Pituitary Gland Tumors

TO Eyes, skin, thyroid [in animals liver, thyroid pituitary gland tumors]... 

ACTH-dependent Cushing s syndrome is usually caused by overproduction of ACTH by the pituitary gland, causing adrenal hyperplasia (Cushing s disease). Pituitary adenomas account for about 80% of these cases. Ectopic ACTH-secreting tumors and nonneoplastic corticotropin hypersecretion are responsible for the remaining 20% of cases. 

Mechanism of Action A hormone and antineoplastic agent that suppresses the release of luteinizing hormone from the anterior pituitary gland by inhibiting pituitary function. Therapeutic Effect Shrinks tumors. Also increases appetite by an unknown mechanism. 

The EPA Office of Pesticide Programs reviewed the data for the tumorigenicity of triphenyltin hydroxide and classified it as a possible human carcinogen (Group B2) based on the tumors found in both rats and mice during chronic studies of carcinogenicity. The most appropriate estimate of the unit risk in human equivalents was a q1 of 2.8 (mg/kg/day) from the data on pituitary gland adenomas in female rats. 

Administration of estrogens is well known to cause an increase in plasma prolactin (PRL) levels in man (43, 44) as well as in the rat (45-48). This stimulatory effect of estrogens is also observed in vitro in anterior pituitary gland explants (49), tumoral adenohypophysial cells (50) and normal rat anterior pituitary cells in primary culture (39, 40, 42, 51). Seventeen-g-estradiol (E2) does not only stimulate basal and TRH-induced PRL secretion in rat anterior pituitary cells in culture but it can also reverse almost completely the inhibitory effect of dopamine (DA) agonists on PRL release (40). 

GRF has been isolated and characterized from a human tumor of the pancreas (61) as well as from rat (62), porcine (63), bovine (64), caprine (65), ovine (65), and human (65) hypothalamus stalk-median eminence. It is a 40-44-amino-acid peptide hormone produced in the arcuate nucleus of the hypothalamus and released from neurosecretory nerve terminals of these arcuate neurons, and it is carried by the hypothalamo-hypophysial portal circulation to the anterior pituitary gland where it stimulates growth hormone (GH) secretion (66). 

Beech J 1987 Tumors of the pituitary gland (pars intermedia). In Robinson N E (ed) Current therapy in equine medicine, 2nd edn. Saunders, Philadelphia, PA, pp. 182-185... 

Similar to some other triazine herbicides, propazine induces mammary gland tumors in female (but not male) rats, likely through pituitary neuroendocrine disruption. No such tumors are noted in either sex of mice, however. Propazine delayed vaginal opening and affected testes weights in rat pups from exposed dams. After administering 500 mg kg for 1 ... 

Diabetes insipidus (DI) is a deficiency in antidiuretic hormone resulting from trauma to the hypothalamus and pituitary gland or brain tumor that causes the kidneys to excrete large amounts of water, leading to severe fluid volume deficit and electrolyte imbalances. Diabetes insipidus is treated by replacing the antidiuretic hormone with the administration of ... 

Hypersecretion of growth hormone is treated by destroying the pituitary tumor with radiation, administering Bromocriptine (inhibits release of growth hormone from the pituitary gland), and administering Octreotide (suppresses release of the growth hormone). 

The ERs and PRs are found in target tissue cells, such as in the uterus, pituitary gland, hypothalamus, and breast, and appear to be involved in tumor development and progression. Furthermore, ER and PR status correlate with both prognosis and treatment response, therefore measuring the levels of ER and PR is clinically useful. 

Transsphenoidal pituitary surgery is the treatment of choice for TSH-secreting adenomas. Pituitary gland irradiation is often given following surgery to prevent tumor recurrence. Bromocriptine has been used to treat tumors that co-secrete prolactin. 

Destruction of the pituitary gland may result in secondary hypothyroidism, hypogonadism, adrenal insufficiency, growth hormone deficiency, and hypoprolactinemia. The formation of certain types of pituitary tumors may result in pituitary hormone excess. Pituitary tumors may also physically compress the pituitary and prevent the release of the trophic hypothalamic factors that regulate pituitary hormones. In this chapter, the pathophysiology and role of pharmacotherapy in the treatment of acromegaly, short stature, hyperprolactinemia, and panhypopituitarism will be discussed. 

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