CRF-binding Protein Research Articles

The corticotropin releasing factor binding protein: A strange case of Dr. Jekyll and Mr. Hyde in the stress system?

The corticotropin releasing factor (CRF) exerts its effects by acting on its receptors and on the binding protein (CRFBP). Extensive literature suggests a role of CRF in alcohol use disorder (AUD). Less is known about the specific role, if any, of CRFBP in AUD. In this review, we summarize recent interdisciplinary efforts toward identifying the contribution of CRFBP in mediating CRF activation. The role of CRFBP in alcohol-related behaviors has been evaluated with the ultimate goal of designing effective novel therapeutic strategies for AUD. A series of invitro, invivo, exvivo, and genetic studies presented here provides initial evidence that CRFBP may possess both inhibitory and excitatory roles, and supports the original hypothesis that it represents a novel pharmacological target for the treatment of AUD. This report summarizes the proceedings of one of the talks at the Young Investigator Award symposium at the Alcoholism and Stress: A Framework for Future Treatment Strategies Conference, Volterra, Italy.

High environmental ammonia exposure has developmental-stage specific and long-term consequences on the cortisol stress response in zebrafish

The capacity for early life environmental stressors to induce programming effects on the endocrine stress response in fish is largely unknown. In this study we determined the effects of high environmental ammonia (HEA) exposure on the stress response in larval zebrafish, assessed the tolerance of embryonic and larval stages to HEA, and evaluated whether early life HEA exposure has long-term consequences on the cortisol response to a novel stressor. Exposure to 500–2000μM NH4Cl for 16h did not affect the gene expression of corticotropin-releasing factor (CRF) system components in 1day post-fertilization (dpf) embryos, but differentially increased crfa, crfb and CRF binding protein (crfbp) expression and stimulated both dose- and time-dependent increases in the whole body cortisol of 5dpf larvae. Pre-acclimation to HEA at 1dpf did not affect the cortisol response to a subsequent NH4Cl exposure at 5dpf. In contrast, pre-acclimation to HEA at 5dpf caused a small but significant reduction in the cortisol response to a second NH4Cl exposure at 10dpf. While continuous exposure to 500–2000μM NH4Cl between 0 and 5dpf had a modest effect on mean survival time, exposure to 400–1000μM NH4Cl between 10 and 14dpf decreased mean survival time in a dose-dependent manner. Moreover, pre-acclimation to HEA at 5dpf significantly decreased the risk of mortality to continuous NH4Cl exposure between 10 and 14dpf. Finally, while HEA at 1dpf did not affect the cortisol stress response to a novel vortex stressor at 5dpf, the same HEA treatment at 5dpf abolished vortex stressor-induced increases in whole body cortisol at 10 and 60dpf. Together these results show that the impact of HEA on the cortisol stress response during development is life-stage specific and closely linked to ammonia tolerance. Further, we demonstrate that HEA exposure at the larval stage can have persistent effects on the capacity to respond to stressors in later life.

Protein Discovery: Combined Transcriptomic and Proteomic Analyses of Venom from the Endoparasitoid Cotesia chilonis (Hymenoptera: Braconidae).

Many species of endoparasitoid wasps provide biological control services in agroecosystems. Although there is a great deal of information on the ecology and physiology of host/parasitoid interactions, relatively little is known about the protein composition of venom and how specific venom proteins influence physiological systems within host insects. This is a crucial gap in our knowledge because venom proteins act in modulating host physiology in ways that favor parasitoid development. Here, we identified 37 possible venom proteins from the polydnavirus-carrying endoparasitoid Cotesia chilonis by combining transcriptomic and proteomic analyses. The most abundant proteins were hydrolases, such as proteases, peptidases, esterases, glycosyl hydrolase, and endonucleases. Some components are classical parasitoid venom proteins with known functions, including extracellular superoxide dismutase 3, serine protease inhibitor and calreticulin. The venom contains novel proteins, not recorded from any other parasitoid species, including tolloid-like proteins, chitooligosaccharidolytic β-N-acetylglucosaminidase, FK506-binding protein 14, corticotropin-releasing factor-binding protein and vascular endothelial growth factor receptor 2. These new data generate hypotheses and provide a platform for functional analysis of venom components.

Don't stress about CRF: assessing the translational failures of CRF1antagonists.

