Identification of molecules potentially involved in mediating the in vivo actions of the corticotropin-releasing hormone receptor 1 antagonist, NBI30775 (R121919)

Sex-specific alterations in visual properties induced by single prolonged stress model

Patients with post-traumatic stress disorder (PTSD) exhibit sex differences in symptomology, with women more likely to report higher rates of intrusive and avoidance symptoms than men, underscoring the need for sex-informed approaches to research and treatment. Our study delved into the sex-specific aspects of stress-induced visual impairments using the single prolonged stress (SPS) model, a partially validated rodent model for PTSD. Male SPS mice exhibit heightened optimal spatial frequency (SF) of primary visual cortex (V1) neurons, while female counterparts exhibit decreased optimal temporal frequency (TF) of V1 neurons. This phenomenon persisted until the 29th day after SPS modeling, and it may be the physiological basis for the observed increase in visual acuity in male SPS mice in visual water task. Furthermore, our study found that corticotropin-releasing factor receptor 1 regulated optimal TF and optimal SF of V1 in mice, but did not exhibit sex differences. These findings indicated that severe stress induces sex-specific effects on visual function.

Auricular Vagus Nerve Stimulation Ameliorates Functional Dyspepsia with Depressive-Like Behavior and Inhibits the Hypothalamus-Pituitary-Adrenal Axis in a Rat Model

BACKGROUND

The hypothalamus-pituitary-adrenal axis is the most important endocrine system to control irritability response. Functional dyspepsia (FD) is closely related to irritability. This study aimed to preliminarily explore the corticotropin-releasing factor (CRF) mechanism of auricular vagus nerve stimulation (aVNS) for FD model rats.

METHODS

Sprague-Dawley adult male rats were randomly divided into normal group, model group, aVNS group, and sham-aVNS group. Except for the normal rats, all other rats were induced into the FD model through tail-clamping stimulation for 3 weeks. Once the rat model was developed successfully, rats in the aVNS group and sham-aVNS group were intervened with aVNS or sham-aVNS for 2 weeks. No intervention was given to rats in the normal and model groups. The effect of aVNS was assessed. The expressions of hippocampal corticotropin-releasing hormone receptor 1 (CRHR1), hypothalamus CRF, adrenocorticotropic hormone (ACTH), and corticosterone in serum were assessed.

RESULTS

1. Compared with normal rats, model-developing rats showed FD-like behavior. 2. Compared with model rats, rats in the aVNS group showed an improved general condition score and gastric motility, and increased horizontal and vertical motion scores. 3. The release of corticosterone, ACTH in serum, and CRF in the hypothalamus all increased in model rats but decreased with aVNS instead of sham-aVNS. 4. The expression of hippocampus CRHR1 was lower in model rats but higher in the aVNS group.

CONCLUSION

aVNS ameliorates gastric motility and improves the mental state in the FD-like rat, probably via inhibiting the CRF pathway.

Neuropeptide FF and Its Receptors: Therapeutic Applications and Ligand Development

The endogenous neuropeptide FF (NPFF) and its two cognate G protein-coupled receptors, Neuropeptide FF Receptors 1 and 2 (NPFFR1 and NPFFR2), represent a relatively new target system for many therapeutic applications including pain regulation, modulation of opioid side effects, drug reward, anxiety, cardiovascular conditions, and other peripheral effects. Since the cloning of NPFFR1 and NPFFR2 in 2000, significant progress has been made to understand their pharmacological roles and interactions with other receptor systems, notably the opioid receptors. A variety of NPFFR ligands with different mechanisms of action (agonists or antagonists) have been discovered although with limited subtype selectivities. Differential pharmacological effects have been observed for many of these NPFFR ligands, depending on assays/models employed and routes of administration. In this Perspective, we highlight the therapeutic potentials, current knowledge gaps, and latest updates of the development of peptidic and small molecule NPFFR ligands as tool compounds and therapeutic candidates.

