Reference

Glossary

Plain-language definitions for the mechanism terms, hormones, lab markers, and units used across the library — 60 terms and counting.

60 terms

Mechanism & cell biology

Agonist: A molecule that binds a receptor and switches it on, triggering the cell's response. Most peptides here are agonists of a specific receptor.
Amino acid: The building blocks of peptides and proteins. A peptide's sequence is its specific order of amino acids.
AMPK: A cellular energy sensor that switches on when energy is low, promoting fat-burning and mitochondrial work.
Analog: A man-made molecule designed to closely mimic a natural one, often modified to last longer or act more strongly.
Angiogenesis: The growth of new blood vessels — central to how tissue-repair peptides bring fresh blood supply to healing tissue.
Antagonist: A molecule that binds a receptor and blocks it, preventing the normal signal from firing.
cAMP: A small messenger inside the cell that relays a receptor's signal onward; many hormone receptors raise cAMP when activated.
Cytokine: A small signaling protein immune cells release to coordinate a response; 'pro-inflammatory' cytokines amplify inflammation.
Desensitization: When a receptor becomes less responsive after sustained stimulation — the reason many peptides are cycled with planned breaks.
Lipohypertrophy: Fatty lumps under the skin from injecting the same spot repeatedly; rotating injection sites prevents it.
MAP kinaseMAPK: A signaling pathway that relays growth and stress messages from the cell surface to the nucleus.
mTOR: A central cellular sensor that drives growth and protein-building when nutrients and growth signals are plentiful.
NF-κB: A master 'switch' protein inside cells that drives inflammatory signaling. Several peptides act by turning it down.
PepT1: A transporter protein that carries small two- and three-amino-acid peptides into cells; some peptides rely on it to get inside.
Peptide: A short chain of amino acids — smaller than a protein. Every compound in this library is a peptide or a peptide-like molecule.
Receptor: A protein — usually on the cell surface — that acts as a switch: when the right molecule docks, it starts a signal inside the cell.
Secretagogue: A compound that prompts a gland to secrete a hormone. A GH secretagogue prompts the pituitary to release growth hormone.
SirtuinsSIRT1: A family of enzymes that regulate metabolism, stress resistance, and aging. They depend on NAD+ to work.
Tachyphylaxis: Rapid loss of response to a compound with repeated dosing — why some peptides are pulsed rather than run continuously.

Hormones & signaling

ACTH: Adrenocorticotropic hormone: the pituitary signal that tells the adrenal glands to make cortisol.
BDNF: Brain-derived neurotrophic factor: a protein that supports the survival and growth of neurons. Several nootropic peptides raise it.
FSH: Follicle-stimulating hormone: a pituitary hormone that governs sperm and egg production.
GHRH: Growth-hormone-releasing hormone: the natural signal that tells the pituitary to release GH. Several peptides are GHRH analogs.
GHRP / ghrelin receptor: Growth-hormone-releasing peptides act on the ghrelin receptor to trigger a GH pulse — a lever complementary to GHRH.
GIP: Glucose-dependent insulinotropic polypeptide: a second incretin gut hormone. Some newer molecules target both GIP and GLP-1.
GLP-1: Glucagon-like peptide-1: a gut hormone that boosts insulin, slows the stomach, and reduces appetite — the basis of the GLP-1 weight class.
Growth hormoneGH: The pituitary hormone that drives growth, repair, and metabolism. Many peptides here aim to raise it.
hCG: Human chorionic gonadotropin: mimics LH to stimulate the gonads; used to keep the testes functioning during other protocols.
HPA axis: The hypothalamic-pituitary-adrenal axis: the body's central stress-response system, ending in cortisol release.
HPG axis: The hypothalamic-pituitary-gonadal axis: the chain of signals (GnRH → LH/FSH → testosterone/estrogen) that controls reproduction.
IGF-1: Insulin-like growth factor 1: the downstream hormone (mostly made by the liver) through which GH produces much of its growth and repair effect. Also a key lab marker.
Insulin: The hormone that lowers blood sugar by moving glucose out of the blood and into cells.
Luteinizing hormoneLH: A pituitary hormone that signals the gonads — testosterone production in men, ovulation in women.
Melanocortin receptorsMC1R–MC5R: A family of five receptors that α-MSH-like peptides act on — MC1R for pigment, MC4R for appetite and erection, others for immune and adrenal roles.
NAD+: A coenzyme central to energy production and DNA repair that declines with age. Sirtuins depend on it to work.
Prolactin: The pituitary hormone behind milk production. Some peptides can raise it, which matters for side effects.
SHBG: Sex-hormone-binding globulin: a blood protein that binds sex hormones and sets how much is free and active.
VEGF: Vascular endothelial growth factor: the main signal that drives new blood-vessel growth.
α-MSH: Alpha-melanocyte-stimulating hormone: drives skin pigmentation and carries anti-inflammatory activity. Several peptides are fragments or analogs of it.

Administration & formulation

Bacteriostatic water: Sterile water with 0.9% benzyl alcohol added as a preservative, so a single vial can be drawn from repeatedly over weeks.
Every other dayEOD: A dosing schedule of one dose every two days — common for longer-acting peptides.
Insulin unitIU: The marks on an insulin syringe. On a U-100 syringe, 100 units = 1 mL; the calculator converts a dose to units.
IntramuscularIM: An injection into muscle. It absorbs on a different curve than a subcutaneous injection.
Intranasal: Delivery as a nasal spray — the primary route for a few peptides such as Semax and Selank.
Lyophilized: Freeze-dried into a stable powder — how peptides ship before you reconstitute them.
Reconstitution: Dissolving a lyophilized peptide powder in bacteriostatic water to make an injectable solution. The calculator does the math.
SubcutaneousSubQ: An injection into the fat just under the skin — the standard route for the research peptides in this library.
Titration: Starting low and stepping the dose up gradually to limit side effects — standard for the GLP-1 peptides.
Washout: A planned break between cycles that lets receptors re-sensitize before dosing resumes.

Lab markers

Fasting insulin: Insulin measured after an overnight fast — a marker of how sensitive the body is to insulin.
Ferritin: The body's stored-iron marker; checked around recovery and performance protocols.
HbA1c: A blood test reflecting average blood sugar over the past ~3 months; tracked with metabolic peptides.
hs-CRP: High-sensitivity C-reactive protein: a blood marker of low-grade, body-wide inflammation.
Lipid panel: A blood test of cholesterol and triglycerides; watched with the GLP-1 and metabolic peptides.
MCAS: Mast cell activation syndrome: a condition of over-reactive mast cells releasing histamine and other inflammatory mediators.

Pharmacology & units

Bioavailability: The fraction of a dose that actually reaches the bloodstream — high for injection, lower for oral or nasal routes.
Half-life: The time it takes for the blood level of a compound to fall by half. It sets how often you need to dose.
IC50: The concentration of a compound that produces half its maximum effect — a potency measure reported in lab studies.
mcg / mg: Units of mass: 1 mg = 1,000 mcg (micrograms). Peptide doses are usually given in mcg or mg.
PharmacokineticsPK: How the body absorbs, distributes, and clears a compound over time — the source of a peptide's half-life.