Dr. Athina Markou sought treatments for a common neural substrate shared by depression and drug dependence. Antagonists of corticotropin-releasing factor (CRF) receptors, a target of interest to her, have not reached the clinic despite strong preclinical rationale and sustained translational efforts. We explore potential causes for the failure of CRF1 antagonists and review recent findings concerning CRF-CRF1 systems in psychopathology. Potential causes for negative outcomes include (1) poor safety and efficacy of initial drug candidates due to bad pharmacokinetic and physicochemical properties, (2) specificity problems with preclinical screens, (3) the acute nature of screens vs. late-presenting patients, (4) positive preclinical results limited to certain models and conditions with dynamic CRF-CRF1 activation not homologous to tested patients, (5) repeated CRF1 activation-induced plasticity that reduces the importance of ongoing CRF1 agonist stimulation, and (6) therapeutic silencing which may need to address CRF2 receptor or CRF-binding protein molecules, constitutive CRF1 activity, or molecules that influence agonist-independent activity or to target structural regions other than the allosteric site bound by all drug candidates. We describe potential markers of activation towards individualized treatment, human genetic, and functional data that still implicate CRF1 systems in emotional disturbance, sex differences, and suggestive clinical findings for CRF1 antagonists in food craving and CRF-driven HPA-axis overactivation. The therapeutic scope of selective CRF1 antagonists now appears narrower than had been hoped. Yet, much remains to be learned about CRF's role in the neurobiology of dysphoria and addiction and the potential for novel anti-CRF therapies therein.

Binge Drinking Decreases Corticotropin‐Releasing Factor‐Binding Protein Expression in the Medial Prefrontal Cortex of Mice

Dysregulation of the corticotropin-releasing factor (CRF) system has been observed in rodent models of binge drinking, with a large focus on CRF receptor 1 (CRF-R1). The role of CRF-binding protein (CRF-BP), a key regulator of CRF activity, in binge drinking is less well understood. In humans, single-nucleotide polymorphisms in CRHBP are associated with alcohol use disorder and stress-induced alcohol craving, suggesting a role for CRF-BP in vulnerability to alcohol addiction. The role and regulation of CRF-BP in binge drinking were examined in mice exposed to the drinking in the dark (DID) paradigm. Using insitu hybridization, the regulation of CRF-BP, CRF-R1, and CRF mRNA expression was determined in the stress and reward systems of C57BL/6J mice after repeated cycles of DID. To determine the functional role of CRF-BP in binge drinking, CRF-BP knockout (CRF-BP KO) mice were exposed to 6 cycles of DID, during which alcohol consumption was measured and compared to wild-type mice. CRF-BP mRNA expression was significantly decreased in the prelimbic (PL) and infralimbic medial prefrontal cortex (mPFC) of C57BL/6J mice after 3 cycles and in the PL mPFC after 6 cycles of DID. No significant changes in CRF or CRF-R1 mRNA levels were observed in mPFC, ventral tegmental area, bed nucleus of the stria terminalis, or amygdala after 3 cycles of DID. CRF-BP KO mice do not show significant alterations in drinking compared to wild-type mice across 6 cycles of DID. These results reveal that repeated cycles of binge drinking alter CRF-BP mRNA expression in the mPFC, a region responsible for executive function and regulation of emotion and behavior, including responses to stress. We observed a persistent decrease in CRF-BP mRNA expression in the mPFC after 3 and 6 DID cycles, which may allow for increased CRF signaling at CRF-R1 and contribute to excessive binge-like ethanol consumption.

Brain CRF-binding protein modulates aspects of maternal behavior under stressful conditions and supports a hypo-anxious state in lactating rats

