Peptide & Biohacking Glossary
63 essential terms for understanding research peptides, bioregulators, nootropics, and the surrounding regulatory and analytical landscape.
Adenosylcobalamin
One of the two bioactive coenzyme forms of vitamin B12, used specifically in mitochondrial energy metabolism. The enzyme methylmalonyl-CoA mutase requires adenosylcobalamin to convert methylmalonyl-CoA to succinyl-CoA. When this pathway is impaired, methylmalonic acid accumulates in the blood and urine, which is one of the most sensitive markers for functional B12 deficiency. Distinguished from methylcobalamin, which handles the separate methionine synthase pathway.
Amino Acid
The individual building blocks from which peptides and proteins are constructed. The human body uses 20 standard amino acids. Nine of these are "essential," meaning the body cannot synthesize them and must obtain them through food or supplementation. The remaining 11 are "non-essential," meaning healthy individuals can produce them internally, though demand can outpace synthesis under stress or illness. Amino acids are not just structural materials — they serve as precursors to neurotransmitters, hormones, and signaling molecules.
AMPK (AMP-Activated Protein Kinase)
Often called the cell's master energy sensor, AMPK is an enzyme that activates when cellular energy levels drop. It responds by switching on energy-producing pathways (glucose uptake, fatty acid oxidation) and switching off energy-consuming ones (fat storage, protein synthesis that is not immediately necessary). AMPK activation is one of the primary mechanisms by which exercise, caloric restriction, and certain research compounds like MOTS-c produce metabolic benefits.
Angiogenesis
The formation of new blood vessels from existing ones. Relevant in the peptide space because several research compounds, notably BPC-157, promote angiogenesis at injury sites to accelerate tissue repair. New blood vessels deliver oxygen and nutrients that healing tissue requires. Angiogenesis is a double-edged mechanism in medicine: it is essential for wound healing and regeneration but also plays a role in tumor growth, which is why growth factor compounds that drive angiogenesis warrant careful consideration.
Androgenic
Relating to the promotion of male sex hormone characteristics. Testosterone is the primary androgenic hormone. Compounds with androgenic activity stimulate the androgen receptor, which drives effects including muscle protein synthesis, bone density, red blood cell production, libido, and secondary male sex characteristics. The challenge with anabolic-androgenic steroids is that the androgenic and anabolic effects are difficult to separate — SARMs were developed specifically to achieve better separation.
Anxiolytic
A compound that reduces anxiety. In the peptide context, this term is most associated with Selank and its enhanced derivative Adalank, both of which produce documented anxiolytic effects through modulation of GABA-A receptors and enkephalin breakdown inhibition. Importantly, peptide-based anxiolytics have so far demonstrated these effects without the sedation, tolerance, or dependence associated with benzodiazepine-class drugs, which is one reason they have attracted significant research interest.
BAC Water (Bacteriostatic Water)
The standard diluent used to reconstitute lyophilized peptide vials. It contains 0.9 percent benzyl alcohol, which inhibits bacterial growth and extends the usable life of a reconstituted vial to approximately 28 days when refrigerated. The 28-day window is a sterility limit tied to benzyl alcohol's preservative efficacy, not a statement about the peptide molecule's chemical stability. Using sterile water without the benzyl alcohol preservative drops the safe use window to 24 to 48 hours.
BDNF (Brain-Derived Neurotrophic Factor)
A protein the brain produces to support the growth, survival, and differentiation of neurons. BDNF is often described as "fertilizer for the brain." It promotes neuroplasticity, the brain's ability to form new connections, consolidate memories, and adapt to new information. Chronic stress, poor sleep, and sedentary behavior suppress BDNF. Exercise, fasting, and certain research compounds including Semax, Adamax, and Selank have been documented to upregulate BDNF expression.
Bioavailability
The proportion of a compound that reaches systemic circulation in a form the body can actually use. A compound can be effective in theory and nearly useless in practice if it degrades before it is absorbed. Oral bioavailability for most peptides is extremely low because digestive enzymes break down amino acid chains before they can be absorbed intact. This is why most research peptides require subcutaneous injection or intranasal delivery. Exceptions include Noopept and select orally-stable compounds.
