Endocrine

The objective of the study was to evaluate the effect of valproic acid (VPA) on ovarian androgen biosynthesis in primary cultures of theca-interstitial (T-I) cells isolated from rat ovaries. Ovarian T-I cells were cultured with VPA in the presence or absence of hCG. VPA did not increase basal or hCG-stimulated androgen synthesis when added to primary cultures of T-I cells. However, the addition of VPA caused a marked concentration-dependent inhibitory effect on hCG-stimulated androstendione synthesis. Treatment of T-I cells with 8-Bromo-cAMP resulted in a marked increase in the production of androstenedione, and VPA inhibited this stimulatory effect, suggesting that the mechanism of VPA’s inhibitory effect on androstenedione production occurs at a step after second messenger activation. Treatment of T-I cells with hCG resulted in a significant increase in the mRNA expression of steroidogenic enzymes CYP17A1 and 17β-hydroxysteroid dehydrogenase. Addition of VPA sharply blunted the stimulatory effect of hCG, reducing the mRNA expression of the steroidogenic enzymes to basal levels. In conclusion, VPA exerts an inhibitory effect on hCG-stimulated androgen synthesis in rat T-I cells.

Effects of hypothyroidism on the glucose and insulin levels are controversial, and its impact on the Langerhans islet morphology of adult subjects has been poorly addressed. In spite of hypothyroidism and diabetes mellitus are more frequent in females than in males, most studies using animal models have been done in males. The effect of hypothyroidism on the immunolabeling of thyroid hormone receptors (TRs) and thyrotropin receptor (TSHR) of islet cells is unknown. The aim of this study was to determine the effect of hypothyroidism on the glucose and insulin concentrations, morphometry of islets, and immunostaining of TRs α1–2 and β1 and TSHR of islet cells in female rabbits. Control and hypothyroid (0.02 % of methimazole for 30 days) animals were used to quantify blood levels of glucose and insulin, density of islets, cross-sectional area (CSA) of islets, number of cells per islet, cell proliferation, and the immunolabeling of TRs α1–2, TRβ1, and TSHR. Student’s t or Mann–Whitney-U tests, two-way ANOVAs, and Fischer’s tests were applied. Concentrations of glucose and insulin, as well as the insulin resistance were similar between groups. Hypothyroidism did not affect the density or the CSA of islets. The analysis of islets by size showed that hypothyroidism reduced the cell number in large and medium islets, but not in small ones. In small islets, cell proliferation was increased. The immunoreactivity of TRα1–2, TRβ1, and TSHR was increased by hypothyroidism in all islet sizes. Our results show that hypothyroidism affects differentially the islet cells depending on the size of islets.

Estrogen has been comprehensively studied as a neuroprotective agent in women, animals, and a variety of in vitro models of neural injury and degeneration. Most data suggest that estrogen can benefit the ischemic brain and reduce cell death. However, recent data from the Women’s Health Initiative have raised concerns about the utility and safety of chronic estrogen use in women. While estrogen is a potent and reproducible neuroprotectant in animals and in vitro, its current administration in women has had unanticipated and paradoxical effects. Nonetheless, estrogen’s diverse actions make it an ideal prototype for developing new neuroprotectants such as selective estrogen receptor modulators (SERMs). SERMs represent a class of drugs with mixed estrogen agonistic and antagonistic activity. Experimental and clinical data suggest a neuroprotective role for SERMs in normal and injured brain. The discrepancy among observational studies, preclinical data, and clinical trials emphasizes the need for further study of the mechanisms leading to the increased incidence of stroke observed in postmenopausal women. Research is still needed to optimize combined or estrogen alone hormone replacement therapy options as well as the prevention/management of cerebrovascular/central nervous system disorders. This review critiques estrogen and SERMs’ neuroprotective potential in experimental and clinical studies of stroke and cerebrovascular disease.

