Peptide Science
Glossary

Amino acids are organic molecules that serve as the building blocks of peptides and proteins, with 20 standard amino acids encoded by the genetic code.

An agonist is a molecule that binds to a receptor and activates it, producing a biological response similar to the natural ligand.

An antagonist is a molecule that binds to a receptor but does not activate it, blocking the action of the natural ligand or agonist.

AMP-activated protein kinase (AMPK) is a cellular energy sensor that activates catabolic pathways and inhibits anabolic pathways when cellular energy is low.

Angiogenesis is the physiological process of forming new blood vessels from existing ones, essential for wound healing and tissue repair.

Bioavailability is the fraction of an administered dose of a substance that reaches the systemic circulation unchanged.

Brain-Derived Neurotrophic Factor (BDNF) is a protein that supports neuron survival, growth, and synaptic plasticity, often called "fertilizer for the brain."

Exercise mimetics are compounds that activate the same metabolic and molecular pathways as physical exercise, producing similar adaptations without activity.

Follistatin is a glycoprotein that binds and neutralizes myostatin and activin, removing the inhibitory brake on muscle growth.

Growth hormone (GH or HGH) is a peptide hormone produced by the pituitary gland that stimulates growth, cell reproduction, and regeneration.

Growth Hormone-Releasing Hormone (GHRH) is a hypothalamic peptide that stimulates the pituitary gland to release growth hormone.

Ghrelin is a peptide hormone produced in the stomach that stimulates hunger and growth hormone release through the GHS-R1a receptor.

Glucagon-Like Peptide-1 (GLP-1) is an incretin hormone that stimulates glucose-dependent insulin secretion and suppresses appetite.

Half-life is the time required for the concentration of a substance in the body to decrease by half, determining dosing frequency.

Insulin-like Growth Factor 1 (IGF-1) is a hormone produced primarily in the liver in response to growth hormone, mediating many of GH's anabolic effects.

Incretins are gut hormones (GLP-1 and GIP) released after eating that amplify insulin secretion in a glucose-dependent manner.

A ligand is a molecule that binds to a specific receptor or protein, initiating or modulating a biological response.

Lipolysis is the metabolic breakdown of triglycerides into free fatty acids and glycerol, releasing stored fat for energy use.

Lipogenesis is the metabolic process of synthesizing new fat (triglycerides) from non-fat sources like carbohydrates.

Mitochondria are organelles that produce cellular energy (ATP) through oxidative phosphorylation and play central roles in metabolism, signaling, and cell death.

Myostatin (GDF-8) is a protein that negatively regulates skeletal muscle mass, limiting muscle growth.

Melanocortin receptors are a family of G-protein-coupled receptors (MC1R-MC5R) that mediate pigmentation, sexual function, appetite, and inflammation.

Nerve Growth Factor (NGF) is a neurotrophin that supports the growth, maintenance, and survival of neurons, particularly sensory and sympathetic neurons.

Neuroplasticity is the brain's ability to reorganize itself by forming new neural connections throughout life, enabling learning and recovery from injury.

Neurogenesis is the process by which new neurons are formed in the brain, primarily occurring in the hippocampal dentate gyrus in adults.

Oxidative stress is an imbalance between free radical production and antioxidant defenses, causing cellular damage associated with aging and disease.

A peptide is a short chain of amino acids (typically 2-50) linked by peptide bonds, which are smaller than proteins and often act as signaling molecules in biological systems.

A peptide bond is a covalent chemical bond formed between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of water.

Pharmacokinetics is the study of how a substance is absorbed, distributed, metabolized, and excreted by the body over time.

Pharmacodynamics is the study of the biochemical and physiological effects of a substance on the body and its mechanism of action.

Proteins are large, complex molecules composed of one or more chains of amino acids (typically >50) that perform essential functions in cells.

A receptor is a protein molecule on or within a cell that binds specific molecules (ligands) and triggers a cellular response, mediating the effects of peptides and drugs.

A peptide sequence is the ordered list of amino acids that make up a peptide or protein, written from the N-terminus to the C-terminus.

Signal transduction is the process by which a chemical or physical signal is transmitted through a cell via a series of molecular events, ultimately causing a cellular response.

Synaptogenesis is the formation of new synapses between neurons, essential for learning, memory, and neural circuit development.

Cellular senescence is a state in which cells stop dividing but do not die, accumulating with age and contributing to tissue dysfunction and inflammation.

Selective Androgen Receptor Modulators (SARMs) are compounds that activate the androgen receptor in muscle and bone while minimizing activity in reproductive tissues.

Telomeres are protective caps at the ends of chromosomes that shorten with each cell division, eventually leading to cellular senescence when critically short.

Telomerase is an enzyme that adds telomeric DNA repeats to chromosome ends, counteracting the shortening that occurs during cell division.