Bioregulator
A class of very short peptides, typically 2 to 7 amino acids, originally developed by Soviet researcher Dr. Vladimir Khavinson at the St. Petersburg Institute of Bioregulation and Gerontology beginning in the 1970s. Bioregulators are designed to modulate gene expression within specific tissues and organs rather than producing systemic pharmacological effects. They are categorized as either Cytomaxes (natural, derived from animal tissue extracts) or Cytogens (fully synthetic).
Blood-Brain Barrier (BBB)
A highly selective membrane formed by specialized cells lining the brain's blood vessels. It allows oxygen, glucose, and certain small molecules to pass while blocking pathogens, large molecules, and most drugs. This barrier is one of the central challenges in neuropharmacology: a compound can be highly effective in peripheral tissue but completely useless for brain applications if it cannot cross the BBB. Several research peptides including Semax, Selank, Dihexa, and Adamax are specifically studied for their ability to cross it.
Bulk Drug Substance
The raw active pharmaceutical ingredient used in compounding before it is formulated into a finished product. In the regulatory context of 503A and 503B compounding pharmacies, a bulk drug substance must appear on the FDA-approved list or meet specific criteria before a compounding pharmacy can legally use it. The question of which bulk drug substances are permitted for compounding is at the center of the peptide regulatory debate in 2025 and 2026.
Certificate of Analysis (COA)
The documentation issued by a laboratory confirming the analytical test results for a specific batch of a compound. A legitimate COA from an independent third-party laboratory is the minimum quality verification required before purchasing any research peptide. Key tests that should appear on a quality COA include identification (mass spectrometry confirming the compound matches its label), net content (confirming the quantity matches the label claim), and net purity (HPLC analysis confirming impurity levels).
Cholinergic
Relating to the acetylcholine neurotransmitter system. Acetylcholine is the primary neurotransmitter involved in memory encoding, attention, and learning. Compounds described as "cholinergic" either increase acetylcholine production, slow its breakdown, or sensitize acetylcholine receptors. Several nootropic compounds including Noopept enhance cholinergic transmission, which is part of the mechanistic basis for their documented effects on memory and cognitive processing.
Compounding Pharmacy
A state-licensed pharmacy that prepares customized medications to specifications not available in commercial manufactured form. There are two relevant designations. A 503A pharmacy requires a patient-specific prescription and is regulated primarily at the state level. A 503B outsourcing facility is FDA-registered, complies with current Good Manufacturing Practices (cGMP), and can produce large quantities for distribution to healthcare facilities without patient-specific prescriptions.
Corticotropin (ACTH)
Adrenocorticotropic hormone. A pituitary hormone that stimulates the adrenal cortex to produce cortisol and other glucocorticoids. Relevant in the peptide space because Semax is derived from ACTH fragments (specifically ACTH 4-10) with a stabilizing peptide extension added. The ACTH-derived portion gives Semax access to melanocortin receptor pathways without producing the cortisol-stimulating effects of the full ACTH molecule.
Cycle / Cycling
The practice of using a compound for a defined period (on-cycle), then stopping for a defined rest period (off-cycle) before resuming. Cycling serves multiple purposes: preventing receptor desensitization or downregulation, allowing the body to reset baseline signaling, providing comparison windows to evaluate whether the compound is producing meaningful effects, and managing cumulative exposure risk. Cycle lengths vary considerably by compound.
Cytogen
The synthetic category of bioregulator peptides, also called tissue-specific peptides. Cytogens are fully synthesized versions of the bioactive peptide sequences identified within natural tissue extracts. Epitalon is the most well-known Cytogen. Because they are fully synthetic with defined amino acid sequences, Cytogens offer greater batch-to-batch consistency than their natural Cytomax counterparts and are more amenable to third-party analytical verification.
Cytomax
The natural category of bioregulator peptides, derived from animal organ and tissue extracts. Cytomaxes contain a complex mixture of peptide sequences extracted from specific tissues (thymus, pineal gland, liver, etc.) rather than a single defined compound. Thymalin is the most well-known Cytomax. Because they are derived from tissue extracts rather than synthesized to a single sequence, Cytomaxes are harder to characterize analytically and exhibit more biological complexity than Cytogens.
