Reference

Peptide Glossary

Plain-English definitions of the 136 terms you’re most likely to meet reading about peptides — from the science to the syringe to the lab report.

The basics

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Amino acid
The organic building block that chains together to form peptides and proteins. The human body uses 20 standard amino acids, sorted into three groups: essential (must come from food — the body can't make them), nonessential (the body makes on its own), and conditional (normally nonessential but needed in larger amounts during illness or stress). They also build tissue, hormones, neurotransmitters, and immune antibodies.
Analog
A deliberately modified copy of a natural peptide — typically with one or two amino acids swapped, added, or removed — usually so it lasts longer in the body or binds more strongly than the original. Most peptides you'll read about are analogs of something the body already makes.
Enzyme
A protein whose job is to speed up one specific chemical reaction. The enzymes that matter most for peptides are the chopping enzymes (peptidases) in blood and gut that break peptide chains apart — the reason many peptides don't survive being swallowed.
Fragment
A shorter piece snipped out of a longer peptide or protein's sequence. Researchers study fragments when one region of a molecule seems to carry most of its activity — the fragment alone is cheaper to make and easier to test.
Hormone
A chemical messenger released into the bloodstream to tell other organs what to do. Insulin is a hormone; so are growth hormone and GLP-1.
Peptide
A short chain of amino acids — typically 2 to around 50. Beyond that length the chains fold into what we call proteins, so peptides are the smaller cousins. A peptide's identity and effects come from which amino acids it contains and in what order.
Peptide bond
The chemical link that joins two amino acids into a chain. It forms when the carboxyl group of one amino acid reacts with the amino group of the next, releasing a molecule of water. Repeated peptide bonds are the backbone of every peptide and protein.
Protein
A long chain of amino acids — beyond roughly 50 — that folds into a specific three-dimensional shape to do its job. Peptides and proteins are the same chemistry at different lengths; the size difference changes how the body handles them.
Sequence
The exact order of amino acids in a peptide — its molecular identity. Change the order and you change the molecule: BPC-157 and TB-500 are different peptides precisely because their sequences differ, which is why they're studied for different things.

How peptides work in the body

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Agonist
A compound that binds a receptor and switches it on, mimicking the body's own signal. Think of it as turning the key in a lock: a growth-hormone secretagogue is an agonist at the receptor that releases growth hormone.
Antagonist
The opposite of an agonist: it occupies the receptor without activating it, blocking the natural signal from getting through.
Binding affinity
How tightly a compound attaches to its receptor — the strength of the fit. Higher affinity generally means less compound is needed for the same effect.
Bioavailability
The fraction of a dose that actually reaches the bloodstream — or its target — still active. Injected peptides are typically high bioavailability; swallowed peptides usually aren't, because digestion breaks them down first.
Endogenous
Made inside your own body. Endogenous growth hormone is what your pituitary produces; many peptides copy, mimic, or amplify an endogenous signal.
Exogenous
Coming from outside the body — injected, inhaled, or otherwise supplied rather than made by you. The complement of endogenous.
Half-life
The time it takes for half of a dose to be cleared from the body. A peptide with a 2-hour half-life needs far more frequent dosing than one engineered to last a week — one of the biggest reasons analogs exist.
Receptor
A molecular docking station on or inside a cell. A compound that fits the receptor triggers it and the cell responds — most peptides work by binding receptors on cell surfaces, and each receptor type governs a different effect.
Signaling pathway
The chain reaction that runs inside a cell after a receptor is triggered — one messenger switches on the next until the instruction reaches the cell's machinery. Effects described as 'downstream' are the later links in that chain.
Transporter
A molecular machine that shuttles specific substances across barriers — from blood into brain, or gut into blood. Whether a peptide uses (or blocks) a transporter often decides where in the body it can go.

