Leptin interferes with adrenocorticotropin/3',5'-cyclic adenosine monophosphate (cAMP) signaling, possibly through a Janus kinase 2-phosphatidylinositol 3-kinase/Akt-phosphodiesterase 3-cAMP pathway, to down-regulate cholesterol side-chain cleavage cytochrome P450 enzyme in human adrenocortical NCI-H295 cell line

Intertwined regulators: hypoxia pathway proteins, microRNAs, and phosphodiesterases in the control of steroidogenesis

Oxygen sensing is of paramount importance for maintaining cellular and systemic homeostasis. In response to diminished oxygen levels, the hypoxia-inducible factors (HIFs) orchestrate various biological processes. These pivotal transcription factors have been identified as key regulators of several biological events. Notably, extensive research from our group and others has demonstrated that HIF1α exerts an inverse regulatory effect on steroidogenesis, leading to the suppression of crucial steroidogenic enzyme expression and a subsequent decrease in steroid levels. These steroid hormones occupy pivotal roles in governing a myriad of physiological processes. Substantial or prolonged fluctuations in steroid levels carry detrimental consequences across multiple organ systems and underlie various pathological conditions, including metabolic and immune disorders. MicroRNAs serve as potent mediators of multifaceted gene regulatory mechanisms, acting as influential epigenetic regulators that modulate a broad spectrum of gene expressions. Concomitantly, phosphodiesterases (PDEs) play a crucial role in governing signal transduction. PDEs meticulously manage intracellular levels of both cAMP and cGMP, along with their respective signaling pathways and downstream targets. Intriguingly, an intricate interplay seems to exist between hypoxia signaling, microRNAs, and PDEs in the regulation of steroidogenesis. This review highlights recent advances in our understanding of the role of microRNAs during hypoxia-driven processes, including steroidogenesis, as well as the possibilities that exist in the application of HIF prolyl hydroxylase (PHD) inhibitors for the modulation of steroidogenesis.

The anti-platelet drug cilostazol enhances heart rate and interrenal steroidogenesis and exerts a scant effect on innate immune responses in zebrafish

RATIONALE

Cilostazol, an anti-platelet phosphodiesterase-3 inhibitor used for the treatment of intermittent claudication, is known for its pleiotropic effects on platelets, endothelial cells and smooth muscle cells. However, how cilostazol impacts the endocrine system and the injury-induced inflammatory processes remains unclear.

METHODS

We used the zebrafish, a simple transparent model that demonstrates rapid development and a strong regenerative ability, to test whether cilostazol influences heart rate, steroidogenesis, and the temporal and dosage effects of cilostazol on innate immune cells during tissue damage and repair.

RESULTS

While dosages of cilostazol from 10 to 100 μM did not induce any noticeable morphological abnormality in the embryonic and larval zebrafish, the heart rate was increased as measured by ImageJ TSA method. Moreover, adrenal/interrenal steroidogenesis in larval zebrafish, analyzed by whole-mount 3β-Hsd enzymatic activity and cortisol ELISA assays, was significantly enhanced. During embryonic fin amputation and regeneration, cilostazol treatments led to a subtle yet significant effect on reducing the aggregation of Mpx-expressing neutrophil at the lesion site, but did not affect the immediate injury-induced recruitment and retention of Mpeg1-expressing macrophages.

CONCLUSIONS

Our results indicate that cilostazol has a significant effect on the heart rate and the growth as well as endocrine function of steroidogenic tissue; with a limited effect on the migration of innate immune cells during tissue damage and repair.

Effects of High-Fat Diet on Stress Response in Male and Female Wildtype and Prolactin Knockout Mice

Prolactin (PRL) is well characterized for its roles in initiation and maintenance of lactation, and it also suppresses stress-induced responses. Feeding a high-fat diet (HFD) disrupts activity of the hypothalamic-pituitary-adrenal (HPA) axis. Whether PRL regulates HPA axis activation under HFD feeding is not clear. Male and female wildtype (WT) and PRL knockout (KO) mice were fed either a standard low-fat diet (LFD) or HFD for 12 weeks. Circulating corticosterone (CORT) levels were measured before, during, and after mice were subjected to an acute restraint stress or remained in their home cages as no stress controls. HFD feeding increased leptin levels, but the increase was lower in KO than in WT mice. All stressed female groups and only LFD-fed stressed males had elevated CORT levels compared to their no stress same-sex counterparts regardless of genotype. These results indicated that HFD consumption blunted the HPA axis response to acute stress in males but not females. Additionally, basal hypothalamic CRH content was lower in HFD than LFD males, but was similar among female groups. Furthermore, although basal CORT levels were similar among KO and WT groups, CORT levels were higher in KO mice than their WT counterparts during stress, suggesting that loss of PRL led to greater HPA axis activation. Basal PRL receptor mRNA levels in the choroid plexus were higher in HFD than LFD same-sex counterparts, suggesting activation of central PRL’s action by HFD feeding in both males and females. Current results confirmed PRL’s roles in suppression of the stress-induced HPA axis activation. Although HFD feeding activated central PRL’s action in both sexes, only the male HPA axis was dampened by HFD feeding.

Granulocyte-colony stimulating factor activates JAK2/PI3K/PDE3B pathway to inhibit corticosterone synthesis in a neonatal hypoxic-ischemic brain injury rat model

OBJECTIVE

Our previous study demonstrated that granulocyte-colony stimulating factor (G-CSF)-induced neuroprotection is accompanied by an inhibition of corticosterone production in a neonatal hypoxic-ischemic (HI) rat model. The present study investigates how G-CSF inhibits corticosterone production, using adrenal cortical cells and HI rat pups.

