NRF2 is required for neonatal mouse beta cell growth by maintaining redox balance and promoting mitochondrial biogenesis and function

AIMS/HYPOTHESIS

All forms of diabetes result from insufficient functional beta cell mass. Due to the relatively limited expression of several antioxidant enzymes, beta cells are highly vulnerable to pathological levels of reactive oxygen species (ROS), which can lead to the reduction of functional beta cell mass. During early postnatal ages, both human and rodent beta cells go through a burst of proliferation that quickly declines with age. The exact mechanisms that account for neonatal beta cell proliferation are understudied but mitochondrial release of moderated ROS levels has been suggested as one of the main drivers. We previously showed that, apart from its conventional role in protecting beta cells from oxidative stress, the nuclear factor erythroid 2-related factor 2 (NRF2) is also essential for beta cell proliferation. We therefore hypothesised that NRF2, which is activated by ROS, plays an essential role in beta cell proliferation at early postnatal ages.

METHODS

Beta cell NRF2 levels and beta cell proliferation were measured in pancreatic sections from non-diabetic human cadaveric donors at different postnatal ages, childhood and adulthood. Pancreatic sections from 1-, 7-, 14- and 28-day-old beta cell-specific Nrf2 (also known as Nfe2l2)-knockout mice (βNrf2KO) or control (Nrf2lox/lox) mice were assessed for beta cell NRF2 levels, beta cell proliferation, beta cell oxidative stress, beta cell death, nuclear beta cell pancreatic duodenal homeobox protein 1 (PDX1) levels and beta cell mass. Seven-day-old βNrf2KO and Nrf2lox/lox mice were injected daily with N-acetylcysteine (NAC) or saline (154 mmol/l NaCl) to explore the potential contribution of oxidative stress to the phenotypes seen in βNrf2KO mice at early postnatal ages. RNA-seq was performed on 7-day-old βNrf2KO and Nrf2lox/lox mice to investigate the mechanisms by which NRF2 stimulates beta cell proliferation at early postnatal ages. Mitochondrial biogenesis and function were determined using dispersed islets from 7-day-old βNrf2KO and Nrf2lox/lox mice by measuring MitoTracker intensity, mtDNA/gDNA ratio and ATP/ADP ratio. To study the effect of neonatal beta cell-specific Nrf2 deletion on glucose homeostasis in adulthood, blood glucose, plasma insulin and insulin secretion were determined and a GTT was performed on 3-month-old βNrf2KO and Nrf2lox/lox mice fed on regular diet (RD) or high-fat diet (HFD).

RESULTS

The expression of the master antioxidant regulator NRF2 was increased at early postnatal ages in both human (1 day to 19 months old, 31%) and mouse (7 days old, 57%) beta cells, and gradually declined with age (8% in adult humans, 3.77% in adult mice). A significant correlation (R2=0.568; p=0.001) was found between beta cell proliferation and NRF2 levels in human beta cells. Seven-day-old βNrf2KO mice showed reduced beta cell proliferation (by 65%), beta cell nuclear PDX1 levels (by 23%) and beta cell mass (by 67%), and increased beta cell oxidative stress (threefold) and beta cell death compared with Nrf2lox/lox control mice. NAC injections increased beta cell proliferation in 7-day-old βNrf2KO mice (3.4-fold) compared with saline-injected βNrf2KO mice. Interestingly, RNA-seq of islets isolated from 7-day-old βNrf2KO mice revealed reduced expression of mitochondrial RNA genes and genes involved in the electron transport chain. Islets isolated from 7-day old βNrf2KO mice presented reduced MitoTracker intensity (by 47%), mtDNA/gDNA ratio (by 75%) and ATP/ADP ratio (by 68%) compared with islets from Nrf2lox/lox littermates. Lastly, HFD-fed 3-month-old βNrf2KO male mice displayed a significant reduction in beta cell mass (by 35%), a mild increase in non-fasting blood glucose (1.2-fold), decreased plasma insulin (by 14%), and reduced glucose tolerance (1.3-fold) compared with HFD-fed Nrf2lox/lox mice.

CONCLUSIONS/INTERPRETATION

Our study highlights NRF2 as an essential transcription factor for maintaining neonatal redox balance, mitochondrial biogenesis and function and beta cell growth, and for preserving functional beta cell mass in adulthood under metabolic stress.

DATA AVAILABILITY

Sequencing data are available in the NCBI Gene Expression Omnibus, accession number GSE242718 ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE242718 ).

Molecular glues of the regulatory ChREBP/14-3-3 complex protect beta cells from glucolipotoxicity

The Carbohydrate Response Element Binding Protein (ChREBP) is a glucose-responsive transcription factor (TF) that is characterized by two major splice isoforms (α and β). In acute hyperglycemia, both ChREBP isoforms regulate adaptive β-expansion; however, during chronic hyperglycemia and glucolipotoxicity, ChREBPβ expression surges, leading to β-cell dedifferentiation and death. 14-3-3 binding to ChREBPα results in its cytoplasmic retention and concomitant suppression of transcriptional activity, suggesting that small molecule-mediated stabilization of this protein-protein interaction (PPI) via molecular glues may represent an attractive entry for the treatment of metabolic disease. Here, we show that structure-based optimizations of a molecular glue tool compound led not only to more potent ChREBPα/14-3-3 PPI stabilizers but also for the first time cellular active compounds. In primary human β-cells, the most active compound stabilized the ChREBPα/14-3-3 interaction and thus induced cytoplasmic retention of ChREBPα, resulting in highly efficient β-cell protection from glucolipotoxicity while maintaining β-cell identity. This study may thus not only provide the basis for the development of a unique class of compounds for the treatment of Type 2 Diabetes but also showcases an alternative 'molecular glue' approach for achieving small molecule control of notoriously difficult targetable TFs.

Transcriptional activation of the Myc gene by glucose in β-cells requires a ChREBP-dependent 3-D chromatin interaction between the Myc and Pvt1 genes

OBJECTIVE

All forms of diabetes result from insufficient functional β-cell mass. Thus, achieving the therapeutic goal of expanding β-cell mass requires a better mechanistic understanding of how β-cells proliferate. Glucose is a natural β-cell mitogen that mediates its effects in part through the glucose-responsive transcription factor, carbohydrate response element binding protein (ChREBP) and the anabolic transcription factor, MYC. However, mechanistic details by which glucose activates Myc at the transcriptional level are poorly understood.

METHODS

Here, siRNA was used to test the role of ChREBP in the glucose response of MYC, ChIP and ChIPseq to identify potential regulatory binding sites, chromatin conformation capture to identify DNA/DNA interactions, and an adenovirus was constructed to expresses x-dCas9 and an sgRNA that specifically disrupts the recruitment of ChREBP to a specific targeted ChoRE.

RESULTS

We found that ChREBP is essential for glucose-mediated transcriptional induction of Myc, and for increases in Myc mRNA and protein abundance. Further, ChIPseq revealed that the carbohydrate response element (ChoRE) nearest to the Myc transcriptional start site (TSS) is immediately upstream of the gene encoding the lncRNA, Pvt1, 60,000 bp downstream of the Myc gene. Chromatin Conformation Capture (3C) confirmed a glucose-dependent interaction between these two sites. Transduction with an adenovirus expressing x-dCas9 and an sgRNA specifically targeting the highly conserved Pvt1 ChoRE, attenuates ChREBP recruitment, decreases Myc-Pvt1 DNA/DNA interaction, and decreases expression of the Pvt1 and Myc genes in response to glucose. Importantly, isolated and dispersed rat islet cells transduced with the ChoRE-disrupting adenovirus also display specific decreases in ChREBP-dependent, glucose-mediated expression of Pvt1 and Myc, as well as decreased glucose-stimulated β-cell proliferation.

CONCLUSIONS

The mitogenic glucose response of Myc is mediated via glucose-dependent recruitment of ChREBP to the promoter of the Pvt1 gene and subsequent DNA looping with the Myc promoter.