Although IGF-I was known to stimulate the growth of pancreatic islet cells from early in vitro experiments and in vivo reports on rodents, recent gene targeting experiments have indicated that IGF-I and its receptor do not play a major role in normal islet cell growth. In our previous reports, liver- or pancreatic-specific IGF-I deficiency caused no decrease in β-cell mass; a general and β-cell-enriched IGF-I overexpression caused no change in normal islet cell growth. On the other hand, increased metabolic demands (such as in obesity and insulin resistance) result in β-cell compensation in cell number and insulin secretion. In order to test whether IGF-I could promote islet cell growth and facilitate islet compensation due to obesity-induced insulin resistance, we have challenged MT-IGF mice to a high-fat diet. After 28 weeks, both MT-IGF mice and wild-type littermates gained comparable 40–57% of body weight, with similar increases in fat masses; all mice maintained a normal sensitivity to insulin and did not become severely hyperglycemic. Nevertheless, compared to wild-type littermates, the equally obese MT-IGF mice maintained improved glucose tolerance and a diminished insulin level; similar to when fed a normal chow diet. More importantly, under IGF-I overexpression, there was no further increase in β-cell mass caused by obesity. Thus, IGF-I overexpression had no significant effect on weight gain and islet cell compensation in response to high-fat diet-induced obesity.

This article describes studies on the glucose-induced responses of intracellular Ca2+ concentration ([Ca2+]i), insulin release, and redistribution of calbindin-D28k, a calcium-binding regulatory protein, in β-cells of pancreatic islets of calbindin-D28k knockout (KO) and wild-type mice (C57BL6) as well as in βHC-13 control cells and βHC-13 CaBP40 cells (β-cell line overexpressing calbindin-D28k). Upon increasing the glucose concentration from 2.8 to 30 mM, islets of KO mice showed a significantly greater increase in [Ca2+]i (mean increase in [Ca2+]i, i.e., Δ[Ca2+], was 296 nM) compared with wild-type mice (Δ[Ca2+]i=97 nM). βHC-13 CaBP40 cells showed little change in [Ca2+]i upon elevation of glucose from 5.5 to 32.7 mM, whereas βHC-13 control cells exhibited significant increases in [Ca2+]i (Δ[Ca2+]i=510 nM). Similarly, upon addition of 30 mM glucose, the rate of insulin release increased from 25.2 (basal rate) to 145.2 pg/mL/min in βHC-13 control cells, whereas in βHC-13 CaBP40 cells the rate of insulin release was only 27.5 pg/mL/min in high glucose. Thus, levels of calbindin-D28k in β-cells affect both [Ca2+]i and insulin secretion in response to glucose. The three-dimensional reconstruct of confocal immunofluorescent images showed that glucose caused redistribution of calbindin-D28k resulting in co-localization in the region of L-type voltage-dependent calcium channels (VDCC). This colocalization may be an important regulatory function concerning Ca2+ influx via L-type VDCC and exocytosis of insulin granules.

Almost 10 years have passed since the first attempts of liquid biopsy aimed at the characterisation of tumor cells present in the bloodstream from a regular sample of peripheral blood were performed. Liquid biopsy has been used to characterise tumor heterogeneity in various types of solid tumors including adrenocortical carcinoma. The development of molecular biology, genetics, and methodological advances such as digital PCR and next-generation sequencing allowed us to use besides circulating tumor cells a variety of circulating cell-free nucleic acids, DNAs, RNAs and microRNAs secreted by tumors into blood and other body fluids as specific molecular markers. These markers are used for diagnosis, to check tumor development, selecting efficient therapies, therapy monitoring and even possess prognostic power. In adrenocortical carcinoma, there are some studies reporting analysis of circulating tumor cells, circulating cell free DNA and microRNAs for assessing tumor heterogeneity. Among microRNAs, hsa-miR-483-5p seems to be the most important player. Combined with other microRNAs like hsa-miR-195, their expression correlates with recurrence-free survival. Most studies support the applicability of liquid biopsy for assessing temporal tumor heterogeneity (i.e. tumor progression) in adrenocortical cancer. In this mini-review, the available findings of liquid biopsy for assessing tumor heterogeneity in adrenocortical cancer are presented.