Use & administration

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Bacteriostatic water
Sterile water containing a small amount of preservative (usually 0.9% benzyl alcohol). It's used to reconstitute lyophilized peptides for multi-dose vials because the preservative slows bacterial growth once the vial is punctured. Single-dose vials instead use plain sterile water.
Cycle
A defined period of use followed by a planned break — for example a 4-week cycle. 'Cycling' is community practice drawn from bodybuilding and anti-aging forums, not an established medical protocol, and the optimal lengths (if any) aren't well studied.
Insulin syringe
The standard measuring tool for injected peptides — marked in units on the same U-100 scale used for insulin. Adding more solvent when reconstituting lowers the concentration, so the same number of units delivers fewer micrograms; that conversion is what the reconstitution calculator does.
Intramuscular (IM)
An injection delivered into a muscle (common sites: deltoid, glute, thigh). Less common than SubQ for peptides; absorption can be faster but it tends to be more uncomfortable.
Nasal delivery
Absorbed through the lining of the nose. A middle ground between injection and swallowing: no needles, and some compounds partly bypass the barriers that stop them in the gut.
Protocol
Research shorthand for a reported dosing routine — the compound, the amount, how often, and for how long, as described in published sources or community reports. We call these routines on this site (a protocol can read like a prescription, and none of these are prescriptions); the word survives here because you will meet it everywhere in the literature.
Reconstitution
Mixing a lyophilized (freeze-dried) peptide powder with a sterile solvent — almost always bacteriostatic water — to turn it into a measurable injectable solution. The total volume of solvent determines the concentration per unit on an insulin syringe.
Route of administration
The way a compound gets into the body: injection under the skin or into muscle, nasal spray, by mouth, or on the skin. The route changes everything downstream — how fast it acts, how much survives, and how long it lasts.
Subcutaneous (SubQ)
An injection into the fatty tissue just beneath the skin (common sites: abdomen, thigh). It's the most common route for injectable peptides because it's easy to self-administer, low pain, and absorbs steadily.
Titration
Adjusting a dose step by step — often starting low — to find the smallest amount with the wanted effect. It's standard practice in prescription medicine; in community peptide use, reported titration schedules are just reports.
Topical
Applied to the skin surface. It works when a compound is small enough to penetrate — copper peptide in skincare creams is the common example.

Doses & amounts

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Microgram (mcg)
One-millionth of a gram — the unit peptide doses are usually measured in. Typical research doses are tens to hundreds of micrograms, and 1 mg equals 1,000 mcg: mixing the two up is a thousand-fold error.
Milligram (mg)
One-thousandth of a gram. Peptide vials are labeled in milligrams of powder (a 5 mg vial), while the dose taken is usually measured in micrograms — a thousand times smaller.
Milliliter (mL)
A unit of volume — one-thousandth of a liter. Reconstitution decides how many milliliters of solution a vial holds, and dosing math converts the milliliters drawn into an insulin syringe into micrograms of peptide.

Categories you'll see here

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Copper peptide (GHK-Cu)
A peptide complexed with a copper ion (GHK is the peptide sequence, Cu is the copper). Researched for skin, collagen, and tissue-repair effects and used topically in many skincare products as well as studied in research contexts.
GHRP / GHRH
Growth-hormone-releasing peptides (GHRP) and growth-hormone-releasing hormones (GHRH) — two classes that each stimulate the body's own growth-hormone pathway through different receptors (e.g. ipamorelin is a GHRP, CJC-1295 is a GHRH analog). They're often discussed, and sometimes combined, in research on GH support.
GLP-1
Glucagon-like peptide-1 — an incretin hormone pathway involved in insulin release and appetite. It's the target of approved medicines such as semaglutide (Ozempic/Wegovy) and tirzepatide (Mounjaro/Zepbound), used for diabetes and weight management.
Secretagogue
A substance that prompts the body to release something. A growth-hormone secretagogue, for instance, signals the body to release more of its own GH rather than supplying GH directly.