Alterations in the corticotropin-releasing hormone (CRH) neurocircuitry: Insights into post stroke functional impairments

Although it is well accepted that changes in the regulation of the hypothalamic-pituitary adrenal (HPA) axis may increase susceptibility to affective disorders in the general population, this link has been less examined in stroke patients. Yet, the bidirectional association between depression and cardiovascular disease is strong, and stress increases vulnerability to stroke. Corticotropin-releasing hormone (CRH) is the central stress hormone of the HPA axis pathway and acts by binding to CRH receptors (CRHR) 1 and 2, which are located in several stress-related brain regions. Evidence from clinical and animal studies suggests a role for CRH in the neurobiological basis of depression and ischemic brain injury. Given its importance in the regulation of the neuroendocrine, autonomic, and behavioral correlates of adaptation and maladaptation to stress, CRH is likely associated in the pathophysiology of post stroke emotional impairments. The goals of this review article are to examine the clinical and experimental data describing (1) that CRH regulates the molecular signaling brain circuit underlying anxiety- and depression-like behaviors, (2) the influence of CRH and other stress markers in the pathophysiology of post stroke emotional and cognitive impairments, and (3) context and site specific interactions of CRH and BDNF as a basis for the development of novel therapeutic targets. This review addresses how the production and release of the neuropeptide CRH within the various regions of the mesocorticolimbic system influences emotional and cognitive behaviors with a look into its role in psychiatric disorders post stroke.

Corticotropin-releasing factor receptor-1 antagonism mitigates beta amyloid pathology and cognitive and synaptic deficits in a mouse model of Alzheimer's disease

INTRODUCTION

Stress and corticotropin-releasing factor (CRF) have been implicated as mechanistically involved in Alzheimer's disease (AD), but agents that impact CRF signaling have not been carefully tested for therapeutic efficacy or long-term safety in animal models.

METHODS

To test whether antagonism of the type-1 corticotropin-releasing factor receptor (CRFR1) could be used as a disease-modifying treatment for AD, we used a preclinical prevention paradigm and treated 30-day-old AD transgenic mice with the small-molecule, CRFR1-selective antagonist, R121919, for 5 months, and examined AD pathologic and behavioral end points.

RESULTS

R121919 significantly prevented the onset of cognitive impairment in female mice and reduced cellular and synaptic deficits and beta amyloid and C-terminal fragment-β levels in both genders. We observed no tolerability or toxicity issues in mice treated with R121919.

DISCUSSION

CRFR1 antagonism presents a viable disease-modifying therapy for AD, recommending its advancement to early-phase human safety trials.

Anxiogenic and Stressor Effects of the Hypothalamic Neuropeptide RFRP-3 Are Overcome by the NPFFR Antagonist GJ14

RFamide-related peptide-3 (RFRP-3) is a recently discovered neuropeptide that has been proposed to play a role in the stress response. We aimed to elucidate the role of RFRP-3 and its receptor, neuropeptide FF (NPFF1R), in modulation of stress and anxiety responses. To achieve this, we characterized a new NPFF1R antagonist because our results showed that the only commercially available putative antagonist, RF9, is in fact an agonist at both NPFF1R and the kisspeptin receptor (KISS1R). We report here the identification and pharmacological characterization of GJ14, a true NPFFR antagonist. In in vivo tests of hypothalamic-pituitary-adrenal (HPA) axis function, GJ14 completely blocked RFRP-3-induced corticosterone release and neuronal activation in CRH neurons. Furthermore, chronic infusion of GJ14 led to anxiolytic-like behavior, whereas RFRP-3 infusion had anxiogenic effects. Mice receiving chronic RFRP-3 infusion also had higher basal circulating corticosterone levels. These results indicate a stimulatory action of RFRP-3 on the HPA axis, consistent with the dense expression of NPFF1R in the vicinity of CRH neurons. Importantly, coinfusion of RFRP-3 and GJ14 completely reversed the anxiogenic and HPA axis-stimulatory effects of RFRP-3. Here we have established the role of RFRP-3 as a regulator of stress and anxiety. We also show that GJ14 can reverse the effects of RFRP-3 both in vitro and in vivo. Infusion of GJ14 causes anxiolysis, revealing a novel potential target for treating anxiety disorders.

CRHR1 links peripuberty stress with deficits in social and stress-coping behaviors

Stressful life events during childhood and adolescence are important risk factors for the development of psychopathologies later in life. The corticotropin releasing hormone (CRH) and the CRH receptor 1 (CRHR1) have been implicated in the link between early life adversity and adult anxiety and depression, with rodent studies identifying the very early postnatal period as highly susceptible to this programming. Here, we investigated whether stress exposure during the peripubertal period - comprising juvenility and puberty - is effective in inducing long-lasting changes in the expression of CRHR1 and CRHR2 in the hippocampus and amygdala, and whether treating animals with a CRHR1 antagonist following stress exposure could reverse behavioral alterations induced by peripuberty stress. We show that peripuberty stress leads to enhanced expression of the Crhr1, but not Crhr2, gene in the hippocampal CA1 and the central nucleus of the amygdala, in association with social deficits in the social exploration test and increased stress-coping behaviors in the forced swim test. Treatment with the CRHR1 antagonist NBI30775 (10 mg/kg) daily for 1 week (from P43 to P49), immediately following peripuberty stress exposure, prevented the occurrence of those psychopathological behaviors at adulthood. These findings highlight peripuberty as a period of plasticity for the enduring modulation of the CRHR1 system and support a growing body of data implicating the CRHR1 system in the programming effects of early life stress on eventual psychopathology. They also support recent evidence indicating that temporarily tackling CRHR1 during development might represent a therapeutic opportunity to correct behavioral trajectories linking early stress to adult psychopathology.

