Structure and function of neurohypophysial hormones.

Vasopressin (VP) and oxytocin (OXT) are neuropeptides that are synthesized in the hypothalamus and stored in/secreted from the neurohypophysis. Although VP and OXT were initially characterized as osmoregulatory and reproductive hormones, respectively, these peptides exert versatile actions not only in peripheral organs but also in the central nervous system via multiple G protein-coupled receptors. Orthologous peptides and receptors have been identified in various animal phyla, reflecting an ancient origin of this hormone family. The aim of this review is to provide basic information on this hormone family and to propose matters to be addressed in future studies. In the earlier sections of this review, we summarize the historical aspect of VP/OXT research as well as the basic features of hormonal peptides and corresponding receptors. The latter sections describe VP/OXT family peptides and their receptors in nonmammalian species, including invertebrates, to introduce the evolutionary aspect of this hormone family. By integrating knowledge from both general and comparative endocrinology perspectives, we highlight current and future research trends about the VP/OXT system.

Biological roles of growth hormone/prolactin from an evolutionary perspective.

Although growth hormone (GH) and prolactin (PRL) are usually recognized as pituitary hormones, their expression is not restricted to the adenohypophysis and can also be found in extra-pituitary tissues including placenta. Furthermore, GH, PRL, and their receptors structurally belong to the cytokine family of proteins, and indeed they have remarkable pleiotropic effects. In this review, we analyzed the biological roles of GH/PRL from an evolutionary perspective. We have recognized that the biological significance of GH/PRL can be summarized as follows: cytokines (metabokines) that regulate the shift of nutrients and even of whole bodies to live in the most appropriate environment(s) for conducting growth and reproduction. In this sense, the common keyword of the two metabokines is "shift" for environmental adaptation. Considering that these metabokines flexibly changed their biological roles, GH/PRL may have played important roles during vertebrate evolution.

Hypopituitarism due to CNS Aspergillus Infection.

A 59-year-old man was admitted to our hospital with hyponatremia. An endocrine examination indicated panhypopituitarism, and magnetic resonance imaging revealed a mass-like lesion in the pituitary gland. Sinus endoscopy revealed a fungal mass in the sphenoid sinus, and the patient was diagnosed with hypopituitarism due to aspergillosis of the central nervous system (CNS). The patient's hyponatremia resolved with hydrocortisone replacement. Although the right internal carotid artery was eventually occluded, antifungal medications were administered for the aspergillosis, and the patient's general condition improved. The patient's CNS lesions have remained under control since discharge. This is the first case to suggest that ACTH secretion may be relatively preserved in Aspergillus-induced hypopituitarism.

Pituitary Tumors: Molecular Insights, Diagnosis, and Targeted Therapy.

The anterior pituitary gland comprises a heterogeneous population of pituitary cells [...].

Animal Models of Cushing's Syndrome.

Endogenous Cushing's syndrome is characterized by unique clinical features and comorbidities, and progress in the analysis of its genetic pathogenesis has been achieved. Moreover, prescribed glucocorticoids are also associated with exogenous Cushing's syndrome. Several animal models have been established to explore the pathophysiology and develop treatments for Cushing's syndrome. Here, we review recent studies reporting animal models of Cushing's syndrome with different features and complications induced by glucocorticoid excess. Exogenous corticosterone (CORT) administration in drinking water is widely utilized, and we found that CORT pellet implantation in mice successfully leads to a Cushing's phenotype. Corticotropin-releasing hormone overexpression mice and adrenal-specific Prkar1a-deficient mice have been developed, and AtT20 transplantation methods have been designed to examine the medical treatments for adrenocorticotropic hormone-producing pituitary neuroendocrine tumors. We also review recent advances in the molecular pathogenesis of glucocorticoid-induced complications using animal models.

Update in Pathogenesis, Diagnosis, and Therapy of Prolactinoma.