METHODS

Cholera toxin was used to induce corticosterone synthesis in a rodent Y1 adrenal cortical cell line by increasing cyclic adenosine monophosphate (cAMP). Both corticosterone and cAMP were quantitatively measured using a commercial enzyme-linked immunosorbent assay (ELISA). The downstream signaling components of the G-CSF receptor, including Janus Kinase 2 (JAK2)/Phosphatidylinositol-3-kinase (PI3K)/Protein kinase B (Akt) and Phosphodiesterase 3B (PDE3B), were detected by western blot. Sprague-Dawley rat pups at the age of 10days (P10) were subjected to unilateral carotid artery ligation followed by hypoxia for 2.5hours. Brain infarction volumes were determined using 2,3,5-triphenyltetrazolium chloride monohydrate (TTC) staining.

RESULTS

G-CSF at 30ng/ml inhibited corticosterone synthesis but lost its inhibitory effect at higher doses. The inhibitory effect of G-CSF was conferred by interfering with cAMP signaling via the activation of the JAK2/PI3K/PDE3B signaling pathway. The degradation of cAMP by G-CSF signaling reduced corticosterone production. This mechanism was further verified in the neonatal HI brain injury rat model, in which inhibition of PDE3B reversed the protective effects of G-CSF.

CONCLUSION

Our data suggest that the neuroprotective G-CSF reduces corticosterone synthesis at the adrenal level by degrading intracellular cAMP via activation of the JAK2/PI3K/PDE3B pathway.

Maternal high fat diet during critical windows of development alters adrenal cortical and medullary enzyme expression in adult male rat offspring

We previously reported that a maternal high fat (HF) diet resulted in adult offspring with increased adiposity and hyperleptinemia. As leptin has an inhibitory effect on adrenal steroidogenesis and a stimulatory effect on epinephrine synthesis, we hypothesized that key adrenal steroidogenic and catecholaminergic enzymes would be altered in these offspring. Wistar rats were randomized into three groups at weaning: (1) control dams fed a standard control chow diet from weaning and throughout pregnancy and lactation (CON), (2) dams fed a HF diet from weaning and throughout pregnancy and lactation (MHF) and (3) dams fed standard control chow diet throughout life until conception, then fed a HF diet in pregnancy and lactation (PLHF). Dams were mated at day 100 (P100). After birth at P22 (weaning), male offspring were fed a standard control chow (con) or high fat (hf) diet. At P160, plasma samples and adrenal tissues were collected. Postweaning hf diet significantly elevated plasma corticosterone concentrations in PLHF-hf offspring compared to PLHF-con. MHF nutrition increased adrenal adrenocorticotrophic hormone receptor (ACTH-R) mRNA levels compared to CON-con. 3β-hydroxysteroid dehydrogenase (3βHSD) mRNA levels were decreased in MHF compared to PLHF offspring. Phenylethanolamine N-methyltransferase (PNMT) mRNA levels were increased in MHF-hf offspring compared to MHF-con. Plasma homocysteine (HCY) concentrations were significantly elevated in CON-hf and MHF-hf offspring compared to chow-fed offspring, associated with elevated intakes of methionine and reduced intakes of pyridoxine. Immunoreactive leptin receptor (ObRb) and PNMT were colocalized in medullary chromaffin cells. This study suggests that a postweaning HF diet in offspring induced changes in adrenal gene expression levels that are dependent upon the level of maternal nutrition.

Antenatal glucocorticoid exposure enhances the inhibition of adrenal steroidogenesis by leptin in a sex-specific fashion

Antenatal treatment with glucocorticoids (GC) poses long-lasting effects on endocrine and cardiovascular function. Given that leptin attenuates adrenal function and the reported sex differences in plasma leptin concentration, we hypothesized that antenatal GC will affect leptin levels and leptin modulation of adrenal function in a sex-specific manner. Pregnant sheep were randomly given betamethasone or vehicle at 80 days of gestational age, and offspring were allowed to deliver at term. Adrenocortical cells (ADC) were studied from male and female animals at 1.5 yr of age. Plasma leptin was increased 66% in male and 41% in female GC-treated animals (P < 0.05), but adrenal leptin mRNA was increased only in GC-treated males (P < 0.05). Whereas mRNA expression of adrenal leptin receptor isoforms showed sex (Ob-Ra and Ob-Rb) and treatment-dependent (Ob-Rb) differences, protein expression remained unchanged. GC-treated females showed greater plasma cortisol and greater ACTH-stimulated cortisol production (P < 0.05) in ADC. Leptin exerted a greater inhibitory effect on basal and stimulated cortisol by ADC from GC-treated males (P < 0.05), with no differences in females. Similarly, greater inhibitory effects on basal and ACTH-stimulated StAR and ACTH-R mRNA expression by leptin were observed in cells from GC males (P < 0.05), with no changes in females. Persistent effects of antenatal GC on leptin levels and leptin modulation of adrenal function are expressed in a sex-specific manner; males are more sensitive than females to the inhibitory influences of leptin on adrenal function, and this effect appears to be mediated by a greater inhibition of StAR and ACTH-R expression in adrenals of adult GC-treated males.

