Oral administration of a corticotropin-releasing hormone receptor antagonist significantly attenuates behavioral, neuroendocrine, and autonomic responses to stress in primates

In vitro and in vivo study of butyrylfentanyl and 4-fluorobutyrylfentanyl in female and male mice: Role of the CRF1 receptor in cardiorespiratory impairment

BACKGROUND AND PURPOSE

Fentanyl analogues have been implicated in many cases of intoxication and death with overdose worldwide. The aim of this study is to investigate the pharmaco-toxicology of two fentanyl analogues: butyrylfentanyl (BUF) and 4-fluorobutyrylfentanyl (4F-BUF).

EXPERIMENTAL APPROACH

In vitro, we measured agonist opioid receptor efficacy, potency, and selectivity and ability to promote interaction of the μ receptor with G protein and β-arrestin 2. In vivo, we evaluated thermal antinociception, stimulated motor activity and cardiorespiratory changes in female and male CD-1 mice injected with BUF or 4F-BUF (0.1-6 mg·kg-1). Opioid receptor specificity was investigated using naloxone (6 mg·kg-1). We investigated the possible role of stress in increasing cardiorespiratory toxicity using the corticotropin-releasing factor 1 (CRF1) antagonist antalarmin (10 mg·kg-1).

KEY RESULTS

Agonists displayed the following rank of potency at μ receptors: fentanyl > 4F-BUF > BUF. Fentanyl and BUF behaved as partial agonists for the β-arrestin 2 pathway, whereas 4F-BUF did not promote β-arrestin 2 recruitment. In vivo, we revealed sex differences in motor and cardiorespiratory impairments but not antinociception induced by BUF and 4F-BUF. Antalarmin alone was effective in blocking respiratory impairment induced by BUF in both sexes but not 4F-BUF. The combination of naloxone and antalarmin significantly enhanced naloxone reversal of the cardiorespiratory impairments induced by BUF and 4F-BUF in mice.

CONCLUSION AND IMPLICATIONS

In this study, we have uncovered a novel mechanism by which synthetic opioids induce respiratory depression, shedding new light on the role of CRF1 receptors in cardiorespiratory impairments by μ agonists.

Crinecerfont, a CRF1 Receptor Antagonist, Lowers Adrenal Androgens in Adolescents With Congenital Adrenal Hyperplasia

CONTEXT

Crinecerfont, a corticotropin-releasing factor type 1 receptor antagonist, has been shown to reduce elevated adrenal androgens and precursors in adults with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD), a rare autosomal recessive disorder characterized by cortisol deficiency and androgen excess due to elevated adrenocorticotropin.

OBJECTIVE

To evaluate the safety, tolerability, and efficacy of crinecerfont in adolescents with 21OHD CAH.

METHODS

This was an open-label, phase 2 study (NCT04045145) at 4 centers in the United States. Participants were males and females, 14 to 17 years of age, with classic 21OHD CAH. Crinecerfont was administered orally (50 mg twice daily) for 14 consecutive days with morning and evening meals. The main outcomes were change from baseline to day 14 in circulating concentrations of ACTH, 17-hydroxyprogesterone (17OHP), androstenedione, and testosterone.

RESULTS

8 participants (3 males, 5 females) were enrolled; median age was 15 years and 88% were Caucasian/White. After 14 days of crinecerfont, median percent reductions from baseline to day 14 were as follows: ACTH, -57%; 17OHP, -69%; and androstenedione, -58%. In female participants, 60% (3/5) had ≥50% reduction from baseline in testosterone.

CONCLUSION

Adolescents with classic 21OHD CAH had substantial reductions in adrenal androgens and androgen precursors after 14 days of oral crinecerfont administration. These results are consistent with a study of crinecerfont in adults with classic 21OHD CAH.

Changes in Corticotropin-Releasing Factor Receptor Type 1, Co-Expression with Tyrosine Hydroxylase and Oxytocin Neurons, and Anxiety-Like Behaviors across the Postpartum Period in Mice

INTRODUCTION

Corticotropin-releasing factor and its primary receptor (CRFR1) are critical regulators of behavioral and neuroendocrine stress responses. CRFR1 has also been associated with stress-related behavioral changes in postpartum mice. Our previous studies indicate dynamic changes in CRFR1 levels and coupling of CRFR1 with tyrosine hydroxylase (TH) and oxytocin (OT) neurons in postpartum mice. In this study, we aimed to determine the time course of these changes during the postpartum period.

METHODS

Using a CRFR1-GFP reporter mouse line, we compared postpartum mice at five time points with nulliparous mice. We performed immunohistochemistry to assess changes in CRFR1 levels and changes in co-expression of TH/CRFR1-GFP and OT/CRFR1-GFP across the postpartum period. Mice were also assessed for behavioral stress responses in the open field test.

RESULTS

Relative to nulliparous mice, CRFR1 levels were elevated in the anteroventral periventricular nucleus (AVPV/PeN) but were decreased in the medial preoptic area from postpartum day 1 (P1) through P28. In the paraventricular hypothalamus (PVN), there is a transient decline in CRFR1 mid-postpartum with a nadir at P7. Co-localization of CRFR1 with TH-expressing neurons was also altered with a transient decrease found in the AVPV/PeN at P7 and P14. Co-expression of CRFR1 and OT neurons of the PVN and supraoptic nucleus was dramatically altered with virtually no co-expression found in nulliparous mice, but levels increased shortly after parturition and peaked near P21. A transient decrease in open field center time was found at P7, indicating elevated anxiety-like behavior.

CONCLUSION

This study revealed various changes in CRFR1 across the postpartum period, which may contribute to stress-related behavior changes in postpartum mice.

The CRHR1/CREB/REST signaling cascade regulates mammalian embryonic neural stem cell properties

Growing evidence suggests that the corticotropin-releasing hormone (CRH) signaling pathway, mainly known as a critical initiator of humoral stress responses, has a role in normal neuronal physiology. However, despite the evidence of CRH receptor (CRHR) expression in the embryonic ventricular zone, the exact functions of CRH signaling in embryonic brain development have not yet been fully determined. In this study, we show that CRHR1 is required for the maintenance of neural stem cell properties, as assessed by in vitro neurosphere assays and cell distribution in the embryonic cortical layers following in utero electroporation. Identifying the underlying molecular mechanisms of CRHR1 action, we find that CRHR1 functions are accomplished through the increasing expression of the master transcription factor REST. Furthermore, luciferase reporter and chromatin immunoprecipitation assays reveal that CRHR1-induced CREB activity is responsible for increased REST expression at the transcriptional level. Taken together, these findings indicate that the CRHR1/CREB/REST signaling cascade plays an important role downstream of CRH in the regulation of neural stem cells during embryonic brain development.

