Reference entries on peptides, receptors, and pharmacology concepts.
The peptide Encyclopedia is a comprehensive reference covering every aspect of polydeoxyribonucleotide science — from molecular mechanisms and receptor pathways to formulation technology and regulatory standards. Each entry is peer-reviewed and regularly updated as new research emerges.
ACE2 sits at the intersection of cardiovascular regulation and viral entry. This enzyme converts angiotensin II into the protective peptide Ang 1-7, activating the Mas receptor axis — a counter-regulatory pathway with therapeutic potential.
The JAK-STAT pathway is the primary signaling cascade for peptide hormones like growth hormone, erythropoietin, and interferons. Understanding it explains both peptide hormone biology and why JAK inhibitors affect hormonal signaling.
Gut bacteria produce, modify, and respond to peptides in ways that profoundly influence immunity, metabolism, and brain function. Understanding these interactions is essential for developing effective oral peptide therapies.
Peptides can misfold and self-assemble into amyloid-like fibrils — a process relevant to both neurodegenerative disease and the stability of peptide therapeutics. Understanding aggregation mechanisms is key to prevention.
Lipidation — attaching fatty acid chains to peptides — transforms drugs that last minutes into therapies that work for days or weeks. This modification underpins semaglutide, liraglutide, and the entire GLP-1 agonist class.
AMP-activated protein kinase (AMPK) is the master fuel gauge of the cell, sensing energy deficits and activating catabolic pathways while suppressing anabolic ones — a critical node for understanding how metabolic peptides like MOTS-c exert their effects.
Bioregulator peptides are ultra-short (2-4 amino acid) synthetic peptides developed by Vladimir Khavinson and colleagues, proposed to modulate gene expression in specific tissues — a distinctive Russian research tradition with decades of clinical use and ongoing debate about evidence quality.
The enteric nervous system is an independent neural network embedded in the gut wall that uses peptide neurotransmitters to coordinate digestion, immune defense, and communication with the brain.
Growth hormone is secreted in discrete pulses rather than continuously — a temporal pattern that is essential for its biological effects on growth, metabolism, and gene expression.
NF-κB is the master transcription factor driving inflammatory gene expression — and a primary target of anti-inflammatory peptides like KPV and alpha-MSH that suppress cytokine production at the nuclear level.
Peptides can self-assemble into aggregates, gels, or amyloid-like fibrils under certain conditions — a process that reduces potency and can alter biological activity in reconstituted solutions.
The PI3K/Akt/mTOR signaling cascade is the central growth and survival pathway activated by IGF-1 and insulin — and indirectly by GH secretagogue peptides — with important implications for both anabolic benefit and cancer risk at sustained supraphysiological levels.
The ubiquitin-proteasome system is the cell's primary machinery for degrading intracellular proteins and peptides — a fundamental barrier to peptide bioavailability that drives modern strategies in peptide drug engineering.
Receptor desensitization is the progressive loss of cellular response to repeated or sustained agonist exposure — a fundamental pharmacological mechanism that shapes how peptide therapies are dosed and cycled.
SNARE proteins drive neurotransmitter vesicle fusion at the neuromuscular junction — the same mechanism targeted by botulinum toxin and mimicked at much lower potency by cosmetic peptides like Argireline and SNAP-8.
The glucose-dependent insulinotropic polypeptide (GIP) receptor mediates the other half of the incretin effect — complementing GLP-1 in glucose-dependent insulin secretion, adipose tissue metabolism, and bone health. Dual GLP-1/GIP agonists like tirzepatide and triple agonists like retatrutide exploit GIPR signaling to achieve metabolic effects beyond what GLP-1 agonism alone can deliver.
The GLP-1 receptor is a class B G-protein-coupled receptor expressed across the pancreas, brain, heart, and gut that mediates the incretin effect — glucose-dependent insulin secretion after oral nutrient intake. GLP-1 receptor agonist peptides like semaglutide and liraglutide have transformed the treatment of type 2 diabetes and obesity.
