While pituitary tumors can be induced in rats by the administration of estrogen, susceptibility to such tumors is highly strain dependent. In this study, 21-day-old male rats of two strains-Fischer 344 (F344) strain, which is particularly susceptible to pituitary tumors, and Sprague-Dawley (SD) strain, which is relatively resistant, were treated with diethylstilbestrol (DES) over a period of 10 days. Reverse-transcriptase polymerase chain reaction (RT-PCR) was used to analyze the expression levels of two tumor suppressor genes, p53 and rb, in the pituitaries. In SD rats, both p53 and rb mRNA appeared to increase in response to DES treatment, while in F344 rats they remained undetectable. Western blot analysis revealed that protein levels of cyclin D, which is a cell cycle regulating protein thought to be a potential oncogene, decreased in response to DES treatment in F344 rats but remained constant in SD rats. The observed differences in the expression levels of p53, rb and cyclin D suggest that they might be involved in the primary process of estrogen-induced pituitary tumor development prior to detectable tumor growth.
The effect of norepinephrine analogue (NA) and norepinephrine antagonists on luteinizing hormone releasing hormone (LHRH) secretion in geese was investigated by monitoring serum levels of LH. Twenty nonlaying geese were selected and randomly assigned to 4 groups of 5 each. The geese received a single intraventricular injection of saline (control), NA (12μg/6μl), phentolamine (1μg/6μl) plus NA or yohimbine (10μg/6μl). Phentolamine, a non-selective adrenoreceptor blocker was given 5min before NA, but yohimbine, an α2-adrenoreceptor blocker, was delivered without NA injection. The results showed that serum levels of LH began to increase 20min after injection of NA, and that high serum levels of LH were maintained until 105min, followed by a decline to the basal level 125min later. Significantly high levels of serum LH were observed at 50 and 105min after the injection as compared with the respective control. Treatment with phentolamine completely blocked the stimulatory effect of NA on serum levels of LH in NA treated geese. Serum levels of LH increased by yohimbine treatment 5min after the injection and the high levels of serum LH were maintained until 125min later. Five out of 8 points were significantly high as compared with their respective control values. The present study also suggested that there is presynaptic modulation in the α-noradrenergic neural pathways which mediate the release of LHRH, and that this modulation may be carried out by α2-adrenoreceptor blocker.
To elucidate the effects of synthetic salmon calcitonin (sCT) on the cells in the rat pituitary gland, we histopathologically and immunohistochemically examined the early changes after 4 or 13 weeks treatment with sCT 120IU/kg. Focal proliferative lesions of the anterior pituitary glands were consistently found after treatment with sCT for 13 weeks. Histologically, the cells with the focal proliferative lesions were classified into the following three groups: 1) enlarged basophilic cell focus, 2) vacuolated cell focus and 3) chromophobe cell focus. These focal proliferative lesions had positive staining only for the alpha-subunit and failed to show Pit-1 protein immunoreactivity. The sCT treatment also increased the thickness of the pars intermedia. Hypertrophy of the pars intermediate cells was characteristically seen. Furthermore, Pit-1 protein immunoreactivity was clearly detected in the nuclei of the hyperplastic pars intermediate cells. All pars intermediate cells were equally stained by alpha- or beta-MSH and beta-endorphin in both vehicle- and sCT-treatment. No difference was seen. These findings strongly suggest a very close relationship between Pit-1 protein immunoreactivity and cellular proliferation induced by sCT.
