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| 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) |
b polypeptide = 93 amino acids
g 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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|
| 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) |
polypeptide 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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| Hormones and Peptides of the Gut |
| additional dicussion 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; acylated and non-acylated forms found in circulation |
appetite stimulation, regulation of energy homeostasis, glucose metabolism, gastric secretion and emptying, insulin secretion |
| Obestatin |
23 amino acids derived from pro-ghrelin 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 |
| 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 |
glycogenolysis, lipid mobilization, smooth muscle contraction, cardiac function |
| Norepinephrine (noradrenalin) |
tyrosine derivative |
lipid mobilization, arteriole contraction |
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| Liver Hormones |
| Angiotensin II |
polypeptide of 8 amino acids derived from angiotensinogen (present in the α2-globin 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 hoemostasis, 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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