Coping with chronic social stress in mice: hypothalamic-pituitary-adrenal/ sympathetic-adrenal-medullary axis activity, behavioral changes and effects of antalarmin treatment: implications for the study of stress-related psychopathologies

The aim of this study was to analyze the individual differences that lead to the development of psychopathological changes in response to chronic social stress. We also assessed the ability of an antagonist of the corticotrophin-releasing hormone (CRH) receptors to reverse the effects of stress. Male adult mice were exposed to repeated defeat experiences for 21 days using a sensorial contact model. After 18 days of defeat, two groups of subjects were established (active and passive), according to their behaviors during social confrontation. Antalarmin treatment was given for 4 and 6 days. The results corroborated previous data indicating that subjects who adopted a passive coping strategy had higher corticosterone levels after 21 days of defeat and decreased resting levels 3 days later. Moreover, they showed higher resting expression levels of hypothalamic CRH than their active counterparts. On day 24, the experimental animals were subjected to another social defeat to determine whether the stress response remained. The increase in corticosterone and hypothalamic CRH levels was similar for all of the stressed subjects, but the passive subjects also had a greater CRH response in the amygdala. Passive subjects had decreased levels of adrenal dopamine β-hydroxylase, tyrosine hydroxylase and plasma adrenaline compared to the active subjects, and lower plasma noradrenaline levels than manipulated controls. The passive profile of physiological changes in both the hypothalamic-pituitary-adrenal and sympathetic-adrenal-medullary (SAM) axes has been associated with changes related to mood disorders, such as posttraumatic stress disorder and depression. The active coping profile is characterized by similar corticosterone resting levels to controls and increased SAM activity. Both profiles showed alterations in the novel palatable and forced swimming tests, with the passive profile being the most vulnerable to the effects of stress in this last test. Pharmacological treatment with antalarmin failed to reverse the effects of stress.

Stress and animal models of inflammatory bowel disease--an update on the role of the hypothalamo-pituitary-adrenal axis

Chronic psychosocial stress has been repeatedly shown in humans to be a risk factor for the development of several affective and somatic disorders, including inflammatory bowel diseases (IBD). There is also a large body of evidence from rodent studies indicating a link between stress and gastrointestinal dysfunction, resembling IBD in humans. Despite this knowledge, the detailed underlying neuroendocrine mechanisms are not sufficiently understood. This is due, in part, to a lack of appropriate animal models, as most commonly used rodent stress paradigms do not adequately resemble the human situation and/or do not cause the development of spontaneous colitis. Therefore, our knowledge regarding the link between stress and IBD is largely based on rodent models with low face and predictive validity, investigating the effects of unnatural stressors on chemically induced colitis. These studies have consistently reported that hypothalamo-pituitary-adrenal (HPA) axis activation during stressor exposure has an ameliorating effect on the severity of a chemically induced colitis. However, to show the biological importance of this finding, it needs to be replicated in animal models employing more clinically relevant stressors, themselves triggering the development of spontaneous colitis. Important in view of this, recent studies employing chronic/repeated psychosocial stressors were able to demonstrate that such stressors indeed cause the development of spontaneous colitis and, thus, represent promising tools to uncover the mechanisms underlying stress-induced development of IBD. Interestingly, in these models the development of spontaneous colitis was paralleled by decreased anti-inflammatory glucocorticoid (GC) signaling, whereas adrenalectomy (ADX) prior to stressor exposure prevented its development. These findings suggest a more complex role of the HPA axis in the development of spontaneous colitis. In the present review I summarize the available human and rodent data in order to provide a comprehensive understanding of the biphasic role of the HPA axis and/or the GC signaling during stressor exposure in terms of spontaneous colitis development.