Nitric oxide (NO) is a gaseous signaling molecule with critical roles in vasodilation, neurotransmission, immune defense, and tissue repair. BPC-157 modulates the NO system at multiple levels — interacting with all three NOS isoforms and the downstream cGMP pathway — which contributes to its broad therapeutic profile across vascular, gastrointestinal, and musculoskeletal contexts.
Satellite cells are the resident stem cells of skeletal muscle, responsible for postnatal muscle growth, repair after injury, and regenerative capacity throughout life. Several peptides — including MGF, IGF-1, HGH, and BPC-157 — directly influence satellite cell activation, proliferation, and differentiation, making them central to muscle recovery protocols.
Somatostatin is the primary inhibitory regulator of growth hormone secretion, acting through five receptor subtypes to suppress GH release from the anterior pituitary. Understanding somatostatin tone is essential for grasping how GH secretagogue peptides like ipamorelin, GHRP-6, and sermorelin achieve their effects.
The thymus gland is the primary organ of T-cell development and adaptive immune education. Its progressive involution with aging drives immune decline (immunosenescence), and thymic peptides — Thymosin Alpha-1, Thymalin, and Thymulin — represent therapeutic strategies to restore thymic function and immune competence.
Vascular endothelial growth factor (VEGF) is the master regulator of angiogenesis — the formation of new blood vessels from existing vasculature. Healing peptides including BPC-157 and TB-500 accelerate tissue repair in part by upregulating VEGF expression and VEGF receptor signaling, providing the vascular infrastructure that all regenerating tissues require.
The Wnt/beta-catenin signaling pathway is a master regulator of stem cell self-renewal, tissue regeneration, and hair follicle cycling. Several peptides modulate Wnt signaling — GHK-Cu through gene expression reprogramming, BPC-157 through tissue repair interactions, and TB-500 through developmental pathway crosstalk.
Cytokines are small signaling proteins that orchestrate immune responses, inflammation, and tissue repair. Several therapeutic peptides exert their effects by modulating cytokine production — either dampening pro-inflammatory cascades or restoring balance between opposing cytokine networks.
Fibroblasts are the primary cells responsible for producing and maintaining the extracellular matrix — including collagen, elastin, and fibronectin. They are the direct cellular target of many regenerative and cosmetic peptides.
Immunomodulation is the targeted adjustment of immune responses — enhancing underactive immunity or suppressing overactive inflammation. Peptides derived from the thymus, mucosal surfaces, and synthetic design offer precise immunomodulatory mechanisms distinct from broad-spectrum immunosuppressants.
Proteolysis is the enzymatic hydrolysis of proteins into smaller peptides and amino acids. It is both the primary obstacle to peptide drug stability and the biological process that generates many bioactive peptides in vivo.
Telomerase is the reverse transcriptase enzyme that extends telomeres, counteracting the replicative clock of cellular aging. Its therapeutic activation by peptides like Epitalon represents one of the most direct molecular interventions in the biology of aging.
Apoptosis is the genetically programmed process of cell death that eliminates damaged, infected, or unnecessary cells. Peptides such as humanin, SS-31, and FOXO4-DRI modulate apoptotic signaling through the Bcl-2 family, caspase cascades, and senescent cell clearance.
Epigenetics governs gene expression changes that occur without altering the underlying DNA sequence — through DNA methylation, histone modifications, and non-coding RNA regulation. Bioregulator peptides (Khavinson peptides) and telomerase-activating peptides like Epitalon interact with epigenetic mechanisms to influence aging and cellular function.
Hormesis is the biological phenomenon where low-dose stressors trigger adaptive responses that enhance cellular resilience and longevity. Understanding hormetic dose-response curves is essential for appreciating how peptides like MOTS-c interact with exercise, fasting, and cold exposure pathways.
