Neuroendocrine cell

Neuroendocrine cellsare cells that receive neuronal input (throughneurotransmittersreleased by nerve cells or neurosecretory cells) and, as a consequence of this input, release messenger molecules (hormones) into the blood. In this way they bring about an integration between thenervous systemand theendocrine system,a process known asneuroendocrine integration.An example of a neuroendocrine cell is a cell of theadrenal medulla(innermost part of theadrenal gland), which releasesadrenalineto the blood. The adrenal medullary cells are controlled by thesympathetic divisionof theautonomic nervous system.These cells are modifiedpostganglionic neurons.Autonomic nerve fibers lead directly to them from the central nervous system. The adrenal medullary hormones are kept in vesicles much in the same way neurotransmitters are kept in neuronal vesicles. Hormonal effects can last up to ten times longer than those of neurotransmitters.^{[citation needed]}Sympatheticnervefiber impulses stimulate the release of adrenal medullary hormones. In this way the sympathetic division of the autonomic nervous system and the medullary secretions function together.

The major center of neuroendocrine integration in the body is found in thehypothalamusand thepituitary gland.Here hypothalamic neurosecretory cells release factors to the blood. Some of these factors (releasing hormones), released at the hypothalamicmedian eminence,control the secretion of pituitary hormones, while others (the hormonesoxytocinandvasopressin) are released directly into the blood.

APUDcells are considered part of the neuroendocrine system, and share many staining properties with neuroendocrine cells.

Major neuroendocrine systems

Hypothalamic–pituitary–adrenal axis^[1](HPA axis)
Hypothalamic–pituitary–thyroid axis^[1](HPT axis)
Hypothalamic–pituitary–gonadal axis^[1](HPG axis)
Hypothalamic–neurohypophyseal system^[1]

Pulmonary neuroendocrine cells

Pulmonary neuroendocrine cells(PNECs) are specialized airwayepithelial cellsthat occur as solitary cells or as clusters called neuroepithelial bodies (NEBs) in thelung.Pulmonary neuroendocrine cells are also known asbronchialKulchitsky cells.^[2]They are located in therespiratory epitheliumof the upper and lowerrespiratory tract.PNECs and NEBs exist fromfetaland neonatal stages in the lung airways.

These cells are bottle- or flask-like in shape, and reach from thebasement membraneto thelumen.They can be distinguished by their profile of bioactive amines and peptides, namelyserotonin,calcitonin,calcitonin gene-related peptide(CGRP),chromogranin A,gastrin-releasing peptide(GRP), andcholecystokinin.

These cells can be the source of several types of lung cancer, most notably small cell carcinoma of the lung, and bronchial carcinoid tumor.^[3]^[4]

Function

PNECs may play a role with chemoreceptors inhypoxiadetection. This is best supported by the presence of an oxygen-sensitive potassium channel coupled to an oxygen sensory protein in the rabbit lumenal membrane. They are hypothetically involved in regulating localized epithelial cell growth and regeneration through aparacrine mechanism,whereby their signaling peptides are released into the environment. In addition, they contain neuroactive substances which are released from basal cytoplasm. These substances induce autonomic nerve terminals or vasculature in the deeplamina propria.

Role in fetal lung

In the fetal lung, they are frequently located at the branching points of airway tubules, and in humans are present by 10 weeks gestation. Peptides and amines released by PNEC are involved in normal fetal lung development including branching morphogenesis. The best-characterized peptides are GRP, the mammalian form of bombesin, and CGRP; these substances exert direct mitogenic effects on epithelial cells and exhibit many properties akin to growth factors.

Example

Examples

Specialized groups of neuroendocrine cells can be found at the base of thethird ventriclein thebrain(in a region called thehypothalamus). This area controls mostanterior pituitarycells and thereby regulates functions in the entire body, like responses tostress,cold,sleep,and thereproductive system.The neurons send processes to a region connecting to thepituitary stalkandreleasing hormonesare delivered into the bloodstream. They are carried by portal vessels to thepituitarycells where they may stimulate, inhibit, or maintain the function of a particular cell type.