An activator of the cAMP/PKA/CREB pathway promotes osteogenesis from human mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent adult stem cells capable of differentiating along the osteoblast, adipocyte, and chondrocyte lineages. Regulation of MSCs differentiation may be a useful tool for regenerative medicine and cell-based therapy. The discovery of small molecule that activates the osteogenic differentiation of MSCs could aid in the development of a new anabolic drug for osteoporosis treatment. We identified CW008, a derivative of pyrazole-pyridine, that stimulates osteoblast differentiation of human MSCs and increases bone formation in ovariectomized mice. CW008 promotes osteogenesis by activating cAMP/PKA/CREB signaling pathway and inhibiting leptin secretion. These results suggest that CW008 is an agonist of cAMP/PKA/CREB pathway in osteogenic differentiation and that application of CW008 may be useful for the treatment of bone-related diseases and for the study of bone biology.

Biological roles of cAMP: variations on a theme in the different kingdoms of life

Cyclic AMP (cAMP) plays a key regulatory role in most types of cells; however, the pathways controlled by cAMP may present important differences between organisms and between tissues within a specific organism. Changes in cAMP levels are caused by multiple triggers, most affecting adenylyl cyclases, the enzymes that synthesize cAMP. Adenylyl cyclases form a large and diverse family including soluble forms and others with one or more transmembrane domains. Regulatory mechanisms for the soluble adenylyl cyclases involve either interaction with diverse proteins, as happens in Escherichia coli or yeasts, or with calcium or bicarbonate ions, as occurs in mammalian cells. The transmembrane cyclases can be regulated by a variety of proteins, among which the α subunit and the βγ complex from G proteins coupled to membrane receptors are prominent. cAMP levels also are controlled by the activity of phosphodiesterases, enzymes that hydrolyze cAMP. Phosphodiesterases can be regulated by cAMP, cGMP or calcium-calmodulin or by phosphorylation by different protein kinases. Regulation through cAMP depends on its binding to diverse proteins, its proximal targets, this in turn causing changes in a variety of distal targets. Specifically, binding of cAMP to regulatory subunits of cAMP-dependent protein kinases (PKAs) affects the activity of substrates of PKA, binding to exchange proteins directly activated by cAMP (Epac) regulates small GTPases, binding to transcription factors such as the cAMP receptor protein (CRP) or the virulence factor regulator (Vfr) modifies the rate of transcription of certain genes, while cAMP binding to ion channels modulates their activity directly. Further studies on cAMP signalling will have important implications, not only for advancing fundamental knowledge but also for identifying targets for the development of new therapeutic agents.

Different levels of leptin regulate different target enzymes involved in progesterone synthesis

OBJECTIVE

To study the effects of different doses of leptin on the expression of proteins involved in P synthesis, such as steroidogenic acute regulatory protein (StAR), cytochrome P450 side chain cleavage (P450scc), and 3β-hydroxysteroid dehydrogenase (3βHSD).

DESIGN

Experimental studies.

SETTING

Research laboratory.

ANIMAL(S)

Immature rats primed with gonadotropins to induce ovulation.

INTERVENTION(S)

In vivo studies: rats received either an acute or daily treatment with leptin. In vitro studies: ovarian explants were cultured in the absence or presence of leptin (0.3-500 ng/mL).

MAIN OUTCOME MEASURE(S)

The expression of both messenger RNA and protein of StAR, P450scc, and 3βHSD were measured by reverse transcription-polymerase chain reaction (PCR) and Western blot, respectively.

RESULT(S)

The acute treatment with leptin, which inhibits the ovulatory process, caused a significant reduction in the ovarian expression of P450scc without changes in StAR or 3βHSD. In contrast, the daily treatment, which induces the ovulatory process, showed an increased expression of the ovarian 3βHSD protein, without differences in the other proteins measured. We also found that leptin increased the protein of both P450scc and 3βHSD at physiological levels and inhibited both messenger RNA and protein of 3βHSD at higher concentrations.

CONCLUSION(S)

The results indicate that 1) leptin is able to regulate the expression of the 3βHSD protein in a dose-dependent manner; and 2) leptin seems to exert its dual effects on P synthesis on different targets in a dose-dependent manner.

Adrenal incidentaloma and the Janus Kinase 2 V617F mutation: A case-based review of the literature

Adrenal incidentaloma was detected in an 81-year-old male patient and a 37-year-old female patient who had been diagnosed with essential thrombocytosis. Each patient's Janus Kinase 2 (JAK2) V617F mutation was positive, and they were evaluated as having non-functional adrenal incidentaloma. The JAK2 activates the signal transducers and activators of transcription (STAT) proteins which then activate the phosphoinositol-3 kinases, Ras, mitogen-activated protein (MAP) kinases, and transcription. Constitutive activation causes cell proliferation and dysregulation of apoptosis. It is thought that STAT3 activation-mediated JAK family kinases have a central role in the solid tumor cell series. Permanent activation of STAT3 and STAT5 causes tumor cell proliferation, survival, metastasis, and an increase in tumor-mediated inflammation in solid and hematologic tumors. According to our literature screening, irregular JAK signaling, seen at the pathogenesis of many solid and hematologic tumors, has not been previously evaluated with regard to adrenal tumors. As a result, our cases are the first coexistence of JAK V617F mutation with adrenal incidentaloma in the literature. Because of this, we think that JAK2 mutation must be evaluated to clarify the etiology of adrenal incidentalomas.