Compound families in the library

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Amylin analog
A copy of amylin, a small hormone the pancreas releases alongside insulin that slows stomach emptying and signals fullness. Pramlintide is the approved example; cagrilintide is a longer-acting analog often mentioned alongside the GLP-1 medicines.
Antimicrobial peptide
A peptide the immune system wields as a fast-acting chemical weapon against bacteria, viruses, and fungi. LL-37 and the defensins are the human types you'll see most; both are also studied for wound healing and for calming excess inflammation.
GnRH analog
A copy of gonadotropin-releasing hormone, the brain signal that runs the reproductive hormone assembly line — LH and FSH downstream, then testosterone or estrogen after that. Gonadorelin is the natural-sequence version; leuprorelin and goserelin are modified versions that can either stimulate the axis or shut it down, depending on the dosing pattern.
Gut hormone
A hormone released by the lining of the gut that coordinates digestion, appetite, and blood sugar — the gut is one of the body's biggest hormone producers. Secretin, gastrin, ghrelin, and GLP-1 are all gut hormones, and a large share of the compounds in our library are these hormones or engineered copies of them.
Incretin
A gut hormone released when you eat that tells the pancreas to release insulin and tones down glucagon. GLP-1 and GIP are the two human incretins, and most of the well-known injection medicines for blood-sugar and weight management are incretin copies engineered to last far longer than the natural signal.
Kisspeptin
A brain peptide that conducts the reproductive hormone cascade: it triggers GnRH release, which triggers LH and FSH, which drive testosterone and estrogen. Studied in fertility research and as a gentler way to nudge the same axis that GnRH agonists hit directly.
Melanocortin
A family of signals built from the hormone α-MSH that acts through five receptors with very different jobs: skin pigmentation, appetite, inflammation, and sexual function. Melanotan and bremelanotide are synthetic melanocortin agonists — same family, very different research targets.
Mitochondrial-derived peptide
A recently recognized family of small peptides produced by mitochondria, the cell's power plants — MOTS-c and humanin are the named members. They're studied for metabolism, exercise-like effects, and aging; SS-31 is a separate molecule built to target mitochondria directly.
Multi-agonist
An engineered compound designed to activate two or three different hormone receptors at once — the bet being that matching the combined signals of several gut hormones outperforms copying just one. Tirzepatide (two targets) and retatrutide (three) are the best-known examples.
Myostatin inhibitor
Something that blocks myostatin, the hormone that acts as the body's brake on muscle growth — release the brake and muscle mass increases. Follistatin is a naturally occurring myostatin-binding protein studied for exactly this purpose.
Neuropeptide
A peptide that works as a messenger in the brain and nervous system. Oxytocin, vasopressin, neuropeptide Y, and DSIP are all neuropeptides — they modulate mood, sleep, stress, and social behavior as much as (or more than) physical processes.
Nootropic
A compound studied or taken for cognitive effects — focus, memory, resilience under stress. In the peptide space the examples are Selank and Semax (nasal neuropeptide analogs), Noopept (a small molecule), and Cerebrolysin (a mixture of brain-derived peptides).
PTH analog
A copy of parathyroid hormone, the body's main calcium-regulating hormone — given in intermittent pulses it switches on bone building. Teriparatide and abaloparatide are the approved examples, and both come with a standing requirement to keep calcium and vitamin D intake adequate.
Thymic peptide
A peptide associated with the thymus, the gland behind the breastbone that trains immune cells. Thymosin alpha-1 (immune modulation) and thymosin beta-4 — whose active fragment is TB-500, studied for tissue repair — are the two you'll meet most often.

Blends & stacks

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Blend
Multiple peptides premixed into a single product by the seller — a named blend vial — rather than combined by the user. Convenient, but you take the mix exactly as made and rely on the maker's ratios.
Stack
A combination of compounds taken together for a shared goal. Our stack pages describe reported combinations — what's in them, the claimed rationale, and what the evidence does and doesn't support.
Synergy
The idea that two compounds together produce more than the sum of their parts. Genuine synergy is hard to prove — it takes head-to-head testing of the combination against each compound alone, which most stack claims never had.

