Recent studies have revealed the importance of fish-derived peptide hormones to human endocrinology. These peptides include melanin-concentrating hormone (MCH), urocortins (human urotensin-I), and urotensin-II. MCH, a hypothalamic peptide, is a potent stimulator on appetite. Urocortins, e.g. urocortin 1 and urocortin 3 (stresscopin), are endogenous ligands for the corticotropin-releasing factor (CRF) receptors, particularly CRF type 2 receptor, that mediates a vasodilator action, a positive inotropic action and a central appetite-inhibiting action. These actions mediated by CRF type 2 receptor may ameliorate the stress response. Human urotensin-II is a potent vasoconstrictor peptide, while it acts as a vasodilator on some arteries. Human urotensin-II is expressed in various types of cells and tissues, including cardiovascular tissues, as well as many types of tumor cells. Thus, these fish-derived peptides appear to play important roles in human physiology, such as appetite regulation, stress response and cardiovascular regulation, and also in diseases, for example, obesity, cardiovascular diseases and tumors. Development of antagonists/agonists against the receptors for these peptides may open new strategies for the treatment of various diseases, including obesity-related diseases, hypertension, heart failure and malignant tumors.
Mouse adrenocorticotropin receptor (ACTH-R/MC2R) messenger ribonucleic acid (mRNA) is expressed predominantly in the adrenal gland and, to a lesser extent, in adipose tissue. In this study, we found a novel 135-bp exon 1 (exon 1f) of the ACTH-R gene transcribed in mouse adipose tissue by RNA ligase-mediated rapid amplification of cDNA ends, which was located 1.4 kb downstream in the genome of previously-reported exon 1 (exon 1a) transcribed in the adrenal gland. The novel promoter region, 1.4 kb upstream of exon 1f contained three CCAAT boxes. RT-PCR analysis revealed that ACTH-R mRNA from adipose tissue and differentiated 3T3-L1 adipocytes exclusively contained exon 1f. Thus, the promoter region flanking to exon 1f is thought to be essential for adipose tissue, while that flanking to exon 1a is specific for the adrenal gland. A search for a similar sequence of mouse ACTH-R exon 1f and its flanking region in the human genome sequence database of GenBank Human Genome Resources did not reveal such a sequence in the region of the human ACTH-R gene. This may explain the absence of ACTH-R expression in human adipose tissue.
We studied the incidence of late-onset congenital adrenal hyperplasia (LOCAH) due to 2l-hydroxylase (21-OH) deficiency, its molecular genotype expression, and its association with the major histocompatibility complex in 61 women with hirsutism and polycystic ovary. Ultrasound, clinical and hormonal parameters were used to define polycystic ovary syndrome (PCOS). Baseline and ACTH stimulated 17α-hydroxyprogesterone (17-OHP) levels were measured for screening of LOCAH during follicular phase. Forty-one women were diagnosed as having PCOS (67%) and 20 women were diagnosed as having had LOCAH due to 2l-OH deficiency (33%). In LOCAH patients, the most common mutation (Val281-Leu, V281L) was found in 10 patients (7 heterozygous/3 homozygous). The frequency of V281L mutation was found as 32.5% in 20 patients. All patients with the V281L mutation presented HLA-B14 (100%) and six of them presented DR1 (60%), confirming that LOCAH is linked to the histocompatibility complex. Although molecular analysis is a better and more accurate means for an exact and precise definition of LOCAH, it is not routinely available in our country. So, ACTH stimulation test combined with HLA-B14 typing should be more widely utilized in these patients. As a result, LOCAH due to 21-OH deficiency is unexpectedly high in Turkish patients with hirsutism and PCO.
Testosterone and 5α-dihydrotestosterone (DHT) are the principal male hormones (androgens) in mammals. The enzyme, steroid 5α reductase catalyzes the conversion of testosterone (T) to its biologically potent steroid (DHT) in androgen dependent tissues. Two 5α reductase isoenzymes have been identified in rat tissues. The type I isoenzyme has been shown to be predominately expressed in the rat liver, whereas androgen target tissues of the genital tract express mainly isoenzyme II. The effects of androgens and glucocorticoids on the abundance of steroid 5α reductase type I (5αR1) messenger RNA in the rat liver were examined. Steady state levels of 5αR1 mRNA decreased dramatically to 1.5% of control levels 14 days following adrenalectomy (ADX), whereas dexamethasone (Dex) administered (0.5 mg/100 g) to ADX animals enhanced the expression of 5αR1 to twice its' normal values within 40 hours. Bilateral orchiectomy induced, within eight days, the expression of 5αR1 mRNA in the rat liver to 1.75 fold the normal value while testosterone injection failed to reduce this enhanced expression in castrated animals. Addition of Dex (1 μM) to primary cultures of rat hepatocyte resulted in a five- and three-fold reduction in the mRNA expression of 5αR1 after 24 and 48 hours, respectively. DHT (0.5 μM) however, induced the expression of 5αR1 mRNA by two- and seven-fold 24 and 48 hours post-treatment, respectively. In vitro nuclear run-on analysis of the 5αR1 gene showed no correlation between the rate of synthesis and steady state levels of this mRNA either in the intact liver or in cultured hepatocytes. These results appear to suggest that glucocorticoids and androgens differentially regulate 5αR1 mRNA in the rat liver. Moreover, our findings appear to indicate that regulation of 5αR1 gene is primarily at the post-transcriptional level.