The effects of high fat diet on the basal activity of the hypothalamus-pituitary-adrenal axis in mice

Alterations in hypothalamus-pituitary-adrenal (HPA) axis activity have been linked to the development of the metabolic syndrome (MetS). Common features of the MetS, like insulin resistance and obesity, are reproducibly induced by high fat diet (HFD) in animal models of diet-induced obesity. These models, hampered by methodological differences, reveal conflicting results with respect to HPA axis activation. This study was aimed to evaluate in detail nonstressed diurnal HPA axis activity in mice during obesity development. Male C57Bl/6J mice were fed high or low fat diet for 12 weeks. HPA axis activity was evaluated by plasma corticosterone concentrations (at 0700, 1200, and 1800  h), corticotropin-releasing hormone (CRH), and glucocorticoid receptor (GR) mRNA expression in the hippocampus, amygdala, and hypothalamus, and 11β-hydroxysteroid dehydrogenase type-1 and -2 (11β-HSD-1 and -2) expression in adipose tissue and liver. Within 1 week, the HFD induced obesity and decreased corticosterone levels at 1200 and 1800  h, which persisted throughout the experiment. Twelve weeks of HFD decreased CRH mRNA in the paraventricular nucleus (PVN) and amygdala and GR mRNA in the PVN at 0900  h. At 1800  h, CRH mRNA expression increased in the PVN and amygdala, and GR mRNA increased in the CA1 region. 11β-HSD-1 expressions decreased in gonadal, visceral, and subcutaneous adipose tissues at 0900 and 1800  h, whereas hepatic 11β-HSD-1 expression increased at 1800  h, whereas 11β-HSD-2 expression was unaffected. The HFD induces complex changes in the diurnal regulation of the different components of the HPA axis. These changes are not unequivocally characterized by increased, but rather by decreased HPA axis activity.

Recombinant human leptin attenuates stress axis activity in common carp (Cyprinus carpio L.)

Proper functioning of the endocrine stress axis requires communication between the stress axis and other regulatory mechanisms. We here describe an intimate interplay between the stress axis and recombinant human leptin (rhLeptin) in a teleostean fish, the common carp Cyprinus carpio. Restraint stress (by netting up to 96h) increased plasma cortisol but did not affect hepatic leptin expression. Perifusion of pituitary glands or head kidneys with rhLeptin revealed direct effects of rhLeptin on both tissues. RhLeptin suppresses basal and CRF-induced ACTH-secretion in a rapid and concentration-dependent manner. The rhLeptin effect persisted for over an hour after administration had been terminated. RhLeptin decreases basal interrenal cortisol secretion in vitro, and by doing so attenuates ACTH-stimulated cortisol production; rhLeptin does not affect interrenal ACTH-sensitivity. Our findings show that the endocrine stress axis activity and leptin are inseparably linked in a teleostean fish, a notion relevant to further our insights in the evolution of leptin physiology in vertebrates.

Characteristics of glucocorticoid synthesis-related factors in the adrenals of obese Zucker rats (short communication)

To understand the molecular mechanism of hyperglucocorticoidism in obese Zucker rats, this study investigated glucocorticoid synthesis-related factors and their transcription factors in the adrenals. glucocorticoid synthesis-related factors and their transcription factors in the adrenals. The serum corticosterone level after foot shock stress was higher in obese Zucker rats than in lean Zucker rats. after foot shock stress was higher in obese Zucker rats than in lean Zucker rats. In the adrenals from obese Zucker rats, the mRNA and protein levels of steroidogenic acute regulatory protein were higher than those from lean Zucker rats. rats. However, the mRNA level of steroidogenic factor-1(SF-1), an important transcription factor for these glucocorticoid synthesis-related factors, did not differ between lean and obese Zucker rats. glucocorticoid synthesis-related factors, did not differ between lean and obese Zucker rats. Focusing on leptin signal transduction, Akt phosphorylation, which was known to inhibit glucocorticoid secretion, decreased in the adrenals from obese Zucker rats. from obese Zucker rats. We found that the stress-induced glucocorticoid secretion and the glucocorticoid synthesis related factors in the adrenals were increased in obese Zucker rats. factors in the adrenals were increased in obese Zucker rats. The decrease of Akt phosphorylation in the adrenals might induce these increases in obese Zucker rats.adrenals might induce these increases in obese Zucker rats.

Leptin alters adrenal responsiveness by decreasing expression of ACTH-R, StAR, and P450c21 in hypoxemic fetal sheep

The late gestation increase in adrenal responsiveness to adrenocorticotropin (ACTH) is dependent upon the upregulation of the ACTH receptor (ACTH-R), steroidogenic acute regulatory protein (StAR), and steroidogenic enzymes in the fetal adrenal. Long-term hypoxia decreases the expression of these and adrenal responsiveness to ACTH in vivo. Leptin, an adipocyte-derived hormone which attenuates the peripartum increase in fetal plasma cortisol is elevated in hypoxic fetuses. Therefore, we hypothesized that increases in plasma leptin will inhibit the expression of the ACTH-R, StAR, and steroidogenic enzymes and attenuate adrenal responsiveness in hypoxic fetuses. Spontaneously hypoxemic fetal sheep (132 days of gestation, PO(2) ≈ 15 mm Hg) were infused with recombinant human leptin (n = 8) or saline (n = 7) for 96 hours. An ACTH challenge was performed at 72 hours of infusion to assess adrenal responsiveness. Plasma cortisol and ACTH were measured daily and adrenals were collected after 96 hours infusion for messenger RNA (mRNA) and protein expression measurement. Plasma cortisol concentrations were lower in leptin- compared with saline-infused fetuses (14.8 ± 3.2 vs 42.3 ± 9.6 ng/mL, P < .05), as was the cortisol:ACTH ratio (0.9 ± 0.074 vs 46 ± 1.49, P < .05). Increases in cortisol concentrations were blunted in the leptin-treated group after ACTH(1-24) challenge (F = 12.2, P < .0001). Adrenal ACTH-R, StAR, and P450c21 expression levels were reduced in leptin-treated fetuses (P < .05), whereas the expression of Ob-Ra and Ob-Rb leptin receptor isoforms remained unchanged. Our results indicate that leptin blunts adrenal responsiveness in the late gestation hypoxemic fetus, and this effect appears mediated by decreased adrenal ACTH-R, StAR, and P450c21 expression.