DAC (Drug Affinity Complex)
A modification applied to certain peptides, most commonly associated with CJC-1295 with DAC, that allows the peptide to bind to albumin (a blood protein) after injection. This binding dramatically extends the peptide's half-life by protecting it from enzymatic degradation. CJC-1295 without DAC has a half-life of approximately 30 minutes; CJC-1295 with DAC has a half-life of approximately 6 to 8 days. The trade-off is that albumin binding reduces the natural pulsatile nature of growth hormone release.
Dopaminergic
Relating to the dopamine neurotransmitter system. Dopamine governs motivation, reward processing, executive function, movement control, and certain aspects of mood. Compounds described as "dopaminergic" either increase dopamine production, slow its reuptake or degradation, or modulate dopamine receptors. Several research peptides including Semax modulate dopaminergic signaling as part of their broader cognitive mechanism, contributing to improved focus and motivated cognitive performance.
Endotoxin
A toxic substance released from the outer cell wall of gram-negative bacteria when those cells die and break apart — specifically, bacterial lipopolysaccharide (LPS). The immune system mounts a powerful inflammatory response to even very small amounts of LPS, which is why endotoxin contamination in an injectable compound is a serious safety concern. Critically, a vial can pass sterility testing (no living organisms present) and still carry a significant endotoxin burden, because endotoxin persists after the bacteria that produced it are dead.
Enkephalin
Naturally occurring opioid peptides produced by the brain that play key roles in pain modulation, mood regulation, and stress response. Enkephalins bind opioid receptors to produce analgesic and mood-elevating effects. Selank's anxiolytic mechanism partly involves inhibiting the enzyme that breaks down enkephalins, thereby extending their activity and supporting mood stability and stress resilience without the receptor tolerance and dependence that external opioid compounds produce.
Gene Expression
The process by which information encoded in a gene is used to produce a functional product, typically a protein. Bioregulators are specifically described as operating by modulating gene expression within target tissues, meaning they influence which genes are turned on or off at the cellular level rather than simply adding or removing a signaling molecule from circulation. This distinction is part of why bioregulator researchers describe their effects as regulatory and foundational rather than pharmacological in the traditional stimulant or inhibitor sense.
GHS-R (Growth Hormone Secretagogue Receptor)
Also called the ghrelin receptor. A receptor found primarily in the pituitary gland and hypothalamus that, when activated, triggers the release of growth hormone pulses. Growth hormone secretagogues (GHS) including ipamorelin, GHRP-2, and GHRP-6 work by binding this receptor. The selectivity of different GHS compounds for this receptor versus related receptors is what determines their side effect profile. Ipamorelin is notable for its selectivity: it activates GHS-R without meaningfully stimulating cortisol or prolactin release.
GLP-1 (Glucagon-Like Peptide-1)
An incretin hormone produced in the gut in response to food intake. GLP-1 stimulates insulin secretion in proportion to blood glucose levels, suppresses glucagon release, slows gastric emptying to extend satiety, and acts on the brain's appetite regulation centers to reduce food intake. GLP-1 receptor agonists including semaglutide and tirzepatide are among the most clinically impactful compounds in modern medicine. The research peptide community intersects with GLP-1 biology primarily through the question of compounding pharmacy access to these compounds.
Gray Market
The informal term for the space where research peptides are sold and purchased outside the formal pharmaceutical and licensed compounding pharmacy framework. Gray market vendors operate under "research use only" labeling that technically disclaims human use while the commercial reality is that many purchasers use the products for personal health optimization. Testing data from independent platforms in 2025 found approximately 30 percent of gray market peptide products were mislabeled, under- or overdosed, or contaminated — the core reason COA verification and vendor vetting exist as a discipline.
Half-Life
The time it takes for the concentration of a compound in the body to decrease by 50 percent. Half-life determines how often a compound needs to be dosed to maintain consistent effect. A compound with a 30-minute half-life requires different dosing frequency than one with a 6-day half-life. Structural modifications like the DAC modification on CJC-1295 and the adamantane modification on Adamax are specifically designed to extend half-life by protecting the peptide from enzymatic degradation.