In an effort to clarify the role of telomerase in the pathogenesis of pheochromocytomas and neuroblastomas, and to test whether its component could serve as a marker of malignancy, we measured telomerase reverse transcriptase (TERT) mRNA in 31 human pheochromocytoma tissue samples (5 malignant, 23 benign and 3 suspected malignant) and 16 neuroblastoma tissues (9 unfavorable and 7 favorable). All cases were classified by both the clinical course and histopathological examination. Malignancy was defined as the presence of metastasis and/or extensive local invasion. TERT mRNA was determined by nested PCR and a real-time PCR system (LightCycler). By nested PCR methods, 5 of the 5 malignant pheochromocytoma samples were positive (sensitivity = 100%), and 21 of 23 benign pheochromocytoma samples were negative (specificity = 91%) in pheochromocytomas. Four out of five malignant tumors were positive for either hTERT expression or Ki-67/MIB-1 immunoreactivity. In the neuroblastoma tissues, 9 of the 9 unfavorable samples were positive (sensitivity = 100%), and only 2 of 7 favorable samples were negative (specificity = 29%). We also determined the expression of the hTERT mRNA by real-time PCR to quantitate the mRNA. The mean values of hTERT mRNA by real time PCR in benign and malignant pheochromocytomas were 2 and 26 arbitrary units (AU), respectively. The difference was not significant by the U-test. The mean values of hTERT mRNA in favorable and unfavorable neuroblastoma were 203 and 497 AU, respectively. This difference was also not significant (U-test). N-Myc mRNA expression correlated with the expression of hTERT mRNA in the neuroblastoma samples (r = 0.534, p = 0.0317). Thus, hTERT mRNA might be a potential marker for estimating the malignancy of pheochromocytomas and neuroblastomas.
hCG, LH, FSH, and TSH are a family of heterodimeric glycoprotein hormones that contain a common α-subunit, but differ in their hormone-specific β-subunits. hCGβ is unique among β-subunits due to a carboxyl-terminal peptide (CTP) bearing four O-linked oligosaccharides. We previously reported that there were differences in O-glycosylation between two chimeras consisting of α-subunit and CTP, i.e. a variant with CTP at the N-terminal region (Cα) and another analog with CTP at the C-terminus (αC) of the α-subunit. To address whether O-glycosylation is influenced by the heterodimer formation, Cα and αC were expressed alone or with FSHβ-subunit in Chinese hamster ovary cells. The O-linked glycosylation was assessed by continuous labeling with [35S]methionine/cysteine, immunoprecipitation with anti-α or anti-FSH serum, serial digestion with endoglycosidase-F and neuraminidase, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The decrease in molecular weight of dimeric chimeras digested with endoglycosidase-F was greater in Cα than that in αC after treatment with neuraminidase, revealing that both chimeras have different numbers of sialic acids on O-linked carbohydrates. By treating with endoglycosidase-F, the dimeric αC migrated faster than its free form, whereas the mobility difference between assembled and unassembled forms of Cα was very little. These data indicate that processing of O-glycosylation is affected by the backbone polypeptide chain(s).
The objective of this study was to investigate the effect of administration of recombinant human growth hormone (hGH) in patients with Noonan syndrome. hGH was administered (0.5 IU/kg/week) to 15 patients with Noonan syndrome over a 2 year period. Average patient age prior to therapy was 7.5 ± 2.5 (mean ± SD) yr, the height SD score was –2.8 ± 0.7, and the pretreatment height velocity and bone age were 4.8 ± 1.0 cm/yr and 5.8 ± 2.1 yr, respectively. The height velocity in the year prior to treatment, and 0–12 and 12–24 months after commencing treatment was 4.8 ± 1.0 cm/yr, 7.0 ± 1.2 cm/yr, and 5.5 ± 0.6 cm/yr, respectively. The height velocity in the first year of treatment was significantly greater (P = 0.0001, n = 14) than the pretreatment value, but there was no significant difference in the second year. The height SD scores at the commencement of treatment, and after 12 and 24 months of treatment were –2.8 ± 0.7, –2.4 ± 0.7, and –2.2 ± 0.5, respectively. Bone age advanced by 1.1 ± 0.5 yr in the 12 months after commencing treatment. We conclude that the use of hGH may be beneficial in the treatment of Noonan syndrome, although further research is required.
