Pituitary gland hormones

In the anterior pituitary gland (see Hormones, anteriorpituitaryhormones), both adrenocorticotropic hormones (ACTH) and the endogenous opiate hormone, P-endorphin, are synthesized from a common prohormone (2) (see Opioids,endogenous). In the adrenal medulla, five to seven copies of another opiate hormone, methionine—enkephalin (Met-enkephalin), and one copy of leucine—enkephalin (Leu-enkephalin) are synthesized from each precursor molecule (3). 

It was known as early as the 1920s that the pituitary gland contained a factor that could promote growth, but not until 1956 (1) was the factor isolated. hGH is extremely abundant in the pituitary, representing as much as 10% of this gland s dry weight, or 8 mg of hormone per gland (2). 

Natural Product hGH. In 1944 the preparation of a highly purified growth hormone from bovine pituitary glands was reported (37). Subsequendy, growth hormones derived from animal pituitaries were found to be ineffective in humans the existence of specificity among species for growth hormone was thus estabUshed. 

Pregnenolone is transported from the mitochondria to the ER, where a hydroxyl oxidation and migration of the double bond yield progesterone. Pregnenolone synthesis in the adrenal cortex is activated by adrenocorticotropic hormone (ACTH), a peptide of 39 amino acid residues secreted by the anterior pituitary gland. 

It has been found that the growth hormone can be obtained in crystalline form from human pituitary glands by procedures comprising (1) extraction of the fresh glands with acetone, (2) extraction of the acetone residue with aqueous salt solutions, (3) precipitation from aqueous salt solutions by the addition of suitable miscible organic solvents of alkaline and acid pH, and finally crystallization from aqueous salt solutions by the addition of suitable miscible organic solvents. 

A disulfide bond between cysteine residues in different peptide chains links the otherwise separate chains together, while a disulfide bond between cysteine residues in the same chain forms a loop. Such is the case, for instance, with vasopressin, an antidiuretic hormone found in the pituitary gland. Note that the C-terminal end of vasopressin occurs as the primary amide, -CONHz, rather than as the free acid. 

Oxytocin, a nonapeptide hormone secreted by the pituitary gland, functions by stimulating uterine contraction and lactation during childbirth. Its sequence was determined from the following evidence ... 

Brain structure below the thalamus and main portion of the ventral region of the diencephalon, controlling homeostatic and nonhomeostatic basic body and brain functions, including circadian and feeding rhythms, energy metabolism, thermogenesis, sympathoadrenal, and neuroendocrine outflow (secretion of hormones by the pituitary gland), behavioral state and memory functions. 

Prolactin is peptide hormone secreted by the pituitary gland. It acts on prolactin receptors in breast tissue where it stimulates production of casein and lactalbu-min. It also acts on the testes and ovaries to inhibit the effects of gonadotrophins. Since the secretion of prolactin is under tonic dopaminergic inhibition by the hypothalamus, dopamine D2-receptor antagonists... 

Thyroid autonomy appears as a solitary toxic nodule or toxic multinodular goitre. In toxic thyroid, the nodule s synthesis and secretion of thyroid hormones is autonomous from the thyroid-stimulating hormone (TSH), which is produced in the pituitary gland. Accordingly TSH is suppressed and the extranodular thyroid tissue is functionally downregulated. Thyroid autonomy occurs frequently in iodine-deficient countries, whereas it is much less common in iodine-sufficient areas. Constitu-tively activating mutations in the TSH receptor and in the Gs a protein are the major molecular aetiology of toxic thyroid nodules. 

List the hormones produced by the pituitary gland and the adrenal cortex. 

Figure 50-2. The pituitary gland, and the hormones secreted by the anterior pituitary and the posterior putuitary.

There may be a decreased resistance and inability to The posterior pituitary gland produces two hormones localize infection. The nurse observes the skin daily for vasopressin (antidiuretic hormone) and oxytocin (see localized signs of infection, especially at injection sites Chap. 53). Posterior pituitary hormones are summarized or IV access sites. Visitors are monitored to protect the in the Summary Drag Table Anterior and Posterior patient against those witii infectious illness. Pituitary Hormones. 

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