Prolactinomas comprise 30-50% of all pituitary neuroendocrine tumors, frequently occur in females aged 20 to 50, and cause hypogonadism and infertility. In typical cases, female patients exhibit galactorrhea and amenorrhea due to serum prolactin (PRL) elevation, and patients during pregnancy should be carefully treated. During diagnosis, other causes of hyperprolactinemia must be excluded, and an MRI is useful for detecting pituitary neuroendocrine tumors. For treating prolactinoma, dopamine agonists (DAs) are effective for decreasing PRL levels and shrinking tumor size in most patients. Some DA-resistant cases and the molecular mechanisms of resistance to a DA are partially clarified. The side effects of a DA include cardiac valve alterations and impulse control disorders. Although surgical therapies are invasive, recent analysis shows that long-term remission rates are higher than from medical therapies. The treatments for giant or malignant prolactinomas are challenging, and the combination of medication, surgery, and radiation therapy should be considered. Regarding pathogenesis, somatic SF3B1 mutations were recently identified even though molecular mechanisms in most cases of prolactinoma have not been elucidated. To understand the pathogenesis of prolactinomas, the development of new therapeutic approaches for treatment-resistant patients is expected. This review updates the recent advances in understanding the pathogenesis, diagnosis, and therapy of prolactinoma.

Adult-onset Langerhans cell histiocytosis changing CNS lesion from pituitary to suprasellar extension.

Summary: Langerhans cell histiocytosis (LCH) is a rare disease characterized by the proliferation of abnormal Langerhans cells in various tissues and organs, including bone, skin, the lungs, and the pituitary gland. Hypothalamic-pituitary lesions in LCH often cause central diabetes insipidus (CDI), but the natural course of LCH in the CNS remains to be elucidated. In this study, we report an interesting case of altered LCH lesions in the CNS from the pituitary to the hypothalamus in a 45-year-old woman. She developed symptoms of polyuria and was diagnosed with CDI with lymphocytic hypophysitis due to an enlarged pituitary gland with stalk thickening shown on MRI. Short-term glucocorticoid therapy cured pituitary enlargement, but serum prolactin levels gradually increased. Six years later, the immunohistological findings of a skin biopsy revealed positive for leukocyte common antigen, S-100, and CD1a expression, indicating a diagnosis of LCH. MRI revealed a new lesion in the hypothalamus without pituitary involvement, likely due to LCH. Chemotherapy improved LCH lesions both in the skin and hypothalamus, but therapy was stopped on the patient's request. Although adult-onset LCH is rare, it should be considered as a differential diagnosis in cases of CDI as the primary disease. The clinical course in the present case indicated that LCH lesion was altered from pituitary to suprasellar extension; where such changes were observed, the possibility of LCH should be considered. Learning points: Diagnosing the primary disease of CDI is challenging; therefore, careful observation is necessary in pathologically unknown cases. Enhanced MRI should be performed in cases with suspected hypothalamic lesions, such as elevated serum prolactin. Although adult-onset LCH is rare, it should be considered a differential diagnosis in cases of CDI as the primary disease. The direction of changing CNS lesion from pituitary to suprasellar extension might be a unique MRI finding in LCH.

Tissue-specific regulation of 11ß hydroxysteroid dehydrogenase type-1 mRNA expressions in Cushing's syndrome mouse model.