Quality & sourcing

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Batch (lot) number
The identifier tying a specific vial to when and where it was made — printed on the label and matched to the COA. If a problem ever surfaces, the batch number is what makes a retest or recall possible.
COA (Certificate of Analysis)
A lab report confirming what's actually in a batch — typically the peptide's identity and purity, sometimes quantified by method (e.g. HPLC). Only a third-party (independent) COA is meaningful; a vendor's in-house lab has a built-in conflict of interest and isn't independent verification.
Counterion (salt form)
The mild acid or base attached to a peptide to keep it stable as a powder — usually acetate or TFA (trifluoroacetate). The same peptide can ship as either salt; it doesn't change the peptide itself, but it appears on the COA and slightly changes the powder's weight.
Endotoxin
Fragments of certain bacteria that survive sterilization and, if present in an injectable, can cause fever and strong immune reactions. A clean purity number says nothing about endotoxin — it's a separate test on a proper COA.
HPLC
High-performance liquid chromatography — the lab technique a COA usually relies on to separate what's in a sample and measure purity. When a vendor quotes '98% pure,' HPLC is typically how it was measured.
Lyophilized
Freeze-dried into a dry powder. It's the stable, shippable form most research peptides come in — dehydrated for shelf life, then reconstituted with bacteriostatic water before use.
Mass spectrometry
A lab technique that weighs molecules to confirm identity — the standard 'is this actually the peptide on the label' check, often reported alongside HPLC purity on a COA.
Purity
The fraction of the sample that is the stated peptide — e.g. '99%+ pure' — as measured on the COA (usually by HPLC). Purity is about how much of the powder is the right molecule, which is distinct from whether it's sterile, endotoxin-free, or accurately dosed.
Research chemical
The legal label under which most peptides are sold — 'for research use only, not for human consumption.' This is the category that allows them to be sold at all, and it's also exactly why buyers should be cautious: the label means no assurance of human-grade quality, sterility, or dosing accuracy.
Sterility
Freedom from living microbes. It's a separate property from purity — a vial can be 99% pure peptide and still be contaminated — and it's guaranteed by how and where the vial was filled, not by the peptide itself.

Reading the research

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Anecdotal evidence
Individual reports of what happened to one person — forum posts, reviews, a friend's story. Useful for spotting questions worth asking; unreliable as proof, because there's no control group, no measurement, and memory keeps the highlights.
Clinical trial
A controlled study in humans, with defined doses and measured outcomes. It's the step that separates 'looks good in rats' from 'did what we expected in people.'
Double-blind
Neither the participants nor the researchers know who gets the real compound until the study ends — preventing expectation from coloring what's measured or reported.
Efficacy
How well something works under a study's conditions — the size of the measured effect, not just whether any effect appeared at all.
In vitro / in vivo
Latin shorthand you'll meet in study summaries: in vitro means outside a living body (cells or tissue in a dish); in vivo means inside a living organism. A result can hold in vitro and fail in vivo — the body is more complicated than a dish.
Mechanism of action
How a compound produces its effect — the specific biological steps, not just the outcome. 'Lowers appetite' is an effect; 'activates the GLP-1 receptor and slows stomach emptying' is a mechanism.
Peer-reviewed
Screened by independent experts before publication — a journal's basic quality gate. It catches many errors, but it's a floor, not a gold star: peer review approves a study for publication, not its conclusions for you.
Placebo
An inactive look-alike given to a control group so expectation alone can be ruled out. If a study has no placebo arm, 'people felt better' can simply mean 'people expected to.'
Preclinical
Research done before human testing — cells in a dish or animal studies. Most peptide claims start here; it's a promising signal, not proof of what happens in people.
Randomized controlled trial
The cleanest common study design: participants are randomly assigned to the compound or a control group, so differences in outcomes trace to the compound rather than to selection or expectation.
Trial phases
The staged sequence of human testing: Phase 1 checks safety in a small group, Phase 2 tests effect and dose, Phase 3 confirms the result against standard treatment in large groups. A compound can stall at any phase — most do.

