Peptide Glossary
Scientific terms explained in plain English. Bookmark this page — you'll need it.
A
Agonist
A substance that binds to a receptor and activates it, producing a biological response. For example, semaglutide is a GLP-1 agonist — it activates GLP-1 receptors.
AMPK
AMP-activated protein kinase. A cellular energy sensor that regulates metabolism. Activated by exercise and certain peptides like MOTS-c. Think of it as your cells' "fuel gauge" that triggers fat burning when energy is low.
Angiogenesis
The formation of new blood vessels. Important for healing and tissue repair. BPC-157 promotes angiogenesis, which is why it helps injuries heal faster.
Antagonist
A substance that blocks a receptor, preventing its activation. The opposite of an agonist.
B
BDNF
Brain-Derived Neurotrophic Factor. A protein that supports neuron survival and growth. Often called "brain fertilizer." Semax and exercise both increase BDNF levels.
Bioavailability
The proportion of a substance that enters circulation and is able to have an active effect. Oral peptides often have lower bioavailability than injected ones.
C
Cytoprotection
Protection of cells from harmful agents or conditions. BPC-157 is known for its cytoprotective effects on gut and other tissues.
D
Dual Agonist
A compound that activates two different types of receptors. Tirzepatide is a dual GLP-1/GIP agonist, hitting both receptors for enhanced effects.
F
FDA Approved
Officially approved by the U.S. Food and Drug Administration for specific medical uses. Means extensive human trials have proven safety and efficacy. Semaglutide, tirzepatide, and PT-141 are FDA approved.
G
GABA
Gamma-aminobutyric acid. The main inhibitory neurotransmitter in the brain — it calms neural activity. Selank modulates GABA for its anti-anxiety effects.
Gastric Emptying
The process of food leaving the stomach and entering the small intestine. GLP-1 agonists slow gastric emptying, which helps you feel full longer.
GH (Growth Hormone)
A hormone produced by the pituitary gland that stimulates growth, cell reproduction, and regeneration. Peptides like Ipamorelin and CJC-1295 stimulate natural GH release.
GHRH
Growth Hormone Releasing Hormone. The natural hormone that signals your pituitary to release GH. CJC-1295 is a GHRH analog.
GHRP
Growth Hormone Releasing Peptide. A class of peptides that stimulate GH release by mimicking ghrelin. Ipamorelin is considered one of the "cleanest" GHRPs.
GIP
Glucose-dependent Insulinotropic Polypeptide. An incretin hormone that enhances insulin secretion. Tirzepatide hits both GLP-1 and GIP receptors.
GLP-1
Glucagon-Like Peptide-1. An incretin hormone that reduces appetite, slows digestion, and improves blood sugar. The target of weight loss peptides like semaglutide.
Ghrelin
The "hunger hormone." Produced in the stomach, it signals your brain that you're hungry. Ipamorelin mimics ghrelin to trigger GH release.
Glucagon
A hormone that raises blood sugar and increases energy expenditure. Retatrutide is a triple agonist that includes glucagon receptor activation for additional fat-burning.
H
Half-Life
The time it takes for half of a substance to be eliminated from the body. Longer half-life means less frequent dosing. Semaglutide has a ~7 day half-life, enabling weekly dosing.
Hypothalamus
A brain region that controls hunger, thirst, body temperature, and hormone release. GLP-1 agonists work partly by affecting the hypothalamus to reduce appetite.
I
IGF-1
Insulin-like Growth Factor 1. A hormone produced in response to GH that mediates many of GH's effects on growth and metabolism.
Incretin
Gut hormones released after eating that stimulate insulin secretion. GLP-1 and GIP are the main incretins. "Incretin mimetics" like semaglutide mimic these hormones.
Intramuscular (IM)
Injection into a muscle. Some peptides like BPC-157 can be injected IM near an injury site for localized effects.
M
Melanocortin
A family of hormones and receptors involved in skin pigmentation, appetite, and sexual function. PT-141 works on melanocortin-4 receptors for sexual arousal.
Mitochondria
The "powerhouses" of cells — organelles that produce energy (ATP). MOTS-c is a mitochondrial-derived peptide that affects cellular energy metabolism.
N
Neuroprotection
Protection of nerve cells from damage or degeneration. Semax and BPC-157 both have neuroprotective properties.
Neuroplasticity
The brain's ability to reorganize and form new neural connections. BDNF-boosting peptides like Semax may enhance neuroplasticity.
Nootropic
A substance that enhances cognitive function — memory, focus, creativity, motivation. Semax and Selank are nootropic peptides.
P
PCT
Post Cycle Therapy. A protocol used after anabolic steroid cycles to restore natural hormone production. Kisspeptin is being explored for PCT applications.
Peptide
A short chain of amino acids (typically 2-50). Smaller than proteins. Many hormones and signaling molecules are peptides. All compounds on this site are peptides.
Pituitary
A small gland at the base of the brain that produces and releases hormones including GH, LH, and FSH. Many peptides work by stimulating the pituitary.
R
Receptor
A protein on or in cells that receives signals from hormones, drugs, or other molecules. Peptides work by binding to specific receptors.
Research Chemical
A compound sold for research purposes that hasn't been approved for human use. Most peptides outside of semaglutide/tirzepatide/PT-141 are technically research chemicals.
S
Secretagogue
A substance that promotes secretion. A "GH secretagogue" causes growth hormone to be secreted. Ipamorelin is a GH secretagogue.
Subcutaneous (SubQ)
Injection under the skin into the fat layer. The most common injection method for peptides. Easier and less painful than intramuscular.
T
Telomerase
An enzyme that maintains telomeres (chromosome caps). Epithalon activates telomerase, which is why it's called the "longevity peptide."
Telomeres
Protective caps at the ends of chromosomes that shorten with age. Longer telomeres are associated with longevity. Epithalon may help maintain telomere length.
Titration
Gradually increasing a dose over time. Semaglutide is titrated from 0.25mg up to 2.4mg over weeks to reduce side effects.
Triple Agonist
A compound that activates three different types of receptors. Retatrutide is a triple GLP-1/GIP/glucagon agonist with the highest weight loss seen in trials.
V
VEGF
Vascular Endothelial Growth Factor. A protein that promotes blood vessel formation (angiogenesis). BPC-157 increases VEGF expression.
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