The 11ß hydroxysteroid dehydrogenase type-1 (11ßHSD-1) is a predominant 11ß-reductase regenerating bioactive glucocorticoids (cortisol, corticosterone) from inactive 11-keto forms (cortisone, dehydrocorticosterone), expressed mainly in the brain, liver and adipose tissue. Although the expression levels of 11ß HSD-1 mRNA are known to be influenced by glucocorticoids, its tissue-specific regulation is not completely elucidated. In this study, we examined the effect of persistent glucocorticoid excess on the expression of 11ß HSD-1 mRNA in the hippocampus, liver, and abdominal adipose tissue in vivo using quantitative real-time PCR. We found that, in C57BL/6J mice treated with corticosterone (CORT) pellet for 2 weeks, 11ß HSD-1 mRNA decreased in the hippocampus (HIPP) and liver, whereas it increased in the abdominal fat (FAT), compared with placebo treatment [HIPP: placebo 1.00 ± 0.14, CORT 0.63 ± 0.04; liver: placebo 1.00 ± 0.08, CORT 0.73 ± 0.06; FAT: placebo 1.00 ± 0.16, CORT 2.26 ± 0.39]. Moreover, in CRH transgenic mice, an animal model of Cushing's syndrome with high plasma CORT level, 11ß HSD-1 mRNA was also decreased in the hippocampus and liver, and increased in the abdominal adipose tissue compared to that in wild-type mice. These changes were reversed after adrenalectomy in CRH-Tg mice. Altogether, these results reveal the differential regulation of 11ß HSD-1 mRNA by glucocorticoid among the tissues examined.

Unilateral adrenalectomy partially improved hyperglycemia in a patient with primary bilateral macronodular adrenal hyperplasia.

Primary bilateral macronodular adrenal hyperplasia (PBMAH) is characterized by bilateral multiple adrenal macro-nodules that often cause mild over-secretion of cortisol in the form of subclinical Cushing's syndrome. We herein describe a case, wherein unilateral adrenalectomy partially improved hyperglycemia in a patient with PBMAH and suggest the usefulness and limitations of this surgical strategy. A 64-year-old woman with type 2 diabetes had an incidental diagnosis of bilateral adrenal lesions. She had a family history of type 2 diabetes, and her HbA1c level was 8.9% under insulin therapy. She did not present with any symptoms associated with Cushing's syndrome. The basal cortisol level was in the normal range (12.0 µg/dL); however, the adrenocorticotropic hormone (ACTH) level was suppressed (2.1 pg/mL) and the serum cortisol level was not suppressed in the dexamethasone test. Computed tomography and magnetic resonance imaging showed bilateral adrenal macro-nodules and 131I-adosterol accumulated in the bilateral adrenal lesions. Collectively, she was diagnosed with subclinical Cushing's syndrome due to PBMAH complicated with diabetes mellitus, hypertension, and dyslipidemia. Laparoscopic left adrenalectomy was performed, and the pathologic findings were consistent with PBMAH. After unilateral adrenalectomy, serum cortisol levels decreased, and hypertension improved. Both HbA1c levels and insulin requirement also decreased, but insulin therapy was continuously needed. It should be noted that hyperglycemia may not be cured after successful surgery in a patient with PBMAH. Additional operation or medical therapy should be considered if unilateral adrenalectomy is unable to correct hypercortisolism in PBMAH patients.

Immunohistochemistry for aldosterone synthase CYP11B2 and matrix-assisted laser desorption ionization imaging mass spectrometry for in-situ aldosterone detection.

PURPOSE OF REVIEW: Immunohistochemistry for aldosterone synthase (CYP11B2) has markedly provided a comprehensive picture of the adrenocortical diseases, particularly primary aldosteronism. The findings from CYP11B2-immunohistochemistry are consistent with the clinical courses of most patients with primary aldosteronism. We herein review the updated pathophysiology and usefulness of the method for understanding individual patients with different subtypes of primary aldosteronism. RECENT FINDINGS: After our discovery of aldosterone-producing cell clusters (APCCs) using the immunohistochemistry for CYP11B2, we found possible APCC-to-APA transitional lesions (pAATLs) in a few cases that had been hitherto classified as unilateral hyperplasia or multiple nodules. On the basis of morphological and functional features of pAATLs as well as distributions of somatic mutations within the lesions, we have made a hypothesis that APCC grows to APA via pAATL for one of developmental courses of APA. Recently, we successfully performed in-situ detection of aldosterone on adrenal tissue sections using a state-of-the-art technique, matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-imaging). This method revealed in-situ synthesis of aldosterone in APCCs and APAs in addition to several other steroids. SUMMARY: CYP11B2 immunohistochemistry revealed the pathophysiology of aldosterone production in the past decade, especially formation of APCC in normal adrenals and pAATL that is a possible lesion developing from APCC to APA. The term 'idiopathic hyperaldosteronism' may soon become obsolete.