Regulatory terms

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Controlled substance
A drug scheduled under federal law (DEA schedules I–V) based on abuse potential — the category that restricts opioids and stimulants. Most peptides aren't controlled substances; their gray zone comes from being unapproved rather than scheduled.
Dietary supplement
A legal product category (vitamins, herbs, protein powders) regulated as food, with no approval needed before sale. Pure peptide products don't qualify — anything injectable sold as a 'supplement' is mislabeled.
FDA
The U.S. Food and Drug Administration — the agency that approves medicines and polices what may be sold for human use. Most research peptides are not FDA-approved; they occupy a gray zone sold 'for research use only.'
FDA-approved
Formally cleared by the FDA as safe and effective for a specific use in people — the bar prescription medicines clear. When a page here marks something approved, it means an approved medicine containing that ingredient (semaglutide, for example), not the research-grade market.
Investigational drug
A compound in the formal pipeline of human testing but not yet approved — it has an Investigational New Drug (IND) application on file with the FDA. That's a legal status, not a promise it will ever be approved.

Blood sugar & metabolism

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Beta cell
The insulin-producing cells in the pancreas. Much diabetes research is about protecting them or nudging them to work harder; 'β-cell mass' is how many are left alive and functioning.
DPP-4
An enzyme whose job is to chop up GLP-1 and other incretins soon after the body releases them. DPP-4 inhibitor drugs (sitagliptin, vildagliptin) work by blocking the chopper, letting the body's own GLP-1 last longer.
GIP
The second human incretin alongside GLP-1 — released by the gut after eating, acting on its own receptor to shape insulin release. Tirzepatide copies GLP-1 and GIP together, which is why it's called a dual agonist.
HbA1c
A blood test that reports your average blood sugar over the past two to three months, as a percentage. It's the standard yardstick in diabetes research: a compound that 'lowers HbA1c' lowered average blood sugar over time, not today's reading.
Insulin resistance
When the body's response to insulin grows weak, so it takes more and more insulin to move the same sugar out of the blood. It sits upstream of type 2 diabetes and is a common target in metabolic research.
Lipolysis
The breakdown of stored fat into fatty acids the blood can carry off to be burned. Fat-loss compounds are usually described as 'promoting lipolysis' — releasing fat from storage is step one of using it.
Metabolism
The sum of the body's chemistry — every reaction that builds, breaks, and converts. 'Metabolic' research covers blood sugar, fat, appetite, and energy, which is where many of these compounds sit.
SGLT2 inhibitor
A class of diabetes and kidney-protecting medicine (empagliflozin, dapagliflozin) that makes the kidneys flush excess sugar out in urine. Appears in these pages as a comparison therapy.
Thermogenesis
Heat production by the body — burning fuel for warmth rather than work. 'Increased thermogenesis' in a research summary means more calories burned as heat.
Type 2 diabetes (T2D)
The form of diabetes where the body still makes insulin but responds to it poorly, so blood sugar stays high. Most of the metabolic peptides and GLP-1 medicines are studied against it.

