Last Updated: January 2, 2025
| Hormone | Structure | Functions |
| Skeletal Muscle Hormones (Myokines): more information included in Secreted Factors: Tissue “Kines” page | ||
| Irisin | 22kDa proteolytic fragment of the transmembrane protein FNDC5 (fibronectin type III domain-containing protein 5) | expression induced, in skeletal muscle, by PGC1-α in response to exercise, induces a conversion of white adipose tissue (WAT) into a more brown fat (BAT) type, generally referred to as beige or brite fat cells |
| Pituitary Hormones | ||
| Oxytocin | posterior pituitary peptide; polypeptide of 9 amino acids CYIQNCPLG (C residues are disulfide bonded) | uterine contraction, causes milk ejection in lactating females (the “let-down” response), responds to suckling reflex and estradiol, lowers steroid synthesis in testes |
| Vasopressin (antidiuretic hormone, ADH) | posterior pituitary peptide; polypeptide of 9 amino acids CYFQNCPRG (C residues are disulfide bonded) | responds to osmoreceptor which senses extracellular [Na+], blood pressure regulation, increases H2O reabsorption from distal tubules in kidney, loss results in dilute urine and polydipsia (constant thirst) condition termed diabetes insipidus |
| Melanocyte-stimulating hormones (MSH) | anterior pituitary peptides derived from POMC: α polypeptide: 13 amino acids β polypeptide: 18 amino acids γ polypeptide: 12 amino acids | α-MSH most significant, involved in control of appetite and feeding behaviors via melanocortin receptor (MC4R)-expressing neurons in hypothalamus, immunomodulation via MC1R-expressing monocytes, macrophages, and dendritic cells (DCs), down-regulates the production of proinflammatory and immunomodulating cytokines (IL-1, IL-6, TNF-α, IL-2, IFN-γ, IL-4, IL-13) as well as the expression of costimulatory molecules (CD86, CD40, ICAM-1) on antigen-presenting DCs |
| Adrenocorticotropic hormone (ACTH) also called corticotropin | anterior pituitary peptide derived from POMC; polypeptide: 39 amino acids | stimulates cells of adrenal gland to increase steroid synthesis and secretion |
| Lipotropin (LPH) | anterior pituitary peptides derived from POMC: β polypeptide: 93 amino acids γ polypeptide: 60 amino acids | increases fatty acid release from adipocytes |
| Thyrotropin (thyroid-stimulating hormone, TSH) | anterior pituitary peptides; two peptides: α peptide is 96 amino acids; β peptide is 112 amino acids | acts on thyroid follicle cells to stimulate thryoid hormone synthesis |
| Growth hormone (GH, or somatotropin) | anterior pituitary peptide: 191 amino acids | general anabolic stimulant, increases release of insulin-like growth factor-I (IGF-I), cell growth and bone sulfation |
| Prolactin (PRL) | anterior pituitary peptide: 197 amino acids | stimulates differentiation of secretory cells of mammary gland and stimulates milk synthesis |
| Luteinizing hormone (LH); human chorionic gonadotropin (hCG) is similar and produced in placenta | anterior pituitary peptides; two peptides: α peptide is 96 amino acids; β peptide is 121 amino acids | increases ovarian progesterone synthesis, luteinization; acts on Leydig cells of testes to increase testosterone synthesis and release and increases interstitial cell development |
| Follicle-stimulating hormone (FSH) | anterior pituitary peptides; two proteins: α peptide is 96 amino acids; β peptide is 120 amino acids | ovarian follicle development and ovulation, increases estrogen production; acts on Sertoli cells of seminiferous tubule to increase spermatogenesis |
| Hypothalamic Hormones and Peptides | ||
| Orexins | two peptides from single preproprotein; orexin A is 33 amino acids, orexin B is 28 amino acids | important roles in the emotional and motivational aspects of feeding behavior, increases food consumption (orexigenic) hence derivation of peptide name; increases wakefulness and suppresses REM sleep |
| Melanin-concentrating hormone, MCH | 19 amino acid cyclic peptide | important orexigenic (appetite stimulating) hormone |
| Neuropeptide Y, NPY | 36 amino acids, five receptors termed Y receptors | effects on hypothalamic function in appetite, controls feeding behavior and energy homeostasis, levels increase during starvation to induce food intake |
| Corticotropin-releasing factor (CRF or CRH) | peptide of 41 amino acids | acts on corticotrope to release ACTH and β-endorphin (lipotropin) |
| Gonadotropin-releasing factor (GnRF or GnRH) | peptide of 10 amino acids | acts on gonadotrope to release LH and FSH |
| Prolactin-release inhibiting factor (PIF or PIH) | is the neurotransmitter dopamine | acts on lactotrope to inhibit prolactin release |