Insulin resistance is the diminished cellular response to insulin that underlies metabolic syndrome, type 2 diabetes, and cardiovascular disease. Peptides including GLP-1 receptor agonists, MOTS-c, and 5-Amino-1MQ address insulin resistance through distinct mechanisms involving incretin signaling, AMPK activation, and NNMT inhibition.
Neuroplasticity is the brain's ability to reorganize its structure and function throughout life by forming new synaptic connections and generating new neurons. Peptides like Semax, Cerebrolysin, and Dihexa enhance neural plasticity through BDNF upregulation, NGF modulation, and HGF receptor activation.
Emerging research on how peptides interact with the gut microbiome — from endogenous antimicrobial peptides (defensins, LL-37) that shape microbial communities to exogenous peptides like BPC-157 and GLP-1 agonists that alter gut flora composition and barrier function.
Receptor downregulation is the reduction in receptor density or sensitivity following sustained agonist exposure. It is the molecular basis for peptide cycling protocols and explains why continuous use of GH secretagogues, GnRH agonists, and other peptides often produces diminishing returns.
Visceral adipose tissue (VAT) is metabolically active fat surrounding the abdominal organs. It drives insulin resistance, systemic inflammation, and cardiovascular risk — and several peptides (tesamorelin, GLP-1 agonists) preferentially target it.
The ghrelin receptor (GHSR) is the primary target of growth hormone secretagogues like ipamorelin, GHRP-6, and hexarelin. Understanding its signaling, desensitization, and constitutive activity explains why GH secretagogue protocols require specific dosing strategies.
Oxidative stress occurs when reactive oxygen species overwhelm cellular antioxidant defenses. Peptides like SS-31, GHK-Cu, and MOTS-c modulate oxidative damage through distinct mechanisms — from mitochondrial membrane stabilization to gene expression reprogramming.
Tight junctions are the protein complexes that seal the spaces between epithelial cells. Their integrity determines intestinal permeability — and their dysfunction is central to 'leaky gut' and the rationale for peptides like BPC-157 and larazotide.
Angiogenesis — the formation of new blood vessels from existing vasculature — is a critical mechanism through which healing peptides like BPC-157, TB-500, and GHK-Cu accelerate tissue repair.
The blood-brain barrier is the primary challenge for neuroactive peptides. Understanding how it works — and which peptides can cross it — determines whether a peptide can have central nervous system effects.
How circadian biology affects peptide dosing timing — why GH secretagogues are taken before bed, why cortisol-affecting peptides should align with the HPA axis rhythm, and how peptides like DSIP and Epithalon interact with the circadian system.
Understanding dose-response curves in peptide therapy — why more is not always better, how hormetic responses work, and why peptide dosing often follows non-linear patterns.
How inflammatory signaling works at the molecular level and how peptides like BPC-157, KPV, LL-37, and thymosin alpha-1 modulate these pathways — targeting NF-κB, inflammasomes, and cytokine networks.
How the body produces collagen — from gene transcription to cross-linked fibrils — and how peptides, nutrients, and signals regulate this process.
The hypothalamic-pituitary axes explained — the neuroendocrine command system that peptide therapies target to modulate growth hormone, thyroid, gonadal, and stress hormone output.
The mechanistic target of rapamycin (mTOR) — the central kinase governing cell growth, protein synthesis, and autophagy — and its relevance to peptide therapy.
Cardiolipin is the signature phospholipid of the inner mitochondrial membrane, essential for electron transport chain function. Its oxidation with age is a primary target for peptides like SS-31.
The incretin effect describes the enhanced insulin response to oral versus intravenous glucose — mediated by gut hormones GLP-1 and GIP. It is the biological basis for GLP-1 agonist medications.
Myostatin (GDF-8) is a TGF-beta family member that serves as the body's primary negative regulator of skeletal muscle mass. Its inhibition is one of the most actively pursued targets in muscle biology.
