Intracrine refers to a

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

that acts inside a

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

, regulating intracellular events. In simple terms it means that the cell stimulates itself by cellular production of a factor that acts within the cell. Steroid hormones act through intracellular (mostly nuclear) receptors and, thus, may be considered to be intracrines. In contrast,

peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. ...

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

hormones, in general, act as endocrines, autocrines, or paracrines by binding to their receptors present on the cell surface. Several peptide/protein hormones or their

isoforms A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene or gene family and are the result of genetic differences. While many perform the same or similar biological roles, some iso ...

also act inside the cell through different mechanisms. These peptide/protein hormones, which have intracellular functions, are also called intracrines. The term 'intracrine' is thought to have been coined to represent peptide/protein hormones that also have intracellular actions. To better understand intracrine, we can compare it to paracrine, autocrine and endocrine. The autocrine system deals with the autocrine receptors of a cell allowing for the hormones to bind, which have been secreted from that same cell. The paracrine system is one where nearby cells get hormones from a cell, and change the functioning of those nearby cells. The endocrine system refers to when the hormones from a cell affect another cell that is very distant from the one that released the hormone. Paracrine physiology has been understood for decades now and the effects of paracrine hormones have been observed when for example, an obesity associate tumor will face the effects of local adipocytes, even if it is not in direct contact with the fat pads in concern. Endocrine physiology on the other hand is a growing field and has had a new area explored, called intracrinology. In intracrinology, the sex steroids produced locally, exert their action in the same cell where they are produced. The biological effects produced by intracellular actions are referred as intracrine effects, whereas those produced by binding to cell surface receptors are called endocrine,

autocrine Autocrine signaling is a form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell. This can be contrasted with p ...

, or

paracrine Paracrine signaling is a form of cell signaling, a type of cellular communication in which a cell produces a signal to induce changes in nearby cells, altering the behaviour of those cells. Signaling molecules known as paracrine factors diffuse over ...

effects, depending on the origin of the hormone. The intracrine effect of some of the peptide/protein hormones are similar to their endocrine, autocrine, or paracrine effects; however, these effects are different for some other hormones. Intracrine can also refer to a hormone acting within the cell that synthesizes it. Examples of intracrine peptide hormones: There are several protein/peptide hormones that are also intracrines. Notable examples that have been described in the references include: * Peptides of the

renin–angiotensin system The renin–angiotensin system (RAS), or renin–angiotensin–aldosterone system (RAAS), is a hormone system that regulates blood pressure, fluid and electrolyte balance, and systemic vascular resistance. When renal blood flow is reduced, ...

angiotensin II Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adr ...

and angiotensin (1-7) * Fibroblast growth factor 2 *

Parathyroid hormone-related protein Parathyroid hormone-related protein (PTHrP) is a proteinaceous hormone and a member of the parathyroid hormone family secreted by mesenchymal stem cells. It is occasionally secreted by cancer cells (for example, breast cancer, certain types of ...

References

# ''Park, Jiyoung; Euhus, David M.; Scherer, Philipp E. (August 2011). "Paracrine and Endocrine Effects of Adipose Tissue on Cancer Development and Progression". Endocrine Reviews. 32 (4): 550–570. .'' # ''Labrie, Fernand; Luu-The, Van; Labrie, Claude; Bélanger, Alain; Simard, Jacques; Lin, Sheng-Xiang; Pelletier, Georges (April 2003). "Endocrine and Intracrine Sources of Androgens in Women: Inhibition of Breast Cancer and Other Roles of Androgens and Their Precursor Dehydroepiandrosterone". Endocrine Reviews. 24 (2): 152–182. .'' # # # # # ;Specific Cell biology {{Cell-biology-stub

See also

References