Does Iodine Intake Modify the Effect of Maternal Dysglycemia on Birth Weight in Mild-to-Moderate Iodine-Deficient Populations? A Mother-Newborn Prospective Cohort Study

It is unclear how maternal glycemic status and maternal iodine status influence birth weight among individuals with mild-to-moderate iodine deficiency (ID). We studied the association between birth weight and both maternal glucose levels and iodine intake among pregnant women with mild-to-moderate ID. Glucose values were assessed using a glucose challenge test (GCT) and non-fasting glucose levels that were determined before delivery; individuals' iodine statuses were assessed using an iodine food frequency questionnaire; and serum thyroglobulin (Tg) and urinary iodine concentrations (UIC) were used to assess each group's iodine status. Thyroid antibodies and free thyroxine (FT4) levels were measured. Obstetric and anthropometric data were also collected. Large-for-gestational age (LGA) status was predicted using a Cox proportional hazards model with multiple confounders. Tg > 13 g/L was independently associated with LGA (adjusted hazard ratio = 3.4, 95% CI: 1.4-10.2, p = 0.001). Estimated iodine intake correlated with FT4 among participants who reported consuming iodine-containing supplements (ICS) after adjusting for confounders (β = 0.4, 95% CI: 0.0002-0.0008, p = 0.001). Newborn weight percentiles were inversely correlated with maternal FT4 values (β = -0.2 95% CI:-0.08--56.49, p = 0.049). We conclude that in mild-to-moderate ID regions, insufficient maternal iodine status may increase LGA risk. Iodine status and ICS intake may modify the effect that maternal dysglycemia has on offspring weight.

T3 and glucose increase expression of phosphoenolpyruvate carboxykinase (PCK1) leading to increased β-cell proliferation

OBJECTIVES

Thyroid hormone (T3) and high glucose concentrations are critical components of β-cell maturation and function. In the present study, we asked whether T3 and glucose signaling pathways coordinately regulate transcription of genes important for β-cell function and proliferation.

METHODS

RNA-seq analysis was performed on cadaveric human islets from five different donors in response to low and high glucose concentrations and in the presence or absence of T3. Gene expression was also studies in sorted human β-cells, mouse islets and Ins-1 cells by RT-qPCR. Silencing of the thyroid hormone receptors (THR) was conducted using lentiviruses. Proliferation was assessed by ki67 immunostaining in primary human/mouse islets. Chromatin immunoprecipitation and proximity ligation assay were preformed to validate interactions of ChREBP and THR.

RESULTS

We found glucose-mediated expression of carbohydrate response element binding protein alpha and beta (ChREBPα and ChREBPβ) mRNAs and their target genes are highly dependent on T3 concentrations in rodent and human β-cells. In β-cells, T3 and glucose coordinately regulate the expression of ChREBPβ and PCK1 (phosphoenolpyruvate carboxykinase-1) among other important genes for β-cell maturation. Additionally, we show the thyroid hormone receptor (THR) and ChREBP interact, and their relative response elements are located near to each other on mutually responsive genes. In FACS-sorted adult human β-cells, we found that high concentrations of glucose and T3 induced the expression of PCK1. Next, we show that overexpression of Pck1 together with dimethyl malate (DMM), a substrate precursor, significantly increased β-cell proliferation in human islets. Finally, using a Cre-Lox approach, we demonstrated that ChREBPβ contributes to Pck1-dependent β-cell proliferation in mouse β-cells.

CONCLUSIONS

We conclude that T3 and glucose act together to regulate ChREBPβ, leading to increased expression and activity of Pck1, and ultimately increased β-cell proliferation.

Maladaptive positive feedback production of ChREBPβ underlies glucotoxic β-cell failure

Preservation and expansion of β-cell mass is a therapeutic goal for diabetes. Here we show that the hyperactive isoform of carbohydrate response-element binding protein (ChREBPβ) is a nuclear effector of hyperglycemic stress occurring in β-cells in response to prolonged glucose exposure, high-fat diet, and diabetes. We show that transient positive feedback induction of ChREBPβ is necessary for adaptive β-cell expansion in response to metabolic challenges. Conversely, chronic excessive β-cell-specific overexpression of ChREBPβ results in loss of β-cell identity, apoptosis, loss of β-cell mass, and diabetes. Furthermore, β-cell "glucolipotoxicity" can be prevented by deletion of ChREBPβ. Moreover, ChREBPβ-mediated cell death is mitigated by overexpression of the alternate CHREBP gene product, ChREBPα, or by activation of the antioxidant Nrf2 pathway in rodent and human β-cells. We conclude that ChREBPβ, whether adaptive or maladaptive, is an important determinant of β-cell fate and a potential target for the preservation of β-cell mass in diabetes.

Nrf2 Regulates β-Cell Mass by Suppressing β-Cell Death and Promoting β-Cell Proliferation

Finding therapies that can protect and expand functional β-cell mass is a major goal of diabetes research. Here, we generated β-cell-specific conditional knockout and gain-of-function mouse models and used human islet transplant experiments to examine how manipulating Nrf2 levels affects β-cell survival, proliferation, and mass. Depletion of Nrf2 in β-cells results in decreased glucose-stimulated β-cell proliferation ex vivo and decreased adaptive β-cell proliferation and β-cell mass expansion after a high-fat diet in vivo. Nrf2 protects β-cells from apoptosis after a high-fat diet. Nrf2 loss of function decreases Pdx1 abundance and insulin content. Activating Nrf2 in a β-cell-specific manner increases β-cell proliferation and mass and improves glucose tolerance. Human islets transplanted under the kidney capsule of immunocompromised mice and treated systemically with bardoxolone methyl, an Nrf2 activator, display increased β-cell proliferation. Thus, by managing reactive oxygen species levels, Nrf2 regulates β-cell mass and is an exciting therapeutic target for expanding and protecting β-cell mass in diabetes.

Pharmacological blockade of the EP3 prostaglandin E2 receptor in the setting of type 2 diabetes enhances β-cell proliferation and identity and relieves oxidative damage

OBJECTIVE

Type 2 diabetes is characterized by hyperglycemia and inflammation. Prostaglandin E2, which signals through four G protein-coupled receptors (EP1-4), is a mediator of inflammation and is upregulated in diabetes. We have shown previously that EP3 receptor blockade promotes β-cell proliferation and survival in isolated mouse and human islets ex vivo. Here, we analyzed whether systemic EP3 blockade could enhance β-cell mass and identity in the setting of type 2 diabetes using mice with a spontaneous mutation in the leptin receptor (Leprdb).

METHODS

Four- or six-week-old, db/+, and db/db male mice were treated with an EP3 antagonist daily for two weeks. Pancreata were analyzed for α-cell and β-cell proliferation and β-cell mass. Islets were isolated for transcriptomic analysis. Selected gene expression changes were validated by immunolabeling of the pancreatic tissue sections.

RESULTS

EP3 blockade increased β-cell mass in db/db mice through enhanced β-cell proliferation. Importantly, there were no effects on α-cell proliferation. EP3 blockade reversed the changes in islet gene expression associated with the db/db phenotype and restored the islet architecture. Expression of the GLP-1 receptor was slightly increased by EP3 antagonist treatment in db/db mice. In addition, the transcription factor nuclear factor E2-related factor 2 (Nrf2) and downstream targets were increased in islets from db/db mice in response to treatment with an EP3 antagonist. The markers of oxidative stress were decreased.

CONCLUSIONS

The current study suggests that EP3 blockade promotes β-cell mass expansion in db/db mice. The beneficial effects of EP3 blockade may be mediated through Nrf2, which has recently emerged as a key mediator in the protection against cellular oxidative damage.

Nrf2: The Master and Captain of Beta Cell Fate

Prolonged hyperglycemia is toxic to pancreatic β cells, generating excessive reactive oxygen species, defective glucose-stimulated insulin secretion, decreased insulin production, and eventually β cell death and diabetes. Nrf2 is a master regulator of cellular responses to counteract dangerous levels of oxidative stress. Maintenance of β cell mass depends on Nrf2 to promote the survival, function, and proliferation of β cells. Indeed, Nrf2 activation decreases inflammation, increases insulin sensitivity, reduces body weight, and preserves β cell mass. Therefore, numerous pharmacological activators of Nrf2 are being tested in clinical trials for the treatment of diabetes and diabetic complications. Modulating Nrf2 activity in β cells is a promising therapeutic approach for the treatment of diabetes.

The many lives of Myc in the pancreatic β-cell

Diabetes results from insufficient numbers of functional pancreatic β-cells. Thus, increasing the number of available functional β-cells ex vivo for transplantation, or regenerating them in situ in diabetic patients, is a major focus of diabetes research. The transcription factor, Myc, discovered decades ago lies at the nexus of most, if not all, known proliferative pathways. Based on this, many studies in the 1990s and early 2000s explored the potential of harnessing Myc expression to expand β-cells for diabetes treatment. Nearly all these studies in β-cells used pathophysiological or supraphysiological levels of Myc and reported enhanced β-cell death, dedifferentiation, or the formation of insulinomas if cooverexpressed with Bcl-xL, an inhibitor of apoptosis. This obviously reduced the enthusiasm for Myc as a therapeutic target for β-cell regeneration. However, recent studies indicate that "gentle" induction of Myc expression enhances β-cell replication without induction of cell death or loss of insulin secretion, suggesting that appropriate levels of Myc could have therapeutic potential for β-cell regeneration. Furthermore, although it has been known for decades that Myc is induced by glucose in β-cells, very little is known about how this essential anabolic transcription factor perceives and responds to nutrients and increased insulin demand in vivo. Here we summarize the previous and recent knowledge of Myc in the β-cell, its potential for β-cell regeneration, and its physiological importance for neonatal and adaptive β-cell expansion.