Reduced corticotropin-releasing factor (CRF) receptor activation in the postpartum period is essential for adequate maternal behavior. One of the factors contributing to this hypo-activity might be the CRF-binding protein (CRF-BP), which likely reduces the availability of free extracellular CRF/urocortin 1. Here, we investigated behavioral effects of acute CRF-BP inhibition using 5μg of CRF(6-33) administered either centrally or locally within different parts of the bed nucleus of the stria terminalis (BNST) in lactating rats. Additionally, we assessed CRF-BP expression in the BNST comparing virgin and lactating rats.Central CRF-BP inhibition increased maternal aggression during maternal defense but did not affect maternal care or anxiety-related behavior. CRF-BP inhibition in the medial-posterior BNST had no effect on maternal care under non-stress conditions but impaired the reinstatement of maternal care following stressor exposure. Furthermore, maternal aggression, particularly threat behavior, and anxiety-related behavior were elevated by CRF-BP inhibition in the medial-posterior BNST. In the anterior–dorsal BNST, CRF-BP inhibition increased only non-maternal behaviors following stress. Finally, CRF-BP expression was higher in the anterior compared to the posterior BNST but was not different between virgin and lactating rats in either region.Our study demonstrates a key role of the CRF-BP, particularly within the BNST, in modulating CRF's impact on maternal behavior. The CRF-BP is important for the reinstatement of maternal care after stress, for modulating threat behavior during an aggressive encounter and for maintaining a hypo-anxious state during lactation. Thus, the CRF-BP likely contributes to the postpartum-associated down-regulation of the CRF system in a brain region-dependent manner.

CRF binding protein facilitates the presence of CRF type 2α receptor on the cell surface

Corticotropin releasing factor binding protein (CRF-BP) was originally recognized as CRF sequestering protein. However, its differential subcellular localization in different brain nuclei suggests that CRF-BP may have additional functions. There is evidence that CRF-BP potentiates CRF and urocortin 1 actions through CRF type 2 receptors (CRF2R). CRF2R is a G protein-coupled receptor (GPCR) that is found mainly intracellularly as most GPCRs. The access of GPCRs to the cell surface is tightly regulated by escort proteins. We hypothesized that CRF-BP binds to CRF2R, exerting an escort protein role. We analyzed the colocalization of CRF-BP and CRF2R in cultured rat mesencephalic neurons, and the localization and interaction of heterologous expressed CRF-BP and CRF2αR in yeast, human embryonic kidney 293, and rat pheochromocytoma 12 cells. Our results showed that CRF-BP and CRF2R naturally colocalize in the neurites of cultured mesencephalic neurons. Heterologous expression of each protein showed that CRF-BP was localized mainly in secretory granules and CRF2αR in the endoplasmic reticulum. In contrast, CRF-BP and CRF2αR colocalized when both proteins are coexpressed. Here we show that CRF-BP physically interacts with the CRF2αR but not the CRF2βR isoform, increasing CRF2αR on the cell surface. Thus, CRF-BP emerges as a GPCR escort protein increasing the understanding of GPCR trafficking.

Effects of acute and chronic stress on telencephalic neurochemistry and gene expression in rainbow trout (Oncorhynchus mykiss).

By filtering relevant sensory inputs and initiating stress responses, the brain is an essential organ in stress coping and adaptation. However, exposure to chronic or repeated stress can lead to allostatic overload, where neuroendocrinal and behavioral reactions to stress become maladaptive. This work examines forebrain mechanisms involved in allostatic processes in teleost fishes. Plasma cortisol, forebrain serotonergic (5-HTergic) neurochemistry, and mRNA levels of corticotropin-releasing factor (CRF), CRF-binding protein (CRF-BP), CRF receptors (CRFR1 and CRFR2), mineralocorticoid receptor (MR), glucocorticoid receptors (GR1 and GR2) and serotonin type 1A (5-HT1A) receptors (5-HT1Aα and 5-HT1Aβ) were investigated at 1 h before and 0, 1 and 4 h after acute stress, in two groups of rainbow trout held in densities of 25 and 140 kg m-3 for 28 days. Generally, being held at 140 kg m-3 resulted in a less pronounced cortisol response. This effect was also reflected in lower forebrain 5-HTergic turnover, but not in mRNA levels in any of the investigated genes. This lends further support to reports that allostatic load causes fish to be incapable of mounting a proper cortisol response to an acute stressor, and suggests that changes in forebrain 5-HT metabolism are involved in allostatic processes in fish. Independent of rearing densities, mRNA levels of 5-HT1Aα and MR were downregulated 4 h post-stress compared with values 1 h post-stress, suggesting that these receptors are under feedback control and take part in the downregulation of the hypothalamic-pituitary-interrenal (HPI) axis after exposure to an acute stressor.

Corticotropin-releasing factor type-2 receptor and corticotropin-releasing factor-binding protein coexist in rat ventral tegmental area nerve terminals originated in the lateral hypothalamic area.

