reward and motivation circuits. This is the route by which a compound that raises prolactin ends up flattening drive: dopamine holds prolactin down, so a sustained prolactin rise is read backwards as reduced dopaminergic tone.

Death by over-stimulation. Glutamate opens calcium channels, calcium floods in past what the mitochondria can hold, and the cell triggers its own destruction. It is the final common path for a large share of neuronal death, and it is the exact process estrogen defends against.

Releasing stored fat for fuel. Androgen receptor density on fat cells is part of why some compounds visibly change body composition beyond their muscle effect.

The shortening of each hair’s growth phase until the follicle produces a thinner, shorter shaft. This is the actual mechanism of pattern hair loss, and it is gradual.

The brain's main inhibitory signal, and the channel that alcohol, benzodiazepines and the neurosteroid allopregnanolone all act on. Anabolic steroids act on it directly too, at a site that overlaps the benzodiazepine site, which is a route to mental effects that has nothing to do with the androgen receptor.

How fast the stomach passes food on. Incretin drugs slow it, which is what makes a smaller meal feel like enough, and also what causes the nausea and the fullness that will not clear.

Genes being read into protein. The androgen receptor is a transcription factor, so this is the actual first step after binding: everything else downstream is a consequence of which genes get switched on and in which tissue.

Moving glucose out of the blood and into muscle. It can happen through insulin or, independently of it, through the AMPK pathway that exercise uses.

The brain's main excitatory signal. Everything fast the brain does runs on it, and too much of it is how neurons die. Long-term users show a chemical signature consistent with raised turnover, which is the nearest thing to direct human evidence of a neurotoxic process in this literature.

Burning fuel as heat. Raising it increases energy expenditure without requiring more activity, which is the appeal of the glucagon component in the dual and triple agonists.

The stress axis: hypothalamus to pituitary to adrenal cortex, ending in cortisol. Relevant to mood twice over. A compound that blocks the glucocorticoid receptor removes the brake the axis runs on, and a compound that shuts down the gonadal axis leaves this one carrying more of the load.

How well tissue responds to insulin. Falling sensitivity means higher fasting insulin for the same blood sugar, and it is one of the quieter costs of long steroid use.

How much passes between gut cells. Raised permeability lets partly digested material reach the immune system, which is the mechanism behind the leaky gut claim.

The brain makes its own estradiol from testosterone, in neurons and astrocytes, independently of what the testes supply. This single fact is why a blood estradiol reading does not tell you what the brain has, and why an aromatase inhibitor is a different kind of intervention from simply having low testosterone.

Pigment production in the skin. Driving it produces a tan without sun exposure, and it is the only proven effect of the melanotans.

Turning the day's experience into durable memory, which happens during deep and REM sleep. This is the step that breaks first when sleep breaks, and it is why memory complaints on these compounds usually trace back to sleep.

How much calcium a neuron's mitochondria can absorb before the cell dies. This is the single most underrated number in the whole estrogen argument: estradiol does not stop calcium entering the neuron, it raises the amount the neuron can survive.

How efficiently cells turn fuel into usable energy. When it degrades the leak shows up as oxidative stress.

The rate at which muscle is built. Androgen receptor activation raises it and holds it raised, which is the entire point of the exercise.

The insulation on axons that sets how fast signals travel. It is maintained continuously, and it is sensitive to thyroid hormone and to sex steroids, both of which these protocols move.

The nuclei inside a muscle fibre, each running a patch of it. Androgens add them, and animal work shows the added ones persist for a long time after the drug is gone. This is the cell-level reason a past cycle is never entirely undone.

The body's own brake on muscle growth. Lowering it removes a ceiling, which is a different kind of effect from raising protein synthesis.

Immune activation inside brain tissue. Short bursts are protective. Sustained activation is not, and it limits the very functions the immune cells were maintaining. Estrogen is one of the main brakes on it, which is the mechanistic core of why crashing estrogen has a cost.

Programmed neuron death. Unlike muscle, these cells are largely not replaced, so this process is where a reversible effect becomes a permanent one. Everything protective in this module ultimately resolves to whether it raises or lowers this.

Steroids made or converted inside the brain that act on ion channels. The route by which an androgen changes anxiety and sleep without touching the androgen receptor.

Vesicles fusing with the nerve terminal to release their signal. The SNARE proteins do the fusing, and the cosmetic peptides that soften expression lines work by interfering with them.

Whether the body is holding more protein than it loses. A practical readout of net anabolism.

Arousal, vigilance and the physical side of stress. It sets whether the person is alert or wired, and it is the transmitter most directly raised by the stimulants that are commonly stacked alongside these compounds.

Damage from reactive oxygen outpacing the cell's ability to mop it up. One of the mechanisms behind androgen effects on liver and heart tissue that are not explained by the receptor alone.

Muscle being taken apart, driven largely by cortisol at the glucocorticoid receptor. Blocking it is the anti-catabolic half of how steroids work.

Red cell manufacture, driven by erythropoietin from the kidney. Androgens raise both the signal and the marrow's response to it.

HDL clearing cholesterol out of vessel walls and back to the liver. Oral steroids induce hepatic lipase, which dismantles this clean-up crew.

Dormant stem cells beside each muscle fibre. Androgens push them to divide and fuse into the fibre, which is where new myonuclei come from.

How much oil the skin’s glands put out. Androgens drive it up, and it is the step between receptor binding in the gland and a visible breakout.

Removing cells that have stopped dividing but refuse to die and keep releasing inflammatory signals. Senolytics are built to force that clearance.

How strongly serotonin is signalling. The system most often named when 19-nor androgens are linked to impulse control, irritability and sleep. Almost all of the evidence is rodent work; nothing has been measured at these receptors in a human on these compounds.

Holding onto salt and the water that follows it. Shows up as a smoother look, a heavier scale reading and a higher blood pressure.

Needs FSH plus a testosterone concentration inside the testis roughly a hundred times blood level. External steroid raises blood level and shuts the internal one down, which is why fertility goes first.

How hard the fight-or-flight side of the nervous system is running. Androgens raise tyrosine hydroxylase and change adrenergic receptor density, so a compound can lift this without touching mood directly. It is the shared cause behind a cluster people treat as four separate problems: a higher resting pulse, night sweats, a short fuse, and sleep that will not come.

The brain's ability to strengthen and rebuild connections. It is what learning physically is, and it is the endpoint almost every nootropic peptide claims.

Turning immature precursors into working T-cells in the thymus. It falls off with age, and it is what every thymic peptide claims to restore.

Preserving the protective caps on chromosome ends that shorten each time a cell divides. Claims of telomerase activation belong here, and human evidence for them is thin.

The heart wall thickening and stiffening in response to sustained load and to androgen signalling in cardiac muscle. It is measured on an echocardiogram.