Paracrine signalling

Paracrine signaling involves diffusion of a ligand from one cell to another locally within tissues. 

Fig. 3.5. Endocrine, paracrine and autocrine signal transduction, a) endocrine signal transduction the hormone is formed in the specialized endocrine tissue, released into the extracellular medium and transported via the circulatory system to the target cells, b) paracrine signal transduction the hormone reaches the target cell, which is found in close juxtaposition to the hormone producing cell, via diffusion, c) autocrine signal transduction the hormone acts on the same ceU type as the one in which it is produced.

Valet P, Pages C, Jeanneton O, Daviaud D, Barbe P, Record M, Saulnier-Blache JS, Lafontan M (1998) Alpha2-adrenergic receptor-mediated release of lysophosphatidic acid by adipocytes. A paracrine signal for preadipocyte growth. J Clin Invest 101 1431-1438... 

Kaya N, Shen T, Lu SG, Zhao FL, Herness S. 2004. A paracrine signaling role for serotonin in rat taste buds Expression and localization of serotonin receptor subtypes. Am J Physiol 286 R649-R658. 

Paracrine signaling occurs when the cells that express the receptor are located in the same tissue as those which produce its ligand. 

---