Endocrine glands pituitary

Peptide hormones are produced by the endocrine glands (pituitary, thyroid, pineal, adrenal, and pancreas) or by various organs such as the kidney, stomach, intestine, placenta, or liver (Table 3.4). Peptide hormones can have complex, convoluted structures with hundreds of amino acids. Figure 3.2 illustrates the chemical structure of human insulin and its three-dimensional shape. Insulin is made of two amino acid sequences. The A-Chain has 21-amino acids, and the B-Chain has 30-amino acids. The chains are linked together through the sulfur atoms of cysteine (Cys). Peptide hormones are generally different for every species, but they may have similarities [11]. Human insulin is identical to pig insulin, except that the last amino acid of the B-Chain for the pig is alanine (Ala) instead of threonine (Thr) (lUPAC and lUBMB) [9] and [11]. 

Pituitary. The primary endocrine gland that controls many of the endocrine tissues of the body. The pituitary is in turn con-... 

Adrenal gland weights were not affected in rats treated by gavage with 1,500 mg/kg/day trichloroethylene in com oil for 14 days (Berman et al. 1995). Histopathological changes in endocrine glands (thyroid, parathyroid, pancreas, adrenals, pituitary) have not been observed in rats or mice exposed by gavage to trichloroethylene in oil for intermediate or chronic durations (Maltoni et al. 1986 NCI 1976 NIP 1988, 1990). 

A trophic hormone acts on another endocrine gland to stimulate secretion of its hormone. For example, thyrotropin, or thyroid-stimulating hormone (TSH), stimulates the secretion of thyroid hormones. Adrenocorticotropin, or adrenocorticotropic hormone (ACTH), stimulates the adrenal cortex to secrete the hormone cortisol. Both trophic hormones are produced by the pituitary gland in fact, many trophic hormones are secreted by the pituitary. The pituitary gland is sometimes referred to as the "master gland" because its hormones regulate the activity of other endocrine glands. 

For many years it was considered that there were seven major endocrine glands the hypothalamus, pituitary,... 

Anterior lobe of pituitary is the master gland of the endocrine system as a whole because it produces peptide trophic hormones which affect the other ductless/endocrine glands. The anterior lobe secretes the following hormones ... 

All the hormones produced by the anterior pituitary except prolactin (PRL) are key participants in hormonal systems in which they regulate the production by peripheral tissues of hormones that perform the ultimate regulatory functions. In these systems, the secretion of the pituitary hormone is under the control of a hypothalamic hormone. Each hypothalamic-pituitary-endocrine gland system or axis provides multiple opportunities for complex neuroendocrine regulation of growth, development, and reproductive functions. 

Nerve impulses stimulate the hypothalamus to send specific hormones to the pituitary gland, thus stimulating (or inhibiting) the release of tropic hormones. The anterior pituitary hormones in turn stimulate other endocrine glands (thyroid, adrenals, pancreas) to secrete their characteristic hormones, which in turn stimulate specific target tissues. 

Thyrotropin-releasing hormone is one of several small peptide hormones secreted by the anterior lobe of the pituitary gland. These are the master" hormones that function to stimulate hormone secretion from other endocrine glands. Thyrotropin stimulates the functioning of the thyroid gland. 

Location of major endocrine glands in humans. The hypothalamus regulates the anterior pituitary, which regulates the hormonal secretions of the thyroid, adrenals, and gonads (ovary in the female and testis in the male). 

Other Hormones. Pituitary hormones regulate the function of many other endocrine glands, and hypophysectomy in male rats results in a decrease in the activity of xenobiotic metabolizing enzymes. Administration of adrenocorticotropic hormone (ACTH) also results in a decrease of those oxidative enzyme activities that are gender dependent. In contrast, ACTH treatment of female rats causes an increase in aminopyrine /V-dcmcthylasc but no change in other activities. 

In the studies of long-term exposure of rats to both triphenyltin hydroxide and bis(tributyltin)oxide, most of the tumors were found in endocrine glands. In addition to the pituitary adenomas associated with bis(tributyltin)oxide and triphenyltin hydroxide, there was also an increased incidence of pheochromocytomas of the adrenal gland, parathyroid carcinomas and pancreatic adenocarcinomas in animals from at least one sex. Triphenyltin hydroxide was associated with an increased incidence of testicular Leydig cell tumors in male rats at the highest dose. Hepatic tumors were found in male and female mice following 80 weeks of triphenyltin hydroxide administration. 

The hypothalamus-pituitary, thyroid, parathyroid, pancreas, adrenals, ovary, and testes are considered to be the principal endocrine glands producing hormones. A more complete list of the major endocrine hormones and their primary gland of origin is shown in Table 9.1. 

The endocrine glands such as the thyroid, the pituitary gland, and the pineal gland, are extremely sensitive to fluoride and accumulate aluminum. 

Mariotti S (2002) Normal Physiology of the Hypothalmic-Pituitary-Thyroidal System and Relation to the Neural System and Other Endocrine Glands. [Internet resource] http //www.thyroidmanager.org/Chapter4/4-frame.htm Meinhold H, Altmann R, Bogner U, Finke R, Schleusener H (1994) Evaluation of various immunometric TSH assays. Exp Clin Endocrinol 102 23-26 Oda Y, Sanders J, Roberts S, Maruyama M, Kato R, Perez M, Petersen VB, Wedlock N, Furmaniak 1, Smith RB (1998) Binding characteristics of antibodies to the TSH receptor. J Mol Endocrinol 20 233-244... 

Figure 13.1 Major human endocrine glands (1) pineal gland, (2) pituitary gland, (3) thyroid gland, (4) thymus, (5) adrenal gland, (6) pancreas, (7) ovary and (8) testes.

Figure 13.2 The hierarchical control of hormone release. Releasing hormones from the hypothalamus travel directly to the anterior pituitary hormones secreted by the anterior pituitary control most somatic endocrine glands. 

Hormones synthesised by the antei ior pituitary that regulate the activity of various endocrine glands are referred to as tropic hormones (e.g. thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle-stimulating hormone (FSH)). 

Examples of the use of analytical-scale column systems for the small-scale (i.e., 1 fig to 1 mg) preparative separation of peptides include the extraordinarily potent opoid peptide, dynorphin (I4S) insulin A-, B-, and C-chain peptides (24, 72) j8-chain peptides of the pituitary glycoprotein hormones (8) endorphins (28,60, 126, 137), adrenocorticotropic peptides in plasma, pituitary, and other endocrine glands or secreted from tumor cells iVt vitro (84, I2S, 127, 138, 142. I Si) hypothalamic releasing factors... 

The limbic system and adjacent hypothalamus shift into high gear, and by way of the pituitary gland (and other downstream endocrine glands) and the autonomic nervous system, a multitude of stress hormones are released into the system. The brain and body alike are ready for action. 

Hormones often act as a chain of chemical messengers. For example, a hormone produced by the hypothalamus may stimulate the anterior pituitary to produce another hormone that subsequently causes an endocrine gland to produce still another hormone that ultimately acts on its target cells. 

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