Association between nighttime sleep duration, midday naps, and glycemic levels in Japanese patients with type 2 diabetes.

OBJECTIVES: To clarify the relationship between nighttime sleep duration, midday naps, and glycemic control in Japanese patients diagnosed with type 2 diabetes (n = 355) or impaired glucose tolerance (n = 43). METHODS: A total of 398 patients completed a self-administered questionnaire on sleep duration/quality and were divided into five groups according to their self-reported nighttime sleep duration: <5 h, 5-6 h, 6-7 h, 7-8 h, and >8 h. Each group was further divided into two subgroups each according to the presence or absence of midday naps. Poor glycemic control was defined as HbA1c ≥ 7.0%. RESULTS: Short nighttime sleep (<5 h), poor sleep induction, daytime sleepiness, and low sleep satisfaction were associated with high HbA1c levels. HbA1c was higher in the short nighttime sleep/no nap group than in non-nappers with different nighttime sleep duration, whereas the short nighttime sleep/nap group showed similar HbA1c levels to the other nap subgroups. In multivariate logistic regression models, after adjusting for a number of potential confounders, short (<5 h) nighttime sleep without nap was significantly associated with poor glycemic control compared with 6-7 h nighttime sleep without nap (OR [95% CI]: 7.14 [2.20-23.20]). However, taking naps reduced this risk for poor glycemic control in short sleepers. Other risk factors for poor glycemic control were low sleep satisfaction (1.73 [1.10-2.70]) and poor sleep induction (1.69 [1.14-2.50]). CONCLUSIONS: Poor sleep quality and quantity could aggravate glycemic control in type 2 diabetes. Midday naps could mitigate the deleterious effects of short nighttime sleep on glycemic control. CLINICAL TRIALS REGISTRATION: UMIN 000017887.

Liver X receptor α is involved in the transcriptional regulation of the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene.

The activity of 6-phosphofructo-1-kinase is strictly controlled by fructose-2,6-bisphosphate, the level of which is regulated by another enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK2/FBP2). PFK2/FBP2 is a bifunctional enzyme, having kinase and phosphatase activities, and regulates both glycolysis and gluconeogenesis. Here, we examined the hormonal regulation of the PFK2/FBP2 gene in vitro using the reporter assay, the electromobility shift assay (EMSA), and the chromatin immunoprecipitation (ChIP) assay in HuH7 cells and also using the mouse liver in vivo. We found that the transcriptional activity of the PFK2/FBP2 gene was stimulated by insulin and inhibited by cAMP and glucocorticoid. Liver X receptor (LXR) α showed a potent and specific stimulatory effect on PFK2/FBP2 gene transcription. Deletion and mutagenesis analyses identified the LXR response element (LXRE) in the 5'-promoter region of the PFK2/FBP2 gene. Binding of LXRα was confirmed by the EMSA and ChIP assay. Endogenous PFK2/FBP2 mRNA in the mouse liver was increased in the fasting/refeeding state compared with the fasting state. Altogether, PFK2/FBP2 gene transcription is found to be regulated in a way that is more similar to other glycolytic enzyme genes than to gluconeogenic genes. Furthermore, our data strongly suggest that LXRα is one of the key regulators of PFK2/FBP2 gene transcription.

Corticotropin-releasing hormone (CRH) transgenic mice display hyperphagia with increased Agouti-related protein mRNA in the hypothalamic arcuate nucleus.