There is significant functional evidence showing that corticotropin-releasing factor type-2 receptor (CRF2R) and corticotropin-releasing factor-binding protein (CRF-BP) regulate glutamatergic synapses onto ventral tegmental area (VTA) dopaminergic neurons. It has been shown that CRF requires CRF-BP to potentiate N-methyl-D-aspartate receptors in dopaminergic neurons through CRF2R, and that increases glutamate release in cocaine-treated rats through the activation of CRF2R only by agonists with high affinity to CRF-BP. Furthermore, this CRF-mediated increase in VTA glutamate is responsible for stress-induced relapse to cocaine-seeking behaviour. However, there is a lack of anatomical evidence to explain the mechanisms of CRF actions in VTA. Thus, it was studied whether CRF2R and CRF-BP are expressed in VTA nerve terminals, using a synaptosomal preparation devoid of postsynaptic elements. The current results show that both proteins are co-expressed in glutamatergic and γ-aminobutyric acid (GABA)ergic VTA synaptosomes. A main glutamatergic input to the VTA that has been associated to addictive behaviour is originated in the lateral hypothalamic area (LHA). Thus, this study was focused in the LHA-VTA input using orexin as a marker of this input. The results show that CRF2R and CRF-BP mRNA and protein are expressed in the LHA, and that both proteins are present in orexin-positive VTA synaptosomes. The results showing that CRF2R and CRF-BP are expressed in the LHA-VTA input give anatomical support to suggest that this input plays a role in stress-induced relapse to cocaine-seeking behaviour.

Corticotropin Releasing Factor Binding Protein and CRF2 Receptors in the Ventral Tegmental Area: Modulation of Ethanol Binge Drinking in C57BL/6J Mice.

Most studies with corticotropin releasing factor (CRF) and ethanol (EtOH) consumption have focused on CRF type 1 (CRF1 ) receptors; less is known about other components of the CRF system, such as the CRF type 2 (CRF2 ) receptors and the CRF binding protein (CRFBP). In humans, several nucleotide polymorphisms in the CRFBP gene have been associated with EtOH abuse. The role of the CRFBP within the ventral tegmental area (VTA) and the central nucleus of the amygdala (CeA) was investigated in C57BL/6J mice exposed to an EtOH binge drinking paradigm (drinking in the dark [DID]), or to a dependence-producing drinking protocol (2-bottle choice, intermittent access to alcohol [IAA]) for 4 weeks. Potential interactions between VTA CRFBP and CRF2 receptors on EtOH binge drinking were also assessed. Mice were microinjected with the CRFBP antagonist CRF fragment 6-33 (CRF6-33 ) into the VTA or CeA, or with the CRF2 antagonist astressin-2B (A2B) alone or in combination with CRF6-33 into the VTA, and had access to 20% (w/v) EtOH for 4 hours (DID). Separate cohorts of mice received vehicle and doses of CRF6-33 into the VTA or CeA and had access to EtOH/water for 24 hours (IAA). Blood EtOH concentrations (BECs) were measured, and signs of withdrawal by handling-induced convulsions were determined. Intra-VTA CRF6-33 and A2B reduced EtOH intake dose dependently in mice during DID. Furthermore, a combination of a subeffective dose of CRF6-33 and a lower dose of A2B promoted additive effects in attenuating EtOH binge drinking. Intra-VTA CRF6-33 did not affect EtOH consumption in mice given IAA, and intra-CeA CRF6-33 did not change alcohol consumption in both models of drinking. DID and IAA promoted pharmacologically relevant BECs; however, only mice given IAA exhibited convulsive events during withdrawal. These findings suggest that VTA CRFBP is involved in the initial stages of escalated EtOH drinking by mechanisms that may involve CRF2 receptors.