Corticotropin Releasing Factor Mediates KCa3.1 Inhibition, Hyperexcitability, and Seizures in Acquired Epilepsy

Temporal lobe epilepsy (TLE), the most common focal seizure disorder in adults, can be instigated in experimental animals by convulsant-induced status epilepticus (SE). Principal hippocampal neurons from SE-experienced epileptic male rats (post-SE neurons) display markedly augmented spike output compared with neurons from nonepileptic animals (non-SE neurons). This enhanced firing results from a cAMP-dependent protein kinase A-mediated inhibition of KCa3.1, a subclass of Ca2+-gated K+ channels generating the slow afterhyperpolarizing Ca2+-gated K+ current (IsAHP). The inhibition of KCa3.1 in post-SE neurons leads to a marked reduction in amplitude of the IsAHP that evolves during repetitive firing, as well as in amplitude of the associated Ca2+-dependent component of the slow afterhyperpolarization potential (KCa-sAHP). Here we show that KCa3.1 inhibition in post-SE neurons is induced by corticotropin releasing factor (CRF) through its Type 1 receptor (CRF1R). Acute application of CRF1R antagonists restores KCa3.1 activity in post-SE neurons, normalizing KCa-sAHP/IsAHP amplitudes and neuronal spike output, without affecting these variables in non-SE neurons. Moreover, pharmacological antagonism of CRF1Rs in vivo reduces the frequency of spontaneous recurrent seizures in post-SE chronically epileptic rats. These findings may provide a new vista for treating TLE.SIGNIFICANCE STATEMENT Epilepsy, a common neurologic disorder, often develops following a brain insult. Identifying key cellular mechanisms underlying acquired epilepsy is critical for developing effective antiepileptic therapies. In an experimental model of acquired epilepsy, principal hippocampal neurons manifest hyperexcitability because of downregulation of KCa3.1, a subtype of Ca2+-gated K+ ion channels. We show that KCa3.1 downregulation is mediated by corticotropin releasing factor (CRF) acting through its Type 1 receptor (CRF1R). Congruently, acute application of selective CRF1R antagonists restores KCa3.1 channel activity, leading to normalization of neuronal excitability. In the same model, injection of a CRF1R antagonist to epileptic animals markedly decreases the frequency of electrographic seizures. Therefore, targeting CRF1Rs may provide a new strategy in the treatment of acquired epilepsy.

Basolateral amygdala corticotropin-releasing factor receptor type 1 regulates context-cocaine memory strength during reconsolidation in a sex-dependent manner

The basolateral amygdala (BLA) is a critical brain region for cocaine-memory reconsolidation. Corticotropin-releasing factor receptor type 1 (CRFR1) is densely expressed in the BLA, and CRFR1 stimulation can activate intra-cellular signaling cascades that mediate memory reconsolidation. Hence, we tested the hypothesis that BLA CRFR1 stimulation is necessary and sufficient for cocaine-memory reconsolidation. Using an instrumental model of drug relapse, male and female Sprague-Dawley rats received cocaine self-administration training in a distinct environmental context over 10 days followed by extinction training in a different context over 7 days. Next, rats were re-exposed to the cocaine-paired context for 15 min to initiate cocaine-memory retrieval and destabilization. Immediately or 6 h after this session, the rats received bilateral vehicle, antalarmin (CRFR1 antagonist; 500 ng/hemisphere), or corticotropin-releasing factor (CRF; 0.2, 30 or 500 ng/hemisphere) infusions into the BLA. Resulting changes in drug context-induced cocaine seeking (index of context-cocaine memory strength) were assessed three days later. Female rats self-administered more cocaine infusions and exhibited more extinction responding than males. Intra-BLA antalarmin treatment immediately after memory retrieval (i.e., when cocaine memories were labile), but not 6 h later (i.e., after memory reconsolidation), attenuated drug context-induced cocaine seeking at test independent of sex, relative to vehicle. Conversely, intra-BLA CRF treatment increased this behavior selectively in females, in a U-shaped dose-dependent fashion. In control experiments, a high (behaviorally ineffective) dose of CRF treatment did not reduce BLA CRFR1 cell-surface expression in females. Thus, BLA CRFR1 signaling is necessary and sufficient, in a sex-dependent manner, for regulating cocaine-memory strength.

Restraint stress and elevation of corticotrophin-releasing hormone in female mice impair oocyte competence through activation of the tumour necrosis factor α (TNF-α) system

Studies have observed that restraint stress (RS) and the associated elevation in corticotrophin-releasing hormone (CRH) impair oocyte competence by triggering apoptosis of ovarian cells but the underlying mechanisms are largely unclear. Although one study demonstrated that RS and CRH elevation triggered apoptosis in ovarian cells and oocytes via activating Fas/FasL signalling, other studies suggested that RS might damage cells by activating other pathways as well as Fas signalling. The objective of this study was to test whether RS and CRH elevation impairs oocytes by activating tumour necrosis factor α (TNF-α) signalling. Our invivo experiments showed that RS applied during oocyte prematuration significantly increased expression of TNF-α and its receptor (TNFR1) while inducing apoptosis in both oocytes and mural granulosa cells (MGCs). Invitro treatment of MGCs with CRH significantly increased their apoptotic percentages and levels of TNF-α and TNFR1 expression. Invitro knockdown by interfering RNA, invivo knockout of the TNF-α gene or injection of TNF-α antagonist etanercept significantly relieved the adverse effects of RS and CRH on apoptosis of MGCs and/or the developmental potential and apoptosis of oocytes. The results suggest that RS and CRH elevation in females impair oocyte competence through activating TNF-α signalling and that a TNF-α antagonist might be adopted to ameliorate the adverse effects of psychological stress on oocytes.