Molecular-biology shorthand in research summaries

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AMPK
AMP-activated protein kinase — the cell's fuel-gauge enzyme. When energy runs low it switches on pathways that burn fat and generate energy, which is why exercise-mimicking compounds are often described as 'activating AMPK'.
Angiogenesis
The growth of new blood vessels. Wound-healing research wants more of it where tissue is starved; cancer research wants less of it feeding tumors.
Apoptosis
A cell's orderly, built-in self-destruct — recycling itself without spilling inflammation. Distinct from necrosis (messy, damaging death). 'Anti-apoptotic' means protecting cells from dying.
BDNF
Brain-derived neurotrophic factor — a growth factor that keeps brain cells alive and helps them wire and rewire. 'Increasing BDNF' shows up throughout cognition and neuroprotection research.
Blood-brain barrier
The tightly sealed lining of the brain's blood vessels that keeps most bloodborne substances out of the brain. A peptide 'crossing the BBB' is a big deal: most can't, which is why nasal sprays and direct injections come up.
Cell proliferation
Cells multiplying by division. In these summaries it usually refers to tissue-repair cells (fibroblasts, endothelial cells) multiplying at a repair site.
COX-2
Cyclooxygenase-2 — an enzyme switched on during inflammation that produces pain- and fever-signaling molecules. Classic anti-inflammatory drugs (ibuprofen) block it; some peptides are studied as gentler ways to the same end.
Cytokine
Small messenger proteins the immune system uses to signal — ramping inflammation up or down. IL-6 and TNF-α are the ones you'll meet most often in these summaries.
Dopamine
A neurotransmitter central to motivation, reward, and movement. 'Dopaminergic' describes the systems that use it; Parkinson's drugs and several nootropics act on it.
Endocrine / exocrine
Two ways glands deliver: endocrine means releasing hormones into the bloodstream (far-reaching, slower); exocrine means releasing through ducts to a specific surface (digestive enzymes, sweat).
Fibrosis
Thick scar tissue forming where sustained inflammation or injury has damaged an organ — the lung, liver, or heart stiffening as connective tissue replaces working tissue.
Gene expression
Whether and how strongly a gene is being read into its product at a given moment. 'Increased BDNF expression' means the gene is being read more and more of its protein is being made.
Inflammation
The immune system's response to injury or irritation: redness, swelling, heat, and pain, driven by messenger chemicals. Useful in bursts, damaging when it stays switched on — a large share of peptide research is about calming chronic inflammation.
Interleukin
A family of cytokines (immune messenger proteins), written IL- plus a number — IL-1β, IL-6, IL-8. Each number is a different messenger; most appear in these pages as markers of inflammation rising or falling.
Intracellular / extracellular
Inside a cell versus outside it. An 'intracellular target' means the compound has to get through the cell membrane to work — a high bar that shapes how a peptide must be delivered.
Kinase
An enzyme that attaches a small phosphate tag to other proteins — one of the cell's commonest on/off switches. 'Phosphorylation' is the tagging itself; whole drug classes work by blocking specific kinases.
Neurogenesis
The birth of new neurons — once thought impossible in adults, now measured in small numbers in specific brain regions. A target in cognition and mood research.
Neuroinflammation
Inflammation inside the brain and nervous system — the brain's immune cells switched on. Studied as a contributor to cognitive decline, depression, and neurodegenerative disease.
NF-κB
A master switch protein inside cells that, when activated, travels to the nucleus and switches on inflammation-producing genes. Many anti-inflammatory peptides are described as 'inhibiting NF-κB' — turning that switch down.
Oxidative stress
Damage from reactive oxygen species (ROS) — unstable oxygen by-products of metabolism that attack proteins, fats, and DNA. The body keeps them in check with antioxidants; 'reducing oxidative stress' means restoring that balance.
Permeability
How easily substances pass through a barrier — in these pages, most often the gut lining. 'Increased intestinal permeability' means the barrier has loosened, letting material through that shouldn't pass.
Synaptic plasticity
The ability of the connections between neurons to strengthen or weaken with use — the cellular basis of learning and memory.
TGF-β
Transforming growth factor-beta — a large family of signaling proteins that, among many jobs, tells cells to build connective tissue and can push fibrosis. Myostatin belongs to the same superfamily.
TNF-α
Tumor necrosis factor-alpha — one of the immune system's strongest inflammation signals. Drugs that block TNF-α (like adalimumab) treat autoimmune disease; peptides described as 'reducing TNF-α' are turning the same dial down.
Transcription
The first step of reading a gene — copying its DNA into a working RNA message. A 'transcription factor' is a protein that decides which genes get read.