HB-EGF Signaling Is Required for Glucose-Induced Pancreatic β-Cell Proliferation in Rats

The molecular mechanisms of β-cell compensation to metabolic stress are poorly understood. We previously observed that nutrient-induced β-cell proliferation in rats is dependent on epidermal growth factor receptor (EGFR) signaling. The aim of this study was to determine the role of the EGFR ligand heparin-binding EGF-like growth factor (HB-EGF) in the β-cell proliferative response to glucose, a β-cell mitogen and key regulator of β-cell mass in response to increased insulin demand. We show that exposure of isolated rat and human islets to HB-EGF stimulates β-cell proliferation. In rat islets, inhibition of EGFR or HB-EGF blocks the proliferative response not only to HB-EGF but also to glucose. Furthermore, knockdown of HB-EGF in rat islets blocks β-cell proliferation in response to glucose ex vivo and in vivo in transplanted glucose-infused rats. Mechanistically, we demonstrate that HB-EGF mRNA levels are increased in β-cells in response to glucose in a carbohydrate-response element-binding protein (ChREBP)-dependent manner. In addition, chromatin immunoprecipitation studies identified ChREBP binding sites in proximity to the HB-EGF gene. Finally, inhibition of Src family kinases, known to be involved in HB-EGF processing, abrogated glucose-induced β-cell proliferation. Our findings identify a novel glucose/HB-EGF/EGFR axis implicated in β-cell compensation to increased metabolic demand.

Myc Is Required for Adaptive β-Cell Replication in Young Mice but Is Not Sufficient in One-Year-Old Mice Fed With a High-Fat Diet

Failure to expand pancreatic β-cells in response to metabolic stress leads to excessive workload resulting in β-cell dysfunction, dedifferentiation, death, and development of type 2 diabetes. In this study, we demonstrate that induction of Myc is required for increased pancreatic β-cell replication and expansion during metabolic stress-induced insulin resistance with short-term high-fat diet (HFD) in young mice. β-Cell-specific Myc knockout mice fail to expand adaptively and show impaired glucose tolerance and β-cell dysfunction. Mechanistically, PKCζ, ERK1/2, mTOR, and PP2A are key regulators of the Myc response in this setting. DNA methylation analysis shows hypomethylation of cell cycle genes that are Myc targets in islets from young mice fed with a short-term HFD. Importantly, DNA hypomethylation of Myc response elements does not occur in islets from 1-year-old mice fed with a short-term HFD, impairing both Myc recruitment to cell cycle regulatory genes and β-cell replication. We conclude that Myc is required for metabolic stress-mediated β-cell expansion in young mice, but with aging, Myc upregulation is not sufficient to induce β-cell replication by, at least partially, an epigenetically mediated resistance to Myc action.

Activation of Nrf2 Is Required for Normal and ChREBPα-Augmented Glucose-Stimulated β-Cell Proliferation

Patients with both major forms of diabetes would benefit from therapies that increase β-cell mass. Glucose, a natural mitogen, drives adaptive expansion of β-cell mass by promoting β-cell proliferation. We previously demonstrated that a carbohydrate response element-binding protein (ChREBPα) is required for glucose-stimulated β-cell proliferation and that overexpression of ChREBPα amplifies the proliferative effect of glucose. Here we found that ChREBPα reprogrammed anabolic metabolism to promote proliferation. ChREBPα increased mitochondrial biogenesis, oxygen consumption rates, and ATP production. Proliferation augmentation by ChREBPα required the presence of ChREBPβ. ChREBPα increased the expression and activity of Nrf2, initiating antioxidant and mitochondrial biogenic programs. The induction of Nrf2 was required for ChREBPα-mediated mitochondrial biogenesis and for glucose-stimulated and ChREBPα-augmented β-cell proliferation. Overexpression of Nrf2 was sufficient to drive human β-cell proliferation in vitro; this confirms the importance of this pathway. Our results reveal a novel pathway necessary for β-cell proliferation that may be exploited for therapeutic β-cell regeneration.

T3 and Glucose Coordinately Stimulate ChREBP-Mediated Ucp1 Expression in Brown Adipocytes From Male Mice

Increasing brown adipose tissue (BAT) activity is regarded as a potential treatment of obese, hyperglycemic patients with metabolic syndrome. Triiodothyronine (T3) is known to stimulate BAT activity by increasing mitochondrial uncoupling protein 1 (Ucp1) gene transcription, leading to increased thermogenesis and decreased body weight. Here we report our studies on the effects of T3 and glucose in two mouse models and in mouse immortalized brown preadipocytes in culture. We identified carbohydrate response element binding protein (ChREBP) as a T3 target gene in BAT by RNA sequencing and studied its effects in brown adipocytes. We found that ChREBP was upregulated by T3 in BAT in both hyperglycemic mouse models. In brown preadipocytes, T3 and glucose synergistically and dose dependently upregulated Ucp1 messenger RNA 1000-fold compared with low glucose concentrations. Additionally, we observed increased ChREBP and Ucp1 protein 11.7- and 19.9-fold, respectively, along with concomitant induction of a hypermetabolic state. Moreover, downregulation of ChREBP inhibited T3 and glucose upregulation of Ucp1 100-fold, whereas overexpression of ChREBP upregulated Ucp1 5.2-fold. We conclude that T3 and glucose signaling pathways coordinately regulate the metabolic state of BAT and suggest that ChREBP is a target for therapeutic regulation of BAT activity.

MPI depletion enhances O-GlcNAcylation of p53 and suppresses the Warburg effect

Rapid cellular proliferation in early development and cancer depends on glucose metabolism to fuel macromolecule biosynthesis. Metabolic enzymes are presumed regulators of this glycolysis-driven metabolic program, known as the Warburg effect; however, few have been identified. We uncover a previously unappreciated role for Mannose phosphate isomerase (MPI) as a metabolic enzyme required to maintain Warburg metabolism in zebrafish embryos and in both primary and malignant mammalian cells. The functional consequences of MPI loss are striking: glycolysis is blocked and cells die. These phenotypes are caused by induction of p53 and accumulation of the glycolytic intermediate fructose 6-phosphate, leading to engagement of the hexosamine biosynthetic pathway (HBP), increased O-GlcNAcylation, and p53 stabilization. Inhibiting the HBP through genetic and chemical methods reverses p53 stabilization and rescues the Mpi-deficient phenotype. This work provides mechanistic evidence by which MPI loss induces p53, and identifies MPI as a novel regulator of p53 and Warburg metabolism.

DOI:http://dx.doi.org/10.7554/eLife.22477.001

DNA methylation alters transcriptional rates of differentially expressed genes and contributes to pathophysiology in mice fed a high fat diet

OBJECTIVE

Overnutrition can alter gene expression patterns through epigenetic mechanisms that may persist through generations. However, it is less clear if overnutrition, for example a high fat diet, modifies epigenetic control of gene expression in adults, or by what molecular mechanisms, or if such mechanisms contribute to the pathology of the metabolic syndrome. Here we test the hypothesis that a high fat diet alters hepatic DNA methylation, transcription and gene expression patterns, and explore the contribution of such changes to the pathophysiology of obesity.

METHODS

RNA-seq and targeted high-throughput bisulfite DNA sequencing were used to undertake a systematic analysis of the hepatic response to a high fat diet. RT-PCR, chromatin immunoprecipitation and in vivo knockdown of an identified driver gene, Phlda1, were used to validate the results.

RESULTS

A high fat diet resulted in the hypermethylation and decreased transcription and expression of Phlda1 and several other genes. A subnetwork of genes associated with Phlda1 was identified from an existing Bayesian gene network that contained numerous hepatic regulatory genes involved in lipid and body weight homeostasis. Hepatic-specific depletion of Phlda1 in mice decreased expression of the genes in the subnetwork, and led to increased oil droplet size in standard chow-fed mice, an early indicator of steatosis, validating the contribution of this gene to the phenotype.

CONCLUSIONS

We conclude that a high fat diet alters the epigenetics and transcriptional activity of key hepatic genes controlling lipid homeostasis, contributing to the pathophysiology of obesity.