A CRHR1 antagonist prevents synaptic loss and memory deficits in a trauma-induced delirium-like syndrome

Older patients with severe physical trauma are at high risk of developing neuropsychiatric syndromes with global impairment of cognition, attention, and consciousness. We employed a thoracic trauma (TxT) mouse model and thoroughly analyzed age-dependent spatial and temporal posttraumatic alterations in the central nervous system. Up to 5 days after trauma, we observed a transient 50% decrease in the number of excitatory synapses specifically in hippocampal pyramidal neurons accompanied by alterations in attention and motor activity and disruption of contextual memory consolidation. In parallel, hippocampal corticotropin-releasing hormone (CRH) expression was highly upregulated, and brain-derived neurotrophic factor (BDNF) levels were significantly reduced. In vitro experiments revealed that CRH application induced neuronal autophagy with rapid lysosomal degradation of BDNF via the NF-κB pathway. The subsequent synaptic loss was rescued by BDNF as well as by specific NF-κB and CRH receptor 1 (CRHR1) antagonists. In vivo, the chronic application of a CRHR1 antagonist after TxT resulted in reversal of the observed histological, molecular, and behavioral alterations. The data suggest that neuropsychiatric syndromes (i.e., delirium) after peripheral trauma might be at least in part due to the activation of the hippocampal CRH/NF-κB/BDNF pathway, which results in a dramatic loss of synaptic contacts. The successful rescue by stress hormone receptor antagonists should encourage clinical trials focusing on trauma-induced delirium and/or other posttraumatic syndromes.

Involvement of the ventral, but not dorsal, hippocampus in anxiety-like behaviors in mice exposed to the elevated plus maze: participation of CRF1 receptor and PKA pathway

BACKGROUND

The hippocampus is a limbic structure involved in anxiety-like behaviors. We aimed to evaluate the role of the dorsal (DH) and ventral (VH) hippocampus in anxiety-like behaviors in the elevated plus maze (EPM).

METHODS

We inhibited these brain regions using cobalt chloride (CoCl₂: 1.0 nmol) microinjections. We also investigated the involvement of corticotropin-releasing factor (CRF) action and protein kinase A (PKA) pathway using intra-DH and intra-VH microinjections of the CRF1 receptor antagonist CP376395 (0, 3.0, or 6.0 nmol) and the PKA inhibitor H-89 (0, 2.5, or 5.0 nmol).

RESULTS

The results indicated that intra-VH CoCl₂ microinjection increased the percentage of time spent and entries in the open arms. The mice also exhibited fewer stretch attend postures in the protected area and increased percentage of open arm entries. Further, intra-VH injection of 3.0 nmol CP376395 increased time spent in the open arms. Intra-DH injection of 6.0 nmol CP376395 increased the frequency of unprotected head dipping, whereas intra-VH injection of 6 nmol CP376395 increased the frequency of protected head dipping. Intra-VH, but not intra-DH, microinjection of 2.5 nmol H-89 increased the percentages of open arm entries and time spent in the open arms. Microinjection of 2.5 and 5.0 nmol H-89 reduced the frequency of protected head dipping behavior.

CONCLUSIONS

This study demonstrated that VH modulates anxiety-like behaviors in EPM. Moreover, CRF and the cAMP/PKA pathway seem to modulate these effects.

The blockade of corticotropin-releasing factor 1 receptor attenuates anxiety-related symptoms and hypothalamus-pituitary-adrenal axis reactivity in mice with mild traumatic brain injury

Recent studies have shown that mild traumatic brain injury (mTBI) is associated with higher risk for anxiety-related disorders. Dysregulation in the hypothalamus-pituitary-adrenal (HPA) axis following mTBI has been proposed to be involved in the development of neurobehavioral abnormalities; however, the underlying mechanisms are largely unknown. The aim of this study was to determine whether the corticotropin-releasing-factor-1 (CRF-1) receptor is involved in the regulation of anxiety-related symptoms in a mouse model of mTBI. Animals with or without mTBI received intracerebroventricular injections of a CRF-1 receptor agonist (CRF; 0.01 nmol/mouse) or antagonist (antalarmin; 1 µg/mouse) for 5 days, and then the animals were subjected to anxiety tests (light-dark box and zero maze). The levels of adrenocorticotropic hormone and corticosterone, the most important markers of HPA axis, were also measured after behavioral tests. Our results indicated that mTBI-induced anxiety-related symptoms in mice through increased levels of adrenocorticotropic hormone and corticosterone, showing HPA axis hyperactivity. Interestingly, activation of CRF receptor by a subthreshold dose of CRF resulted in significant increases in anxiety-like behaviors and HPA axis response to stress, whereas blockade of CRF receptors by a subthreshold dose of antalarmin decreased anxiety-related symptoms and HPA axis response to stress in mTBI-induced mice. Collectively, these findings suggest that the CRF-1 receptor plays an important role in the regulation of anxiety-related behaviors following mTBI induction in mice and support the hypothesis that blockade of the CRF-1 receptor may be a promising therapeutic target for anxiety-related disorders in patients with TBI.

[Modern concepts of pathogenetic therapy of anxiety disorders]

The high prevalence of anxiety disorders around the world leads to a high interest in the study of anxiety. At the moment, a lot of knowledge about the pathogenesis and therapy of anxiety disorders has been accumulated, which is well covered in modern domestic and world medical literature. It is known that many areas of the brain are involved in the modulation of anxiety, among which the amygdala is considered the key in the modulation of anxiety and fear. A large body of evidence supports the involvement of different neurotransmitter systems in the processes of anxiogenesis-anxiolysis (GABA, monoamines, glutamate, neuropeptides, neurosteroids). This article provides an analysis of methods of pharmacological impact on each of these systems, which serve to optimize the already known strategies of anxiolytic therapy.

Deletion of CRH From GABAergic Forebrain Neurons Promotes Stress Resilience and Dampens Stress-Induced Changes in Neuronal Activity

Dysregulation of the corticotropin-releasing hormone (CRH) system has been implicated in stress-related psychopathologies such as depression and anxiety. Although most studies have linked CRH/CRH receptor 1 signaling to aversive, stress-like behavior, recent work has revealed a crucial role for distinct CRH circuits in maintaining positive emotional valence and appetitive responses under baseline conditions. Here we addressed whether deletion of CRH, specifically from GABAergic forebrain neurons (Crh ^CKO-GABA mice) differentially affects general behavior under baseline and chronic stress conditions. Expression mapping in Crh ^{CK O-GABA} mice revealed absence of Crh in GABAergic neurons of the cortex and limbic regions including the hippocampus, central nucleus of the amygdala and the bed nucleus of the stria terminals, but not in the paraventricular nucleus of hypothalamus. Consequently, conditional CRH knockout animals exhibited no alterations in circadian and stress-induced corticosterone release compared to controls. Under baseline conditions, absence of Crh from forebrain GABAergic neurons resulted in social interaction deficits but had no effect on other behavioral measures including locomotion, anxiety, immobility in the forced swim test, acoustic startle response and fear conditioning. Interestingly, following exposure to chronic social defeat stress, Crh ^CKO-GABA mice displayed a resilient phenotype, which was accompanied by a dampened, stress-induced expression of immediate early genes c-fos and zif268 in several brain regions. Collectively our data reveals the requirement of GABAergic CRH circuits in maintaining appropriate social behavior in naïve animals and further supports the ability of CRH to promote divergent behavioral states under baseline and severe stress conditions.

