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| Hormone | Structure | Functions |
| Pituitary Hormones | ||
| Oxytocin | polypeptide of 9 amino acids CYIQNCPLG (C's are disulfide bonded) | uterine contraction, causes milk ejection in lactating females, responds to suckling reflex and estradiol, lowers steroid synthesis in testes |
| Vasopressin (antidiuretic hormone, ADH) |
polypeptide of 9 amino acids CYFQNCPRG (C's are disulfide bonded) | responds to osmoreceptor which senses extracellular [Na+], blood pressure regulation, increases H2O readsorption from distal tubules in kidney |
| Melanocyte-stimulating hormones (MSH) | α polypeptide = 13 amino acids β polypeptide = 18 amino acids γ polypeptide = 12 amino acids |
pigmentation |
| Corticotropin (adrenocorticotropin, ACTH) | polypeptide = 39 amino acids | stimulates cells of adrenal gland to increase steroid synthesis and secretion |
| Lipotropin (LPH) | β polypeptide = 93 amino acids γ polypeptide = 60 amino acids |
increases fatty acid release from adipocytes |
| Thyrotropin (thyroid-stimulating hormone, TSH) | 2 proteins: α is 96 amino acids; β is 112 | acts on thyroid follicle cells to stimulate throid hormone synthesis |
| Growth hormone (GH, or somatotropin) | protein of 191 amino acids | general anabolic stimulant, increases release of insulin-like growth factor-I (IGF-I), cell growth and bone sulfation |
| Prolactin (PRL) | protein of 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 | 2 proteins: α is 96 amino acids; β is 121 | 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) | 2 proteins: α is 96 amino acids; β is 120 | ovarian follicle development and ovulation, increases estrogen production; acts on Sertoli cells of semiferous tubule to increase spermatogenesis |
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| Hypothalamic Hormones | ||
| Corticotropin-releasing factor (CRF or CRH) | protein of 41 amino acids | acts on corticotrope to release ACTH and β-endorphin (lipotropin) |
| Gonadotropin-releasing factor (GnRF or GnRH) | polypeptide of 10 amino acids | acts on gonadotrope to release LH and FSH |
| Prolactin-releasing factor (PRF) | this may be TRH | acts on lactotrope to release prolactin |
| Prolactin-release inhibiting factor (PIF) | may be derived from GnRH precursor, 56 amino acids | acts on lactotrope to inhibit prolactin release |
| Growth hormone-releasing factor (GRF or GRH) | protein of 40 and 44 amino acids | stimulates GH secretion |
| Somatostatin (SIF, also called growth hormone-release inhibiting factor, GIF) | polypeptide of 14 and 28 amino acids | inhibits GH and TSH secretion |
| Thyrotropin-releasing factor (TRH or TRF) | peptide of 3 amino acids: EHP | stimulates TSH and prolactin secretion |
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| Thyroid Hormones | ||
| Thyroxine and triiodothyronine | iodinated dityrosin derivatives | responds to TSH and stimulates oxidations in many cells |
| Calcitonin | protein of 32 amino acids | produced in parafollicular C cells of the thyroid, regulation of Ca2+ and Pi metabolism |
| Calcitonin gene-related peptide (CGRP) | protein of 37 amino acids, product of the calcitonin gene derived by alternative splicing of the precursor mRNA in the brain | acts as a vasodilator |
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| Parathyroid Hormone | ||
| Parathyroid hormone (PTH) | protein of 84 amino acids | regulation of Ca2+ and Pi metabolism, stimulates bone resorption thus increasing serum [Ca2+], stimulates Pi secretion by kidneys |
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| Adipose Tissue Hormones | ||
| additional discussion of adipocyte hormones and cytokines | ||
| 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 4 distinct functional domains | major biological actions are increases in insulin sensitivity and fatty acid oxidation |
| Resistin | 108 amino acid pre-protein in humans | induces insulin resistance |
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| Hormones and Peptides of the Gut | ||
| additional discussion of gastrointestinal hormones | ||
| 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 | polypeptide of 42 amino acids | inhibits secretion of gastric acid, enhances insulin secretion |
| 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 |
| Obestatin | 23 amino acids derived from preproghrelin protein | acts in opposition to ghrelin action on appetite |
| Gastrin | 17 amino acids | produced by stomach antrum, stimulates acid and pepsin secretion, also stimulates pancreatic secretions |
| Secretin | 27 amino acids | secreted from duodenum at pH values below 4.5, stimulates pancreatic acinar cells to release bicarbonate and H2O |
| Cholecystokinin, CCK | 33 amino acids | stimulates gallbladder contraction and bile flow, increases secretion of digestive enzymes from pancreas |
| Motilin | 22 amino acids | controls gastrointestinal muscles |
| 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 |
| Somatostatin | 14 amino acid version | inhibits release and action of numerous gut peptides, e.g. CKK, 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 |
| PP, PYY and NPY constitute the Pancreatic Polypeptide family of 36 amino acid peptides. PP and PYY exhibit endocrine functions. NPY functions as a neuropeptide |
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| 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 |
| Neuropeptide Tyrosine, NPY | 36 amino acids, 6 receptors | effects on hypothalamic function in appetite, controls feeding behavior and energy homeostasis, levels increase during starvation to induce food intake |
| Amphiregulin | 2 peptides: 78 amino acid truncated form and 84 amino acid form with 6 additional N-terminal amino acids | homology to EGF and binds to the EGF receptor (EGFR) |
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| Pancreatic Hormones | ||
| 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 | polypeptide of 36 amino acids | increases glycogenolysis, regulation of gastrointestinal activity |
| Somatostatin | 14 amino acid version | inhibition of glucagon and somatotropin release |
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| Placental Hormones | ||
| Estrogens | steroids | maintenance of pregnancy |
| Progestins | steroids | mimic action of progesterone |
| Chorionic gonadotropin | 2 proteins: α is 96 amino acids; β is 147 | activity similar to LH |
| Placental lactogen | protein of 191 amino acids | acts like prolactin and GH |
| Relaxin | 2 proteins of 22 and 32 amino acids | produced in ovarian corpus luteum, inhibits myometrial contractions, secretion increases durin gestation |
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| Gonadal Hormones | ||
| Estrogens (ovarian) | steroids: estradiol and estrone | maturation and function of female secondary sex organs |
| Progestins (ovarian) | steroid: progesterone | implantation of ovum and maintenance of pregnancy |
| Androgens (testicular) | steroid: testosterone | maturation and function of male secondary sex organs |
| Inhibins A and B | 1 protein (α is 134 amino acids; β is 115 and 116 amino acids) | inhibition of FSH secretion |
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| Adrenal Cortical Hormones | ||
| Glucocorticoids | steroids: cortisol and corticosterone | diverse effects on inflammation and protein synthesis |
| Mineralocorticoids | steroids: aldosterone | maintenance of salt balance |
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| 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 |
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| Liver Hormones | ||
| 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 |
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| 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 |
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| Cardiac Hormones | ||
| Atrial natriuretic peptide (ANP) | several active peptides cleaved from a 126 amino acid precursor | released from heart atria in response to hypovolemia, acts on outer adrenal cells to decrease aldosterone production; smooth muscle relaxation |
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| Pineal Hormones | ||
| Melatonin | N-acetyl-5-methoxytryptamine | regulation of circadian rhythms |
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