NAD+ is a coenzyme essential for cellular energy production, DNA repair, and epigenetic regulation. Its decline with age intersects with several peptide mechanisms including MOTS-c and 5-Amino-1MQ.
Senescent cells are damaged cells that stop dividing but resist death, accumulating with age and secreting inflammatory factors. Senolytics are compounds designed to selectively clear them.
Autophagy is the cell's self-cleaning mechanism — degrading damaged organelles and misfolded proteins to maintain homeostasis. Several peptides modulate this pathway through mTOR inhibition, AMPK activation, and related signaling cascades.
Cell-penetrating peptides (CPPs) are short sequences that cross biological membranes without causing damage — making them powerful vehicles for delivering drugs, nucleic acids, and proteins into cells that would otherwise be inaccessible.
The gut-brain axis is a bidirectional communication network linking the enteric nervous system, vagus nerve, and central nervous system — with peptides like GLP-1, BPC-157, and neuropeptide Y serving as key molecular mediators.
Insulin-like growth factors (IGF-1 and IGF-2) are peptide hormones structurally similar to insulin that mediate growth, tissue repair, and anabolic signaling — with IGF-1 serving as the primary downstream effector of growth hormone.
How peptides are formulated and delivered — from lyophilized powders and subcutaneous injection to nasal sprays, depot formulations, and the persistent challenge of oral delivery — determines their therapeutic effectiveness.
Peptide hormones — from insulin to oxytocin to GnRH — are the body's primary long-range signaling molecules. They regulate metabolism, growth, reproduction, and stress, but their susceptibility to enzymatic degradation shapes how they must be delivered therapeutically.
Post-translational modifications — phosphorylation, glycosylation, acetylation, amidation, PEGylation — alter peptide activity, stability, and pharmacokinetics, determining whether a peptide becomes a viable therapeutic.
Stapled peptides use hydrocarbon crosslinks to lock alpha-helical conformations, dramatically improving protease resistance, cell permeability, and target binding — bridging the gap between small molecules and biologics.
Reference entry on growth hormone secretagogues: GHRH analogs, ghrelin mimetics, receptor pharmacology, and how GHS peptides compare to exogenous GH.
Reference entry on incretin hormones: GLP-1 and GIP biology, the incretin effect, DPP-4 degradation, and how incretin-based therapeutics work.
Reference entry on the melanocortin system: five MC receptors, POMC-derived peptides, and why this system matters for tanning, appetite, sexual function, and inflammation.
Reference entry on peptide conjugation: fatty acid acylation, PEGylation, antibody-peptide conjugates, and how chemical modification overcomes peptide limitations.
Reference entry on tachyphylaxis: rapid tolerance to repeated drug doses, receptor-level mechanisms, and why it matters for peptide cycling and protocol design.
Cyclization converts linear peptides into ring structures — improving metabolic stability, receptor selectivity, and oral bioavailability. It is one of the most important strategies in modern peptide drug design.
Oral delivery is the biggest pharmacological challenge for peptides. Gastric acid, proteolytic enzymes, and poor membrane permeability conspire to destroy most peptides before absorption. This article covers the barriers, current solutions, and emerging technologies.
PEGylation attaches polyethylene glycol chains to peptides, dramatically extending half-life by reducing renal clearance and enzymatic degradation. It is one of the most clinically validated strategies for improving peptide pharmacokinetics.
Bioregulators are short peptides (2-4 amino acids) that interact directly with DNA to regulate gene expression. Developed by Vladimir Khavinson, they represent a distinct class of peptide therapeutics with tissue-specific effects.
Mitochondria-derived peptides (MDPs) like MOTS-c, Humanin, and SS-31 represent a frontier in longevity science — encoded in the mitochondrial genome and declining with age, they regulate metabolism, stress resistance, and cellular energy.
Receptor binding is the mechanism through which peptides exert their biological effects — binding to cell-surface or intracellular receptors with specificity determined by shape, charge, and amino acid sequence.