Role of corticotropin-releasing factor on bladder function in rats with psychological stress

Stress-related peptide corticotropin-releasing factor (CRF) and CRF-related peptides are distributed in the peripheral viscera such as the bladder. We investigated the contribution of psychological stress (PS) and CRF on bladder function. Male rats received sham stress (SS) or PS using a communication box method for 120 min every day for 7 days. One group of rats received the intraperitoneal CRF-R1 antagonist antalarmin for 7 days during stress exposure. Mean voided volume per micturition was significantly lower in PS rats compared to SS rats, which was antagonized by antalarmin treatment. Increases in plasma and bladder CRF, and mRNA expressions of bladder CRF, CRF-R1, and M2/3 muscarinic receptors, were found in PS rats. CRF did not influence bladder contraction in itself; however, stress increased the response of muscarinic contraction of bladder strips. These changes were antagonized by antalarmin treatment. In conclusion, PS reinforces M3 receptor-mediated contractions via CRF-R1, resulting in bladder storage dysfunction.

Emotional Stress Facilitates Micturition Reflex: Possible Inhibition by an α1-Adrenoceptor Blocker in the Conscious and Anesthetized State

Purpose

To test the hypothesis that naftopidil prolongs intercontraction intervals in rats undergoing chronic stress as observed in previous animal models, voiding behavior and bladder function were measured and analyzed.

Methods

Female Sprague-Dawley rats weighing 200–230 g were exposed to repeated variate stress (RVS) for 1 week, chronic variable mild stress for 2 weeks, or simple mild stress for 1 week. Voiding behavior was assessed in metabolic cages. Voiding frequency and urine output were measured, and changes of these values were compared for the different types of stress. Micturition reflex was analyzed using unconscious cystometry. Naftopidil was administered orally at 30 mg/kg/day for 2 weeks.

Results

Unexpectedly, no stress-exposed rats exhibited increased micturition frequency compared to the normal nonstressed control. However, intercontraction intervals were shortened with each type of stress in the unconscious condition, especially by RVS (P<0.01). Naftopidil prolonged the shortened intervals.

Conclusions

Although voiding behavior appears approximately normal in rats chronically exposed to emotional stress, internal bladder function can be affected. With anesthesia, micturition intervals were moderately shortened by emotional stress and clearly improved by naftopidil. Therefore, naftopidil appears to act at the spinal level at least.

Corticotropin-Releasing Factor in the Brain and Blocking Spinal Descending Signals Induce Hyperalgesia in the Latent Sensitization Model of Chronic Pain

Latent sensitization is a model of chronic pain in which an injury triggers a period of hyperalgesia followed by an apparent recovery, but in which pain sensitization persists but is suppressed by opioid and adrenergic receptors. One important characteristic of latent sensitization is that hyperalgesia can be triggered by acute stress. To determine whether the effect of stress is mimicked by the activation of corticotropin-releasing factor (CRF) signaling in the brain, rats with latent sensitization induced by injecting complete Freund's adjuvant (CFA, 50 μl) in one hind paw were given an intracerebroventricular (i.c.v.) injection of CRF. The i.c.v. injection of CRF (0.6 μg, 10 μl), but not saline, induced bilateral mechanical hyperalgesia in rats with latent sensitization. In contrast, CRF i.c.v. did not induce hyperalgesia in rats without latent sensitization (injected with saline in the hind paw). To determine whether descending pain inhibition mediates the suppression of hyperalgesia in latent sensitization, rats with CFA-induced latent sensitization received an intrathecal injection of lidocaine (10%, 1 μl) at the cervical-thoracic spinal cord to produce a spinal block. Lidocaine-injected rats, but not rats injected intrathecally with saline, developed bilateral mechanical hyperalgesia. Intrathecal lidocaine did not induce hyperalgesia in rats without latent sensitization (injected with saline in the hind paw). These results show that i.c.v. CRF mimicked the hyperalgesic response triggered by stress during latent sensitization, possibly by blocking inhibitory spinal descending signals that suppress hyperalgesia.

Brain corticotropin-releasing factor signaling: Involvement in acute stress-induced visceral analgesia in male rats

BACKGROUND

Water avoidance stress (WAS) induces a naloxone-independent visceral analgesia in male rats under non-invasive conditions of monitoring. The objective of the study was to examine the role of brain CRF signaling in acute stress-induced visceral analgesia (SIVA).

METHODS

Adult male Sprague-Dawley rats were chronically implanted with an intracerebroventricular (ICV) cannula. The visceromotor response (VMR) to graded phasic colorectal distension (CRD: 10, 20, 40, 60 mm Hg, 20 seconds, 4 minutes intervals) was monitored using manometry. The VMR to a first CRD (baseline) was recorded 5 minutes after an ICV saline injection, followed 1 hour later by ICV injection of either CRF (30, 100, or 300 ng and 1, 3, or 5 μg/rat) or saline and a second CRD, 5 minutes later. Receptor antagonists against CRF₁ /CRF₂ (astressin-B, 30 μg/rat), CRF₂ (astressin₂ -B, 10 μg/rat), oxytocin (tocinoic acid, 20 μg/rat), or vehicle were injected ICV 5 minutes before CRF (300 ng/rat, ICV) or 15 minutes before WAS (1 hour).

KEY RESULTS

ICV CRF (100 and 300 ng) reduced the VMR to CRD at 60 mm Hg by -36.6% ± 6.8% and -48.7% ± 11.7%, respectively, vs baseline (P < 0.001), while other doses had no effect and IP CRF (10 µg/kg) induced visceral hyperalgesia. Astressin-B and tocinoic acid injected ICV induced hyperalgesia and prevented the analgesic effect of ICV CRF (300 ng/rat) and WAS, while astressin₂ -B only blocked WAS-induced SIVA.

