Osteoporosis is the most common complication of Cushing's syndrome. We retrospectively examined the prevalence and risk factors for osteoporosis in 42 female patients with Cushing's syndrome. Osteoporosis and atraumatic fractures were assessed by bone mineral density of the lumbar vertebral spine (L2-L4) using dual energy X-ray absorptiometry (DXA) and X-ray examination. The prevalence of osteoporosis and fracture were 54.8% and 21.4%, respectively. The prevalence of osteoporosis (69.6% vs. 37.8%) and atraumatic bone fracture (26.1% vs. 15.8%) were significantly higher in patients with adrenal Cushing's than in those with pituitary Cushing's. AP and lateral BMD was significantly higher in patients with pituitary origin than in those with adrenal origin. Among several variables examined by multiple logistic regression, the etiology of Cushing's syndrome (adrenal vs. pituitary origin) was a significant factor affecting the prevalence of osteoporosis. Neither age, body mass index, duration of amenorrhea, nor extent of hypercortisolism were significant factors in this analysis. Plasma DHEA-S and urinary 17-KS excretion were significantly higher in pituitary Cushing's than in adrenal Cushing's. The present study shows that the prevalence of osteoporosis in patients with Cushing's syndrome is influenced by its etiology. A factor associated with pituitary Cushing's syndrome, such as adrenal androgen, may protect these patients from glucocorticoid-induced osteoporosis.

Objective Papillary thyroid carcinoma (PTC) sometimes occurs with Hashimoto's thyroiditis (HT).

To differentiate between ectopic ACTH syndrome and Cushing's disease, gene expression of corticotropin-releasing hormone (CRH), proopiomelanocortin (POMC), and glucocorticoid receptor was examined in 10 pituitary adenomas (Cushing's disease) and in 10 ectopic ACTH-producing tumors. CRH increased plasma ACTH levels in all patients with Cushing's disease and in five patients with ectopic ACTH syndrome whose tumors contained CRH and CRH mRNA. In five CRH nonresponders, CRH was not detected in tumors that contained no CRH mRNA or that contained only long-size CRH mRNA. Dexamethasone (Dex) decreased plasma ACTH levels in all patients with Cushing's disease and in three patients with ectopic ACTH-producing bronchial carcinoid. These tumors contained glucocorticoid receptor mRNA. CRH increased and Dex decreased ACTH release and POMC mRNA levels in pituitary adenoma and bronchial carcinoid cells. PMA increased POMC mRNA levels only in carcinoid cells. These results reveal characteristics of ectopic ACTH-producing tumors: long-size CRH mRNA and PMA-induced POMC gene expression. In addition, there are two ectopic ACTH syndrome subtypes: tumors containing ACTH with CRH (CRH responder) and tumors without CRH. Dex decreases ACITH release and POMC mRNA levels in some bronchial carcinoids. Therefore, CRH and Dex tests have limited usefulness in differentiating between Cushing's disease and ectopic AC1H syndrome. (J.

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To examine the physiological role of cholinergic input in the regulation of CRF neurons in the paraventricular nucleus (PVN) of the hypothalamus, acetylcholine (ACh) was microinjected bilaterally into the dorsolateral border of the PVN of conscious rats. Changes in the levels of POMC messenger RNA (mRNA) in the anterior pituitary, CRF mRNA in hypothalamic tissue containing the PVN, and plasma ACTH were assessed. Plasma ACTH concentrations increased in a dose-dependent manner after ACh injection (1-100 pmol/side), reaching a peak 30 min after ACh injection and returning to baseline within 120 min. The POMC mRNA level in the anterior pituitary and the hypothalamic CRF mRNA level increased in a dose-dependent manner 120 min after ACh (0.1-10 pmol/side) injection. Intracerebroventricular pretreatment with atropine completely abolished the ACh-induced increase in plasma ACTH concentrations, whereas pretreatment with hexamethonium was without significant effect. The intracerebroventricular injection of ACh also increased plasma ACTH concentrations in a dose-dependent manner in conscious rats, but not in pentobarbital-anesthetized animals. Thus, cholinergic hypothalamic input stimulates CRF gene expression in the PVN and CRF secretion into the portal circulation under physiological conditions. The use of conscious animals is essential in elucidating the physiological roles of neurotransmitters and other modulators regulating CRF neurons.

To examine the physiological role of cholinergic input in the regulation of CRF neurons in the paraventricular nucleus (PVN) of the hypothalamus, acetylcholine (ACh) was microinjected bilaterally into the dorsolateral border of the PVN of conscious rats. Changes in the levels of POMC messenger RNA (mRNA) in the anterior pituitary, CRF mRNA in hypothalamic tissue containing the PVN, and plasma ACTH were assessed. Plasma ACTH concentrations increased in a dose-dependent manner after ACh injection (1-100 pmol/side), reaching a peak 30 min after ACh injection and returning to baseline within 120 min. The POMC mRNA level in the anterior pituitary and the hypothalamic CRF mRNA level increased in a dose-dependent manner 120 min after ACh (0.1-10 pmol/side) injection. Intracerebroventricular pretreatment with atropine completely abolished the ACh-induced increase in plasma ACTH concentrations, whereas pretreatment with hexamethonium was without significant effect. The intracerebroventricular injection of ACh also increased plasma ACTH concentrations in a dose-dependent manner in conscious rats, but not in pentobarbital-anesthetized animals. Thus, cholinergic hypothalamic input stimulates CRF gene expression in the PVN and CRF secretion into the portal circulation under physiological conditions. The use of conscious animals is essential in elucidating the physiological roles of neurotransmitters and other modulators regulating CRF neurons.

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