| Growth hormone-releasing factor (GHRF or GHRH) | protein of 40 and 44 amino acids | stimulates GH secretion |
| Somatostatin (SIF, also called growth hormone-release inhibiting factor, GHIF) | peptide of 14 and 28 amino acids | inhibits GH and TSH secretion |
| Thyrotropin-releasing factor (TRF; also called thyrotropin releasing hormone: TRH) | peptide of 3 amino acids derived from a 242 amino acid precursor; when fully processed the C-terminal Gln residue is converted to pyroglutamate which is a cyclic amino acid; active peptide is NH2-Pro-His-Glu(pyro) | stimulates TSH and prolactin secretion |
| Thyroid Hormones | ||
| Thyroxine and triiodothyronine | iodinated dityrosine derivatives | responds to TSH and stimulates oxidations in many cells |
| Calcitonin | protein of 32 amino acids | produced in parafollicular C cells of the thyroid; its role in the regulation of Ca2+ homeostasis is insignificant in humans |
| Calcitonin gene-related peptide (CGRP) | hormone is termed αCGRP; protein of 37 amino acids; product of the calcitonin gene (CALCA) as a result of alternative splicing of the precursor mRNA in the brain; a related protein (βCGRP) is derived from the CALCB gene | functions in nociception (sensation of pain) and in homeostasis of the cardiovascular system through functioning as a potent vasodilator |
| Parathyroid Hormone | ||
| Parathyroid hormone (PTH) | protein of 84 amino acids | regulation of Ca2+ and Pi homeostasis, stimulates renal reabsorption of Ca2+ and bone Ca2+ release thus increasing serum Ca2+, also stimulates renal phosphate (PO43–) efflux |
| Adipose Tissue Hormones (Adipokines) | ||
| go to the Adipose Tissue: Not Just Fat page for a more complete listing of factors secreted by adipose tissue | ||
| Leptin | 167 amino acid precursor processed to 146 amino acids | regulation of overall body weight by limiting food intake and increasing energy expenditure, regulation of the neuroendocrine axis, inflammatory responses, blood pressure, and bone mass |
| Adiponectin | 244 amino acid protein with four distinct functional domains | major biological actions are increases in insulin sensitivity and fatty acid oxidation |
| Resistin | 108 amino acid preprotein in humans | induces insulin resistance |
| Hormones and Peptides of the Gut | ||
| additional discussion of gut hormones: Gut-Brain Interrelationships and the Control of Feeding Behaviors page | ||
| Cholecystokinin, CCK | predominant form is 33 amino acids | stimulates gallbladder contraction and bile flow, increases secretion of digestive enzymes from pancreas |
| Enterostatin | derived from N-terminal end of pancreatic colipase; pentapeptide sequence of human enterostatin is APGPR | regulates fat intake, peripheral or central administration inhibits consumption of a high-fat diet but not a low-fat diet |
| Famsin | 178 amino acids; cleaved from the membrane bound protein encoded by the C17orf78 gene | release is induced by fasting and promotes fasting-induced metabolism upon binding to the olfactory family receptor encoded by the OR10P1 (olfactory receptor family 10 subfamily P member 1) gene |
| FGF19 | 216 amino acids; member of the large FGF family of growth factors | produced in ileum, expression of gene activated by transcription factor FXR, FXR is activated when ileal enterocytes absorb bile acids, when released to the portal circulation FGF19 stimulates hepatic glycogen and protein synthesis while inhibiting glucose production |
| Gastrin | 17 amino acids (little gastrin) and 34 amino acids (big gastrin) | produced by stomach antrum, stimulates acid and pepsin secretion, also stimulates pancreatic secretions |
| Gastrin-releasing peptide (GRP); a bombesin-like peptide family member | 27 amino acids | stimulates release of gastrin from G cells of the stomach and CCK from small intestinal enteroendocrine I cells |
| Ghrelin | 28 amino acids derived from preproghrelin protein; acylated on Ser3 with n-octanoic acid, non-acylated forms found in circulation also but not bioactive | appetite stimulation, stimulates NPY release, regulation of energy homeostasis, glucose metabolism, gastric secretion and emptying, insulin secretion |
| Glucagon-like peptide 1 (GLP-1) formerly called enteroglucagon | two forms: 31 amino acids, GLP-1(7-37) and 30 amino acids, GLP-1(7-36)amide | potentiates glucose-dependent insulin secretion, inhibits glucagon secretion, inhibits gastric emptying |
| Glucose-dependent insulinotropic polypeptide (GIP) originally called gastric inhibitory polypeptide | 42 amino acids | inhibits secretion of gastric acid, enhances insulin secretion |
