Neuroendocrine cells are a type of cells that have molecular substances that allow them to uptake and release neurotransmitters and neuropeptide hormones. These cells enable autocrine communication both with paracrine and endocrine cells throughout the body. The adrenal medullary cells are connected with the sypathetic division of the autonomic nervous system. These cells are modified postgaglionic 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. 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.

See also: Neuroendocrinology

Nervous tissue cells

Pulmonary Neuroencodrince Cells

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Pulmonary neuroendocrine cells (PNEC) are specialized airway epithelial cells that occur as solitary cells or as clusters called neuroepithelial bodies (NEB) in the lung. They are located in the nasal respiratory epithelium, laryngeal mucosa and throughout the entire respiratory tract from the trachea to the terminal 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.

Function of Pulmonary Neuroendocrine Cells

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NEB may play a role as chemoreceptors in hypoxia (medical) detection. This is best supported by the presence of an oxygen-sensitive potassium channel coupled to an oxygen sensory protein in the lumenal membrane in the rabbit. They are considered to be involved in regulating localized epithelial cell growth and regeneration through a paracrine mechanism, whereby their bioactive peptides are released into the environment. Additionally, they contain neuroactive substances which are released from their basal cytoplasm. These substances affect autonomic nerve terminals or vasculature in the lamina propria deep to the cells.

Role of PNEC in Fetal lung

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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 growth factor-like properties.