Mitotane exhibits dual effects on steroidogenic enzymes gene transcription under basal and cAMP-stimulating microenvironments in NCI-H295 cells

Adrenocortical carcinoma (ACC) is an extremely rare and aggressive endocrine malignancy with a poor prognosis. The most common symptom of ACC is hypercortisolism (Cushing's syndrome), which has the highest mortality. Mitotane is used as a steroidogenesis inhibitor for Cushing's syndrome or as a chemical adrenalectomy drug for ACC. Mitotane induces adrenal cortex necrosis, mitochondrial membrane impairment, and irreversible binding to CYP proteins. In this study, we explored the molecular effect of mitotane on steroidogenesis in human adrenocortical cancer NCI-H295 cells. Mitotane (10-40μM) inhibited basal and cAMP-induced cortisol secretion but did not cause cell death. Mitotane exhibited an inhibitory effect on the basal expression of StAR and P450scc protein. Furthermore, 40μM of mitotane significantly diminished StAR, CYP11A1 and CYP21 mRNA expression. HSD3B2 and CYP17 seem to be insensitive to mitotane. The stimulatory effects of mitotane on CYP11B1 were more remarkable than its inhibitory effects. In contrast, the activation of cAMP signaling strongly elevated the expression of all these genes. Mitotane (40μM) almost completely neutralized this positive effect and returned 8-Br-cAMP-induced StAR, CYP11A1, CYP17 and CYP21 mRNA to control levels. After cAMP activation, mitotane did not change the levels of CYP11B1 mRNA. The present study demonstrates that mitotane can inhibit cortisol biosynthesis due to a non-specific interference with the gene transcription of steroidogenic enzymes under both basal and 8-Br-cAMP-activated conditions in NCI-H295 cells. We also identified that StAR and CYP11A1 key enzymes that participate in the rate-limiting step of steroidogenesis, were more sensitive to mitotane. In addition, the biphasic effect of mitotane on CYP11B1 was also elucidated.

Leptin action in pubertal development: recent advances and unanswered questions

In recent years we have witnessed a considerable advance in the understanding of the processes involved in pubertal development. This is partially due to the discovery of the kisspeptin system and its fundamental role in the control of reproductive physiology. In addition, the suspected relationship between increasing rates of childhood obesity and the apparent reduction in the age of puberty onset in girls has generated a growing interest in identifying the mechanisms by which nutrition may influence reproductive maturation. This review will focus on recent data unveiling the sites of leptin action in pubertal development that were generated using novel molecular techniques and genetically engineered mouse models. It will also emphasize areas of contention and the many relevant questions that remain unanswered.

Maternal undernutrition programs offspring adrenal expression of steroidogenic enzymes

The aim of this study was to determine the influence of maternal undernutrition (MUN) on maternal and offspring adrenal steroidogenic enzymes. Pregnant Sprague-Dawley rats were 50% food-restricted from day 10 of gestation until delivery. Control animals received ad libitum food. Offspring were killed on day 1 of life (P1) and at 9 months. We determined the messenger RNA (mRNA) expression of steroidogenic enzymes by real-time reverse transcriptase polymerized chain reaction (RT-PCR). Maternal undernutrition inhibited maternal adrenal expression of P450 cholesterol side-chain cleavage enzyme (CYP11A1), 11 beta-hydroxylase (CYP11B1), aldosterone synthase (CYP11B2), and adrenocorticotropic hormone (ACTH) receptor (ACTH-R; MC2 gene) compared with control offspring. There was a marked downregulation in the expression of CYP11B1, CYP11B2, 11 β-hydroxysteroid dehydrogenase type 1 and 2 (HSD1 and HSD2), CYP11A1, ACTH receptor, steroidogenic acute regulatory protein (STAR), and mineralocorticoid receptor (MCR; NR3C2 gene) mRNA in P1 MUN offspring (both genders), with no changes in glucocorticoid receptor (GCR). Quantitative immunohistochemical analysis confirmed the PCR data for GCR and MCR in P1 offspring and demonstrated lower expression of leptin receptor protein (Ob-Ra/Ob-Rb) and mRNA in P1 MUN offspring. In 9-month adult male MUN offspring, the expression of HSD1, CYP11A1, CYP11B2, Ob-Ra/Ob-Rb, and GCR mRNA were significantly upregulated with a trend toward an increase in ACTH-R and a decrease in 17 alpha-hydroxylase (CYP17A1) expression. In adult female MUN offspring, similar to males, the expression of CYP11A1, ACTH-R, and Ob-Rb mRNA were increased, whereas GCR and CYP17A1 mRNA were decreased. These results indicate that the adrenal gland is a target of nutritional programming. In utero undernutrition has a global suppressive effect on maternal and P1 offspring adrenal steroidogenic enzymes in association with reduced circulating corticosterone levels in P1 offspring, which may be secondary to a negative feedback from elevated maternal GC levels and or leptin levels in MUN dams. Gender-specific differences in steroidogenic enzyme expression were found in adult MUN offspring. The common finding of increased ACTH receptor expression in MUN adults of both genders suggests an increased sensitivity of these offspring to stress.