Pituitary somatotrophs secrete growth hormone (GH) into the bloodstream, to act as a hormone at receptor sites in most, if not all, tissues. These endocrine actions of circulating GH are abolished after pituitary ablation or hypophysectomy, indicating its pituitary source. GH gene expression is, however, not confined to the pituitary gland, as it occurs in neural, immune, reproductive, alimentary, and respiratory tissues and in the integumentary, muscular, skeletal, and cardiovascular systems, in which GH may act locally rather than as an endocrine. These actions are likely to be involved in the proliferation and differentiation of cells and tissues prior to the ontogeny of the pituitary gland. They are also likely to complement the endocrine actions of GH and are likely to maintain them after pituitary senescence and the somatopause. Autocrine or paracrine actions of GH are, however, sometimes mediated through different signaling mechanisms to those mediating its endocrine actions and these may promote oncogenesis. Extrapituitary GH may thus be of physiological and pathophysiological significance.

In arthropods, development is controlled by cholesterol-derived steroid hormones: the ecdysteroids. In vertebrates and insects, steroidogenesis is positively regulated and this is mediated by cAMP. In crustaceans, ecdysteroid biosynthesis by steroidogenic organs (Y-organs) is negatively regulated by a neuropeptide, the Molt Inhibiting Hormone (MIH). This neuropeptide-induced inhibition occurs via cyclic nucleotides and depends on protein synthesis. In the present work, we provide evidence that a major 36.2-kDa cytosolic protein (P36; pl: 6.8) from crab Y-organs is positively correlated with steroidogenic activity. On the basis of its amino acid sequence, P36 could be related to transaldolase, an enzyme of the pentose phosphate pathway which generates NADPH. In Y-organs, the enzymatic activity ofCarcinus transaldolase increases with steroidogenic activity, and MIH treatment decreases both synthesis and activity of transaldolase. Various transaldolases have been characterized in very distantly related groups, namely bacteria, yeasts, and humans. These enzymes are highly conserved and present strong structural homologies, interestingly the crab transaldolase is closest to that enzyme characterized in human cells.

High-fidelity simulation calls heavily upon cognitive capacities and generates stress and anxiety. The objective of this prospective, observational study was to evaluate the degree of stress in medical students by measuring hormone levels during critical care classes. Overall, 55 students (senior years of medical faculty) of both sexes were divided into 5-person teams. Demographic data and information on diagnosed diseases, stimulants used, and previous experience in the field of medical simulation were collected with a personal questionnaire. Before starting the scenario (T0), after the end of the scenario (T1), and 120 min thereafter (T2), stress level was measured. For this purpose, systolic blood pressure, diastolic blood pressure, mean blood pressure, heart rate and blood oxygen saturation were evaluated. In addition, saliva was collected to determine alpha-amylase activity and the concentrations of secretory immunoglobulin class A, cortisol, and testosterone. Among hemodynamic parameters, systolic and mean blood pressure and heart rate were significantly higher in T1 than in T0 and T2 time points (p < 0.05). Cortisol concentration was higher at T2 compared with T0 and T1. Alpha-amylase activity was highest at T1. Secretory immunoglobulin class A concentration was highest at T0, followed by T1 and then T2. These differences were not statistically significant. Testosterone concentration showed significantly higher values at T2 compared with T0 and T1 (p < 0.05). The analysis of team leaders vs. other members revealed significantly lower cortisol and alpha-amylase values in leaders (p < 0.05). High-fidelity simulation is a useful education method in medical subjects, especially in cases where a mistake could produce serious or irreversible consequences. It can increase stress hormone concentrations and thus can be assumed effective as a learning aid even in senior-year students of medical faculty.