The effect of imidapril, an angiotensin-converting enzyme (ACE) inhibitor, on insulin resistance was studied in high-fructose-fed rats. A sequential hyperinsulinemic euglycemic clamp procedure (insulin infusion rates: 3 and 30 mU/kg BW/min) was employed in 15 high-fructose-fed rats and 10 normal chow-fed rats under the awake condition. Five of the high-fructose-fed and five of the normal chow-fed rats, respectively, were continuously given imidapril (5 mg/kg BW/min) or saline during the two-step euglycemic clamp study. Furthermore, both imidapril and L-NMMA were infused in another 5 high-fructose-fed rats during the low-dose insulin clamp. Glucose infusion rate (GIR) was regarded as an index of the whole-body insulin action. In the low-dose insulin infusion, the high-fructose feeding resulted in a marked decrease in GIR (p<0.05). Imidapril infusion significantly raised the GIRs in the high-fructose-fed rats (p<0.05). There was no significant difference in GIRs between the chow-fed rats and the imidapril-infused rats with high-fructose diet. In the high-fructose-fed rats, L-NMMA abolished the increase in GIR induced by imidapril (p<0.05). Imidapril did not significantly change the GIRs in the chow-fed rats. In the high-dose insulin infusion, no significant difference in GIR was found among the chow-fed rats, the chow-fed rats given imidapril, the high-fructose-fed rats, and the high-fructose-fed rats given imidapril. These results suggest that, in insulin-resistant rats induced by the high-fructose feeding, an ACE inhibitor, such as imidapril, can improve the whole-body insulin-mediated glucose disposal and that this effect of imidapril is essentially linked to increased activation of NO-pathway.
A patient with multiple endocrine neoplasia type 1 (MEN1) who manifested various MEN1-unrelated tumors was reported. The patient was a 43-year-old woman who manifested typical features of MEN1 including primary hyperparathyroidism, prolactinoma, adrenal adenoma and visceral lipomas. During the course, she also manifested chondrosarcoma, B cell lymphoma and mesothelioma. The patient had no apparent family history of MEN1 or any other neoplastic diseases. Genetic analysis of DNA from peripheral mononuclear cells of the patient revealed no germline mutations in MEN1 gene. Genetic instability due to yet unidentified cause is the possible explanation of occurrence of multiple tumors. Careful periodic screening of endocrine and other disorders for her siblings and children as well as for the patient is warranted.
Glycyrrhizic acid (GA) inhibits the activity of 11β-hydroxysteroid dehydrogenase type 2 in the kidney, with the resulting increase in intrarenal cortisol concentration leading to hypertension and suppression of the renin-aldosterone system. In this paper we describe an interesting case of pseudoaldosteronism, associated with hypocalcemia and an exaggerated ACTH response. A 72-year-old woman was referred to our department for further evaluation of hypokalemia and hypocalcemia. The patient had been taking GA (150 mg/day) for the previous year for treatment of liver damage. Plasma renin activity and aldosterone concentration were both within lower normal limits. Urinary excretion of potassium and calcium was within the upper limit of the normal range and increased with administration of supplements. Plasma ACTH levels increased markedly in response to an intravenous injection of CRH. Cessation of GA and the potassium and calcium supplements on admission, led to a gradual normalization of serum potassium and calcium levels and blood pressure. The hypocalcaemia in our patient was related to decreased tubular reabsorption of calcium as a consequence of renal corticoid excess. It is possible that an increase in the number of CRH receptors in the pituitary following GA treatment caused the exaggerated ACTH response in association with pseudoaldosteronism. The existence of hypocalcemia and an exaggerated ACTH response should be observed carefully when managing pseudoaldosteronism.
Diffuse or nodular hyperplasia of adrenal glands is associated frequently with ACTH-dependent Cushing's syndrome. We carried out a retrospective analysis of 28 patients with ACTH-dependent Cushing's syndrome admitted to our institution between 1984 and 1999 in order to clarify the incidence of adrenal hyperplasia in ACTH-dependent Cushing's syndrome and also to determine the correlation between adrenal gland images and clinical, biochemical and endocrinological data. Of the 28 patients, 16 (57%) showed diffuse adrenal hyperplasia while only 3 had focal adrenal nodules in the hypertrophied adrenals. There was a positive, significant correlation between the width of the adrenal glands measured on CT and circulating plasma ACTH, cortisol levels and urinary free cortisol (UFC) levels. Duration of the disease also correlated positively with adrenal width. No correlation was found between age and adrenal size and there was no difference in the prevalence of diffuse hyperplasia between normotensive and hypertensive patients. These results suggest that chronic ACTH hypersecretion may lead to diffuse adrenal hyperplasia in patients with ACTH-dependent Cushing's syndrome.