Is there any relationship between imatinib mesylate medication and hypothalamic-pituitary-adrenal axis dysfunction?

BACKGROUND

Imatinib mesylate [tyrosine kinase (TK) inhibitor] is a novel medication in the treatment of chronic myelogenous leukaemia (CML). TK is also essential in hypothalamo-pituitary-adrenal (HPA) axis.

PURPOSE

The aim of this study was to evaluate HPA axis in patients treated with imatinib. Twenty-five patients were included in this study.

METHODS

Glucagon stimulation test (GST) and low-dose (1 microg) adrenocorticotropin test (LDSST) were used to assess the HPA gland axis.

RESULTS

Seventeen (68%) subjects had impaired peak response when a cortisol cut-off value is accepted as 500 nmol/L. Twelve (48%) out of 17 subjects also failed to show a response to LDSST. Therefore, 12 patients (48%) were defined as HPA deficient. Only two of these 25 patients had morning serum cortisol < 200 nmol/l (7.22 microg/dl), and failed the GST and/or LDSST, indicating that the majority had partial glucocorticoid deficiency. If the cut-off presume for LDSST is from 500 to 600 nmol/l, 16 patients (64%) would have failed both the GST and LDSST.

CONCLUSION

Our results indicate an increased prevalence of subclinical glucocorticoid deficiency in patients receiving imatinib mesylate for CML. Therefore under stressed conditions, such as intercurrent illness state, overt and untreated partial glucocorticoid deficiency in CML patients become life threatening.

Subclinical hypercortisolism among polycythemia vera patients

BACKGROUND

JAK2V617F, a somatic gain-of-function mutation involving the JAK2 tyrosine kinase gene, occurs in nearly all patients with polycythemia vera (PV). JAK2 is also essential in hypothalamo-pituitary-adrenal (HPA) axis system which is known to play a role in subsequent steroid secretion. The purpose of this study was to determine whether or not PV induces subclinical hypercortisolism (SH).

DESIGN

Cross-sectional study. In order to compare the prevalence of SH in PV and matched control individuals, we performed a case-controlled study, enrolling 31 PV and 20 age- and body mass index-matched patients.

METHODS AND RESULTS

Adrenal endocrine function was assessed in a cohort of 31 patients with PV. Baseline serum cortisol levels and 2-day 2 mg DST (dexamethasone suppression test, 0.5 mg dexamethasone orally every 6 hours for two days) showed a trend for higher serum cortisol levels in PV patients than in control subjects. Among the 31 patients, 6 had biological abnormality of the hypothalamic-pituitary-adrenal axis and were diagnosed as subclinical hypercortisolism. None of the subjects in the control group exhibited cortisol responses to DST higher than 50 nmol/L.

DISCUSSION

In conclusion, a relatively high prevalence of hypercortisolism was found in PV patients. As these observations were in a small cohort of PV, further studies are needed to evaluate HPA axis in PV patients.

Administration of human leptin differentially affects parameters of cortisol secretion in socially housed female rhesus monkeys

Chronic exposure to psychosocial stress may lead to a dysregulation of the limbic-hypothalamic-pituitary-adrenal axis that results in a number of adverse health outcomes. The fat-derived hormone leptin has been indicated as a potential key component to maintaining homeostasis by enhancing glucocorticoid negative feedback. Using an established model of nonhuman primate social stress, notably social subordination, this study examined the effects of continuous leptin administration on cortisol secretion in female rhesus monkeys. The 20 subjects were maintained in stable five-member social groups with established dominance hierarchies. All females were ovariectomized but received estradiol throughout the study to maintain serum concentrations at early follicular phase levels. Three parameters of cortisol secretion were examined in dominant and subordinate females during control and leptin-treatment conditions: diurnal cortisol secretion; response to a dexamethasone suppression test; and response to a brief separation from their social group. We hypothesized that leptin supplementation would attenuate the hypercortisolemia characteristic of subordinate females. During baseline conditions, subordinate female rhesus monkeys had significantly lower levels of serum leptin compared with more dominant monkeys and were less sensitive to glucocorticoid negative feedback. Exogenous administration of leptin improved glucocorticoid negative feedback in subordinate females and decreased morning cortisol in all animals. However, there were no status differences in response to a social separation test and diurnal rhythm in cortisol during baseline conditions. However, leptin administration did not attenuate the increase in cortisol in response to a social separation. The data presented in this study demonstrate that leptin can attenuate several parameters of cortisol secretion in female rhesus monkeys and thus may play a role in the response of the adrenal glands to socio-environmental stimuli.