Use of Whole Genome Sequencing and Patient Interviews To Link a Case of Sporadic Listeriosis to Consumption of Prepackaged Lettuce

We report on a case of listeriosis in a patient who probably consumed a prepackaged romaine lettuce-containing product recalled for Listeria monocytogenes contamination. Although definitive epidemiological information demonstrating exposure to the specific recalled product was lacking, the patient reported consumption of a prepackaged romaine lettuce-containing product of either the recalled brand or a different brand. A multinational investigation found that patient and food isolates from the recalled product were indistinguishable by pulsed-field gel electrophoresis and were highly related by whole genome sequencing, differing by four alleles by whole genome multilocus sequence typing and by five high-quality single nucleotide polymorphisms, suggesting a common source. To our knowledge, this is the first time prepackaged lettuce has been identified as a likely source for listeriosis. This investigation highlights the power of whole genome sequencing, as well as the continued need for timely and thorough epidemiological exposure data to identify sources of foodborne infections.

Stress-induced activation of brown adipose tissue prevents obesity in conditions of low adaptive thermogenesis

BACKGROUND

Stress-associated conditions such as psychoemotional reactivity and depression have been paradoxically linked to either weight gain or weight loss. This bi-directional effect of stress is not understood at the functional level. Here we tested the hypothesis that pre-stress level of adaptive thermogenesis and brown adipose tissue (BAT) functions explain the vulnerability or resilience to stress-induced obesity.

METHODS

We used wt and triple β1,β2,β3-Adrenergic Receptors knockout (β-less) mice exposed to a model of chronic subordination stress (CSS) at either room temperature (22 °C) or murine thermoneutrality (30 °C). A combined behavioral, physiological, molecular, and immunohistochemical analysis was conducted to determine stress-induced modulation of energy balance and BAT structure and function. Immortalized brown adipocytes were used for in vitro assays.

RESULTS

Departing from our initial observation that βARs are dispensable for cold-induced BAT browning, we demonstrated that under physiological conditions promoting low adaptive thermogenesis and BAT activity (e.g. thermoneutrality or genetic deletion of the βARs), exposure to CSS acted as a stimulus for BAT activation and thermogenesis, resulting in resistance to diet-induced obesity despite the presence of hyperphagia. Conversely, in wt mice acclimatized to room temperature, and therefore characterized by sustained BAT function, exposure to CSS increased vulnerability to obesity. Exposure to CSS enhanced the sympathetic innervation of BAT in wt acclimatized to thermoneutrality and in β-less mice. Despite increased sympathetic innervation suggesting adrenergic-mediated browning, norepinephrine did not promote browning in βARs knockout brown adipocytes, which led us to identify an alternative sympathetic/brown adipocytes purinergic pathway in the BAT. This pathway is downregulated under conditions of low adaptive thermogenesis requirements, is induced by stress, and elicits activation of UCP1 in wt and β-less brown adipocytes. Importantly, this purinergic pathway is conserved in human BAT.

CONCLUSION

Our findings demonstrate that thermogenesis and BAT function are determinant of the resilience or vulnerability to stress-induced obesity. Our data support a model in which adrenergic and purinergic pathways exert complementary/synergistic functions in BAT, thus suggesting an alternative to βARs agonists for the activation of human BAT.

Induction of the ChREBPβ Isoform Is Essential for Glucose-Stimulated β-Cell Proliferation

Carbohydrate-responsive element-binding protein (ChREBP) is a glucose-sensing transcription factor required for glucose-stimulated proliferation of pancreatic β-cells in rodents and humans. The full-length isoform (ChREBPα) has a low glucose inhibitory domain (LID) that restrains the transactivation domain when glucose catabolism is minimal. A novel isoform of ChREBP (ChREBPβ) was recently described that lacks the LID domain and is therefore constitutively and more potently active. ChREBPβ has not been described in β-cells nor has its role in glucose-stimulated proliferation been determined. We found that ChREBPβ is highly expressed in response to glucose, particularly with prolonged culture in hyperglycemic conditions. In addition, small interfering RNAs that knocked down ChREBPβ transcripts without affecting ChREBPα expression or activity decreased glucose-stimulated expression of carbohydrate response element-containing genes and glucose-stimulated proliferation in INS-1 cells and in isolated rat islets. Quantitative chromatin immunoprecipitation, electrophoretic mobility shift assays, and luciferase reporter assays were used to demonstrate that ChREBP binds to a newly identified powerful carbohydrate response element in β-cells and hepatocytes, distinct from that in differentiated 3T3-L1 adipocytes. We conclude that ChREBPβ contributes to glucose-stimulated gene expression and proliferation in β-cells, with recruitment of ChREBPα to tissue-specific elements of the ChREBPβ isoform promoter.

Heritability of fat accumulation in white adipocytes

Since individual cells from freshly isolated white adipose tissue (WAT) exhibit variable levels of fat accumulation, we attempted to determine which factor(s) cause this variation. We used primary WAT cells from adult mice and the mouse 3T3-L1 cell-line of preadipocytes for these studies. Cells were labeled with BODIPY (boron-dipyrromethene) lipid probe, a marker for fat accumulation in live cells, and sorted on a fluorescence-activated cell sorter into two populations exhibiting low or high BODIPY fluorescence intensity. After more than 12 doublings as dedifferentiated cells in growth medium, the sorted populations were exposed to adipogenic medium for 7 days and analyzed for BODIPY accumulation and mRNA expression of adipogenic markers. WAT-derived cells initially sorted to have low or high BODIPY fluorescence intensity maintained a similar low or high lipid phenotype after redifferentiation. Cell surface TSH receptor expression, which is known to increase when preadipocytes are differentiated, correlated with BODIPY staining in all states. mRNA levels of Pparγ, Srebp1c, aP2, and Pref1, key regulators of adipogenesis, and leptin, Glut4, Fasn, and Tshr, markers of adipocyte differentiation, correlated with the levels of fat accumulation. Overexpression of Pparγ in 3T3-L1 cells, as expected, caused cells from low- and high-BODIPY populations to accumulate more fat. More importantly, prior to differentiation, the endogenous Pparγ promoter exhibited higher levels of acetylated histone H3, an activatory modification, in high-BODIPY- compared with low-BODIPY-derived populations. We conclude that fat accumulation is a heritable trait in WAT and that epigenetic modification on the Pparγ promoter contributes to this heritability.

Platelet-derived growth factor BB mimics serum-induced dispersal of pancreatic epithelial cell clusters

We showed previously that proliferating human islet-derived de-differentiated cells (DIDs) exhibit many characteristics of mesenchymal stem cells. Dispersed DIDs can be induced by serum deprivation to undergo mesenchymal-to-epithelial transition and aggregate into epithelial cell clusters (ECCs). Conversely, ECCs can be induced to disperse and undergo epithelial-to-mesenchymal transition (EMT) by re-addition of mammalian sera. In this study, we show that platelet-derived growth factor BB (PDGF-BB) mimics and mediates serum-induced ECCs' dispersal accompanied by accumulation of cytoplasmic β-catenin and a decrease in the levels of insulin and glucagon mRNAs. Moreover, we show that PDGF-BB-induced dispersal of ECCs is a more general phenomenon that occurs also with bone marrow mesenchymal stem cells (BM-MSCs) and dermal fibroblasts (DFs). In DIDs, BM-MSCs, and DFs, PDGF decreased the levels of DKK1 mRNA, suggesting involvement of the Wnt signaling pathway. PDGF-BB stimulated a significant increase in S473 phosphorylation of Akt and the PI3K specific inhibitor (PIP828) partially inhibited PDGF-BB-induced ECC dispersal. Lastly, the PDGF-receptor (PDGF-R) antagonist JNJ-10198409 inhibited both PDGF-BB--and serum-induced ECC dispersal. Epidermal growth factor (EGF), which shares most of the PDGF signaling pathway, did not induce dispersal and only weakly stimulated Akt phosphorylation. Our data suggest that PDGF-BB mediates serum-induced DIDs dispersal, correlated with the activation of the PI3K-Akt pathway.