A 32-year-old woman with an ectopic adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma (EAPA) is presented. She had rapidly gained weight and suffered recurrent facial acne for a few years but lacked the typical Cushingoid features. Endocrine examinations revealed that her plasma ACTH was markedly high (196 to 280 pg/ml) without showing normal circadian rhythm and failed to respond to corticotropin-releasing hormone stimulation. Her cortisol levels ranged from 22 to 30 μg/dl throughout observation but low doses (1 and 2 mg) of dexamethasone failed to suppress either ACTH or cortisol level. Magnetic resonance imaging study revealed a 3-cm mass occupying the sphenoidal sinus with partial enhancement by gadolinium, which was separated from the normal pituitary in the sella region. The tumor resected by transsphenoidal surgery was histologically diagnosed as an ACTH-producing pituitary adenoma. After surgery her weight gain and acne remitted in accordance with decreases in plasma ACTH. Analysis of patient plasma by gel filtration method revealed the existence of big ACTH molecules eluted with a peak of authentic 1-39 ACTH, suggesting that this biologically less-active ACTH might be the reason why overt features of Cushing's syndrome failed to develop in this case. Although EAPA is clinically rare in parasellar disorders, the presence of ectopic pituitary adenoma should be considered in such cases showing ACTH hypersecretion without typical Cushingoid features.
A 48-year-old woman was referred to our hospital because of secondary hypothyroidism. Upon admission a left adrenal tumor was also detected using computed tomography. Laboratory data and adrenal scintigraphy were compatible with Cushing syndrome due to the left adrenocortical adenoma, although she showed no response to the TRH stimulation test. Hypercortisolism resulting in secondary hypothyroidism was diagnosed. After a left adrenalectomy, hydrocortisone administration was begun and the dose was reduced gradually. After discharge on the 23rd postoperative day, she began to suffer from anorexia. ACTH level remained low, and serum cortisol, free thyroxine and TSH levels were within the normal range. Since her condition became worse, she was re-admitted on the 107th postoperative day at which time serum calcium level was high (15.6 mg/dl). Both ACTH response to the CRH stimulation test and TSH response to the TRH stimulation test were restored to almost normal levels, but there was no response of cortisol to CRH stimulation test. We diagnosed that the hypercalcemia was due to adrenal insufficiency. Although the serum calcium level decreased to normal after hydrocortisone was increased (35 mg/day), secondary hypothyroidism recurred. It was suggested that sufficient glucocorticoids suppressed TSH secretion mainly at the pituitary level, which resulted in secondary (corticogenic) hypothyroidism. However, both postoperative glucocorticoid deficiency and adequate amounts of thyroxine due to the elimination of inhibition of TSH secretion by glucocorticoids might cause hypercalcemia possibly through increased bone reabsorption of calcium.
A 60-year-old man was hospitalized with complaints of general malaise and weight loss. On admission, ACTH and cortisol levels were low, and thyroid function tests revealed hyperthyroidism. These findings and further examination led to a diagnosis of isolated ACTH deficiency (IAD) with Graves' disease. It is known that IAD is frequently associated with thyroid disease, but its association with Graves' disease is rare. The present case is worth noting, because some reports indicate that aggravation of associated Graves' disease may concomitantly aggravate adrenal insufficiency in patients with IAD.
Hyperhomocysteinemia is a risk factor for premature atherosclerotic vascular diseases. It is known that plasma homocysteine levels are higher in hypothyroid patients compared to healthy subjects. The aim of our study was to assess plasma total homocysteine concentrations in hyperthyroid patients before and after treatment when euthyroid status was reached and compare them with control group. Thirteen hyperthyroid patients (age, 42.9 ± 15.6 year) and eleven healthy subjects (age, 39.9 ± 12.5 year) were involved in the study. Plasma levels of homocysteine and serum cholesterol, triglyceride, HDL cholesterol, urea, creatinine, vitamin B12, folate were measured before and after treatment. LDL cholesterol and creatinine clearences were calculated. Pretreatment homocycteine levels of the hyperthyroid patients were significantly lower than healthy controls (11.5 ± 3.6 μmol/L vs. 15.1 ± 4.5 μmol/L, respectively, p<0.05). Posttreatment homocysteine levels were significantly higher than pretreatment levels (13.9 ± 6.3 μmol/L vs. 11.5 ± 3.6 μmol/L, respectively, p<0.05) and posttreatment creatinine clearance were lower than pretreatment level (103.5 ± 12.7 ml/min vs. 114.2 ± 9.3 ml/min, respectively, p<0.01). Lower homocysteine levels in hyperthyroidism can be partially explained with the changes in creatinine clearance.