Chronic intrahypothalamic rather than subcutaneous liraglutide treatment reduces body weight gain and stimulates the melanocortin receptor system.

BACKGROUND: The GLP-1 receptor agonist liraglutide is marketed for obesity treatment where it induces body weight reduction possibly via the hypothalamus, which regulates energy homeostasis. In animal studies, acute liraglutide treatment triggers satiety, weight loss and activates thermogenesis in adipose tissue. However, the precise mechanisms how liraglutide affects in particular chronic weight loss are still under investigation. OBJECTIVES: We aimed to evaluate whether chronic hypothalamic or chronic subcutaneous administration of liraglutide induces sustained weight loss through altered adipose tissue function and to what extent hypothalamic neuronal appetite regulators are involved in the liraglutide-induced weight loss in healthy lean rats on a normal diet. MATERIALS/METHODS: We continuously administered liraglutide either intrahypothalamically (10 µg per day) or subcutaneously (200 µg kg-1 per day) for 28 days to lean Sprague Dawley rats (n=8 each). We assessed changes in body weight, adipose tissue mass, adipocyte size and adipose tissue volume in the abdominal region by using micro-CT. We analyzed genetic expression patterns of browning, thermogenic and adipocyte differentiation regulators in adipose tissues as well as particular neuronal appetite regulators in the hypothalamus. RESULTS: Intrahypothalamic liraglutide administration induced an 8% body weight reduction at day 9 compared with the control group (P<0.01) and a 7% body weight loss at day 9 compared with subcutaneous liraglutide treatment (P<0.01), supported by a significant reduction in adipose tissue mass and volume with intrahypothalamic liraglutide administration (P<0.05). Our data show that chronic intrahypothalamic liraglutide treatment triggered an 18-fold induction of the hypothalamic mc4r gene (P<0.01) accompanied by a significant increase in circulating thyroxine (T4) levels (P<0.05). CONCLUSIONS: Chronic intrahypothalamic liraglutide administration resulted in a profound reduction in body weight and fat mass loss most likely mediated by the hypothalamic melanocortin system rather than by adipose tissue browning or improved thermogenesis.

High salivary testosterone-to-androstenedione ratio and adverse metabolic phenotypes in women with polycystic ovary syndrome.

BACKGROUND: Polycystic ovary syndrome (PCOS) is characterized by a combination of hormonal and metabolic disturbances, such as insulin resistance, glucose intolerance, anovulation and hyperandrogenism. Clinical phenotypes of PCOS show different patterns of steroid hormones that have been investigated to some extent. This study aimed to establish a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of salivary testosterone and androstenedione and to describe the salivary testosterone-to-androstenedione (T/A4) ratio as a new tool for the assessment of hyperandrogenism and metabolic health. MATERIAL AND METHODS: Saliva and serum samples of 274 patients with PCOS and 51 healthy women were used for the quantification of steroid hormones. A comprehensive clinical and metabolic assessment was performed. Salivary testosterone and androstenedione were measured via LC-MS/MS. The salivary T/A4 ratio was calculated and correlated with hormones and metabolic parameters. RESULTS: Salivary testosterone (P < 0·001), androstenedione (P < 0·001) and the salivary T/A4 ratio (P < 0·001) were significantly higher in patients with patients compared to healthy women. In patients with PCOS, a high salivary T/A4 ratio was associated with an adverse metabolic phenotype, that is glucose intolerance (P = 0·019), insulin resistance (P < 0·001), metabolic syndrome (P < 0·001), obesity (P < 0·001) and oligo-/anovulation (P = 0·001). Significant correlations of the salivary T/A4 ratio with adverse metabolic parameters were found. CONCLUSION: Quantification of salivary androgens provides an attractive alternative to serum analysis and helps in characterizing metabolic health in women with PCOS. Our data show a strong link between a high salivary T/A4 ratio and an adverse metabolic phenotype in patients with PCOS.

MicroRNAs 223-3p and 93-5p in patients with chronic kidney disease before and after renal transplantation.

Chronic kidney disease (CKD) is associated with a multifactorial dysregulation of bone and vascular calcification and closely linked to increased cardiovascular mortality and concomitant bone disease. We aimed to investigate specific microRNA (miRNA) signatures in CKD patients to find indicators for vascular calcification and/or bone mineralization changes during CKD and after kidney transplantation (KT). A miRNA array was used to investigate serum miRNA profiles in CKD patients, then selected miRNAs were quantified in a validation cohort comprising 73 patients in CKD stages 3 to 5, 67 CKD patients after KT, and 36 healthy controls. A spectrum of biochemical parameters including markers for kidney function, inflammation, glucose, and mineral metabolism was determined. The relative expression of miR-223-3p and miR-93-5p was down-regulated in patients with CKD stage 4 and 5 compared to healthy controls. This down-regulation disappeared after kidney transplantation even when lower glomerular filtration rates (eGFR) persisted. MiR-223-3p and miR-93-5p were associated with interleukin-6 (IL-6) and eGFR levels, and by trend with interleukin-8 (IL-8), C-peptide, hematocrit, and parathyroid hormone (PTH). This study contributes new knowledge of serum miRNA expression profiles in CKD, potentially reflecting pathophysiological changes of bone and calcification pathways associated with inflammation, vascular calcification, mineral and glucose metabolism. Identified miRNA signatures can contribute to future risk markers or future therapeutic targets in bone and kidney disease.

