Tissues adrenal cortex

Gene expression In normal tissues Adrenal cortex, liver, High in lung, bladder,... 

A substantial amount of the NADPH required for reductive processes (i.e., lipid biosynthesis) and antioxidant mechanisms is supplied by these reactions. For this reason this pathway is most active in cells in which relatively large amounts of lipids are synthesized, for example, adipose tissue, adrenal cortex, mammary glands, and the liver. 

Control of secretion of anterior pituitary hormones also includes inhibition by hormones produced by target organs. For example, CRH stimulates the anterior pituitary to secrete ACTH, which in turn stimulates the adrenal cortex to secrete corticosteroids. Corticosteroids then feed back to inhibit the secretion of ACTH. Feedback mechanisms are important for the control of most hormones. For example, insulin (qv) secretion from the pancreas increases in response to increased blood glucose resulting from ingestion of a meal. Insulin increases tissue uptake and metaboHsm of glucose, which lowers blood glucose and in turn reduces insulin secretion. 

Sulfoxides occur widely in small concentrations in plant and animal tissues, eg, aHyl vinyl sulfoxide [81898-53-5] in garlic oil and 2,2 -sulfinylbisethanol [3085-45-8] as fatty esters in the adrenal cortex (1,2). Homologous methyl sulfinyl alkyl isothiocyanates, which are represented by the formula CH3SO(CH2) NCS, where n = 3 [37791-20-1], 4 [4478-93-7], 5 [646-23-1], 8 [75272-81-0], 9 [39036-83-4], or 10 [39036-84-5], have been isolated from a number of mustard oils in which they occur as glucosides (3). Two methylsulfinyl amino acids have also been reported methionine sulfoxide [454-41-1] from cockroaches and the sulfoxide of i -methylcysteine, 3-(methylsulfinyl)alaiiine [4740-94-7]. The latter is the dominant sulfur-containing amino acid in turnips and may account in part for their characteristic odor (4). 

Mitochondrial cytochrome P450 systems are found in steroidogenic tissues such as adrenal cortex, testis, ovary, and placenta and are concerned with the biosyn-... 

Steroidogenic agents—including ACTH and cAMP in the adrenal cortex angiotensin 11, K", serotonin, ACTH, and cAMP in the zona glomerulosa of the adrenal LH in the ovary and LH and cAMP in the Ley dig cells of the testes—have been associated with increased amounts of phosphatidic acid, phosphatidylinositol, and polyphosphoinositides (see Chapter 14) in the respective target tissues. Several other examples could be cited. 

Responses to stress by altering blood flow to skeletal muscles and other tissues as well as enhancing secretion of hormones from the adrenal cortex (glucocorticoids) whose metabolic activities enable the body to physically cope with stress... 

In almost all tissues where 5-HT4 receptors are present, 5-HT or any other agonists increase intracellular cAMP synthesis [12], as has been shown for hippocampus, atrium, esophagus, intestinal tissue and adrenal cortex. A number of processes can be triggered by an increase in intracellular cAMP. For instance in the intestine, an increase in intracellular cAMP concentrations following activation of 5-HT4 receptors can trigger a relaxation of the smooth muscle. However, activation of 5-HT4 receptors present on intestinal inter- and motor-neurons leads to a facilitation of acetylcholine release and, thereby, to increased contractions of intestinal smooth muscle [13]. 

Steroid hormones are produced by only two tissue types, the adrenal cortex and the gonads. A summary of the steroid hormones is given in Table 4.2. Steroid hormones are synthesized from cholesterol (Figure 4.2). This sterol lipid may itself be synthesized within the steroidogenic cell or it may be delivered to the cell by circulating lipoprotein complexes such as low density lipoprotein (LDL) or high density lipoprotein (HDL). 

Named after Thomas Addison who first described the clinical condition in the mid 1850s, Addison s disease is one of the commonest endocrinopathies. At one time, most cases of Addison s were due to infection, usually by tuberculosis, of the adrenal cortex but nowadays the likely cause is autoimmune destruction of the tissue, and may be associated with dysfunction of other endocrine glands. 

Angiotensin-II-receptor antagonists These block the binding of this messenger to its receptors on the two target tissues, i.e. smooth muscle in the arterioles and the aldosterone-secreting cells in the adrenal cortex. 

Desoxycorticosterone causes an increase in reabsorption of sodium ions and excretion of potassium ions from the renal tubules, which leads to increased tissue hydrophilicity. This facilitates an elevated volume of plasma and increased arterial pressure. Muscle tonicity and work capability are increased. It is used for an insufficiency of function of the adrenal cortex, myasthenia, asthenia, adynamia, and overall muscle weakness. Synonyms of this drug are percorten, docabolin, cortitron, and others. 

A. Synthesis of cholesterol occurs in the cytoplasm of most tissues, but the liver, intestine, adrenal cortex, and steroidogenic reproductive tissues are the most active. 

Mitotane, or o,p -DDD, is an oral medication used in the treatment of adrenocortical carcinoma. Chemically it is an isomere of DDT. Following its metabolism in the adrenal cortex to a reactive acyl chloride intermediate, mitotane covalently binds to adrenal proteins, specitically inhibiting adrenal cortical hormone production. The drug accumulates in fat tissue. It is eliminated mainly by the kidneys with a half-life of 18-159 days. Common side effects include anorexia, nausea, lethargy, sleepiness and skin problems. 

Adrenal cortex also produces small quantities of weak androgens (androstenedione and dehydroepiandrosterone) which are partially converted to testosterone in peripheral tissues. In females, ovaries also secrete small quantities of testosterone. 

Biosynthesis in anterior pituitary, stimulation of formation of corticosteroids in adrenal cortex, release of fatty acids from adipose tissue,... 

Mitochondrial system The function of the mitochondrial cyto chrome P450 monooxygenase system is to participate in the hydroxylation of steroids, a process that makes these hydropho bic compounds more water soluble. For example, in the steroid hormone-producing tissues, such as the placenta, ovaries, testes, and adrenal cortex, it is used to hydroxylate intermediates in the conversion of cholesterol to steroid hormones. The liver uses this system in bile acid synthesis (see p. 222), and the kidney uses it to hydroxylate vitamin 25-hydroxycholecalciferol (vitamin D, see p. 384) to its biologically active 1,25-hydroxylated form. 

Steroid hormones are secreted on demand from their tissues of origin in response to hormonal signals. The corticosteroids and androgens are made in different regions of the adrenal cortex, and are secreted into blood in response to different signals. 

Androgens Both the inner and middle layers of the adrenal cortex produce androgens, primarily dehydroepiandrosterone and androstenedione. Although adrenal androgens themselves are weak, they are converted in peripheral tissues to testosterone—a strong androgen—and to estradiol. 

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