Starling's original definition of a hormone from 1905 was "a hormone is a substance produced by glands with internal secretion, which serve to carry signals through the blood to target organs". Today, this definition is understood to be lacking, but newer definitions also do not encompass the entire meaning of hormones as specific carriers of information. One main problem is that there is no delineation between hormones and other signaling molecules such as cytokines, growth factors or autacoid compounds. It seems that a precise definition is not even possible, since some cytokines and growth factors, such as the cytokines erythropoietin, lipocalin-2 and asprosin or fibroblast growth factor 23, act as hormones under certain conditions.

Department of Steroids and Proteofactors Institute of Endocrinology Prague Czech Republic

Zobrazit více v PubMed

ADHR CONSORTIUM. Autosomal dominant hypophosphataemic rickets is associated with mutations in FGF23. Nat Genet. 2000;26:345–348. doi: 10.1038/81664. PubMed DOI

ALNAEELI M, RAAKA BM, GAVRILOVA O, TENG R, CHANTURIYA T, NOGUCHI CT. Erythropoietin signaling: a novel regulator of white adipose tissue inflammation during diet-induced obesity. Diabetes. 2014;63:2415–2431. doi: 10.2337/db13-0883. PubMed DOI PMC

BARRET KE, BARMAN SM, YUAN J, BROOKS HL. Ganong’s Review of Medical Physiology. 26th Edition. McGraw-Hill Education; 2019.

BARRINGTON EJW. Encyclopaedia Britanica. 2019. Hormone.

BIOLOGY DICTIONARY. https://biologydictionary.net/2019 .

DICTIONARY.COM. https://www.dictionary.com/2019 .

JELKMANN W, WAGNER K. Beneficial and ominous aspects of the pleiotropic action of erythropoietin. Ann Hematol. 2004;83:673–686. doi: 10.1007/s00277-004-0911-6. PubMed DOI

LAW IK, XU A, LAM KS, BERGER T, MAK TW, VANHOUTTE PM, LIU JT, SWEENEY G, ZHOU M, YANG B, WANG Y. Lipocalin-2 deficiency attenuates insulin resistance associated with aging and obesity. Diabetes. 2010;59:872–882. doi: 10.2337/db09-1541. PubMed DOI PMC

MOSIALOU I, SHIKHEL S, LIU JM, MAURIZI A, LUO N, HE Z, HUANG Y, ZONG H, FRIEDMAN RA, BARASCH J, LANZANO P, DENG L, LEIBEL RL, RUBIN M, NICKOLAS T, CHUNG W, ZELTSER LM, WILLIAMS KW, PESSIN JE, KOUSTENI S. MC4R-dependent suppression of appetite by bone-derived lipocalin 2. Nature. 2017;543:385–390. doi: 10.1038/nature21697. PubMed DOI PMC

ROMERE C, DUERRSCHMID C, BOURNAT J, CONSTABLE P, JAIN M, XIA F, SAHA PK, Del SOLAR M, ZHU B, YORK B, SARKAR P, RENDON DA, GABER MW, LEMAIRE SA, COSELLI JS, MILEWICZ DM, SUTTON VR, BUTTE NF, MOORE DD, CHOPRA AR. Asprosin, a fasting-Induced glucogenic protein hormone. Cell. 2016;165:566–579. doi: 10.1016/j.cell.2016.02.063. PubMed DOI PMC

ŽOFKOVÁ I. Bone tissue as a systemic endocrine regulator. Physiol Res. 2015;64:439–445. doi: 10.33549/physiolres.932900. PubMed DOI

ZOFKOVA I. Involvement of bone in systemic endocrine regulation. Physiol Res. 2018;67:669–677. doi: 10.33549/physiolres.933843. PubMed DOI