References

^^a ^b ^c ^dMalenka RC, Nestler EJ, Hyman SE (2009). "Chapter 10: Neural and Neuroendocrine Control of the Internal Milieu". In Sydor A, Brown RY (ed.).Molecular Neuropharmacology: A Foundation for Clinical Neuroscience(2nd ed.). New York: McGraw-Hill Medical. pp. 246,248–259.ISBN 9780071481274.
•The hypothalamic–neurohypophyseal system secretes two peptide hormones directly into the blood, vasopressin and oxytocin....
•The hypothalamic–pituitary–adrenal (HPA) axis. It comprises corticotropin-releasing factor (CRF), released by the hypothalamus; adrenocorticotropic hormone (ACTH), released by the anterior pituitary; and glucocorticoids, released by the adrenal cortex.
•The hypothalamic–pituitary–thyroid axis consists of hypothalamic thyrotropin-releasing hormone (TRH); the anterior pituitary hormone thyroid–stimulating hormone (TSH); and the thyroid hormones T₃and T₄.
•The hypothalamic–pituitary–gonadal axis comprises hypothalamic gonadotropin–releasing hormone (GnRH), the anterior pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the gonadal steroids.
^Addis, B. J. (1995)."Neuroendocrine differentiation in lung carcinoma".Thorax.50(2):113–115.doi:10.1136/thx.50.2.113.PMC473889.PMID 7701446.
^Chong S, Lee KS, Chung MJ, Han J, Kwon OJ, Kim TS (2006). "Neuroendocrine tumors of the lung: clinical, pathologic, and imaging findings".Radiographics.26(1):41–57, discussion 57–8.doi:10.1148/rg.261055057.PMID 16418242.
^Becker, KL; Silva, OL (July 1981). "Hypothesis: the bronchial Kulchitsky (K) cell as a source of humoral biologic activity".Medical Hypotheses.7(7):943–9.doi:10.1016/0306-9877(81)90049-9.PMID 6270516.

External links

Media related toNeuroendocrine cellsat Wikimedia Commons
Neuroendocrine+Systemat the U.S. National Library of MedicineMedical Subject Headings(MeSH)

[NHM-Neuroendocrine_systems-1] Malenka RC, Nestler EJ, Hyman SE (2009). "Chapter 10: Neural and Neuroendocrine Control of the Internal Milieu". In Sydor A, Brown RY (ed.).Molecular Neuropharmacology: A Foundation for Clinical Neuroscience(2nd ed.). New York: McGraw-Hill Medical. pp. 246,248–259.ISBN 9780071481274.
•The hypothalamic–neurohypophyseal system secretes two peptide hormones directly into the blood, vasopressin and oxytocin....
•The hypothalamic–pituitary–adrenal (HPA) axis. It comprises corticotropin-releasing factor (CRF), released by the hypothalamus; adrenocorticotropic hormone (ACTH), released by the anterior pituitary; and glucocorticoids, released by the adrenal cortex.
•The hypothalamic–pituitary–thyroid axis consists of hypothalamic thyrotropin-releasing hormone (TRH); the anterior pituitary hormone thyroid–stimulating hormone (TSH); and the thyroid hormones T₃and T₄.
•The hypothalamic–pituitary–gonadal axis comprises hypothalamic gonadotropin–releasing hormone (GnRH), the anterior pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the gonadal steroids.

[French-2] Addis, B. J. (1995)."Neuroendocrine differentiation in lung carcinoma".Thorax.50(2):113–115.doi:10.1136/thx.50.2.113.PMC473889.PMID 7701446.

[3] Chong S, Lee KS, Chung MJ, Han J, Kwon OJ, Kim TS (2006). "Neuroendocrine tumors of the lung: clinical, pathologic, and imaging findings".Radiographics.26(1):41–57, discussion 57–8.doi:10.1148/rg.261055057.PMID 16418242.

[Becker-4] Becker, KL; Silva, OL (July 1981). "Hypothesis: the bronchial Kulchitsky (K) cell as a source of humoral biologic activity".Medical Hypotheses.7(7):943–9.doi:10.1016/0306-9877(81)90049-9.PMID 6270516.

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