CONCLUSIONS & INFERENCES

These data support a role for brain CRF signaling via CRF₂ in SIVA in a model of WAS and CRD likely mediated by the activation of brain oxytocin pathway.

Enhancing the Utility of Preclinical Research in Neuropsychiatry Drug Development

Most large pharmaceutical companies have downscaled or closed their clinical neuroscience research programs in response to the low clinical success rate for drugs that showed tremendous promise in animal experiments intended to model psychiatric pathophysiology. These failures have raised serious concerns about the role of preclinical research in the identification and evaluation of new pharmacotherapies for psychiatry. In the absence of a comprehensive understanding of the neurobiology of psychiatric disorders, the task of developing "animal models" seems elusive. The purpose of this review is to highlight emerging strategies to enhance the utility of preclinical research in the drug development process. We address this issue by reviewing how advances in neuroscience, coupled with new conceptual approaches, have recently revolutionized the way we can diagnose and treat common psychiatric conditions. We discuss the implications of these new tools for modeling psychiatric conditions in animals and advocate for the use of systematic reviews of preclinical work as a prerequisite for conducting psychiatric clinical trials. We believe that work in animals is essential for elucidating human psychopathology and that improving the predictive validity of animal models is necessary for developing more effective interventions for mental illness.

Brain and Gut CRF Signaling: Biological Actions and Role in the Gastrointestinal Tract

BACKGROUND

Corticotropin-releasing factor (CRF) pathways coordinate behavioral, endocrine, autonomic and visceral responses to stress. Convergent anatomical, molecular, pharmacological and functional experimental evidence supports a key role of brain CRF receptor (CRF-R) signaling in stress-related alterations of gastrointestinal functions. These include the inhibition of gastric acid secretion and gastric-small intestinal transit, stimulation of colonic enteric nervous system and secretorymotor function, increase intestinal permeability, and visceral hypersensitivity. Brain sites of CRF actions to alter gut motility encompass the paraventricular nucleus of the hypothalamus, locus coeruleus complex and the dorsal motor nucleus while those modulating visceral pain are localized in the hippocampus and central amygdala. Brain CRF actions are mediated through the autonomic nervous system (decreased gastric vagal and increased sacral parasympathetic and sympathetic activities). The activation of brain CRF-R2 subtype inhibits gastric motor function while CRF-R1 stimulates colonic secretomotor function and induces visceral hypersensitivity. CRF signaling is also located within the gut where CRF-R1 activates colonic myenteric neurons, mucosal cells secreting serotonin, mucus, prostaglandin E2, induces mast cell degranulation, enhances mucosal permeability and propulsive motor functions and induces visceral hyperalgesia in animals and humans. CRF-R1 antagonists prevent CRF- and stressrelated gut alterations in rodents while not influencing basal state.

DISCUSSION

These preclinical studies contrast with the limited clinical positive outcome of CRF-R1 antagonists to alleviate stress-sensitive functional bowel diseases such as irritable bowel syndrome.

CONCLUSION

The translational potential of CRF-R1 antagonists in gut diseases will require additional studies directed to novel anti-CRF therapies and the neurobiology of brain-gut interactions under chronic stress.

Neuropeptide and steroid hormone mediators of neuroendocrine regulation

To maintain the health and well-being of all mammals, numerous aspects of physiology are controlled by neuroendocrine mechanisms. These mechanisms ultimately enable communication between neurones and glands throughout the body and are centrally mediated by neuropeptides and/or steroid hormones. A recent session at the International Workshop in Neuroendocrinology highlighted the essential roles of some of these neuropeptide and steroid hormone mediators in the neuroendocrine regulation of stress-, reproduction- and behaviour-related processes. Accordingly, the present review highlights topics presented in this session, including the role of the neuropeptides corticotrophin-releasing factor and gonadotrophin-releasing hormone in stress and reproductive physiology, respectively. Additionally, it details an important role for gonadal sex steroids in the development of behavioural sex preference.

The Corticotropin-Releasing Factor Family: Physiology of the Stress Response

The physiological stress response is responsible for the maintenance of homeostasis in the presence of real or perceived challenges. In this function, the brain activates adaptive responses that involve numerous neural circuits and effector molecules to adapt to the current and future demands. A maladaptive stress response has been linked to the etiology of a variety of disorders, such as anxiety and mood disorders, eating disorders, and the metabolic syndrome. The neuropeptide corticotropin-releasing factor (CRF) and its relatives, the urocortins 1–3, in concert with their receptors (CRFR1, CRFR2), have emerged as central components of the physiological stress response. This central peptidergic system impinges on a broad spectrum of physiological processes that are the basis for successful adaptation and concomitantly integrate autonomic, neuroendocrine, and behavioral stress responses. This review focuses on the physiology of CRF-related peptides and their cognate receptors with the aim of providing a comprehensive up-to-date overview of the field. We describe the major molecular features covering aspects of gene expression and regulation, structural properties, and molecular interactions, as well as mechanisms of signal transduction and their surveillance. In addition, we discuss the large body of published experimental studies focusing on state-of-the-art genetic approaches with high temporal and spatial precision, which collectively aimed to dissect the contribution of CRF-related ligands and receptors to different levels of the stress response. We discuss the controversies in the field and unravel knowledge gaps that might pave the way for future research directions and open up novel opportunities for therapeutic intervention.

Anxiety, Depression, and the Microbiome: A Role for Gut Peptides

The complex bidirectional communication between the gut and the brain is finely orchestrated by different systems, including the endocrine, immune, autonomic, and enteric nervous systems. Moreover, increasing evidence supports the role of the microbiome and microbiota-derived molecules in regulating such interactions; however, the mechanisms underpinning such effects are only beginning to be resolved. Microbiota-gut peptide interactions are poised to be of great significance in the regulation of gut-brain signaling. Given the emerging role of the gut-brain axis in a variety of brain disorders, such as anxiety and depression, it is important to understand the contribution of bidirectional interactions between peptide hormones released from the gut and intestinal bacteria in the context of this axis. Indeed, the gastrointestinal tract is the largest endocrine organ in mammals, secreting dozens of different signaling molecules, including peptides. Gut peptides in the systemic circulation can bind cognate receptors on immune cells and vagus nerve terminals thereby enabling indirect gut-brain communication. Gut peptide concentrations are not only modulated by enteric microbiota signals, but also vary according to the composition of the intestinal microbiota. In this review, we will discuss the gut microbiota as a regulator of anxiety and depression, and explore the role of gut-derived peptides as signaling molecules in microbiome-gut-brain communication. Here, we summarize the potential interactions of the microbiota with gut hormones and endocrine peptides, including neuropeptide Y, peptide YY, pancreatic polypeptide, cholecystokinin, glucagon-like peptide, corticotropin-releasing factor, oxytocin, and ghrelin in microbiome-to-brain signaling. Together, gut peptides are important regulators of microbiota-gut-brain signaling in health and stress-related psychiatric illnesses.