| Motilin | 22 amino acids | controls gastrointestinal muscles, stimulates release of PP, stimulates gallbladder contractions |
| Nesfatin-1 | 82 amino acids | proteolytic product of the 420 amino acid precursor protein encoded by the NUCB2 (nucleobindin 2) gene; following removal of the 24 amino acid signal peptide the 396 amino acid peptide is cleaved by proprotein convertases 1/3 (PC 1/3) and PC2; nesfatin-1 consists of amino acids 1–82; proteolytic processing also generates nesfatin-2 (amino acids 85–163) and nesfatin-3 (amino acids 166–396); stimulates reduced feeding via actions in the hypothalamus |
| Neuromedin B; a bombesin-like peptide family member | 10 amino acids (amidated) | secretion of gastrin, CCK, GIP, insulin; smooth muscle contraction; enhances food intake |
| Obestatin | 23 amino acids derived from preproghrelin protein | acts in opposition to ghrelin action on appetite |
| Oxyntomodulin | 37 amino acids, the first 29 are identical to glucagon | contains all of the amino acids of glucagon (see Figure below); inhibits meal-stimulated gastric acid secretion similar to GLP-1 and GLP-2 action; induces satiety, decreases weight gain, and increases energy consumption; has weak affinity for GLP-1 receptor as well as glucagon receptor, may mimic glucagon actions in liver and pancreas |
| Secretin | 27 amino acids | secreted from duodenum at pH values below 4.5, stimulates pancreatic acinar cells to release bicarbonate and H2O |
| Somatostatin | 14 amino acid version | inhibits release and action of numerous gut peptides, e.g. CCK, OXM, PP, gastrin, secretin, motilin, GIP; also inhibits insulin and glucagon secretion from pancreas |
| Substance P, a member of the tachykinin family that includes neurokinin A (NKA) and neurokinin B (NKB) | 11 amino acids | CNS function in pain (nociception), involved in vomit reflex, stimulates salivary secretions, induces vasodilation; antagonists have anti-depressant properties |
| Vasoactive intestinal peptide (VIP) | 28 amino acids | produced by hypothalamus and GI tract, relaxes the GI, inhibits acid and pepsin secretion, acts as a neurotransmitter in peripheral autonomic nervous system, increases secretion of H2O and electrolytes from pancreas and gut |
| Pancreatic Polypeptide (polypeptide fold) Family | ||
| Pancreatic Polypeptide, PP | 36 amino acids | suppresses glucose-induced insulin secretion, inhibits bicarbonate and protein secretion from pancreas |
| Peptide Tyrosine Tyrosine, PYY | 36 amino acids | inhibits gastric motility by inhibiting cholinergic neurotransmission, inhibits gastric acid secretion, induces sensations of satiety |
| Neuropeptide Y, NPY | 36 amino acids, five receptors termed Y receptors | effects on hypothalamic function in appetite, controls feeding behavior and energy homeostasis, levels increase during starvation to induce food intake |
| Amphiregulin | two peptides: 78 amino acid truncated form and 84 amino acid form with six additional N-terminal amino acids | homology to EGF and binds to the EGF receptor (EGFR) | Pancreatic Hormones |
| Amylin | 37 amino acids, intrachain disulfide bonded | also called islet amyloid polypeptide (IAPP), produced by β-cells of the pancreas, co-secreted with insulin; reduces the rate of gastric emptying, suppresses of food intake, and suppresses post-meal glucagon secretion |
| Insulin | disulfide bonded dipeptide of 21 and 30 amino acids | produced by β-cells of the pancreas, increases glucose uptake and utilization, increases lipogenesis, general anabolic effects |
| Glucagon | polypeptide of 29 amino acids | produced by α-cells of the pancreas, increases lipid mobilization and glycogenolysis in order to increase blood glucose levels |
| Pancreatic polypeptide, PP | polypeptide of 36 amino acids | increases glycogenolysis, regulation of gastrointestinal activity |
| Somatostatin | 14 amino acid version | inhibition of glucagon and somatotropin release from pancreatic islet cells |
| Placental Hormones | ||
| Estrogens | steroids | maintenance of pregnancy |
| Progestins | steroids | mimic action of progesterone |
| Chorionic gonadotropin | two proteins: α form is 96 amino acids; β form is 147 | activity similar to LH |
| Chorionic somatomammotropin also called placental lactogen | protein of 191 amino acids | acts like prolactin and GH |
| Relaxin | two proteins of 22 and 32 amino acids | produced in ovarian corpus luteum, inhibits myometrial contractions, secretion increases during gestation | Gonadal Hormones |
