Neuroendocrine cell

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Neuroendocrine
)

Neuroendocrine cells are cells that receive neuronal input (through

postganglionic 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] Sympathetic nerve
fiber 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 the

releasing hormones), released at the hypothalamic median eminence, control the secretion of pituitary hormones, while others (the hormones oxytocin and vasopressin
) are released directly into the blood.

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

Major neuroendocrine systems

Pulmonary neuroendocrine cells

Pulmonary neuroendocrine cells (PNECs) are specialized airway

epithelial cells that occur as solitary cells or as clusters called neuroepithelial bodies (NEBs) in the lung. Pulmonary neuroendocrine cells are also known as Kulchitsky cells or K cells.[2] They are located in the respiratory epithelium of the upper and lower respiratory tract. PNECs and NEBs exist from fetal
and neonatal stages in the lung airways.

These cells are bottle- or flask-like in shape, and reach from the basement membrane to the lumen. They can be distinguished by their profile of bioactive amines and peptides, namely serotonin, calcitonin, calcitonin gene-related peptide (CGRP), chromogranin A, gastrin-releasing peptide (GRP), and cholecystokinin.

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 in

paracrine 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 deep lamina 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 the

pituitary
cells where they may stimulate, inhibit, or maintain the function of a particular cell type.

See also

References

  1. ^
    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 T3 and 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.
  2. PMID 7701446
    .
  3. PMID 16418242
    .
  4. PMID 6270516
    .

External links
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