We determined the in vivo effects of thiazolidinediones on insulin resistance induced by dexamethasone (Dx), as well as that observed in Wistar fatty (WF) rats, using glucose clamp technique to measure glucose uptake (Gu) and percent suppression of hepatic glucose output (HGOsup) to evaluate insulin resistance. Male Wistar rats were treated with Dx (0.5mg/kg/day) for 7 days. Pioglitazone (P) or troglitazone (T) was coadministered orally for the same period at 10 and 200mg/kg/day, respectively. Two, 5 and 20mU/kg/min. of insulin infusion rates (IIR) were used. The Gu levels at clamp steady-state at IIR20 in rats treated with Dx (16.4±4.7mg/kg/min.) were significantly lower than those in control rats (36.3±2.4). The Gu levels at the same IIR in rats coadminstered with P (19.6±3.2) and T (21.3±6.3) were slightly but significantly higher than that in rat treated with Dx. HGOsup at IIR5 in control rats (97.5±6.2%) was decreased by Dx treatment (52.1±31.3). This decrease was slightly but significantly ameliorated by addition of T (78.3±12.2). The Gu levels at IIR20 in WF rats (6.6±0.9) were decreased significantly from that in lean littermates of WF (WL) rats (25.8±2.1). This attenuation of Gu increase was completely ameliorated with administration of P (20.9±2.8) or T (22.2±3.9). The HGOsup at IIR20 in WF rats (17.4±11.2) was significantly decreased from that in WL rats. Administration of P or T ameliorated this decrease completely. These results indicate that Dx induces insulin resistance by mechanisms different from those in WF rat, hence thiazolidinedione administration can be only partially useful to treat insulin resistance induced by Dx.
Familial hypocalciuric hypercalcemia (FHH) is a benign syndrome with elevated levels of serum calcium, relative hypocalciuria, and non-suppressed serum parathyroid hormone (PTH) levels. FHH usually occurs by a heterozygous mutation of the calcium sensing receptor (Casr), but some FHH patients show no mutations of the Casr. We encountered a unique FHH family in which the proband and her mother had many calcium deposits on their skin. The proband was medicated with Levothyroxine for hypothyroidism due to an iodine transport defect (ITD). We searched for mutation of the Casr, but found none. The only change distinguishing the proband and her mother from her father was at codon 990, reported to be a polymorphic site. We investigated the frequency of polymorphism at codon 990, but a significant relationship between the three genotypes and the serum calcium concentration was excluded. At the other polymorphic sites at codon 536, 926, 986, and 1011, polymorphisms were rare in Japanese, and we could not confirm a significant relationship. In conclusion, mutation in the Casr gene alone does not explain all cases of FHH. The other mechanisms should be identified.
We report monozygotic twins who showed different MEN1 phenotypes. The proband (28 y.o., female) had both primary hyperparathyroidism (PHP) and insulinoma, and genetic analysis revealed a point mutation (569del1, exon 3) of the MEN1 gene. This mutation causes a frameshift and produces a stop codon at codon 184. Restriction digestion (HinfI) analysis confirmed the same mutation of the MEN1 gene in six of the affected members including her two sisters, the monozygotic twins, and no such mutation in two unaffected members. In two generations of this family, eight of eleven family members had PHP and four of them were found to have other MEN1-related lesions. Both of the monozygotic twins had PHP. Interestingly, one had pancreatic tumor but the other had no evidence of it. Pituitary MRI showed no pituitary lesion in either of them. This is the first Japanese case of monozygotic twins with different MEN1 phenotypes.
A 51-year-old woman who had been treated with levothyroxine sodium because of hypothyroidism after total thyroidectomy for thyroidal cancer was admitted to our hospital for persistent hypothyroidism despite large dose administration of levothyroxine (600μg/day). The patient complained of severe general fatigue and body weight gain. Free thyroxine, free triiodothyronine and thyrotropin levels were 0.97ng/dl, 1.55pg/ml and 24.51μU/ml, respectively, under oral administration of levothyroxine. Levothyroxine loading test performed by liquid form, pulverized tablets via nasogastric tube and intravenous administration revealed no evidence of malabsorption or metabolic disorder of levothyroxine, although oral intake of tablets was ineffective due to her factitiousness. We report here a possible case of upseudomalabsorption of levothyroxine to emphasize the clinical recognition of this disorder in patients with resistant hypothyroidism.