Persistent anxiolytic affects after chronic administration of the CRF₁ receptor antagonist R121919 in rats

Corticotropin-releasing factor (CRF) functions as one of the major mediators of the mammalian stress response and appears to play a key role in the pathophysiology of mood and anxiety disorders. Small molecule CRF₁ receptor antagonists may represent a novel form of pharmacotherapy for these disorders. The therapeutic success of CRF₁ receptor antagonists will depend, in part, upon whether tolerance develops to the actions of these compounds and whether appropriate patterns of HPA axis function is maintained. This study evaluated the effects of long term (~4 week) treatment with the CRF₁ receptor antagonist R121919, on CRF receptor function, HPA axis activity, behavioral measures, adrenal gland size, and body weight gain. Animals treated with 20 mg/kg/day of R121919 spent significantly more time in the open field in a defensive withdrawal test (138±36s for R121919 vs 52±12s for vehicle, p=0.01). No significant effect of chronic CRF₁ receptor blockade on basal ACTH or corticosterone concentrations were detected, nor were significant changes detected in an elevated plus maze test. Both vehicle- and R121919- treated rats showed increases in AUC and peak ACTH and corticosterone concentrations following air puff startle stress, without any overall group differences, although a clear but non-significant attenuation in HPA axis response was observable in R121919 treated animals. Chronic CRF₁ receptor blockade increased CRF peptide mRNA expression in the PVN and decreased CRF peptide mRNA expression in the central nucleus of the amygdala. Overall our results suggest that anxiolytic effects of chronic CRF₁ receptor antagonism persist following chronic administration without significant attenuation of the HPA axis's ability to mount a stress response. This article is part of a Special Issue entitled 'Trends in neuropharmacology: in memory of Erminio Costa'.

The corticotropin releasing factor system in cancer: expression and pathophysiological implications

Malignant tumors express multiple factors that have some role in the regulating networks supporting their ectopic growth. Recently, increased interest has been developing in the expression and biological role of the neuropeptides and receptors of the corticotropin releasing factor (CRF) system, the principal neuroendocrine mediator of the stress response, especially in the light of several R&D programs for small molecule antagonists that could present some anticancer therapeutic benefit. In the present article, we review the literature suggesting that the CRF system could be involved in the regulation of human cancer development. Potential implication in growth, metastasis, angiogenesis, or immune parameters via activation of locally expressed receptors could be clinically exploited by presenting targets of new therapeutic approaches.

Consequences of chronic social stress on behaviour and vasopressin gene expression in the PVN of DBA/2OlaHsd mice--influence of treatment with the CRHR1-antagonist R121919/NBI 30775

Accumulating evidence suggests that corticotropin-releasing hormone (CRH) neurocircuitry modulate the neuroendocrine and behavioural phenotypes in depression and anxiety. Thus, the administration of the selective CRH-receptor 1 (CRHR1)-antagonist R121919/NBI 30775 has proven its ability to act as an anxiolytic in rats. It is still unclear whether vasopressinergic neuronal circuits, which are known to be involved in the regulation of emotionality, are affected by R121919/NBI 30775. Using DBA/2OlaHsd mice, we investigated the effects of chronic social defeat and concomitant treatment with R121919/NBI 30775 on 1) the behavioural profile in the modified hole board test and 2) in-situ hybridization analysis-based expression of arginine vasopressin (AVP) and CRH mRNA in both the hypothalamic paraventricular nucleus and supraoptic nucleus. The results suggest that chronic social defeat leads to increased avoidance behaviour and reduction in directed exploration, general exploration, and locomotion. Chronic treatment with the CRHR1-antagonist was effective in reversing the directed exploration to control level. The dissection of the antagonist-treated group into responders and non-responders using the parameter time spent on board revealed further positive effects of R121919/NBI 30775 on avoidance behaviour and locomotion. Behavioural changes were accompanied by alterations in AVP gene expression in the paraventricular nucleus. Taken together, the anxiolytic action of the CRHR1 antagonist was found in a subgroup of animals only, and further studies have to be done to clarify the inter-individual biological differences in response patterns to this compound to optimise its application under clinical conditions.

Antidepressant-like effects of psoralen isolated from the seeds of Psoralea corylifolia in the mouse forced swimming test

The forced swimming test (FST) is suggested to produce abnormalities in the serotonergic and hypothalamic-pituitary-adrenal (HPA) axis systems. Therefore, compounds that attenuate these neurobiological alterations may have potential as antidepressants. The behavioral and biochemical effects of psoralen, a major furocoumarin isolated from Psoralea corylifolia, were investigated in the FST model of depression in male mice. Psoralen significantly reduced immobility and increased swimming without altering climbing in the mouse FST. Psoralen remarkably reversed FST-induced alterations in serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels in frontal cortex and hippocampus in mice. Furthermore, psoralen attenuated FST-induced elevations in serum corticotropin-releasing factor (CRF) and corticosterone concentrations to normalize the HPA axis activity. These results suggested that psoralen possessed potent antidepressant-like properties which were at least in part mediated by improving the abnormalities in the serotonergic and the HPA axis systems.