PAR-3 knockdown enhances adhesion rate of PANC-1 cells via increased expression of integrinαv and E-cadherin

The balance between the adhesion of cancer cells to extracellular matrix and their migratory potential, as well as their proteolytic activity, are important parameters that determine cancer cells invasiveness and metastasis. Since thrombin has been implicated in cancer progression, we studied the role(s) of thrombin-activated receptors in the adhesion process. We stably knocked down proteinase-activated receptors (PARs) -1, or -3 in human pancreatic adenocarcinoma PANC-1 cells. PANC-1 cells exhibit rapid adhesion to cell culture treated plastic and much faster kinetics of adhesion to Matrigel coated surface. Knockdown of PAR-1 had no effect on cells' adhesiveness, while PAR-3 knockdowns (KDs) exhibited much faster adhesion kinetics. PAR-3 KDs also exhibited slower in vitro wound closure than vector-control and PAR-1 KD cells. To study the molecular mechanism(s) of PAR-3 KD cells' enhanced rate of adhesion, we assayed the expression of the molecules that mediate cell-surface and cell-cell adhesion. ITGαv, as well as ITGα6 and ITGα10 mRNAs, were greatly enriched (>40-fold) in a rapidly-adhering sub-population of PAR-3 KD cells. The whole population of both PAR-1 and -3 KDs exhibited enhanced expression of a number of integrins (ITGs) mRNAs. However, ITGαv mRNA and protein expression was increased in PAR-3 KD and markedly decreased in PAR-1 KD. PAR-3 KD cells also expressed more E-cadherin mRNA and protein. The enhanced adhesion kinetics of PAR-3 KDs was almost fully inhibited by calcium chelation, or by a HAV-motive decapeptide that affects E-cadherin intermolecular interactions. We propose that the enhanced rate of adhesion of PAR-3 KDs results from enhanced expression of E-cadherin, leading to a greater adhesion of free-floating cells to cells rapidly bound to the surface via their integrins, and particularly ITGαv.

Reprogramming adult human dermal fibroblasts to islet-like cells by epigenetic modification coupled to transcription factor modulation

In this article, we describe novel conditions for culture, expansion, and transdifferentiation of primary human dermal fibroblasts (hDFs) to induce expression of transcription factors (TFs) and hormones characteristic of the islets of Langerhans. We show that histones associated with the insulin gene are hyperacetylated and that insulin gene DNA is less methylated in islet cells compared to cells that do not express insulin. Using two compounds that alter the epigenetic signature of cells, romidepsin (Romi), a histone deacetylase inhibitor, and 5-Azacytidine (5-AzC), a chemical analogue of cytidine that cannot be methylated, we show that hDFs exhibit a distinctive regulation of expression of TFs involved in islet development as well as of induction of glucagon and insulin. Overexpression of Pdx1, a TF important for islet differentiation, and silencing of musculoaponeurotic fibrosarcoma oncogene homolog B, a TF that is expressed in mature glucagon-producing cells, result in induction of insulin to a higher level compared to Romi and 5-AzC alone. The cells obtained from this protocol exhibit glucose-stimulated insulin secretion and lower blood glucose levels of diabetic mice. These data show that fully differentiated nonislet-derived cells could be made to transdifferentiate to islet-like cells and that combining epigenetic modulation with TF modulation leads to enhanced insulin expression.

Pax6 is crucial for β-cell function, insulin biosynthesis, and glucose-induced insulin secretion

The Pax6 transcription factor is crucial for endocrine cell differentiation and function. Indeed, mutations of Pax6 are associated with a diabetic phenotype and a drastic decrease of insulin-positive cell number. Our aim was to better define the β-cell Pax6 transcriptional network and thus provide further information concerning the role of Pax6 in β-cell function. We developed a Pax6-deficient model in rat primary β-cells with specific small interfering RNA leading to a 75% knockdown of Pax6 expression. Through candidate gene approach, we confirmed that Pax6 controls the mRNA levels of the insulin 1 and 2, Pdx1, MafA, GLUT2, and PC1/3 genes in β-cells. Importantly, we identified new Pax6 target genes coding for GK, Nkx6.1, cMaf, PC2, GLP-1R and GIPR which are all involved in β-cell function. Furthermore, we demonstrated that Pax6 directly binds and activates specific elements on the promoter region of these genes. We also demonstrated that Pax6 knockdown led to decreases in insulin cell content, in insulin processing, and a specific defect of glucose-induced insulin secretion as well as a significant reduction of GLP-1 action in primary β-cells. Our results strongly suggest that Pax6 is crucial for β-cells through transcriptional control of key genes coding for proteins that are involved in insulin biosynthesis and secretion as well as glucose and incretin actions on β-cells. We provide further evidence that Pax6 represents a key element of mature β-cell function.

Pax6 controls the expression of critical genes involved in pancreatic {alpha} cell differentiation and function

The paired box homeodomain Pax6 is crucial for endocrine cell development and function and plays an essential role in glucose homeostasis. Indeed, mutations of Pax6 are associated with diabetic phenotype. Importantly, homozygous mutant mice for Pax6 are characterized by markedly decreased β and δ cells and absent α cells. To better understand the critical role that Pax6 exerts in glucagon-producing cells, we developed a model of primary rat α cells. To study the transcriptional network of Pax6 in adult and differentiated α cells, we generated Pax6-deficient primary rat α cells and glucagon-producing cells, using either specific siRNA or cells expressing constitutively a dominant-negative form of Pax6. In primary rat α cells, we confirm that Pax6 controls the transcription of the Proglucagon and processing enzyme PC2 genes and identify three new target genes coding for MafB, cMaf, and NeuroD1/Beta2, which are all critical for Glucagon gene transcription and α cell differentiation. Furthermore, we demonstrate that Pax6 directly binds and activates the promoter region of the three genes through specific binding sites and that constitutive expression of a dominant-negative form of Pax6 in glucagon-producing cells (InR1G9) inhibits the activities of the promoters. Finally our results suggest that the critical role of Pax6 action on α cell differentiation is independent of those of Arx and Foxa2, two transcription factors that are necessary for α cell development. We conclude that Pax6 is critical for α cell function and differentiation through the transcriptional control of key genes involved in glucagon gene transcription, proglucagon processing, and α cell differentiation.

The effectiveness of program developed from cognitive-experiential self-theory and life skills technique on adolescent coping with stress

Many methodologies to decrease stress in adolescents have been introduced and implemented. However, it seems that the problems in their physical, mental, emotional, and learning conditions still exist, especially for long-term. The proposed program with some booster was used to solve the long run problems. To examine the effectiveness of program developed from cognitive-experiential self-theory and life skills technique on adolescent coping with stress. A quasi-experimental research in two groups is used to modify theoretical concepts of cognitive-experiential self-theory and life skills technique on adolescent coping with stress. The students of secondary schools in Nakhon Sawan Province Thailand were the target population. Two schools were randomly chosen, one for control and the other for experiment. The sample size of 84 students was randomly selected and requested to be volunteers and 44 volunteers were trained on concept of thinking, strategies to resolve the problem and control emotion for 5 days and booster in school for 9 months in every fortnight and was measured 5 times, before and after interventions at 3rd, 6th and 9th months. We used independent t-test, paired t-test, analysis of variance and covariance for data analysis. There were no difference in the mean of summation of knowledge, attitude and practice of pre-test score between treatment and control group (P = 0.124). After the training program, the volunteers showed significant improvement of knowledge, attitude and practice (P < 0.05) and the level of stress decreased was statistically significant (P < 0.05). The results indicated that the training program with modify theoretical concepts of cognitive-experiential self-theory and life skills technique on adolescent enabled the participants to improve knowledge, attitude and practice in coping with stress.

Intravaginal impedance and sexual behavior of ovariectomized goats given estrogen alone or in combination with progesterone1

Intravaginal impedance (IVI) fluctuates during the goat estrous cycle. To understand which ovarian steroids are responsible for IVI changes and whether IVI variations are associated with precopulatory and copulatory behaviors, 8 ovariectomized females were assigned to 4 treatments in a 4 x 4 Latin square replicated over four 8-d periods. The treatments were as follows: progesterone plus estradiol-17beta (P4 + E2), oil plus estradiol-17beta (E2), progesterone plus oil (P4), or oil (OIL). Daily IVI measurements at the vagino-cervical junction were taken at 1 and 70 KHz. Progesterone was given on d 2 and 3. Estradiol was given in the evening of d 5. On d 1 to 8, goats were group-exposed to a sexually experienced male and observed for the expression of sexual behaviors. On d 6 and 7, IVI was less when goats received P4 + E2 or E2 compared with goats given P4 or OIL (P < 0.05). Impedance measured at 1 kHz tended to remain lower on d 8 in P4 + E2-treated females compared with those given P4 or OIL (P < 0.055). Like previous results, P4 + E2 or E2 treatment induced behavioral estrus; 5 of 8 P4 + E2-treated and 5 of 8 E2-treated females were sexually receptive on d 6. On d 7, although IVI remained low and 2 of 8 P4 + E2-treated goats and 4 of 8 E2-treated goats remained sexually receptive, no additional females were in estrus. No IVI decreases and no estrous behavior were observed in goats given P4 or OIL. This experiment demonstrated that E2 initiates the periestrous drop in IVI, and P4 may delay baseline return.