Conditions & lab values in these pages

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ACTH
Adrenocorticotropic hormone — the pituitary's signal telling the adrenal glands to release cortisol. The middle link of the stress-hormone chain.
Anxiolytic
Something that reduces anxiety. The word covers both prescription medicines and compounds described as having calming effects in research.
Atherosclerosis
Cholesterol-laden plaque building up inside artery walls, narrowing and stiffening them — the process behind most heart attacks and strokes.
C-reactive protein (CRP)
A protein the liver releases during inflammation — the most common single blood marker for how active inflammation is. 'Lowered CRP' is how many anti-inflammatory effects get measured.
Cholesterol (LDL/HDL)
The standard blood-fat panel: LDL and VLDL are the carriers that deliver fat to artery walls (lower is better); HDL carries it back out (higher is better).
CNS
The central nervous system — brain and spinal cord, as opposed to the nerves running out to the body. 'CNS effects' means effects on mood, cognition, sleep, or pain processing.
Fatty liver disease (MASLD/MASH)
Fat building up in the liver (steatosis, now called MASLD), which in some people progresses to inflammation and damage (MASH, formerly NASH). It's the liver version of metabolic disease — the condition GLP-1 medicines are increasingly studied for.
First-line treatment
The treatment guidelines recommend trying first for a condition — usually the best-evidence, best-tolerated option. 'Second-line' comes after.
FSH / LH
Follicle-stimulating hormone and luteinizing hormone — the pituitary signals that run the reproductive cascade: FSH grows follicles and the sperm supply, LH triggers ovulation and testosterone production. Kisspeptin and GnRH work upstream of both.
GLP-1 receptor
The docking site GLP-1 and its copies activate. A 'GLP-1 receptor agonist' (GLP-1RA) is a molecule built to switch it on — the drug class semaglutide and tirzepatide belong to.
Hypertension
Blood pressure that stays too high (hypertension) — a silent strain on heart, brain, and kidneys. Hypotension is the opposite: pressure too low, causing dizziness and fainting.
Hypogonadism
The sex glands (testes or ovaries) producing too little hormone — low testosterone or estrogen. A target of HCG, kisspeptin, and GnRH-related research.
IBD
Inflammatory bowel disease — the umbrella for Crohn's disease and ulcerative colitis, chronic inflammation of the digestive tract. Gut-repair peptides (BPC-157, KPV) are mostly studied in IBD models.
Immunogenicity
A substance's tendency to provoke an immune reaction — antibodies forming against it. High immunogenicity can make a therapeutic protein stop working over time; it's a watched safety measure for injected peptides.
Infarction
Tissue dying because its blood supply was cut off. A myocardial infarction is the heart-muscle version — the classic heart attack.
Ischemia / reperfusion
Ischemia is blood flow being cut off, depriving tissue of oxygen; reperfusion is flow returning. Counterintuitively, the return itself injures tissue — 'ischemia-reperfusion injury' is a standard model in cardiac and organ research.
Murine model
An experiment in mice or rats (murine means mouse-family). The workhorse of early peptide research — suggestive, but a mouse result is a reason to study something in humans, not evidence it works in them.
Osteoporosis
Bones thinning past the point of strength, until ordinary stresses can fracture them. Bone mineral density (BMD) is the scan measurement used to track it — 'increased BMD' means denser bone.
Pancreatitis
Inflammation of the pancreas — the gland behind the stomach that makes insulin and digestive enzymes. It comes on as severe upper-abdominal pain, and some diabetes medicines carry it as a watched side effect.
PCOS
Polycystic ovary syndrome — a common hormonal disorder where ovaries produce excess male-type hormones, disrupting cycles and fertility, often traveling with insulin resistance.
Priapism
An erection that lasts hours and will not subside — a medical emergency that can permanently damage tissue. Listed wherever melanotan-type compounds carry it as a reported risk.

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