Telomeres are repetitive DNA sequences that cap chromosome ends, shortening with each cell division. Their length is a biomarker of biological aging — and the target of longevity peptides like Epitalon.
How much of a peptide dose actually reaches systemic circulation depends on the route. This entry compares bioavailability across subcutaneous, oral, intranasal, topical, and IV routes.
How peptides degrade — the chemical and enzymatic pathways that limit shelf life, and the storage, formulation, and modification strategies that counteract them.
Your body produces hundreds of peptide hormones, neuropeptides, and signaling molecules. Understanding endogenous peptides — the ones already in you — is the foundation for understanding why exogenous peptide therapy works.
Why most peptides can't be taken as pills — first-pass metabolism destroys oral peptides before they reach the bloodstream. Understanding this barrier explains peptide delivery routes and the engineering behind oral GLP-1 drugs.
Neuropeptides are signaling molecules used by neurons to communicate — they modulate pain, mood, appetite, stress, and virtually every aspect of brain function. Here's how they differ from neurotransmitters and why they matter for peptide therapy.
How peptides are actually manufactured — from solid-phase peptide synthesis (SPPS) to recombinant expression to emerging enzymatic methods. The production method directly affects purity, cost, and what you're actually getting.
Amylin is a 37-amino-acid peptide co-secreted with insulin that controls postprandial glucose and satiety. It is the target of pramlintide and the next-generation obesity drug cagrilintide.
Not every peptide dissolves in water. Understanding charge, hydrophobicity, and solvent selection prevents wasted product and ensures accurate dosing.
Peptides degrade through hydrolysis, oxidation, and aggregation. Understanding these pathways is essential for proper storage, reconstitution, and knowing when a peptide has lost potency.
Signal peptides tell skin cells to produce more collagen, elastin, and other structural proteins. They are the foundation of evidence-based peptide skincare — here's how they actually work.
The 20 standard amino acids are the alphabet of peptide chemistry. Their side-chain properties — charge, hydrophobicity, reactivity — determine everything from receptor binding to proteolytic vulnerability.
Half-life determines how long a peptide stays active in the body and how often it must be dosed. From 2-minute native GLP-1 to 7-day semaglutide — the pharmacological engineering that bridges the gap.
Subcutaneous injection is the default delivery method for most self-administered peptides. Understanding the pharmacokinetics of the SC depot, site selection, and technique optimization makes the difference between consistent and erratic results.
The process that transforms liquid peptide solutions into stable powders — how it works, why it matters for peptide stability, and what happens during reconstitution.
When a vendor claims '99% purity,' what does that actually measure? A breakdown of analytical methods used to verify peptide identity and quality.
How the body absorbs, distributes, metabolizes, and eliminates peptides — and why peptide pharmacokinetics differ fundamentally from small-molecule drugs.
Antimicrobial peptides are ancient defense molecules produced by virtually all living organisms. They kill bacteria, fungi, and viruses through membrane disruption — a mechanism that resists the antibiotic resistance crisis.
Growth hormone is the master anabolic hormone — a 191-amino-acid polypeptide released by the anterior pituitary that drives growth, body composition, and tissue repair. Most peptides in the GHS category work by stimulating its release.
Bioavailability is the fraction of an administered drug that reaches systemic circulation unchanged. For peptides, this single concept explains why most require injection.
GLP-1 is an incretin hormone produced in the gut that regulates blood sugar, appetite, and gastric emptying. Its synthetic analogs — semaglutide and tirzepatide — have reshaped obesity medicine.
Reconstitution is the process of dissolving a lyophilized peptide powder into a sterile solution for injection. Proper technique preserves peptide integrity and safety.
The peptide bond is the covalent amide link that joins amino acids into chains. Its planar, partially-double-bonded geometry dictates peptide folding and signaling.
Peptides are short chains of amino acids linked by peptide bonds. This entry covers the chemistry, classification, and why peptides sit at the center of a growing therapeutic landscape.