The effect of magnesium sulfate on the placental corticotropin-releasing factor (CRF) and CRF binding protein mRNA expression in perfused human placental cotyledon

Objectives: Stress stimuli and inflammation influence the secretion of the placental corticotropin-releasing factor CRF (CRF) that has a significant role in controlling the timing of birth. The CRF-binding protein (CRF-BP) binds CRF with high affinity and inhibits its activity. Magnesium sulfate (MgSO4) has been known to ameliorate maternal, fetal and gestational tissue-associated inflammatory response. We aimed to study the effect of MgSO4 on the CRF and CRF-BP mRNA expression levels in perfused human cotyledon.Methods: Placentas from elective caesarean section were obtained and selected cotyledons were cannulated and dually perfused ex-vivo within 30 min. MgSO4 (7 mg/dl) was added to the maternal reservoir. Each perfusion experiment was conducted for 180 min. At the end of the experiment, RNA was extracted from the perfused cotyledon, and RT-PCR was performed to quantify the expression of CRF and CRF-BP. Human HPRT gene served as a reference gene.Results: Perfusion with MgSO4 (n = 3) induced a significantly lower CRF and higher CRF-BP mRNA expression compared to placentas perfused only with medium (n = 3).Conclusion: In the human placenta, MgSO4 possibly exerts its action through different modulation on the CRF and CRF-BP expression.

Differential stress response in rats subjected to chronic mild stress is accompanied by changes in CRH-family gene expression at the pituitary level

The purpose of this study was to examine molecular markers of the stress response at the pituitary and peripheral levels in animals that responded differently to chronic mild stress (CMS). Rats were subjected to 2-weeks CMS and symptoms of anhedonia was measured by the consumption of 1% sucrose solution. mRNA levels of CRH-family neuropeptides (Crh—corticotropin-releasing hormone, Ucn1—urocortin 1, Ucn2—urocortin 2, Ucn3—urocortin 3), CRH receptors (Crhr1—corticotropin-releasing hormone receptor 1, Crhr2—corticotropin-releasing hormone receptor 2) and Crhbp (corticotropin-releasing factor binding protein) in the pituitaries of rats were determined with real-time PCR. Plasma levels of ACTH (adrenocorticotropin), CRH and urocortins were measured with ELISA assays. CMS procedure led to the development of anhedonia manifested by the decreased sucrose consumption (stress-reactive, SR, stress-susceptible group). Additionally, the group of animals not exhibiting any signs of anhedonia (stress non-reactive, SNR, stress-resilient group) and the group characterized by the increased sucrose consumption (stress invert-reactive group SIR) were selected. The significant increases in ACTH plasma level accompanied by the decreases in the pituitary gene expression of the Crh, Ucn2 and Ucn3 in both stress non-reactive and stress invert-reactive groups were observed. The only molecular change observed in stress-reactive group was the increase in UCN2 plasma level. The differentiated behavioral stress responses were reflected by gene expression changes in the pituitary. Alterations in the mRNA levels of Crh, Ucn2 and Ucn3 in the pituitary might confirm the paracrine and/or autocrine effects of these peptides in stress response. The opposite behavioral effect between SNR vs. SIR groups and the surprising similarity at gene expression and plasma ACTH levels in these two groups may suggest the discrepancy between molecular and behavioral stress responses; however, there results might indicate to similarity underlying different ways to cope with stress conditions.

Fear extinction learning can be impaired or enhanced by modulation of the CRF system in the basolateral nucleus of the amygdala

The neuropeptide corticotropin-releasing factor (CRF) is released during periods of anxiety and modulates learning and memory formation. One region with particularly dense concentrations of CRF receptors is the basolateral nucleus of the amygdala (BLA), a critical structure for both Pavlovian fear conditioning and fear extinction. While CRF has the potential to modify amygdala-dependent learning, its effect on fear extinction has not yet been assessed. In the present study, we examined the modulatory role of CRF on within-session extinction and fear extinction consolidation. Intra-BLA infusions of the CRF binding protein ligand inhibitor CRF(6–33) which increases endogenous levels of free CRF, or intra-BLA infusions of exogenous CRF made prior to fear extinction learning did not affect either fear expression or within-session extinction learning. However, when these animals were tested twenty-four hours later, drug free, they showed impairments in extinction memory. Conversely, intra-BLA infusions of the CRF receptor antagonist α-helical CRF(9–41) enhanced memory of fear extinction. These results suggest that increased CRF levels within the BLA at the time of fear extinction learning actively impair the consolidation of long-term fear extinction.