HPLC (High-Performance Liquid Chromatography)
The standard analytical method used to measure peptide purity on a COA. The sample runs through a column that separates components by their chemical properties, producing a chromatogram showing peaks for each substance in the sample. The target peptide produces the main peak; everything else (impurities, byproducts, synthesis artifacts) produces smaller peaks. Purity is calculated as the main peak area divided by the total of all peak areas. For research peptides, 98 percent or higher is the standard worth accepting.
Homocysteine
An amino acid that accumulates in the blood when the methionine cycle is impaired, most commonly due to insufficient B12, folate, or B6. Elevated homocysteine is an independent risk factor for cardiovascular disease, stroke, and cognitive decline. Methylcobalamin (active B12) is required for the enzyme methionine synthase to convert homocysteine back to methionine, which is one reason injectable methylcobalamin carries clinical significance beyond simple energy support.
IGF-1 (Insulin-Like Growth Factor 1)
A hormone produced primarily by the liver in response to growth hormone stimulation. IGF-1 is the primary downstream mediator of many of growth hormone's anabolic effects, including muscle protein synthesis, bone growth, and tissue repair. When GH secretagogues like ipamorelin and CJC-1295 increase GH pulses, IGF-1 rises in parallel. IGF-1 is prohibited under WADA's S2 category and is also a primary biomarker used to monitor the effects of GH-axis compounds.
Intramuscular Injection (IM)
Injection directly into muscle tissue rather than the fatty layer beneath the skin. Common sites include the outer thigh (vastus lateralis), upper outer quadrant of the glutes, and the deltoid of the upper arm. IM injections use longer needles than subcutaneous injections, typically 23 to 25 gauge and 1 to 1.5 inches, to reach the muscle belly beneath the subcutaneous fat layer. Absorption is generally faster than subcutaneous injection because muscle tissue is highly vascular, delivering the compound more rapidly into systemic circulation. In the research peptide context, IM administration is most commonly used for PEG-MGF, where injection near the target muscle tissue is a feature of the research design rather than just a delivery consideration. Compounds like BPC-157 and TB-500 can be administered either subcutaneously or intramuscularly depending on protocol design. For most peptide research applications, subcutaneous injection is the standard default route unless a specific intramuscular rationale exists for the compound in question.
Intranasal Administration
Delivery of a compound through the nasal mucosa rather than by injection. For peptides and nootropic compounds, the primary advantage of intranasal delivery is that the nasal cavity provides direct access to the brain via the olfactory and trigeminal nerve pathways, partially bypassing the blood-brain barrier. Semax, Selank, Adalank, and Adamax are all administered intranasally, which is a significant practical advantage over injectable compounds.
Khavinson Peptides
The informal collective name for the bioregulator peptides developed by Dr. Vladimir Khavinson and his research team at the St. Petersburg Institute of Bioregulation and Gerontology. Beginning in the 1970s under Soviet military funding, Khavinson's research identified tissue-specific peptide sequences capable of modulating gene expression and organ function. After the Soviet Union's dissolution in 1991, this research became publicly available, eventually producing six approved pharmaceutical preparations and over 60 supplements used in Russia. Epitalon is the most internationally recognized Khavinson peptide.
Lipotropic
A compound that promotes the breakdown and mobilization of fat, specifically in the liver. Lipotropic agents facilitate the export of triglycerides from the liver by supporting the synthesis of phosphatidylcholine, the primary phospholipid component of VLDL particles that transport fat out of the liver and into circulation. Methionine, inositol, and choline (the MIC components) are the classic lipotropic nutrients. Choline deficiency is one of the most reliably documented causes of non-alcoholic fatty liver disease in controlled research settings.
Lyophilization
The freeze-drying process used to convert liquid peptide solutions into the dry powder or cake form that research peptides arrive in. Lyophilization removes water in three stages: freezing, primary drying (sublimation under vacuum), and secondary drying (removal of residual bound water). The result is a stable dry compound that can be stored for months to years, because the vast majority of peptide degradation pathways require water to proceed. The moment bacteriostatic water is added to reconstitute a lyophilized peptide, the stability clock restarts.