Aldo keto reductase 1B7 and prostaglandin F2alpha are regulators of adrenal endocrine functions

Prostaglandin F_2α (PGF_2α), represses ovarian steroidogenesis and initiates parturition in mammals but its impact on adrenal gland is unknown. Prostaglandins biosynthesis depends on the sequential action of upstream cyclooxygenases (COX) and terminal synthases but no PGF_2α synthases (PGFS) were functionally identified in mammalian cells. In vitro, the most efficient mammalian PGFS belong to aldo-keto reductase 1B (AKR1B) family. The adrenal gland is a major site of AKR1B expression in both human (AKR1B1) and mouse (AKR1B3, AKR1B7). Thus, we examined the PGF_2α biosynthetic pathway and its functional impact on both cortical and medullary zones. Both compartments produced PGF_2α but expressed different biosynthetic isozymes. In chromaffin cells, PGF_2α secretion appeared constitutive and correlated to continuous expression of COX1 and AKR1B3. In steroidogenic cells, PGF_2α secretion was stimulated by adrenocorticotropic hormone (ACTH) and correlated to ACTH-responsiveness of both COX2 and AKR1B7/B1. The pivotal role of AKR1B7 in ACTH-induced PGF_2α release and functional coupling with COX2 was demonstrated using over- and down-expression in cell lines. PGF_2α receptor was only detected in chromaffin cells, making medulla the primary target of PGF_2α action. By comparing PGF_2α-responsiveness of isolated cells and whole adrenal cultures, we demonstrated that PGF_2α repressed glucocorticoid secretion by an indirect mechanism involving a decrease in catecholamine release which in turn decreased adrenal steroidogenesis. PGF_2α may be regarded as a negative autocrine/paracrine regulator within a novel intra-adrenal feedback loop. The coordinated cell-specific regulation of COX2 and AKR1B7 ensures the generation of this stress-induced corticostatic signal.

In polycystic ovary syndrome, adrenal steroids are regulated differently in the morning versus in response to nutrient intake

OBJECTIVE

To investigate adrenal steroid regulation in polycystic ovary syndrome.

DESIGN

Five-hour oral glucose tolerance test (OGTT) and frequently sampled-intravenous gluclose tolerance test.

SETTING

University research center.

PATIENT(S)

Thirty patients.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Anthropometrics, leptin, cortisol, DHEAS, glucose, insulin.

RESULT(S)

Morning cortisol correlated with sensitivity index (SI, r = .540), DHEAS correlated inversely with age (r = -.6359), body mass index (BMI, r = -.6199), fat mass (r = -0.630), and leptin (r = -0.5676). Between the second and fourth hour of OGTT, cortisol changes (Delta) exhibited three patterns: I, responders (n = 9, Delta: 10.7 +/- 1.0 microg/dL); II, nonresponders (n = 10, Delta: -3.5 +/- 0.6 microg/dL); III, intermediates (n = 11, Delta: 4.3 +/- 1.0 microg/dL). Compared with nonresponders, responders were more obese (BMI: 37.0 +/- 1.6 vs. 31.7 +/- 1.8 kg/m(2)); had higher leptin (28.9 +/- 1.7 vs. 24.1 +/- 1.1 ng/mL), and lower DHEAS (133 +/- 12 vs. 236 +/- 32 ng/mL), higher glucose at 1 h of OGTT (195 +/- 13 vs. 131 +/- 12 mg/dL), higher area under the curve (AUC)(Glucose) (332 +/- 20 vs. 265 +/- 17 mg/dL), higher AUC(Insulin) (244 +/- 50 vs. 125 +/- 30 muU/mL), and lower nadir glucose (61 +/- 2 vs. 70 +/- 2 mg/dL).

CONCLUSION(S)

Obesity and insulin resistance are associated with lower morning cortisol and DHEAS but increased cortisol and DHEA responses after glucose ingestion. Morning steroid levels may not reflect the day-long exposure.

A cAMP-specific phosphodiesterase (PDE8B) that is mutated in adrenal hyperplasia is expressed widely in human and mouse tissues: a novel PDE8B isoform in human adrenal cortex

Bilateral adrenocortical hyperplasia (BAH) is the second most common cause of corticotropin-independent Cushing syndrome (CS). Genetic forms of BAH have been associated with complex syndromes such as Carney Complex and McCune-Albright syndrome or may present as isolated micronodular adrenocortical disease (iMAD) usually in children and young adults with CS. A genome-wide association study identified inactivating phosphodiesterase (PDE) 11A (PDE11A)-sequencing defects as low-penetrance predisposing factors for iMAD and related abnormalities; we also described a mutation (c.914A > C/H305P) in cyclic AMP (cAMP)-specific PDE8B, in a patient with iMAD. In this study we further characterize this mutation; we also found a novel PDE8B isoform that is highly expressed in the adrenal gland. This mutation is shown to significantly affect the ability of the protein to degrade cAMP in vitro. Tumor tissues from patients with iMAD and no mutations in the coding PDE8B sequence or any other related genes (PRKAR1A, PDE11A) showed downregulated PDE8B expression (compared to normal adrenal cortex). Pde8b is detectable in the adrenal gland of newborn mice and is widely expressed in other mouse tissues. We conclude that PDE8B is another PDE gene linked to iMAD; it is a candidate causative gene for other adrenocortical lesions linked to the cAMP signaling pathway and possibly for tumors in other tissues.