| Estrogens (ovarian) | steroids: estrone (E1), estradiol (E2), and estriol (E3) | estradiol is most potent estrogen and it is the major hormone involved in the maturation and function of female secondary sex organs; estrone is predominant during menopause; estriol predominates in pregnancy; estrogens promote maturation of sperm in males and contribute to libido |
| Progestins (ovarian) | steroid: progesterone | implantation of ovum and maintenance of pregnancy |
| Androgens (testicular) | steroid: testosterone and dihydrotestosterone (DHT) | maturation and function of male secondary sex organs; testosterone in females participates in bone mass and muscle mass and strength, also contributes to female libido |
| Inhibins A and B | the inhibin alpha (α) peptide is 134 amino acids and is encoded by the INHA gene; the α-peptide forms disulfide bonds with either the inhibin beta A (115 amino acids encoded by the INHBA gene) peptide forming inhibin A or with the inhibin beta B (116 amino acid encoded by the INHBB gene) peptide forming inhibin B | inhibition of FSH secretion | Adrenal Cortical Hormones |
| Glucocorticoids | steroids: cortisol and corticosterone | diverse effects on inflammation and protein synthesis |
| Mineralocorticoids | steroids: aldosterone | maintenance of salt balance | Adrenal Medullary Hormones |
| Epinephrine (adrenalin) | derived from tyrosine | classic “fight-or-flight” response, increases glycogenolysis, lipid mobilization, smooth muscle contraction, cardiac function, binds to all classes of catecholamine receptors (α- and β-adrenergic) |
| Norepinephrine (noradrenalin) | derived from tyrosine | classic “fight-or-flight” response, lipid mobilization, arteriole contraction, also acts as neurotransmitter in the CNS, released from noradrenergic neurons, binds all catecholamine receptors except β2-adrenergic | Liver Hormones (Hepatokines) |
| go to the Secreted Factors: Tissue “Kines” page for a more complete listing of hepatokines and their functions | ||
| Angiotensin II | polypeptide of 8 amino acids derived from angiotensinogen (present in the α2-globulin fraction of plasma) which is cleaved by the kidney enzyme renin to give the decapeptide, angiotensin I, the C-terminal 2 amino acids are then released (by action of angiotensin-converting enzyme, ACE) to yield angiotensin II | responsible for essential hypertension through stimulated synthesis and release of aldosterone from adrenal cells | Kidney Hormones |
| Calcitriol [1,25-(OH)2-vitamin D3] | derived from 7-dehydrocholesterol | responsible for maintenance of calcium and phosphorous homeostasis, increases intestinal Ca2+ uptake, regulates bone mineralization |
| Erythropoietin, EPO | derived from 193 amino acid precursor protein | highly glycosylated hormone (40% of total mass) that is also considered a growth factor; is required for erythropoiesis in the bone marrow; exerts its effects by binding the EPO receptor, EPOR | Cardiac and Vascular Hormones |
| Atrial natriuretic peptide (ANP) | 126 amino acid precursor is cleaved to release an N-terminal peptide that is similar to vasoactive peptide, the C-terminus possesses the ANP activity | released from heart atria in response to hypervolemia; actions include natriuresis, diuresis, vasorelaxation, inhibition of renin and aldosterone secretion, also plays a key role in cardiovascular homeostasis |
| Endothelins | three family members: ET-1, ET-2, ET-3; all are 21 amino acid peptides with two Cys-Cys disulfide bonds | released from endothelial cells; interact with G-protein coupled receptors (GPCR) identified as ETA, ETB; endothelins primarily mediate smooth muscle contraction upon binding to endothelin receptors on these cells; can elicit smooth muscle relaxation through interactions with endothelin receptors on endothelial cells which results in increased nitric oxide (NO) production; the ETB receptor had been suggested to exist in two forms, ETB1 and ETB2, but there is no pharmacological evidence to support the existence of two forms in humans; an additional endothelin receptor identified as ETC was proposed but no gene in the human genome has been identified |
| Natriuretic peptide B (BNP) | precursor BNP is cleaved intracellularly and then also when released to the blood | released from heart ventricles in response to hypervolemia; original mammalian BNP was isolated from brain but the human brain natriuretic factor is CNP; BNP and ANP act by binding to the same receptor; actions include natriuresis, diuresis, vasorelaxation, inhibition of renin and aldosterone secretion, also plays a key role in cardiovascular homeostasis | Pineal Hormones |
| Melatonin | derived from tryptophan; structure is N-acetyl-5-methoxytryptamine | regulation of circadian rhythms |