Mass Spectrometry (MS / LC-MS)
The analytical method used to confirm the identity of a compound on a COA. Every molecule has a precise molecular mass; in a mass spectrometer, the sample is ionized and fragmented, and the instrument measures the resulting mass-to-charge ratio pattern, which is compared to the expected pattern for the labeled compound. A match confirms identity; a mismatch indicates mislabeling, substitution, or a synthesis error. Mass spectrometry for identity confirmation is a non-negotiable element of a legitimate COA — HPLC purity testing alone cannot confirm that the right compound is in the vial.
Melanocortin Receptor (MCR)
A family of five receptors (MC1R through MC5R) distributed throughout the body with diverse functions. MC4R in the hypothalamus is involved in appetite regulation, energy homeostasis, and sexual function. Several research peptides target melanocortin receptors: Semax and Adamax activate MC4R as part of their cognitive enhancement mechanism, PT-141 (bremelanotide) activates MC4R and MC3R for sexual arousal, and Melanotan II targets MC1R and MC2R for tanning effects alongside MC3R and MC4R.
Methylation
A biochemical process in which a methyl group (CH3) is added to a molecule. In the human body, methylation governs an enormous range of processes including DNA expression, neurotransmitter synthesis, hormone metabolism, detoxification, and immune function. The methylation cycle depends critically on B12 (specifically methylcobalamin), folate (as methylfolate), and B6. MTHFR gene variants reduce methylation enzyme efficiency in a significant portion of the population, affecting how well these individuals convert synthetic B vitamins to their active forms.
Methylcobalamin
The bioactive, methyl-group-bearing form of vitamin B12. Directly usable by the methionine synthase enzyme without conversion. Preferred over cyanocobalamin for neurological applications, peripheral neuropathy, individuals with MTHFR gene mutations, older adults with reduced gastric acid production, and anyone on medications that impair B12 absorption. More light-sensitive than cyanocobalamin and requires proper storage in amber vials with refrigeration. See our full B12 forms guide for the complete comparison.
MTHFR
A gene that encodes the enzyme methylenetetrahydrofolate reductase, which converts folate to its active form (methylfolate) for use in the methylation cycle. Common variants of this gene (C677T and A1298C) reduce enzyme efficiency by 30 to 70 percent. Individuals with these variants may struggle to utilize synthetic folic acid and cyanocobalamin effectively, making active-form supplementation (methylfolate and methylcobalamin) clinically important. MTHFR status is now a routine component of functional medicine lab panels.
Neuroplasticity
The brain's ability to reorganize itself by forming new neural connections in response to learning, experience, and environmental input. Neuroplasticity is not limited to childhood; the adult brain retains significant capacity for structural reorganization throughout life, though this capacity declines with age. Several research compounds in the nootropic peptide category are studied specifically for their ability to support neuroplasticity through BDNF upregulation (Semax, Adamax), synaptic protein synthesis (Dihexa), and AMPA receptor modulation (Noopept).
Nitrogen Backfilling
A vial sealing method in which pharmaceutical-grade pure nitrogen gas is introduced into the vial headspace before the stopper is crimped. The nitrogen displaces residual oxygen, protecting oxidation-sensitive amino acid residues (methionine, cysteine, tryptophan) from degradation during storage and shipping. Nitrogen-sealed vials do not produce the "vacuum pull" effect when a needle is inserted — internal and external pressure are matched, and the absence of vacuum pull in a nitrogen-sealed vial is correct behavior, not a quality defect.
Nootropic
A compound taken to enhance cognitive function, including memory, focus, processing speed, creativity, or stress resilience. The term was coined by Romanian psychologist and chemist Corneliu Giurgea in 1972, who proposed that a true nootropic should enhance learning and memory, protect the brain against physical or chemical injury, enhance cortical control mechanisms, lack sedative or stimulant effects, and have very low toxicity. Research peptides with documented nootropic properties include Semax, Selank, Noopept, Dihexa, Adamax, and Adalank.
Off-Label Use
The use of a compound, typically a pharmaceutical drug, for a purpose, population, or dose that differs from the FDA-approved indication. Off-label use is legal for licensed physicians and is extremely common in medical practice. A large proportion of peptide-adjacent pharmaceuticals in functional medicine practice involve off-label prescribing, including some GLP-1 receptor agonists at non-approved doses, methylcobalamin for neurological applications beyond deficiency correction, and sermorelin for age-related GH decline without a clinical deficiency diagnosis.