A low plasma ACTH response to insulin-induced hypoglycemia and an exaggerated and delayed plasma ACTH response to CRH stimulation have been considered as an indicator of hypothalamic hypopituitarism. We report a case of hypothalamic adrenal insufficiency which manifested normal ACTH response to insulin-induced hypoglycemia. This case provides important information to categorize hypothalamic adrenal insufficiency caused by abnormal regulation of CRH release.
Autoantibody against glutamic acid decarboxylase (GADA) is a highly sensitive predictor of insulin-dependency in adult diabetic patients as well as young individuals. A considerable number of diabetics who do not reach the insulin-dependent stage have this antibody. Recently, type 1 diabetes has been thought to be caused by T helper 1 (Th1)-type autoimmunity based on studies in non-obese diabetic mice, but it is still difficult to investigate antigen-specific T-cell function in human type 1 diabetes. We therefore assessed an IgG subclass assay for GADA, which should reflect T-helper function against GAD. Sera from 14 type 1 diabetic patients positive for GADA by radioligand binding assay were tested for the IgG subclass of GADA. The assay was based on an enzyme-linked immunosorbent assay, which showed a good correlation with radioligand binding assay. The sera of all but one of the 14 type 1 diabetic patients (93%) were positive for the IgGI subclass of GADA. The IgG2 and IgG3 subclasses of GADA were also detected in one diabetic patient each who were also positive for IgGI. The IgG4 subclass was not detected in any of the sera we tested. We concluded that IgGI is the dominant subclass of GADA in Japanese type 1 diabetic patients.
Adrenocorticotropic hormone receptor (ACTHR) is expressed predominantly in the adrenal glands, and its expression is upregulated by its own ligand, ACTH, via a cAMP-dependent pathway. In the present study, we characterized the 5'-regulatory region of human ACTHR gene to elucidate the molecular mechanisms underlying its adrenal-specific and ACTH/cAMP-dependent expression. The promoter region (-1017/+47 when the transcription start site is regarded as +1) and its serial 5'-deletions (-764/+47, -503/+47, -214/+47 and -561+47) were ligated into the upstream of a luciferase (luc) reporter gene. These constructs were transfected into adrenocortical Y1 cells or non-adrenal JEG3 and Cos-1 cells. In all the cell lines, the luc activity gradually increased with serial 5'-deletions and the maximum activity was conferred by -56/+47. However, the magnitude of luc activity of each deletion construct in non-adrenal cells was much less than that in Y1 cells, suggesting that the promoter functions in an adrenal-specific manner. We identified two Steroidogenic Factor (SF)-1-binding sites at -209 and -35. Electrophoretic mobility shift assay (EMSA) demonstrated that both sites bind to SF-1. Mutation of both sites significantly decreased the activity of -214/+47 promoter in Y1 cells. Transfection of SF-1-expressing plasmid into non-adrenal cells significantly increased the promoter activity, suggesting that SF-1 plays a role in the tissue-specific expression of human ACTHR gene. We identified the region, -764 to -503, that was required for the for- skolin/camp responsiveness of the promoter. This region contains one AP-1 site. EMSA revealed that the binding of AP-1 to this site increased significantly upon treatment of Y1 cells with forskolin. Mutation of the site abolished the forskolin-responsiveness. In non-adrenal cells, the forskolin-responsiveness was observed only when SF-1-expressing plasmid was cotransfected. This is the first demonstration that both AP-1 and SF-1 are required for the cAMP-dependent induction of human ACTHR gene.
We studied the possible relationship between nitric oxide (NO) production and insulin resistance in patients with type 2 diabetes mellitus. Urine NO metabolites (NOx) were measured as an index for NO production by HPLC combined with a Cd column, Griess reaction and a spectrophotometer in 403 healthy control subjects and 102 hospitalized patients with type 2 diabetes. Glucose infusion rate (GIR) was measured as a reverse index for insulin resistance by euglycemic glucose clamp study using an artificial pancreas in 20 of 102 diabetic patients. Urine NOx was lower in the patients with type 2 diabetes than in healthy control subjects (mean±SE: 3.18±0.02 versus 3.25±0.01 log[μmol/gCr], p<0.01). Urine NOx was correlated with body mass index (BMI) in 102 diabetic patients (r=-0.372, p<0.001), but not related to either age, sex, fasting plasma glucose, HbA1c or blood pressure. Urine NOx was correlated with GIR independent of BMI in 20 diabetic patients (r=0.774, P<0.0001). These findings suggest that NO production is closely related with insulin resistance in patients with type 2 diabetes.