Innovative approaches for the treatment of depression: targeting the HPA axis

Altered activity of the hypothalamic pituitary adrenal (HPA) axis is one of the most commonly observed neuroendocrine abnormalities in patients suffering from major depressive disorder (MDD). Altered cortisol secretion can be found in as many as 80% of depressed patients. This observation has led to intensive clinical and preclinical research aiming to better understand the molecular mechanisms which underlie the alteration of the HPA axis responsiveness in depressive illness. Dysfunctional glucocorticoid receptor (GR) mediated negative feedback regulation of cortisol levels and changes in arginine vasopressin (AVP)/vasopressin V1b receptor and corticotrophin-releasing factor/CRF1 receptor regulation of adrenocotricotrophin (ACTH) release have all been implicated in over-activity of the HPA axis. Agents that intervene with the mechanisms involved in (dys)regulation of cortisol synthesis and release are under investigation as possible therapeutic agents. The current status of some of these approaches is described in this review.

Persistent neuroendocrine and behavioral effects of a novel, etiologically relevant mouse paradigm for chronic social stress during adolescence

Chronic stress is widely regarded as a key risk factor for a variety of diseases. A large number of paradigms have been used to induce chronic stress in rodents. However, many of these paradigms do not consider the etiology of human stress-associated disorders, where the stressors involved are mostly of social nature and the effects of the stress exposure persist even if the stressor is discontinued. In addition, many chronic stress paradigms are problematic with regard to stress adaptation, continuity, duration and applicability. Here we describe and validate a novel chronic social stress paradigm in male mice during adolescence. We demonstrate persistent effects of chronic social stress after 1 week of rest, including altered adrenal sensitivity, decreased expression of corticosteroid receptors in the hippocampus and increased anxiety. In addition, pharmacological treatments with the antidepressant paroxetine (SSRI) or with the corticotropin-releasing hormone receptor 1 antagonist DMP696 were able to prevent aversive long-term consequences of chronic social stress. In conclusion, this novel chronic stress paradigm results in persistent alterations of hypothalamus-pituitary-adrenal axis function and behavior, which are reversible by pharmacological treatment. Moreover, this paradigm allows to investigate the interaction of genetic susceptibility and environmental risk factors.

Different responses to dexamethasone and prednisolone in the same depressed patients

RATIONALE

Patients with major depression show hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, but the mechanisms underlying this abnormality are still unclear.

OBJECTIVES

We have compared two synthetic glucorticoids, dexamethasone and prednisolone, in their ability to suppress the hypothalamic-pituitary-adrenal (HPA) axis in depressed patients. Dexamethasone probes glucocorticoid receptor (GR) function, while prednisolone probes both GR and mineralocorticoid receptor (MR) function.

MATERIALS AND METHODS

We used a single-blind, repeated-measure design. We administered placebo, prednisolone (5 mg) or dexamethasone (0.5 mg), at 22:00, to 18 severe, treatment-resistant depressed inpatients (15 of them with a history of childhood trauma) and 14 healthy volunteers. On the following days, we collected salivary cortisol from 9:00 to 22:00.

RESULTS

Depressed patients had higher salivary cortisol levels compared with controls, at baseline and after both prednisolone and dexamethasone (p<0.001). Consistent with previous studies, depressed inpatients showed impaired suppression by dexamethasone: based on the analysis of the areas under the curve (AUCs), suppression by dexamethasone (0.5 mg) was -85% in controls vs -46% in depressed patients (p=0.018). However, the same depressed patients showed normal suppression by prednisolone (5 mg): suppression was -41% in controls and -36% in depressed patients (p=0.6).

CONCLUSIONS

We suggest that the additional effects of prednisolone on the MR explain the different responses to these glucocorticoids in the same depressed patients.

Stress – the battle for hearts and minds: links between depression, stress and ischemic heart disease

Depression and ischemic heart disease (IHD) are strongly related common disorders. Depression itself is an independent cardiac risk factor and is associated with a two- to threefold increase in IHD mortality. Attention has now shifted to identifying the common underlying mechanisms that could make individuals susceptible to both disorders. Abnormalities that have been implicated in this relationship include abnormal platelet activation, decreased baroreceptor sensitivity and endothelial dysfunction. Depression and IHD both have a high association with environmental stress, and depression is characterized by abnormalities of the stress-hormone axis. This review provides a brief overview of some recent developments in our understanding of the pathophysiological links between stress, depression and IHD.