PCAC (Pharmacy Compounding Advisory Committee)
The FDA advisory committee that formally evaluates compounds for potential inclusion on the 503A Bulk Drug Substances List. The PCAC's recommendations are non-binding but carry significant regulatory weight in informing FDA decisions. The July 23 and 24, 2026 PCAC meeting is one of the most consequential regulatory events in the peptide space in years, with BPC-157, TB-500, MOTS-c, KPV, Semax, Epitalon, and DSIP all scheduled for review.
Peptide
A short chain of amino acids linked by peptide bonds. The technical distinction between a peptide and a protein is primarily one of length: peptides generally contain fewer than 50 amino acids, while proteins contain 50 or more. The body uses endogenous peptides as hormones, neurotransmitters, immune modulators, and signaling molecules. Research peptides are synthetic versions or analogs of these naturally occurring compounds, designed to replicate, modulate, or enhance specific biological signals.
Peptide Bond
The covalent chemical bond that links amino acids together to form a peptide chain. Formed when the carboxyl group of one amino acid reacts with the amino group of the next, releasing a water molecule in the process. Peptide bonds are what digestive enzymes target and break down when peptides are consumed orally, which is the primary reason most research peptides require injectable or intranasal delivery to reach their biological targets intact.
Prodrug
A compound that is administered in an inactive or minimally active form and is converted to its active form through metabolic processes after administration. Noopept is the most prominent example in the research peptide space: it is administered as N-Phenylacetyl-L-Prolylglycine Ethyl Ester but is metabolized in the brain to cycloprolylglycine, the pharmacologically active compound that modulates AMPA glutamate receptors. This prodrug design is what allows Noopept to survive oral administration long enough to be absorbed and reach the brain before conversion.
Research Chemical / Research Use Only
A regulatory category describing compounds that are commercially available for research purposes but not approved for human therapeutic use. The "research use only" designation is a legal classification that allows vendors to sell compounds that have not completed the FDA approval process for specific human indications. Under WADA's S0 category, any pharmacological substance not approved for human use by any regulatory authority is automatically prohibited for competitive athletes, regardless of the "research" framing.
Reconstitution
The process of adding a sterile diluent (typically bacteriostatic water) to a lyophilized peptide vial to create a solution for injection or intranasal administration. Proper reconstitution requires directing the liquid stream down the inside wall of the vial rather than directly onto the powder cake, swirling gently (never shaking), and allowing the compound to dissolve fully before drawing the solution. Once reconstituted, vials must be refrigerated, kept away from light, and used within 28 days if bacteriostatic water was used as the diluent.
SARM (Selective Androgen Receptor Modulator)
A class of compounds designed to selectively activate androgen receptors in muscle and bone tissue while minimizing androgenic activity in other tissues such as the prostate, skin, and hair follicles. The goal was to achieve the anabolic benefits of testosterone (muscle protein synthesis, bone density) with reduced androgenic side effects. Examples include Ostarine (MK-2866), Ligandrol (LGD-4033), and RAD-140. SARMs are not FDA-approved for any therapeutic indication and are prohibited under WADA's S1 and S4 categories.
Secretagogue
A compound that stimulates another substance to be secreted. In the peptide space, the term most commonly refers to growth hormone secretagogues (GHS), compounds that stimulate the pituitary gland to secrete growth hormone. Ipamorelin, GHRP-2, GHRP-6, hexarelin, and MK-677 are all GH secretagogues that work through the ghrelin receptor. The appeal of secretagogues over exogenous growth hormone is that they stimulate the body's own production, which preserves pituitary feedback mechanisms and produces more physiological GH pulse patterns.
Serotonergic
Relating to the serotonin neurotransmitter system. Serotonin governs mood regulation, appetite, sleep-wake cycle function, and gut motility. Compounds described as "serotonergic" modulate serotonin production, reuptake, or receptor activity. Selank and its derivative Adalank modulate the serotonergic system as part of their anxiolytic mechanism. PE-22-28 operates through TREK-1 potassium channel blockade that increases serotonergic firing, a mechanistically novel approach compared to conventional antidepressants.