Since neurohypophyseal germinomas occur at the pituitary and hypothalamic axis in children and adolescents, the endocrinopathy is one of the common and critical QOL determinants. We carried out a retrospective study on the outcome of endocrine function in patients with neurohypophyseal germinoma, in order to improve or preserve pituitary function after treatment. Sixteen patients (7 men and 9 women), aged 6 to 26 years were admitted and followed up for 95.3 (14-197) months. DI was noted in 12 patients in pretreatment and 16 in posttreatment regardless of tumor size. We carried out the replacement of GH in all 8 patients, presenting the symptoms under 15 years of age. Gonadal or gonadotropic, thyroid and adrenal hormones were replaced in 9, 12 and 15 patients, respectively. Patients with large tumor compressing chiasm or hypothalamus needed hormonal replacement such as gonadal or gonadotropic and thyroid hormones more frequently (<0.01) than those with small one. In addition, two patients with a small tumor at the pituitary stalk and the 3rd ventricle floor showed the improvement of secretion pattern in gonadotropins and ACTH after chemotherapy, although they later needed radiation therapy to control the tumor. Based on our study and review of literature, the endocrinological studies before and after treatment demonstrated that pituitary dysfunction present before treatment persisted or worsened even after tumor remission, except for patients with small and localized ones. The poor endocrine results is considered to be largely radiation-related. Chemotherapy alone seems to be insufficient to obtain complete response (CR). To avoid radiation related pituitary injury, combination of 24Gy or less dosage of radiation and appropriate chemotherapy is essential. The earlier diagnosis by repeatedly using neuroimaging and serum and CSF tumor markers and earlier initiation of treatment, before irreversible pituitary-hypothalamic damage occurs, contributes to improvement of the outcome of pituitary functions in patients with neurohypophyseal germinomas.
DiGeorge syndrome (DGS) is characterized by aplasia or hypoplasia of the thymus and parathyroid glands, cardiac defects and anomaly face. This syndrome is usually associated with hypocalcemia resulting from hypoparathyroidism. In most cases the initial symptom is tetany caused by hypocalcemia within 24-48 hours after birth, with symptoms by immune abnormality appearing later. We report a woman who passed with no symptoms before age 18 and was diagnosed DiGeorge syndrome by tetany with developing auto-immune thyroid disease (Graves' disease). She had surgery for intraventricular septal defect at age 3, hypoparathyroidism, decrease of T cells in peripheral blood and the deletion of the 22nd chromosome long arm (22q11.2). It is supposed that abnormalities of immune function of this case are not complete as indicated by complicating of Graves' disease, and contributing to her long-term survival.
We previously demonstrated that individual subjects have fairly constant ratios of serum concentrations of 20kDa- (20K) and 22kDa-GH (22K). The aim of this study is to demonstrate the possibility of utilizing the changes in the ratio of 20K/22K for detecting the exogenous administration of 22K. A male patient with idiopathic dilated cardiomyopathy (age 51) received 22K (4U, s.c.) every other day. The concentrations of 20K and 22K in serum and urine were measured using enzyme-linked immunosorbent assays before and after administration. The administration of 22K increased total GH concentration, and markedly decreased the ratio of 20K/22K in serum, especially 2-10h after the administration. From calculations, it became clear that the concentration of exogenous 22K reached a peak between 2-4h after the administration and decreased to a negligible level after 24h. The ratio of 20K/22K in the 0-24h urine was 5 times lower than that in the 24-48h urine. These data suggest that, by monitoring the ratio of 20K/22K in serum or urine, it is possible to determine whether or not GH has been externally administered and to calculate the serum GH that has been administered.