Corticotropin-releasing factor-binding protein (CRF-BP) inhibits CRF- and urotensin-I-mediated activation of CRF receptor-1 and -2 in common carp

Corticotropin-releasing factor-binding protein (CRF-BP) is considered a key determinant for CRF receptor (CRF-R) activation by CRF and several related peptides. Earlier studies have shown that the CRF system is highly conserved in gene structures throughout evolution, yet little is known about the evolutionary conservation of its biological functions. Therefore, we address the functional properties of CRF-BP and CRF-Rs in a teleost fish (common carp; Cyprinus carpio L.). We report the finding of two similar, yet distinct, genes for both CRF-R1 and CRF-R2 in this species. The four receptors are differentially responsive to CRF, urotensin-I (UI), sauvagine, and urocortin-2 (Ucn-2) and -3 (Ucn-3) as shown by luciferase assays. In vitro, carp CRF-BP inhibits CRF- and UI-mediated activation of the newfound CRF-Rs, but its potency to do so varies between receptor and peptide ligand. This is the first paper to establish the functionality and physiological interplay between CRF-BP, CRF-Rs and CRF-family peptides in a teleostean species.

Acute embryonic exposure to nanosilver or silver ion does not disrupt the stress response in zebrafish (Danio rerio) larvae and adults

The antibacterial properties of silver nanoparticles (AgNPs) are widely exploited in a variety of medical and consumer products. AgNPs in these products can be released into the aquatic environment, however, the potential toxicity of AgNPs to organisms, including fish, is yet to be fully understood. The present study aimed to investigate the effects of the early life exposure to AgNPs on the hypothalamic–pituitary–interrenal (HPI) axis-mediated stress response in zebrafish (Danio rerio) larvae and adults. Zebrafish embryos were treated with AgNPs (0.5μg/mL) or Ag+ (0.05μg/mL) starting at 2h post fertilization (hpf). At 96hpf the larvae were either subjected to a swirling stress and euthanized, or raised to adulthood (10months) in silver-free water and then net-stressed, euthanized, and sampled. Whole-body basal or stress-induced cortisol levels in larvae were not affected by either AgNPs or Ag+; however, the transcript levels of corticotropin releasing factor (CRF), CRF-binding protein (CRF-BP), CRF-receptor 2 (CRF-R2), and pro-opiomelanocortin (POMCb) were significantly decreased by Ag+. The ability of the adult fish to release cortisol in response to a stressor was also not affected, although the transcript levels of CRF, CRF-BP, and CRF-R1 in the telencephalon were differentially affected in fish exposed to Ag+ as embryos. This is the first study that investigated the potential endocrine-disrupting effects of AgNPs during the early life stages and although AgNPs or Ag+ did not affect the ability of zebrafish to elevate cortisol levels in response to a stressor, the effects on transcript levels by Ag+ should be investigated further since CRF does not solely regulate the HPI axis but is also implicated in other physiological processes.

Arginine Vasotocin Treatment Induces a Stress Response and Exerts a Potent Anorexigenic Effect in Rainbow Trout, Oncorhynchus mykiss

The peptide arginine vasotocin (AVT), homologous to mammalian arginine vasopressin, is involved in many aspects of fish physiology, such as osmoregulation, regulation of biological rhythms, reproduction, metabolism or responses to stress, and the modulation of social behaviours. Because a decrease in appetite is a general response to stress in fish and other vertebrates, we investigated the role of AVT as a possible food intake regulator in fish. We used i.c.v. injections for central administration of AVT to rainbow trout (Oncorhynchus mykiss). In a first experiment, we evaluated the temporal response of food intake after AVT treatment. In a second experiment, we investigated the effects of central AVT administration on the response of typical stress markers (plasma cortisol, glucose and lactate), as well as brain serotonergic, noradrenergic and dopaminergic activity. In addition, the mRNA levels of genes involved in food intake regulation [neuropetide Y, pro-opiomelanocortin (POMC), cocaine- and amphetamine-regulated transcript (CART) and corticotrophin-releasing factor (CRF)] and in CRF- (CRF-binding protein) and AVT-signalling (pro-VT and AVT receptor), were also assessed after AVT treatment. Our results showed that AVT is a potent anorexigenic factor in fish. Increases of plasma cortisol and glucose after AVT treatment strongly suggest that AVT administration induced a stress response and that AVT action was mediated by hypothalamic-pituitary-interrenal axis activation, which was also supported by the increase of the serotonergic activity in trout telencephalon and hypothalamus. The increased hypothalamic levels of POMC and CART suggest that these peptides might have a role in the anorexigenic action of AVT, whereas the involvement of CRF signalling is unclear.