Solid-Phase Peptide Synthesis (SPPS)
The standard industrial method for manufacturing research peptides. Amino acids are added one at a time to a growing chain anchored to a solid resin support, then cleaved from the resin and purified. Each coupling step introduces the possibility of incomplete reaction, producing truncated or deletion sequences that become impurities in the final product. The purity percentage on a COA reflects how effectively these synthesis impurities were removed during purification.
Subcutaneous Injection (SubQ)
Injection into the fatty tissue layer just beneath the skin, typically in the abdomen, outer thigh, or upper arm. Most research peptides are administered subcutaneously. SubQ injection avoids the need to inject into muscle tissue, uses shorter needles (typically 29 to 31 gauge, 5/16 inch), and produces slower, more gradual absorption than intramuscular injection. Proper subcutaneous technique involves pinching a fold of skin, inserting the needle at a 45 to 90 degree angle, and injecting slowly before withdrawing.
Synaptogenesis
The formation of new synaptic connections between neurons. Synapses are the junctions through which neurons communicate. The density and quality of synaptic connections are fundamental to cognitive function, memory capacity, and learning ability. Dihexa is studied specifically for its synaptogenic effects through the hepatocyte growth factor (HGF) and c-Met receptor pathway, driving the physical formation of new synapses at concentrations far below those required for BDNF to produce similar effects in cell culture models.
Telomere
Protective caps at the ends of chromosomes, analogous to the plastic tips on shoelaces. Telomeres shorten with each cell division and are one of the recognized hallmarks of cellular aging. When telomeres become critically short, cells can no longer divide normally and enter a state called senescence or undergo apoptosis (programmed cell death). Telomerase is the enzyme that can rebuild telomere length. Epitalon is studied specifically for its ability to stimulate telomerase activity in human cells, which is the mechanistic basis for its position in longevity research.
Third-Party Testing
Quality verification performed by an independent laboratory that has no financial relationship with the vendor whose product is being tested. The distinction between third-party and in-house or affiliated laboratory testing is fundamental to the credibility of COA documentation — a vendor that generates its own COA or uses a laboratory it owns is grading its own homework. Recognized independent laboratories in the research peptide space include ILS Laboratories, Freedom Diagnostics, Vanguard Laboratory, Janoshik, Ethos Analytics, and MDx BioAnalytical Laboratory.
TrkB Receptor
The primary receptor for BDNF. When BDNF binds TrkB, it activates intracellular signaling cascades that support neuronal survival, dendritic growth, and synapse formation. Several nootropic research compounds including Semax and Adamax sensitize TrkB receptors or increase BDNF availability to enhance this signaling pathway. The TrkB-BDNF axis is one of the most actively researched targets in both psychiatric and neurodegenerative disease research.
Upregulation
An increase in the expression or sensitivity of a receptor, enzyme, or gene in response to a stimulus — the opposite of downregulation. Many research peptides produce their effects partly through upregulation of specific receptors or signaling proteins. Semax upregulates BDNF and NGF. BPC-157 upregulates VEGFR2. The significance of upregulation depends on context: upregulating BDNF in brain tissue relevant to memory consolidation is generally beneficial, while upregulating growth factor receptors in tissue with oncogenic potential warrants more careful consideration.
VEGF (Vascular Endothelial Growth Factor)
A signaling protein that stimulates angiogenesis by activating VEGF receptors (primarily VEGFR2) on endothelial cells lining blood vessels. BPC-157 promotes angiogenesis partly through VEGFR2 upregulation and downstream PI3K-Akt-eNOS signaling. VEGF-related compounds are prohibited under WADA's S2.3 category as growth factor modulators.
WADA (World Anti-Doping Agency)
The international organization that maintains the Prohibited List governing substance use in competitive sport. For the research community, WADA's Prohibited List is relevant for two reasons: competitive athletes face sanctions for any prohibited compound regardless of intent or knowledge (strict liability), and WADA's categorization of compounds provides a useful external assessment of which substances have sufficient performance-altering potential that an international regulatory body considers them worth restricting. The 2026 WADA Prohibited List's S0 category prohibits all unapproved research compounds for athletes at all times, regardless of how they are labeled or marketed.