Key terms and definitions used across peptide science, skincare formulations, and regenerative medicine.
A G-protein-coupled receptor activated by adenosine. Several regenerative peptides and polynucleotides are thought to exert effects via A2A receptor signaling, including anti-inflammatory cytokine modulation and fibroblast activation.
A half-life-extension strategy where a peptide is engineered with a fatty acid or DAC chain that reversibly binds circulating albumin, slowing renal clearance. Used in semaglutide, tirzepatide, liraglutide, and CJC-1295 DAC.
5′ AMP-activated protein kinase — a cellular energy-sensing enzyme that switches on catabolic (fat-burning, glucose-uptake) pathways in low-energy states. MOTS-c and metformin both act at least partly through AMPK activation.
Sterile water containing 0.9% benzyl alcohol as a bacteriostatic preservative, enabling multi-dose use over 28 days. The standard diluent for peptide reconstitution.
Short peptides (often 2–4 amino acids) developed primarily in Russian gerontology research, proposed to modulate gene expression in specific tissues. Epitalon is the most-studied. Western regulatory recognition is limited.
A chemical modification that allows a peptide to covalently bind serum albumin, dramatically extending half-life. CJC-1295 with DAC has a multi-day half-life vs ~30 minutes without DAC.
The sequential degradation of an orally administered drug by gastric acid, intestinal proteases, and hepatic enzymes before it reaches systemic circulation. First-pass metabolism is the primary reason most peptides cannot be taken orally — bioavailability is typically <1% without engineering solutions.
Read more →Growth-hormone-releasing hormone — a 44-amino-acid hypothalamic peptide that stimulates anterior pituitary somatotrophs to release growth hormone. Synthetic GHRH analogs (CJC-1295, Tesamorelin, Sermorelin) extend GHRH's short native half-life.
Synthetic peptides that bind GHSR-1a to stimulate GH release. Includes GHRP-2, GHRP-6, Hexarelin, Ipamorelin. Ipamorelin is the most receptor-selective.
Growth-hormone secretagogue receptor — a G-protein-coupled receptor bound by endogenous ghrelin and by synthetic GHRP-class peptides like Ipamorelin, GHRP-6, and Hexarelin. Activation amplifies GHRH-driven GH release.
Glucose-dependent insulinotropic polypeptide — the other major incretin alongside GLP-1, released by intestinal K-cells. Tirzepatide agonizes both GIP and GLP-1 receptors.
Glucagon-like peptide-1 — a 30-amino-acid incretin hormone released by intestinal L-cells after meals. Stimulates glucose-dependent insulin secretion, suppresses glucagon, delays gastric emptying, and reduces appetite centrally.
The time required for the concentration of a peptide in circulation to drop by 50%. Semaglutide's ~7-day half-life permits weekly dosing; Sermorelin's ~15-minute half-life requires daily or more frequent dosing.
High-performance liquid chromatography — the standard analytical method for assessing peptide purity. Research-grade peptides are typically sold with a certificate of analysis (COA) showing HPLC purity ≥95–98%.
Insulin-like growth factor 1 — the primary hepatic mediator of growth-hormone's anabolic actions. Serum IGF-1 is the most common biomarker for assessing GH-axis stimulation from GHRH analogs or GHRPs.
Injection directly into muscle tissue via a longer needle. Faster absorption than subcutaneous but more painful and rarely required for peptide protocols.
Abnormal distribution of body fat — can be visceral (belly-dominant, as in HIV lipodystrophy treated with Tesamorelin) or local (caused by repeat-site injections of insulin or peptides).
Freeze-drying — the process of removing water from a frozen peptide solution under vacuum, producing a stable powder. Lyophilized peptides are shelf-stable for years and require reconstitution with bacteriostatic water before use.
A peptide fragment released during extracellular matrix degradation that signals fibroblasts to produce new structural proteins. The cosmetic peptide Matrixyl mimics this endogenous feedback loop — delivering synthetic matrikine fragments to stimulate collagen synthesis topically.