Although glucocorticoid-induced hyperphagia is observed in the patients with glucocorticoid treatment or Cushing's syndrome, its molecular mechanism is not clear. We thus explored the expression of neuropeptide mRNAs in the hypothalamus related to appetite regulation in CRH over-expressing transgenic mice (CRH-Tg), a model of Cushing's syndrome. We measured food intake, body weight (including body fat weight) and plasma corticosterone levels in CRH-Tg and their wild-type littermates (WT) at 6 and 14 weeks old. We also examined neuropeptide Y (NPY), proopiomelanocortin (POMC) and Agouti-related protein (AgRP) mRNAs in the arcuate nucleus (ARC) using in situ hybridization. Circulating corticosterone levels in CRH-Tg were markedly elevated at both 6 and 14 weeks old. Body fat weight in CRH-Tg was significantly increased at 14 weeks old, which is considered as an effect of chronic glucocorticoid excess. At both 6 and 14 weeks old, CRH-Tg mice showed significant hyperphagia compared with WT (14w old: WT 3.9±0.1, CRH-Tg 5.1±0.7 g/day, p<0.05). Unexpectedly, NPY mRNA levels in CRH-Tg were significantly decreased at 14 weeks old (WT: 1571.5±111.2, CRH-Tg: 949.1±139.3 dpm/mg, p<0.05), and there were no differences in POMC mRNA levels between CRH-Tg and WT. On the other hand, AgRP mRNA levels in CRH-Tg were significantly increased compared with WT at both ages (14w old: WT 365.6±88.6, CRH-Tg 660.1±87.2 dpm/ mg, p<0.05). These results suggest that glucocorticoid-induced hyperphagia is associated with increased hypothalamic AgRP. Our results also indicate that hypothalamic NPY does not have an essential role in the increased food intake during glucocorticoid excess.

Regulation of glucocorticoid receptor transcription and nuclear translocation during single and repeated immobilization stress.

We have previously reported reduced glucocorticoid receptor (GR) mRNA levels in the hippocampus and hypothalamic paraventricular nucleus (PVN) during repeated immobilization, which is potentially associated with persistent activation of the hypothalamic-pituitary-adrenocortical axis. We used in situ hybridization and Western blot to examine the transcriptional regulation of the GR gene, GR nuclear translocation, and expression of cytosolic heat shock protein 90 (hsp90), a chaperone protein essential for GR nuclear translocation, in the hippocampus, PVN, and anterior pituitary (AP) during single immobilization (sIMO) and the final immobilization on d 7 after daily IMO for 6 days (rIMO). As with GR mRNA, GR heteronuclear RNA levels decreased in the hippocampus and PVN and increased in the AP during sIMO and rIMO, indicating that the GR mRNA levels in these regions were regulated at the transcriptional level. In both sIMO and rIMO, nuclear GR levels were significantly increased in the hippocampus, medial basal hypothalamus (MBH), and AP. However, GR nuclear translocation was reduced in the hippocampus, unchanged in the MBH, and enhanced in the AP during rIMO, as compared with sIMO. Cytosolic hsp90 expression was unchanged in the hippocampus and MBH, whereas it significantly increased in the AP at 30 min during rIMO but not during sIMO. These results suggest that the site-specific changes in GR nuclear translocation during sIMO vs. rIMO are partially linked to hsp90 responses to immobilization. The reduced nuclear translocation of GR in the hippocampus during rIMO may reflect decreased glucocorticoid-mediated negative feedback on the hypothalamic-pituitary-adrenocortical axis.

Involvement of GCMB in the transcriptional regulation of the human parathyroid hormone gene in a parathyroid-derived cell line PT-r: effects of calcium and 1,25(OH)2D3.

