Diseases of the adrenal medulla

Abstract

The adrenal glands are vital in the organism's response to environmental stress. The outer cortex releases steroid hormones: glucocorticoids, mineralocorticoids and sex hormones, which are crucial to metabolism, inflammatory reactions and fluid homeostasis. The medulla is different developmentally, functionally and structurally. It co-releases catecholamines (primarily adrenaline and to some extent noradrenaline) as well as peptides by the all-or-none process of exocytosis from chromaffin granules, to aid in blood pressure and blood flow regulation, with regulated increments during the activation of the sympathetic nervous system. The co-released peptides function to regulate catecholamine release, blood vessel contraction and innate immune responses. Pathology within the adrenal medulla and the autonomic nervous system is primarily because of neoplasms. The most common tumour, called phaeochromocytoma when located in the adrenal medulla, originates from chromaffin cells and excretes catecholamines, but may be referred to as secreting paragangliomas when found in extra-adrenal chromaffin cells. Neoplasms, such as neuroblastomas and ganglioneuromas, may also be of neuronal lineage. We will also briefly discuss the catecholamine deficiency state. Keywordsadrenal; catecholamine; chromaffin; phaeochromocytoma Anatomy and physiologyThe adrenal medulla is the location of the majority of the organism's chromaffin cells, derived embryologically from neuroectoderm; ganglion cells and sustentacular cells are also found in the medulla. Chromaffin cells, which store catecholamines in secretory vesicles also known as chromaffin granules, are found in clusters (or nests) and in trabeculae, whereas the ganglion cells are found singly or in clusters interspersed among the chromaffin cells or in association with nerve fibres. The sustentacular cells, or support cells, are located at the periphery of clusters of chromaffin cells.The precursor chromaffin cells differentiate at the centre of the adrenal gland in response to the glucocorticoid cortisol. A minority of these cells also migrate to form paraganglia, collections of chromaffin cells on both sides of the aorta, the largest of which is primarily found at the origin of the inferior mesenteric artery or at the bifurcation of the aorta and is referred to as the organ of Zuckerkandl.Correspondence: D. T. O'Connor, Departments of Medicine and Pharmacology, Center for Human Genetics and Genomics (CHGG), University of California at San Diego, Skaggs (SSPPS) room 4256, 9500 Gilman Drive, La Jolla, CA 92093-0838, USA. E-mail: doconnor@ucsd.edu. Conflict of interestThere are no conflicts of interest for any of the authors for this paper. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptThe catecholamines are discharged from the chromaffin granules and sympathetic axons by the process of exocytosis, wherein all soluble components of the granule, including enzymes and chromogranins and bioactive peptides, are co-released into the extra...

Building a Competing Endogenous RNA Network to Find Potential Long Non-Coding RNA Biomarkers for Pheochromocytoma

“…The annual incidence of PCC is between 3-4 per million [3], and its etiology is not yet clear, but it may be related to genetics. Studies have shown that approximately 30% of PCC cases have a heredofamilial background [1,4].…”

Can the ‘neuron theory’ be complemented by a universal mechanism for generic neuronal differentiation

“…Importantly, it is from this lineage that neuroblastoma, the most frequent extra-cranial solid tumor during childhood, is derived (for reviews, see Ilias and Pacak 2005;Fung et al 2008).…”

Tumours of the Adrenal Gland

“…The medulla on the other hand is derived from ectoderm (neural crest) and contains chromaffi n cells, which store noradrenaline (20 %) and adrenaline (80 %) as secretory vesicles also known as chromaffi n granules. Some of the precursor chromaffi n cells migrate to the sides of the aorta mainly found at the origin of inferior mesenteric artery and bifurcation of aorta (organ of Zuckerkandl) [ 1 ]. …”

“…The adrenal gland consists of cortex and medulla, which embryologically, structurally and functionally are two separate entities [ 1 ]. The bulk of the gland is formed by the adrenal cortex, derived from mesoderm.…”