The melanocortin receptor on melanocytes responsible for tanning response. MC1R activation by melanotan-I and melanotan-II drives melanogenesis; PT-141 has MC1R activity as a mild side effect.
A G-protein-coupled receptor in the hypothalamus central to appetite and sexual-arousal regulation. PT-141 (bremelanotide) acts primarily through MC4R; setmelanotide is FDA-approved for MC4R-pathway obesity.
A signaling peptide synthesized inside mitochondria that acts systemically. MOTS-c is the prototype, encoded in mitochondrial 12S rRNA.
A mesotherapy injection pattern of many small, shallow intradermal punctures across a treatment area. Used for polynucleotide skin boosters and some cosmetic peptide applications.
A short peptide (3–100 amino acids) used by neurons as a signaling molecule. Neuropeptides modulate pain, mood, sleep, appetite, and social behavior via volume transmission — diffusing beyond the synapse to affect entire neural circuits. Over 100 neuropeptides are identified in the human nervous system.
Read more →The attachment of polyethylene glycol (PEG) chains to a peptide or protein to extend its half-life. PEG shields the molecule from proteolytic degradation and reduces renal clearance. Used in PEG-MGF and various pharmaceutical peptides.
The covalent amide linkage between the carboxyl group of one amino acid and the amino group of the next, releasing a water molecule. The peptide bond is planar and partially double-bonded, restricting rotation and defining secondary structure.
The physiological pattern of hormone secretion in discrete pulses rather than tonic levels. GH is released in nocturnal and exercise-driven pulses; preserving this pattern is why GHRH analogs are preferred over recombinant GH for some applications.
The process of dissolving a lyophilized peptide in bacteriostatic water to create an injectable solution. Reconstitution technique (gentle swirl, not shake) and solvent volume determine peptide stability and per-unit concentration.
The cocktail of inflammatory cytokines, proteases, and growth factors secreted by senescent cells. SASP drives chronic inflammation, tissue dysfunction, and age-related disease — it is the primary mechanism by which senescent cells cause systemic harm beyond their local presence.
Muscle stem cells that reside between the sarcolemma and basal lamina of muscle fibers. Activated by mechanical damage or MGF signaling, they proliferate and differentiate to repair and grow muscle tissue. PEG-MGF targets satellite cell activation.
A cell that has permanently exited the cell cycle but resists apoptosis, accumulating with age. Senescent cells secrete inflammatory cytokines (SASP — senescence-associated secretory phenotype) that damage surrounding tissue. Senolytics like FOXO4-DRI aim to selectively eliminate these cells.
The hypothalamic counter-hormone to GHRH — suppresses GH release. Pulsatile GHRH agonism preserves somatostatin feedback; continuous rhGH dosing can disrupt it.
The anterior pituitary cell type that synthesizes and secretes growth hormone. Target cell for both GHRH analogs (via GHRH-R) and GHRPs (via GHSR-1a).
The standard chemistry for manufacturing synthetic peptides, developed by Bruce Merrifield (Nobel Prize 1984). Amino acids are added sequentially to a resin-anchored growing chain, enabling industrial-scale peptide production.
Administration into the fatty layer under the skin, typically via a 29–31 gauge insulin needle. The default route for most research and GLP-1 peptides because of predictable absorption and ease of self-administration.
A ribonucleoprotein enzyme that extends telomeres — the protective caps at chromosome ends that shorten with each cell division. Epitalon is proposed to activate telomerase in somatic cells. Most somatic cells have low telomerase activity; cancer cells typically have high activity.
A syringe calibrated so 100 units equals 1 mL. The standard tool for peptide self-administration because it permits precise measurement of small volumes.
Vascular endothelial growth factor receptor 2 — the primary receptor tyrosine kinase driving angiogenesis. BPC-157 appears to upregulate VEGFR2 expression, contributing to its pro-healing vascular effects in preclinical models.
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