Role of the vomeronasal organ in neonatal offspring recognition in sheep

Twenty-five pregnant Dorsett ewes were randomly divided into three groups to test if ewes use their vomeronasal organs for offspring recognition during nursing. One group of eight ewes (procaine) were made anosmic by irrigation of the nasal olfactory apparatus with a zinc sulphate procaine solution. The second group of nine ewes (cauterized) had their vomeronasal organs rendered nonfunctional by cauterization of the nasoincisive duct. The third group of eight ewes were the controls. Parturition was synchronized in all ewes with betamethasone on Day 145 of gestation. Maternal responsiveness was tested two separate times with 1- to 2-day-old alien lambs. Each alien lamb trial was conducted 24 h apart. Cauterized ewes allowed alien lambs to suckle and they were unable to distinguish alien lambs from their own lambs, whereas the ewes in both groups with functional vomeronasal organs (procaine and control) violently rejected any alien lamb's attempt to suckle. Thus, female sheep use their vomeronasal organs for neonatal offspring recognition.

Expression of PTTG and prc1 genes during telencephalic neurogenesis

We present the first time/space analysis using in situ hybridization for PTTG and prc1 genes during development of the mouse telencephalon. During the stages E11.5-E13.5 PTTG and prc1 are expressed in most tissues of the embryo. Within the telencephalon, PTTG and prc1 are found exclusively inside of the ventricular zone (VZ). The intensity of the expression of both genes in the ventricular zone reaches its peak by E15.5. Expression starts to decrease by E18.5, it is still visible at least up to P2 and not detectable in the adult brains. Expression of the prc1 gene, but not that of the PTTG, is also found in the mitoticaly active cells outside of the VZ within the telencephalon. Most of the cells expressing the PTTG gene were found in the lower part of the ventricular zone suggesting that the level of PTTG mRNA is regulated during different phases of the mitotic cycle.

Facilitation of sexual behavior in French-Alpine goats treated with intravaginal progesterone-releasing devices and estradiol during the breeding and nonbreeding seasons

The effectiveness of administering progesterone (P4) using controlled intravaginal drug release (CIDR) devices on estradiol (E2)-induced sexual behaviors was examined in ovariectomized (ovx) French-Alpine goats during the fall and spring. Estradiol-induced attractivity and receptivity were facilitated during the spring when P4-filled CIDR devices were removed 24 or 48 h before injection of 30 microg of E2. During the fall, attractivity was also facilitated by CIDR removal 24 h prior to E2 injection, whereas E2-induced receptivity was unaffected by removal of the CIDR at this interval. Concentrations of P4 in circulation during the 3 d of treatment with a CIDR were similar to those during the late luteal phase of the estrous cycle in intact goats. Treatment with P4-filled CIDR for 3 d, followed by injection with 30 microg of E2 24 h after removal, was determined to be a useful model for inducing sexual behavior in a physiologically relevant manner, and it may also be an effective means for facilitating estrus detection due to the high frequency of display of sexual behavior during a predictable time period following steroid treatment.

Scent of a Ewe: transmission of a social cue by conspecifics affects sexual performance in male sheep

Unlike males from other domestic species, domestic rams (Ovis aries) are not sexually stimulated, as determined by measuring sexual performance, following the opportunity to watch a copulating pair. Previously, we reported that aspects of ram sexual performance were improved when rams interacted with a male conspecific that had mated an estrous ewe. Whether the cues were gender-, estrous state-, or behavior-related was tested in this study. Sexually experienced rams were exposed to male pen mates that had interacted with an estrous ewe, a non-estrous ewe, an estrous ewe with a cloth perineal patch, or a ram, or that had been placed alone in a small pen. The rams were then tested for sexual performance. Rams performed more olfactory investigative behaviors toward pen mates that had interacted with a ewe, regardless of her estrous state, than toward a pen mate that had been exposed to another male. Rams exposed to pen mates that had interacted with a ewe also had shorter postejaculatory and interejaculation intervals and subsequently achieved more ejaculations in standardized sexual performance tests. Results from this experiment confirm that male-male interactions affect sexual performance in male sheep and that olfactory cues likely account for the transfer of information among individuals.

Progesterone facilitation and inhibition of estradiol-induced sexual behavior in the female goat

The effect of progesterone (P4) on estradiol (E2)-induced sexual behaviors in ovariectomized French-Alpine goats, during both the breeding (fall) and the nonbreeding (spring) seasons, was examined. Progesterone facilitated E2-induced attractivity and receptivity in the nonbreeding season when P4 treatment occurred 48 or 72 hr prior to treatment with E2. During the breeding season, P4 facilitated attractivity when treatment occurred 72 hr prior to E2 injection. In contrast, P4 inhibited all sexual behaviors when treatment occurred 12 or 24 hr prior to injection of E2. Progesterone did not facilitate E2-induced proceptivity in either the breeding or the nonbreeding seasons. These findings demonstrate that both season and temporal sequence of P4 and E2 administration affect sexual behavior in ovariectomized French-Alpine goats.

Cortisol increases in plasma of Holstein heifer calves from handling and method of electrical dehorning

Changes in cortisol in plasma were used to assess stress when calves were restrained and then dehorned. Thirteen Holstein heifer calves between 3 and 4 wk of age were used over 4 d; each calf served as its own control. On d 1, 2, and 4, blood was sampled initially while calves were in a pen, 5 min after being placed in a restraint chute, and then at 5, 15, 30, and 45 min and 1, 2, 3, 4, 8, and 12 h after simulated or actual dehorning. On d 1, dehorning was simulated. On d 2 and 4, one horn bud of each calf was cauterized, respectively; sequence of horns (right, left) and dehorning instruments (conventional electrical, Buddex) were alternated for all calves. Day or previous dehorning procedures had no effect on initial concentrations of cortisol in plasma. However, after calves were placed in a chute, cortisol in plasma increased with each entrance. Cortisol in plasma peaked at 5 min posthandling (d 1, 11.3 ng/ml) or 15 min postdehorning (electrical, 21.9 ng/ml; Buddex, 20.7 ng/ml). These data suggest that both dehorning procedures resulted in similar rates of synthesis and secretion of cortisol.

Exposure to constant photoperiod alters serum prolactin concentrations and behavioral response to estradiol in the ovariectomized goat

The effects of constant photoperiod on serum prolactin concentrations and sexual behavior of ovariectomized goats was investigated. Fourteen ovariectomized goats were divided into groups of seven goats each and placed in photoperiod-controlled rooms with either 8L:16D or 16L:8D. All goats received six estradiol (E2) treatments in a Latin square design. Following each treatment six 1-h observation periods were conducted. Blood was collected before E2 treatment and at each observation period for prolactin quantification. During the observation periods measures of attractivity, proceptivity, and receptivity were recorded. Goats exposed to 8L:16D displayed sexual behavior in response to doses of E2 lower than those required by goats exposed to 16L:8D. Prolactin concentrations were higher in goats exposed to 16L:8D than in those exposed to 8L:16D. It was concluded that photoperiod affects prolactin concentrations and behavioral sensitivity to E2 in goats. The effect of continued exposure to constant photoperiod on these variables was then investigated. The goats were held in constant photoperiod for 211 d and behavior tests as described for Exp. 1 were repeated. Scores for attractivity, proceptivity, and receptivity did not differ between the two groups after 211 d of exposure to constant photoperiod. Prolactin concentrations did not differ in this study between the two groups. It was concluded that after chronic exposure to 8L:16D ovariectomized goats become refractory to the stimulatory effects of short photoperiod.

Effects of substance abuse on hallucination rates and treatment responses in chronic psychiatric patients

BACKGROUND

Few data systematically document the effects of illicit drug exposure on psychotic illness. We examined the effect of substance abuse on rates and treatment responses of hallucinations in a chronic psychiatric population.

METHOD

113 cooperative patients consecutively admitted to a state psychiatric hospital were administered the Structured Clinical Diagnostic Interview for DSM-III-R, a Hallucination Interview, and an inventory of past and current substances of abuse. Demographic information was obtained on 104 of 108 patients who declined interview. Medication dosage was analyzed for one third of the interviewed sample; hospital records, nursing reports, contacts with relatives, and urine drug screens were used to confirm information from patient interviews. Hallucination rates and response were compared by diagnostic groups (chi-square).