Intermittent Access to Ethanol Induces Escalated Alcohol Consumption in Primates

BACKGROUND

Escalation of voluntary alcohol drinking is characteristic of alcohol addiction and can be induced in rodents using intermittent access to alcohol. This model has been used to evaluate candidate therapeutics, but key systems involved in the transition into alcohol addiction, such as CRF, differ in their organization between rodents and primates. We examined the ability of an intermittent access schedule to induce escalation of voluntary alcohol drinking in non-human primates and used this model to assess the role of corticotropin releasing hormone (CRF) signaling in this process.

METHODS

Four young adult male rhesus macaques were given access to an 8.4% alcohol solution every other weekday (EOD; M, W, F), while four other young adult males were given the same solution every weekday (ED; M-F). Subjects were then administered a CRF1 antagonist, antalarmin.

RESULTS

EOD increased alcohol intake by up to 50% over baseline, with a more pronounced increase immediately following reintroduction of alcohol. For the morning/daytime sessions, EOD subjects increased their consumption by 83% over baseline. Differences between ED and EOD schedules emerged quickly, and EOD-induced escalation resulted in pharmacologically active BAC's. EOD-induced alcohol consumption was insensitive to CRFR1 blockade by antalarmin, but subjects with high CSF levels of CRF were more responsive.

CONCLUSIONS

Similar to what has been observed in rodents, intermittent access results in an escalation of voluntary alcohol drinking in non-human primates. In contrast to findings in rats, recruitment of the CRF system does not seem to be involved in the escalated alcohol drinking observed under these conditions, though individual differences in CRF system activity may play a role.

Are carriers of CYP21A2 mutations less vulnerable to psychological stress? A population-based national cohort study

BACKGROUND

Congenital adrenal hyperplasia (CAH) is one of the most common monogenic autosomal recessive disorders with an incidence of one in 15 000. About one in 70 individuals in the general population are carriers of a severe CYP21A2 mutation. It has been suggested that this confers a survival advantage, perhaps as a result of increased activity in the hypothalamic-pituitary-adrenal axis. We investigated vulnerability to psychological stress in obligate carriers.

METHOD

The Swedish CAH Registry encompasses more than 600 patients. Parents, that is obligate carriers of the CYP21A2 mutation, were identified through the Multigeneration Register. The diagnosis of the child was used as the psychological stressor. Psychiatric diagnoses before and after the birth of a child with CAH were compared to those of controls derived from (i) the general population, (ii) parents of children with hypospadias and (iii) parents of children with diabetes mellitus type 1 (T1DM).

RESULTS

Parents of children with CAH had less risk of being diagnosed with any psychiatric disorder (OR, 0·6), an affective disorder (OR, 0·5) or substance misuse (OR, 0·5) after the diagnosis of the child, compared to the general population. Their risk was also decreased compared to parents of a child with hypospadias (OR, 0·6, 0·4 and 0·2, respectively) and parents of a child with T1DM (OR 0·7, 0·6 and 0·2, respectively). The CYP21A2 carriers had a lower risk of developing mood and stress-related disorders after the diagnosis of the child.

CONCLUSION

Obligate CYP21A2 carriers had a reduced risk of a psychiatric diagnosis and were less vulnerable to a psychologically stressful situation, at least with respect to receiving a psychiatric diagnosis. This indicates a better ability to cope with psychological stress among heterozygous carriers of severe CYP21A2 mutations, which may contribute to the apparent survival advantage.

Personality Traits in the Siblings and Children of Patients with Frontotemporal Dementia: A Questionnaire-based Study

INTRODUCTION

Frontotemporal dementias (FLD) form a group of relatively young onset, male dominant dementias with significant behavioral abnormalities early in the course of the disease. Routine assessment suggested preexisting traits such as lack of empathy, self-directedness, and persistence in most of these persons even before the onset of disease. Hence, we decided the study, the siblings and children of patients for any specific traits and correlation with hexanucleotide expansion repeats if any traits were identified.

PATIENTS AND METHODS

A total of 35 age- and gender-matched cases and controls were included for the study as per criteria. They were screened for mental illness and cognitive dysfunction using Hindi Mental State Examination and Mini-mental State Examination. Eligible persons were given temperament and character inventory (TCI) scores for the recommended parameters. Hexanucleotide expansion was also studied in the patients, cases and controls.

RESULTS

No specific personality trait was found to have an increased correlation with siblings and children of patients with FLD in this small group using TCI scores.

CONCLUSIONS

7% of cases showed Hexanucleotide expansion suggesting a possible risk. The role of self reporting bias resulting in normal personality trait needs to be addressed in future studies.

Chronic distress and the vulnerable host: a new target for HIV treatment and prevention?

Pathologic stress (distress) disturbs immune, cardiovascular, metabolic, and behavioral homeostasis. Individuals living with HIV and those at risk are vulnerable to stress disorders. Corticotropin-releasing hormone (CRH) is critical in neuroendocrine immune regulation. CRH, a neuropeptide, is distributed in the central and peripheral nervous systems and acts principally on CRH receptor type 1 (CRHR1). CRH in the brain modulates neuropsychiatric disorders. CRH and stress modulation of immunity is two-pronged; there is a direct action on hypothalamic-pituitary-adrenal secretion of glucocorticoids and through immune organ sympathetic innervation. CRH is a central and systemic proinflammatory cytokine. Glucocorticoids and their receptors have gene regulatory actions on viral replication and cause central and systemic immune suppression. CRH and stress activation contributes to central nervous system (CNS) viral entry important in HIV-associated neurocognitive disorders and HIV-associated dementia. CNS CRH overproduction short-circuits reward, executive, and emotional control, leading to addiction, cognitive impairment, and psychiatric comorbidity. CRHR1 is an important therapeutic target for medication development. CRHR1 antagonist clinical trials have focused on psychiatric disorders with little attention paid to neuroendocrine immune disorders. Studies of those with HIV and those at risk show that concurrent stress-related disorders contribute to higher morbidity and mortality; stress-related conditions, addiction, immune dysfunction, and comorbid psychiatric illness all increase HIV transmission. Neuropsychiatric disease, chronic inflammation, and substance abuse are endemic, and chronic distress is a pathologic factor. It is being understood that stress and CRH are fundamental to neuroendocrine immunity; therapeutic interventions with existing and novel agents hold promise for restoring homeostasis, reducing morbidity and mortality for those with HIV and possibly reducing future disease transmission.