Expression of the PTH gene is known to be under strict tissue-specific control and is also regulated by extracellular calcium and 1,25(OH)(2)D. However, the precise mode of transcriptional regulation remains to be elucidated, because of the unavailability of appropriate cell lines derived from the parathyroid gland. We tried to identify the transcription factor(s) regulating the human PTH gene transcription using the PT-r cell line. We found that PT-r cells endogenously express PTH and several parathyroid-related genes. Using the cells, we investigated the transcriptional regulation of human PTH gene. We found that GCMB binds to the PTH gene 5'-promoter (-390/-383 bp) and positively regulates its transcription. On the other hand, 1,25(OH)(2)D(3), and, in the presence of the calcium sensing receptor, high extracellular calcium, exerted inhibitory effects on PTH gene expression. These results indicate that GCMB and vitamin D receptor are involved in the positive and negative regulation of PTH gene expression, respectively. Our data also suggest that PT-r cells retain some of the characteristics of parathyroid cells.

Glucocorticoid receptor-beta and receptor-gamma exert dominant negative effect on gene repression but not on gene induction.

Glucocorticoid has diverse biological effects through induction or repression of its target genes via glucocorticoid receptor (GR). In addition to the wild-type GR (GR-alpha), a variety of GR variants has been reported, and these are thought to modify glucocorticoid action. Among others, GR-beta is reported be responsible for the glucocorticoid resistance frequently observed in steroid-resistant nephrotic syndrome, rheumatoid arthritis, and hematologic tumors, although the precise molecular mechanism remains unclear. In this study, we examined the function of GR-beta and some GR variants (GR-gamma and GR-Delta313-338) using GR-deficient BE(2)C and T84 cells in vitro. We found that GR-beta, when expressed alone, completely lost the capacity of both trans-activation and trans-repression on GR target genes. Interestingly, however, GR-beta showed a dominant-negative effect on GR-alpha only for its trans-repressive effects on cAMP-mediated and cAMP response element-dependent genes. Furthermore, both GR-beta and GR-gamma had dominant-negative effects on GR-alpha selectively for its trans-repressive effects on nuclear factor-kappaB-mediated and inflammation-related genes. These results suggest that 1) the GR-beta variant by itself has no receptor function, but 2) GR-beta and GR-gamma have properties to exert dominant-negative effects on the GR-alpha-mediated trans-repression, which may be responsible for the steroid resistance frequently observed in chronic inflammatory diseases under glucocorticoid therapy.

Hormonal regulation of acetyl-CoA carboxylase isoenzyme gene transcription.

Both glucocorticoid and insulin are known to have an anabolic effect on lipogenesis. Acetyl-CoA, an intermediate product of glycolysis, is supplied for fatty acid synthesis when carbohydrate intake is sufficient. Acetyl-CoA carboxylase (ACC), consisting of two isoenzymes ACC1 and ACC2, mediates the conversion from acetyl-CoA to malonyl-CoA, and thus plays a key role for the regulation of lipogenesis. In this study, we surveyed the effects of glucocorticoid and insulin on the transcriptional activity of the alternative promoters of ACCs (PI-PIII for ACC1, and PI and PII for ACC2) using the HepG2 human hepatocyte cell line in vitro. We also examined the roles of the insulin and/or glucose-regulated transcriptional factor(s) such as SREBP1c, LXRalpha/beta, and ChREBP on each promoter of the ACC genes. We found that both insulin and glucocorticoid had potent positive effects on all the promoters examined, and additive effects of both hormones were recognized in ACC1 PI and ACC2 PI. Furthermore, a representative insulin-responsive transcription factor SREBP1c showed significant stimulatory effects on all the promoters of ACC genes, among which those on ACC1 PIII and ACC2 PI were most prominent. On the other hand, the effect of LXRalpha was rather selective; it showed a marked stimulatory effect only on ACC1 PII. LXRbeta and ChREBP had minimal, if any, effects on some of the promoters. Altogether, our data suggest that insulin and glucocorticoid have positive effects on both ACC1 and ACC2 gene transcription. SREBP1c might be a master regulator of the expression of both genes regardless of the promoter utilized, whereas LXRalpha seems to play a promoter-specific role. Since ACC1 facilitates lipogenesis by stimulating fatty acid synthesis and ACC2 inhibits lipolysis, both insulin and glucocorticoid seem to play an important role in the pathogenesis of obesity and/or hepatic steatosis.