RESULTS

Noninterviewed patients had more frequent hospitalizations, more patients diagnosed with psychosis not otherwise specified or schizoaffective disorder, and fewer females with comorbid substance abuse than the study population. Among interviewed subjects, those with substance abuse and psychiatric illness had first admissions at an earlier age than patients with no substance abuse (p = .005). Schizophrenics experienced higher rates of visual (p = .04) and olfactory (p = .05) hallucinations when using illicit drugs. Substance abuse was associated with decreased treatment responsiveness of auditory (p < .03) and tactile (p < .004) hallucinations in schizophrenic or manic patients. Compared with nonparanoid patients, there was a trend for paranoid schizophrenics with substance abuse to experience more frequent visual (p = .09) and tactile (p = .06) and more refractory auditory (p = .08) hallucinations. No differences in medication dosages were found between patients with treatment-responsive and treatment-refractory hallucinations.

CONCLUSIONS

Abused substances may interact selectively with primary psychiatric illness to increase rates and treatment resistance of specific hallucination modalities; etiologies are discussed.

Effects of bromocriptine treatment on the expression of sexual behavior in male sheep (Ovis aries)

Twenty-three rams were treated twice daily with subcutaneous injections of bromocriptine or vehicle over 30 d during two seasons, spring and fall. Sexual behavior was observed and quantified to determine the effects of bromocriptine-induced hypoprolactinemia on mount attempt (MA), mount (M), and ejaculation (E) frequency of the rams upon exposure to estrous ewes. Behavioral responses and serum prolactin (PRL) concentrations were determined on a weekly basis before, during, and after the treatment period in each season. Treatment with bromocriptine caused a significant decrease in serum concentrations of PRL during both seasons (P < .01). Post-treatment period concentrations of PRL returned to pretreatment levels during the spring, whereas during the fall, post-treatment period PRL concentrations remained low (P < .05). The frequency of MA and M was lower during bromocriptine treatment relative to control rams in the spring (P < .05). The frequency of MA and M returned to pretreatment values after bromocriptine treatment was withdrawn. Ejaculation frequency tended to decrease during and after bromocriptine treatment relative to controls (P < .09). There was no effect of bromocriptine treatment on frequency of MA and M during the fall. During the fall, the frequency of E tended to decrease in bromocriptine-treated rams (P < .1). These data indicate that bromocriptine-induced hypoprolactinemia is associated with a significant diminution in expression of sexual behavior in rams. It is suggested that PRL modulates the intensity of expression of sexual behavior in rams, and this effect may be season-dependent.

Effects of bromocriptine-induced hypoprolactinaemia on gonadotrophin secretion and testicular function in rams (Ovis aries) during two seasons

The influence of low circulating concentrations of prolactin on gonadotrophin and testosterone secretion, sperm production and testicular growth was investigated in rams during two different seasons. Treatment of Dorset rams (n = 23) with bromocriptine (4 mg day-1) during the spring (n = 11) and autumn (n = 12) caused a significant decrease in basal, mean and total serum prolactin concentrations (P < 0.01). In spring, serum prolactin concentrations returned to pretreatment values, one week after the termination of treatment. Basal, mean and total serum concentrations of LH were significantly higher in treated rams than in controls during the treatment period in autumn (P < 0.05). Secretion of LH was not affected by bromocriptine treatment during spring. There were no differences in the secretion of FSH between treated and control rams in either season. Serum concentrations of testosterone were significantly lower in treated rams than in control rams during the treatment period in autumn (P < 0.05) but not during spring. Semen volume from treated rams was significantly lower during the period after treatment in autumn (P < 0.05). Scrotal circumference decreased during both seasons in treated animals, but this change in size was significant only during spring (P < 0.05). Conversely, there was an increase in scrotal circumference in control rams during both seasons. It is concluded that prolactin may (i) affect LH secretion and, (ii) influence testicular function in rams, by directly affecting testosterone and semen production during autumn, and retarding testicular growth in spring.

Evidence for a role of the liver in the luteotropic action of prolactin in rats

Recent studies indicate that the liver may participate in growth-promoting and lactogenic activity of prolactin (PRL). Accordingly, our study was designed to determine whether the liver participates in the luteotropic activity of the hormone in rats. Normally cycling Long-Evans rats received infusions of solvent or 50 micrograms ovine (o) PRL per day into either the external jugular vein (EJV) or the hepatic portal vein (HPV) via osmotic minipumps. The modes of delivery were continuous, 2 pulses of 8 h each per day (2-8), or 4 pulses of 2 h each per day (4-2). Observation of daily vaginal smears was used to classify rats as either cyclic or predominantly diestrus (PD). In a second study, rats fitted with osmotic minipumps received oPRL or vehicle as above, and serial blood samples were obtained for measurement of serum oPRL and rat (r) PRL concentrations. Estrous cycles of normal length were observed in 9 of 11 rats (82%) receiving solvent infusions. All 8 animals receiving continuous oPRL infusions were classified as PD, regardless of site of infusion. In addition, in 4 of 5 (80%) HPV-infused and 5 of 6 (83%) EJV-infused rats on the 2-8 pulse schedule, the smear patterns were classified as PD. However, when rats received 4-2 EJV, 9 of 13 animals (69%) were classified as cyclic, whereas 9 of 11 rats (82%) were classified as PD when oPRL was similarly pulsed into the HPV. Differences in serum concentrations of oPRL between oPRL-treated and vehicle-infused rats were significant only for continuously infused animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Sexual behavior of farm animals

The field of sexual behavior of domestic farm animals is discussed with emphasis on studies of cattle, sheep and goats. Descriptions are provided of behaviors related to the attractivity, proceptivity and receptivity of females, as well as environmental and physiological factors influencing both male and female sexual behavior. The organizational and activational actions of steroid hormones on behavior are also reviewed.

Evidence for a role of the liver in the mammotrophic action of prolactin

The possibility that the liver plays a role in the growth-promoting actions of PRL on the mammary lobuloalveolar (L-A) system was investigated using 6-week-old female rats. Chronic indwelling catheters were inserted into the external jugular vein (EJV) or the hepatic portal vein (HPV) and attached to osmotic minipumps, which were used to infuse pulses of ovine (o) PRL (4/day of 2 h each, total dose = 20 micrograms/day) for 14 days. The rats were hypophysectomized 2 days after catheterization, and given daily sc injections of estradiol + progesterone in oil (2 micrograms and 5 mg/day, respectively) plus twice daily ip injections of porcine GH (50 micrograms/injection) from days 2-13. They were killed on day 14. Controls received the sc and ip hormone injections but were given solvent infusion into the EJV or the HPV instead of oPRL. Infusion of the oPRL into the EJV did not promote mammary L-A growth more than did infusion of solvent into either the EJV or the HPV. By contrast, infusion of the same dose of the hormone into the HPV caused a significant stimulation of the L-A growth. Serum insulin-like growth factor-I (IGF-I) levels were measured by RIA in the rats given the same hormone injections with either intrahepatic infusion of solvent or oPRL, but terminated 7 days after the start of infusion. Intrahepatic delivery of oPRL was not more effective at elevating serum IGF-I concentrations than was the infusion of solvent. These results indicate that the liver may participate in the mammotrophic actions of PRL and serum IGF-I is not responsible for this effect.

Molecular forms of acetylcholinesterase in subcortical areas of normal and Alzheimer disease brain

We have previously reported that the 10s molecular form (G4) of acetylcholinesterase (AChE) is selectively lost from several cortical areas of Alzheimer's disease (AD) brain. In the current follow-up study, we microdissected several areas of nondemented and AD brain, including the hippocampus, amygdala, and cingulate gyrus. Tissue homogenates were separated on sucrose density gradients and the resulting fractions were analyzed for AChE activity in order to define the ratios of the predominant AChE molecular forms (G4/G1). Both the hippocampus and amygdala exhibited distinct patterns of alterations in the G4/G1 ratio which correlate with the known distribution of histopathological changes in AD brain. In order to further define the major pool of AChE that is depleted in AD, we separated fractionated tissue homogenates into salt-soluble and detergent-soluble fractions. The G4/G1 ratios were only altered in the detergent-soluble fractions, indicating that the loss of the G4 AChE molecular form involves a selective depletion of the membrane pool. Available evidence would suggest that this form is the AChE molecular form physiologically relevant at the cholinergic synapse.

Modulation of central muscarinic receptor binding in vitro by ultralow levels of the organophosphate paraoxon

Homogenates of calf caudate nuclei were found to contain at least three distinct subclasses of cholinergic, muscarinic receptors. These subtypes, labeled with [3H]quinuclidinyl benzilate (QNB), can be separated by rapid filtration with the use of the selective ligands, pirenzepine, AF-DX116, and 4-DAMP which have high affinity for the M1, M2, and M3 subtypes, respectively. Paraoxon was found to modulate [3H]QNB binding in a noncompetitive manner at concentrations below those needed to affect acetylcholinesterase activity. Pretreatment of the membrane protein with high concentrations of both the M2 selective antagonist, AF-DX116, and the M3 selective antagonist, 4-DAMP, protected against paraoxon inhibition of [3H]QNB binding, while the M1 selective antagonist pirenzepine did not. Paraoxon sensitive sites, M2 and M3, are found predominantly on presynaptic neurons in the central nervous system. It is postulated that blockade of these sites may interfere with negative feedback inhibition of acetylcholine release and facilitate the development of behavioral and motor deficits that may be associated with chronic exposure to low levels of organophosphates.