Chronic Unpredictable Stress (CUS)-Induced Anxiety and Related Mood Disorders in a Zebrafish Model: Altered Brain Proteome Profile Implicates Mitochondrial Dysfunction

Anxiety and depression are major chronic mood disorders, and the etiopathology for each appears to be repeated exposure to diverse unpredictable stress factors. Most of the studies on anxiety and related mood disorders are performed in rodents, and a good model is chronic unpredictable stress (CUS). In this study, we have attempted to understand the molecular basis of the neuroglial and behavioral changes underlying CUS-induced mood disorders in the simplest vertebrate model, the zebrafish, Danio rerio. Zebrafish were subjected to a CUS paradigm in which two different stressors were used daily for 15 days, and thorough behavioral analyses were performed to assess anxiety and related mood disorder phenotypes using the novel tank test, shoal cohesion and scototaxis. Fifteen days of exposure to chronic stressors appears to induce an anxiety and related mood disorder phenotype. Decreased neurogenesis, another hallmark of anxiety and related disorders in rodents, was also observed in this zebrafish model. The common molecular markers of rodent anxiety and related disorders, corticotropin-releasing factor (CRF), calcineurin (ppp3r1a) and phospho cyclic AMP response element binding protein (pCREB), were also replicated in the fish model. Finally, using 2DE FTMS/ITMSMS proteomics analyses, 18 proteins were found to be deregulated in zebrafish anxiety and related disorders. The most affected process was mitochondrial function, 4 of the 18 differentially regulated proteins were mitochondrial proteins: PHB2, SLC25A5, VDAC3 and IDH2, as reported in rodent and clinical samples. Thus, the zebrafish CUS model and proteomics can facilitate not only uncovering new molecular targets of anxiety and related mood disorders but also the routine screening of compounds for drug development.

Corticotropin-releasing factor-related peptides, serotonergic systems, and emotional behavior

Corticotropin-releasing factor (CRF) is a 41-amino acid neuropeptide that is involved in stress-related physiology and behavior, including control of the hypothalamic-pituitary-adrenal (HPA) axis. Members of the CRF family of neuropeptides, including urocortin 1 (UCN 1), UCN 2, and UCN 3, bind to the G protein-coupled receptors, CRF type 1 (CRF1) and CRF2 receptors. In addition, CRF binding protein (CRFBP) binds both CRF and UCN 1 and can modulate their activities. There are multiple mechanisms through which CRF-related peptides may influence emotional behavior, one of which is through altering the activity of brainstem neuromodulatory systems, including serotonergic systems. CRF and CRF-related peptides act within the dorsal raphe nucleus (DR), the major source for serotonin (5-HT) in the brain, to alter the neuronal activity of specific subsets of serotonergic neurons and to influence stress-related behavior. CRF-containing axonal fibers innervate the DR in a topographically organized manner, which may contribute to the ability of CRF to alter the activity of specific subsets of serotonergic neurons. CRF and CRF-related peptides can either increase or decrease serotonergic neuronal firing rates and serotonin release, depending on their concentrations and on the specific CRF receptor subtype(s) involved. This review aims to describe the interactions between CRF-related peptides and serotonergic systems, the consequences for stress-related behavior, and implications for vulnerability to anxiety and affective disorders.

675: Expression of the placental corticotrophin releasing factor (CRF) and CRF binding protein in perfused cotyledon with lipopolysaccharide and magnesium sulphate

675: Expression of the placental corticotrophin releasing factor (CRF) and CRF binding protein in perfused cotyledon with lipopolysaccharide and magnesium sulphate

Decreased expression of corticotropin-releasing factor-binding protein mRNA in ACTH-secreting pituitary adenomas.

This study was designed to analyze the sequence and the expression of CRF-BP mRNA in ACTH-secreting pituitary adenomas. Direct sequencing analysis revealed no apparent mutations in the CRF-BP mRNA. Thus, we conclude that mutations in the coding region of the CRF-BP gene are not involved in the pathogenesis of Cushing's disease. However, using a semiquantitative PCR approach coamplifying the house-keeping gene GAPDH we detected a reduced expression of CRF-BP mRNA in ACTH-secreting pituitary adenomas when compared with normal pituitaries. We suggest that the decreased CRF-BP gene expression in ACTH-secreting pituitary adenomas is most likely an effect due to high cortisol levels in Cushing patients.