HPA Axis Interactions with Behavioral Systems

Perhaps the most salient behaviors that individuals engage in involve the avoidance of aversive experiences and the pursuit of pleasurable experiences. Engagement in these behaviors is regulated to a significant extent by an individual's hormonal milieu. For example, glucocorticoid hormones are produced by the hypothalamic-pituitary-adrenocortical (HPA) axis, and influence most aspects of behavior. In turn, many behaviors can influence HPA axis activity. These bidirectional interactions not only coordinate an individual's physiological and behavioral states to each other, but can also tune them to environmental conditions thereby optimizing survival. The present review details the influence of the HPA axis on many types of behavior, including appetitively-motivated behaviors (e.g., food intake and drug use), aversively-motivated behaviors (e.g., anxiety-related and depressive-like) and cognitive behaviors (e.g., learning and memory). Conversely, the manuscript also describes how engaging in various behaviors influences HPA axis activity. Our current understanding of the neuronal and/or hormonal mechanisms that underlie these interactions is also summarized. © 2016 American Physiological Society. Compr Physiol 6:1897-1934, 2016.

Factors influencing alopecia and hair cortisol in rhesus macaques (Macaca mulatta)

BACKGROUND

Alopecia can occur in captive non-human primates, but its etiology is poorly understood. The purpose of this study was to assess alopecia and hair cortisol in rhesus monkeys and to identify the potential risk factors.

METHODS

Subjects were 117 rhesus monkeys at two National Primate Research Centers. Photographs and hair samples were obtained during routine physicals. Photographs were analyzed using Image J software to calculate hair loss, and hair samples were assayed for cortisol.

RESULTS

Age, days singly housed, and their interactions contributed to the alopecia model for both facilities. Sex and location changes contributed to the hair cortisol model for Facility 1; sedations contributed for Facility 2. Alopecia and hair cortisol were associated at Facility 1.

CONCLUSIONS

Captive management practices can affect alopecia and hair cortisol. However, there are facility differences in the relationship between alopecia and hair cortisol and in the effect of intrinsic variables and management procedures.

Stress increases GABAergic neurotransmission in CRF neurons of the central amygdala and bed nucleus stria terminalis

Corticotrophin Releasing Factor (CRF) is a critical stress-related neuropeptide in major output pathways of the amygdala, including the central nucleus (CeA), and in a key projection target of the CeA, the bed nucleus of the stria terminalis (BnST). While progress has been made in understanding the contributions and characteristics of CRF as a neuropeptide in rodent behavior, little attention has been committed to determine the properties and synaptic physiology of specific populations of CRF-expressing (CRF(+)) and non-expressing (CRF(-)) neurons in the CeA and BnST. Here, we fill this gap by electrophysiologically characterizing distinct neuronal subtypes in CeA and BnST. Crossing tdTomato or channelrhodopsin-2 (ChR2-YFP) reporter mice to those expressing Cre-recombinase under the CRF promoter allowed us to identify and manipulate CRF(+) and CRF(-) neurons in CeA and BnST, the two largest areas with fluorescently labeled neurons in these mice. We optogenetically activated CRF(+) neurons to elicit action potentials or synaptic responses in CRF(+) and CRF(-) neurons. We found that GABA is the predominant co-transmitter in CRF(+) neurons within the CeA and BnST. CRF(+) neurons are highly interconnected with CRF(-) neurons and to a lesser extent with CRF(+) neurons. CRF(+) and CRF(-) neurons differentially express tonic GABA currents. Chronic, unpredictable stress increase the amplitude of evoked IPSCs and connectivity between CRF(+) neurons, but not between CRF(+) and CRF(-) neurons in both regions. We propose that reciprocal inhibition of interconnected neurons controls CRF(+) output in these nuclei.

Assessing anxiety in nonhuman primates

Anxiety can be broadly described as a psychological state in which normally innocuous environmental stimuli trigger negative emotional expectations. Human anxiety disorders are multidimensional and may be organic or acquired, situational or pervasive. The broad ranging nature of the anxiety phenotype speaks to the need for models that identify its various components and root causes to develop effective clinical treatments. The cross-species comparative approach to modeling anxiety disorders in animals aims to understand mechanisms that both contribute to and modulate anxiety. Nonhuman primate models provide an important bridge from nonprimate model systems because of the complexity of nonhuman primates' biobehavioral capacities and their commonalities with human emotion. The broad goal of this review is to provide an overview of various procedures available to study anxiety in the nonhuman primate, with a focus on the behavioral aspects of anxiety. Commonly used methods covered in this review include assessing animals in their home environment or in response to an ethologically relevant threat, associative conditioning and startle response tests, and cognitive bias tests. We also discuss how these procedures can help veterinarians and researchers care for captive nonhuman primates.

Zinc in gut-brain interaction in autism and neurological disorders

A growing amount of research indicates that abnormalities in the gastrointestinal (GI) system during development might be a common factor in multiple neurological disorders and might be responsible for some of the shared comorbidities seen among these diseases. For example, many patients with Autism Spectrum Disorder (ASD) have symptoms associated with GI disorders. Maternal zinc status may be an important factor given the multifaceted effect of zinc on gut development and morphology in the offspring. Zinc status influences and is influenced by multiple factors and an interdependence of prenatal and early life stress, immune system abnormalities, impaired GI functions, and zinc deficiency can be hypothesized. In line with this, systemic inflammatory events and prenatal stress have been reported to increase the risk for ASD. Thus, here, we will review the current literature on the role of zinc in gut formation, a possible link between gut and brain development in ASD and other neurological disorders with shared comorbidities, and tie in possible effects on the immune system. Based on these data, we present a novel model outlining how alterations in the maternal zinc status might pathologically impact the offspring leading to impairments in brain functions later in life.