Testosterone to dihydrotestosterone ratio as a new biomarker for an adverse metabolic phenotype in the polycystic ovary syndrome.

CONTEXT: Polycystic ovary syndrome (PCOS) is a heterogeneous disease with many different aspects, including hyperandrogenism and metabolic disturbances. Clinical phenotypes show different patterns of steroid hormones that have been investigated to some extent. OBJECTIVE: This study intended to determine the role of the testosterone (TT) to dihydrotestosterone (DHT) ratio (TT/DHT ratio) in PCOS patients and to further assess the correlation of this ratio with hormonal, anthropometric, and metabolic parameters. DESIGN AND SETTING: Serum samples of 275 premenopausal PCOS patients fulfilling Rotterdam criteria and 35 BMI-matched, premenopausal, healthy controls were analyzed for testosterone, DHT, dehydroepiandrosterone (DHEA), and androstenedione using liquid chromatography/mass spectrometry. MAIN OUTCOME MEASURES: We measured total levels of testosterone and DHT and calculated unbound hormone levels as well as the ratio of testosterone to DHT. Further, impaired glucose tolerance, basal and stimulated serum insulin levels, metabolic syndrome and insulin resistance according to the homeostatic model assessment (HOMA-IR) were assessed. RESULTS: PCOS patients showed significantly higher levels of TT (P < .001), free testosterone (P < .001), and free DHT (P < .001) compared to healthy controls. The TT/DHT ratio was significantly higher in PCOS patients (P < .001). No difference was found for total DHT levels (P = .072). In PCOS patients alone, the TT/DHT ratio was significantly higher in obese patients (P < .001) and patients with metabolic syndrome (P < .001), impaired glucose tolerance (IGT) (P < .001) or insulin resistance (P < .001). Significant correlations of the TT/DHT ratio with various adverse anthropometric, hormonal, lipid and liver parameters and parameters of glucose metabolism were found. CONCLUSION: Our data provide evidence for a strong link between a high TT/DHT ratio and an adverse metabolic phenotype in PCOS patients. This correlation was only found in PCOS patients, suggesting the TT/DHT ratio to be a new biomarker for an adverse metabolic phenotype in PCOS patients.

Testicular synthesis and vitamin D action.

CONTEXT: The vitamin D system has pleiotropic effects not only in bone metabolism. Its role in testicular steroidogenesis is new and deserves intensive research. OBJECTIVE: We hypothesize that vitamin D, especially 1,25 dihydroxyvitamin D3 [1,25(OH)2D3 (calcitriol)] induces male steroidogenesis and intend to identify its impact on genes and pathways in testicular androgen regulation. METHODS: Human adult primary testicular cells were isolated, treated with 1,25(OH)2D3, and their gene expression levels profiled by microarray analysis. Highly regulated genes were confirmed by real-time quantitative PCR. In addition, the effects of 1,25(OH)2D3 in combination with LH and IGF-I on the gene expression level of androgens were assessed. T levels in the culture media were determined by a high-resolution ELISA. The expression of vitamin D receptor was confirmed at baseline and after 1,25(OH)2D3 stimulation using immunocytochemistry. RESULTS: Microarrays depicted 63 genes significantly regulated by 1,25(OH)2D3, including genes related to male androgen and vitamin D metabolism, mainly triggered by the vitamin D receptor/retinoid X receptor activation. 1,25(OH)2D3 led to significant changes in the expression profiles of reproductive genes and significantly increased T synthesis in human testicular cell cultures. CONCLUSIONS: Data from our human primary testicular cell culture model suggest that vitamin D plays a major role in male steroidogenesis in vitro.

Suppression of activin A signals inhibits growth of malignant pleural mesothelioma cells.

BACKGROUND: Activins control the growth of several tumour types including thoracic malignancies. In the present study, we investigated their expression and function in malignant pleural mesothelioma (MPM). METHODS: The expression of activins and activin receptors was analysed by quantitative PCR in a panel of MPM cell lines. Activin A expression was further analysed by immunohistochemistry in MPM tissue specimens (N=53). Subsequently, MPM cells were treated with activin A, activin receptor inhibitors or activin-targeting siRNA and the impact on cell viability, proliferation, migration and signalling was assessed. RESULTS: Concomitant expression of activin subunits and receptors was found in all cell lines, and activin A was overexpressed in most cell lines compared with non-malignant mesothelial cells. Similarly, immunohistochemistry demonstrated intense staining of tumour cells for activin A in a subset of patients. Treatment with activin A induced SMAD2 phosphorylation and stimulated clonogenic growth of mesothelioma cells. In contrast, treatment with kinase inhibitors of activin receptors (SB-431542, A-8301) inhibited MPM cell viability, clonogenicity and migration. Silencing of activin A expression by siRNA oligonucleotides further confirmed these results and led to reduced cyclin D1/3 expression. CONCLUSION: Our study suggests that activin A contributes to the malignant phenotype of MPM cells via regulation of cyclin D and may represent a valuable candidate for therapeutic interference.