Leptin inhibits 4-aminopyridine- and pentylenetetrazole-induced seizures and AMPAR-mediated synaptic transmission in rodents

Leptin is a hormone that reduces excitability in some hypothalamic neurons via leptin receptor activation of the JAK2 and PI3K intracellular signaling pathways. We hypothesized that leptin receptor activation in other neuronal subtypes would have anticonvulsant activity and that intranasal leptin delivery would be an effective route of administration. We tested leptin's anticonvulsant action in 2 rodent seizure models by directly injecting it into the cortex or by administering it intranasally. Focal seizures in rats were induced by neocortical injections of 4-aminopyridine, an inhibitor of voltage-gated K+ channels. These seizures were briefer and less frequent upon coinjection of 4-aminopyridine and leptin. In mice, intranasal administration of leptin produced elevated brain and serum leptin levels and delayed the onset of chemical convulsant pentylenetetrazole-induced generalized convulsive seizures. Leptin also reduced neuronal spiking in an in vitro seizure model. Leptin inhibited alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) receptor-mediated synaptic transmission in mouse hippocampal slices but failed to inhibit synaptic responses in slices from leptin receptor-deficient db/db mice. JAK2 and PI3K antagonists prevented leptin inhibition of AMPAergic synaptic transmission. We conclude that leptin receptor activation and JAK2/PI3K signaling may be novel targets for anticonvulsant treatments. Intranasal leptin administration may have potential as an acute abortive treatment for convulsive seizures in emergency situations.

Renal net acid excretion and plasma leptin are associated with potentially bioactive free glucocorticoids in healthy lean women

Primarily experimental evidence suggests that endogenous glucocorticoids may be suppressed by adipocyte-derived leptin and elevated by dietary acidity. Therefore, we examined whether these factors may also be relevant in healthy adults on unrestricted diets. For this we used a new methodological approach in which potentially bioactive free glucocorticoids were determined as the sum of urinary free cortisol and urinary free cortisone and that also takes into account total adrenal glucocorticoid secretion assessed by the sum of the 3 major urinary glucocorticoid metabolites tetrahydrocortisone, tetrahydrocortisol, and 5alpha-tetrahydrocortisol. Body composition, plasma cortisol, plasma leptin, and 24-h urinary excretion rates of net acid and glucocorticoid metabolites were examined cross-sectionally in 30 healthy adults (15 women; 22-44 y old; BMI 20-25 kg/m2). Plasma leptin, percentage body fat, and body surface area-corrected adrenal glucocorticoid secretion showed the usual sex dimorphism (male vs. female, P < 0.05 in each case: 2.8 +/- 1.6 microg/L vs. 7.6 +/- 4.9 microg/L, 16.8 +/- 4.2% vs. 26.9 +/- 4.9%, and 5.1 +/- 1.6 mg x m(-2) x d(-1) vs. 4.0 +/- 1.3 mg x m(-2) x d(-1), respectively), whereas net acid excretion, plasma cortisol, and potentially bioactive free glucocorticoids did not differ between the sexes. Potentially bioactive free glucocorticoids correlated positively with body fat and leptin in men (P < 0.05) but not in women. After adjustment for total adrenal glucocorticoid secretion, net acid excretion was a positive and leptin a negative predictor (P < 0.05) of potentially bioactive free glucocorticoids in women only (total explained variability R2 = 0.71). Our findings indicate that, at least in women, variability of potentially bioactive free glucocorticoids is not only explained by adrenal glucocorticoid secretion but is also metabolically affected by circulating leptin and diet-dependent net acid excretion.

The roles of serum leptin concentration and polymorphism in leptin receptor gene at codon 109 in breast cancer

AIMS

We investigated the relationship between serum leptin concentrations and polymorphism of the leptin receptor gene and breast cancer.

METHODS

Serum leptin concentrations were measured by enzyme-linked immunosorbent assay in 47 women with invasive breast cancer compared with 41 age-matched controls without cancer. Genomic DNA was extracted from peripheral blood leukocytes. Genotyping of the leptin receptor gene at codon 109 (LEPR-109) was performed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Patients with breast cancer had a higher mean serum leptin concentration than women in the control group, but the difference was not statistically significant. Among those with breast cancer, the serum leptin concentration was higher in women with high-grade cancers (p = 0.020). The LEPR-109RR genotype was more frequent in premenopausal patients with tumors larger than 2 cm (p = 0.039) and in premenopausal women who were overweight (p = 0.029). Among patients with the LEPR-109RR genotype, higher mean serum leptin concentrations were present in those with triple-negative cancers (p = 0.048).

CONCLUSIONS

Our study suggests an association between serum leptin concentration and tumor progression. LEPR-109 polymorphism in premenopausal women appears to be associated with obesity and tumor progression.

Transcriptional regulation of human CYP11A1 in gonads and adrenals

The CYP11A1 gene encodes the cholesterol side-chain cleavage enzyme, also termed cytochrome P450scc, which catalyzes the conversion of cholesterol to pregnenolone in the first step of steroid biosynthesis in mitochondria. The adrenal- and gonad-selective, hormonally and developmentally regulated expression of CYP11A1 is principally driven by its 2.3 kb promoter. Multiple trans-acting factors like SF-1, Sp1, AP-2, TReP-132, LBP-1b, LBP-9, AP-1, NF-1, and Ets control CYP11A1 transcription either through DNA-protein interaction with their specific cis-acting elements or through protein-protein interaction between each other, wherein SF-1 plays a central role in adrenals and testes. In addition to binding with its proximal and upstream motifs, SF-1 also physically interacts with TFIIB, CBP/p300, TReP-132, and c-Jun/AP-1 to specifically transmit the regulatory signals of cAMP. Other factors like Sp1 family members, AP-2, and LBP-1b/LBP-9 may be other factors that play a role in CYP11A1 transcription, particularly in placental cells. The TATA sequence could also contribute to tissue-specificity and hormonal regulation of CYP11A1 transcription. This article reviews recent studies focusing on adrenals and gonads.