Sexual performance of rams reared with or without females after weaning

The objective of this study was to determine the effect of postweaning exposure to females on the subsequent sexual performance of young rams. Twenty-five crossbred rams were reared in a group with ovariectomized females from 4.5 to 9 mo of age. Ewes were brought into estrus every 2 wk during this period. A companion group of 23 crossbred rams was not exposed to females following weaning. Four 30-min sexual performance tests were administered at 10 mo of age. Rams reared with males and females (RMF) exhibited more mounts (P less than .001) and more ejaculations (P less than .002) than rams reared only with males (RM). The frequency of successful matings by the latter group did not increase with experience. Nine rams were sexually inactive in the sexual performance tests. Follow-up tests revealed that two of the RMF rams and one RM ram developed and maintained a sexual preference for males. The six remaining rams eventually mated with females when tested in familiar pens and subsequently exhibited normal levels of sexual performance even when tested in an unfamiliar enclosure. Exposure to ewes during the postweaning prepubertal period enhanced sexual performance. However, early exposure to females did not ensure that all males developed sexual preferences for females. The environmental context in which sexual performance tests are administered may inhibit the expression of heterosexual behavior in a small percentage of animals. After heterosexual behavior was expressed, the rams continued to show normal levels of sexual performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin exerts metabolic and growth-promoting effects by a direct action on the liver in vivo: clarification of the functional significance of the portal vascular link between the beta cells of the pancreatic islets and the liver

The functional significance of the portal vascular link between the beta cells of the pancreatic islets and the liver has not been established. Previous studies indicated that insulin does not acutely regulate glucose metabolism by a direct hepatic effect. More recent observations suggest that the role of insulin in regulating body growth may be mediated, at least in part, by the liver. Our experiments were designed to test whether insulin can promote body growth and regulate glucose metabolism by a direct hepatic action in vivo. Rats were made diabetic by injections of streptozotocin, and insulin or solvent was infused into the jugular vein (JV) or the hepatic portal vein (HPV) for 14 days using catheters that were attached to osmotic minipumps. Infusion of a low dose of insulin (2 units per kg per day) into the JV had no effects on the hyperglycemia, body weight gain, tail growth, tibial epiphysial cartilage plate thickness, or serum levels of somatomedin C in the diabetic rats. However, the same dose given into the HPV caused a 30% reduction of blood glucose and stimulated a significant degree of growth, as determined by all indices. Infusion of a higher dose of insulin (5 units per kg per day) into either vein caused full restoration of body weight gain and tail growth and it restored the glycemic status almost to normal. However, it did not increase the tibial epiphysial plate width or serum somatomedin C levels above those of the rats given the low dose of the hormone into the HPV. These results indicate that insulin can act directly on the liver to promote body growth and to regulate glucose metabolism. The significance of direct delivery of insulin from the pancreatic beta cells to the liver may be as much for growth control as for glucose homeostasis.

Endocrine systems and behavior

Estradiol, either directly from the ovary of females or as a metabolite of testosterone from the testes of males, seems to be the necessary and probably sufficient endocrine signal for sexual differentiation and adult sexual expression. Progesterone, in females, may play an important priming or facilitative role prior to estrus, especially following pregnancy, when blood estrogen levels are high for a prolonged period. At high doses, progesterone clearly inhibits the expression of sexual behavior.

The role of penile stimulation and ejaculatory experience on the development and maintenance of reproductive behavior in the bull (Bos taurus)

To determine the role of afferent input from the penis and copulatory experience on the ontogeny of reproductive behavior, 49 bulls were randomly assigned to the following groups: control; surgical penile deflection (penis deviation), which prevents intromission; penile neurectomy; or penis deviation plus neurectomy. Sexual performance tests were conducted at 3-month intervals from 9 to 24 months of age. Bulls deviated but not neurectomized mounted more frequently than bulls in the other groups. The low mount frequency for control bulls in tests in which copulation occurred was due to the sexually quiescent postejaculatory refractory period. Preventing control bulls from copulating by affixing cloth patches to females' perinea increased mount frequency to the level of deviated bulls. It is concluded that copulatory experience is not essential to the development and maintenance of normal mounting activity. However, sensory stimulation from the penis facilitates the expression of sexual behaviors.

Inability to predict sexual and aggressive behaviors by plasma concentrations of testosterone and luteinizing hormone in Hereford bulls

The relationships between sexual and aggressive behaviors and levels of plasma testosterone and luteinizing hormone (LH) were examined in Hereford bulls at 18 and 24 mo of age. Concentrations of hormones in bulls during periods of sexual rest (13 blood samples collected from each animal during a 24-h period) were compared with individual differences in sexual and aggressive behaviors when exposed to restrained females, either individually or in groups. Nearly all correlation coefficients were low and nonsignificant. It was concluded that individual differences in sexual performance and aggressive behavior cannot be predicted based on circulating levels of testosterone and LH in bulls during periods of sexual rest.

On the negative feedback regulation of gonadotropins in castrate and intact cattle with comparison of two FSH radioimmunoassays

Two homologous radioimmunoassays for bovine follicle stimulating hormone (bFSH) were utilized in comparing the differential regulation of FSH and luteinizing hormone (LH) in response to ovariectomy or administration of gonadal steroids in cattle. There appeared to be significant LH cross-reactivity in one of the bFSH systems (bFSH-HS-2-17), but not in the other (bFSH-BP3). Concentrations of FSH in plasma measured by these two systems suggested both qualitative and quantitative differences. Following ovariectomy in heifers, LH concentrations in plasma were increased by 7.5 h, while FSH (measured in the bFSH-BP3 system) was not significantly elevated until 18 h. Administration of 200 micrograms of estradiol-17 beta to ovariectomized heifers inhibited levels of FSH in plasma but large doses of testosterone (100 mg), androstenedione (400 mg) and dihydrotestosterone (800 mg) had no effect. Similarly, LH was not affected by the androgens, while estradiol induced LH surges, leading to increased mean LH concentrations. In contrast to the results in heifers, LH concentrations in plasma from steers were inhibited by administration of androgens as well as by estradiol. In steers, FSH (bFSH-BP3) was marginally inhibited by estradiol and not at all by the androgens. Differences in the secretory patterns of FSH and LH also occurred in intact heifers during the estrous cycle. The 72-h period preceding estrus (follicular phase) was characterized by rapidly declining serum progesterone concentrations, followed by concurrent increases in both LH and estradiol. The circulating levels of bFSH (BP3) tended to decline during this interval. Overall, during the estrous cycle, progesterone levels were positively correlated with bFSH-BP3 (r = .37) and negatively correlated with LH (r = -.39). The gonadotropins were not significantly related (r = -.15). These relationships are consistent with the concept that LH controls the final stages of follicular development in cattle and that FSH may exert only a permissive effect.

Behavioral characteristics of beef steers administered estradiol, testosterone and dihydrotestosterone

Twelve beef steers ranging in age from 6 to 8 mo were randomly assigned to one of four steroid treatment groups so the ability of each hormone to stimulate sexual and(or) agonistic behavior could be assessed. The steers received im injections of either 200 mg of testosterone (T), 200 micrograms of estradiol-17 beta (E2), 200 mg of dihydrotestosterone (DHT) or sesame oil vehicle as control (C), every other day for 10 d. During these 10 d, behavior was studied for 60 min at 0600, 1200, 1800 and 2400 h. Peak activity occurred during the first half of the experiment with maximum behavioral expression observed at the 2400-h observation period. Estradiol was most effective in stimulating eight of the 13 behaviors studied. These included: sniffs received, sniffs given, successful mounts, chin rests given, chin rests received, stands to be mounted, refusals to stand and head butts received. Testosterone was most effective in stimulating Flehmen lip curls, attempted mounts and head butts given. Testosterone significantly increased activity in seven other categories over that of controls. Dihydrotestosterone was never the most effective steroid. It was capable of stimulating several of the behaviors studied above that of controls, but reduced mounting activity of steers. In view of the major responses observed with E2 and the aromatizable androgen, T, these data are interpreted as an indication that E2 plays a significant direct role in sexual behavior in the male bovine.