Redtail and red colobus monkeys show intersite urinary cortisol concentration variation in Kibale National Park, Uganda

Non-invasive measurement of urinary cortisol is a proven method of evaluating the impact of environmental stressors on wild primates. Variation in cortisol concentrations can reflect physiological stress, and prolonged elevation of circulating cortisol can significantly affect individual and population-level health. In a previous study, we found that urinary cortisol concentrations in grey-cheeked mangabeys (Lophocebus albigena) were higher at a highly disturbed site (Mainaro) in Kibale National Park, Uganda compared with a minimally disturbed site (Ngogo) in the same habitat. Here, we expand on this research, reporting on cortisol concentrations in two other cercopithecid monkeys (Cercopithecus ascanius and Piliocolobus rufomitratus) at the same two sites. We hypothesized that C. ascanius would show no difference between sites, given its preference for secondary forests, while P. rufomitratus would have higher cortisol concentrations at the disturbed site. Contrary to expectations, both species exhibited significantly higher cortisol concentrations at Ngogo (minimally disturbed) compared with Mainaro (disturbed). We suggest that these results may be caused by inter- or intragroup social dynamics, intersite differences in predation rate, fruit/food availability and chemistry, or a combination of these factors. These initial evaluations of urinary cortisol concentrations provide testable hypotheses on habitat disturbance and Kibale primate ecophysiology.

Corticotrophin-releasing factor 1 activation in the central amygdale and visceral hyperalgesia

Corticotropin-releasing factor (CRF)-CRF1 receptor in the brain plays a key role in stress-related alterations of behavior including anxiety/depression, and autonomic and visceral functions. In particular, CRF1 signaling mediates hypersensitivity to colorectal distension (CRD) in various models (early life adverse events, repeated psychological stress, chronic high anxiety, postcolonic inflammation, or repeated nociceptive CRD). So far, knowledge of brain sites involved is limited. A recent article demonstrates in rats that CRF microinjected into the central amygdala (CeA) induces a hyperalgesic response to CRD and enhances the noradrenaline and dopamine levels at this site. The visceral and noradrenaline, unlike dopamine, responses were blocked by a CRF1 antagonist injected into the CeA. Here, we review the emerging role that CRF-CRF1 signaling plays in the CeA to induce visceral hypersensitivity. In the somatic pain field, CRF in the CeA was shown to induce pain sensitization. This is mediated by the activation of postsynaptic CRF1 receptors and protein kinase A signaling that increases N-methyl-d-aspartate receptor neurotransmission. In addition, the activation of tetraethylamonium-sensitive ion channels such as Kv3 accelerates repolarization and firing rate. Whether facilitation of pain transmission underlies CRF action in the CeA-induced visceral hypersensitivity will need to be delineated. CRF1 signaling in the CeA is also an important component of the neuronal circuitry inducing anxiety-like behavior and positioned at the interphase of the reciprocal relationship between pain and affective state. The hyperactivity of this system may represent the neuroanatomical and biochemical substrate contributing to the coexpression of hypersensitivity to CRD and mood disorders in subsets of irritable bowel syndrome patients.

Antagonism of corticotrophin-releasing factor type 1 receptors attenuates caloric intake of free feeding subordinate female rhesus monkeys in a rich dietary environment

Social subordination in macaque females is a known chronic stressor and previous studies have shown that socially subordinate female rhesus monkeys consume fewer kilocalories than dominant animals when a typical laboratory chow diet is available. However, in a rich dietary environment that provides access to chow in combination with a more palatable diet (i.e. high in fat and refined sugar), subordinate animals consume significantly more daily kilocalories than dominant conspecifics. Substantial literature is available supporting the role of stress hormone signals in shaping dietary preferences and promoting the consumption of palatable, energy-dense foods. The present study was conducted using stable groups of adult female rhesus monkeys to test the hypothesis that pharmacological treatment with a brain penetrable corticotrophin-releasing factor type 1 receptor (CRF1) antagonist would attenuate the stress-induced consumption of a palatable diet among subordinate animals in a rich dietary environment but would be without effect in dominant females. The results show that administration of the CRF1 receptor antagonist significantly reduced daily caloric intake of both available diets among subordinate females compared to dominant females. Importantly, multiple regression analyses showed that the attenuation in caloric intake in response to Antalarmin (Sigma-Aldrich, St Louis, MO, USA) was significantly predicted by the frequency of submissive and aggressive behaviour emitted by females, independent of social status. Taken together, the findings support the involvement of activation of CRF1 receptors in the stress-induced consumption of excess calories in a rich dietary environment and also support the growing literature concerning the importance of CRF for sustaining emotional feeding.

Corticotropin releasing hormone and imaging, rethinking the stress axis

The stress system provides integration of both neurochemical and somatic physiologic functions within organisms as an adaptive mechanism to changing environmental conditions throughout evolution. In mammals and primates the complexity and sophistication of these systems have surpassed other species in triaging neurochemical and physiologic signaling to maximize chances of survival. Corticotropin releasing hormone (CRH) and its related peptides and receptors have been identified over the last three decades and are fundamental molecular initiators of the stress response. They are crucial in the top down regulatory cascade over a myriad of neurochemical, neuroendocrine and sympathetic nervous system events. From neuroscience, we've seen that stress activation impacts behavior, endocrine and somatic physiology and influences neurochemical events that one can capture in real time with current imaging technologies. To delineate these effects one can demonstrate how the CRH neuronal networks infiltrate critical cognitive, emotive and autonomic regions of the central nervous system (CNS) with somatic effects. Abundant preclinical and clinical studies show inter-regulatory actions of CRH with multiple neurotransmitters/peptides. Stress, both acute and chronic has epigenetic effects which magnify genetic susceptibilities to alter neurochemistry; stress system activation can add critical variables in design and interpretation of basic and clinical neuroscience and related research. This review will attempt to provide an overview of the spectrum of known functions and speculative actions of CRH and stress responses in light of imaging technology and its interpretation. Metabolic and neuroreceptor positron emission/single photon tomography (PET/SPECT), functional magnetic resonance imaging (fMRI), anatomic MRI, diffusion tensor imaging (DTI), and proton magnetic resonance spectroscopy (pMRS) are technologies that can delineate basic mechanisms of neurophysiology and pharmacology. Stress modulates the myriad of neurochemical and networks within and controlled through the central and peripheral nervous system and the effects of stress activation on imaging will be highlighted.

Concepts of scientific integrative medicine applied to the physiology and pathophysiology of catecholamine systems

This review presents concepts of scientific integrative medicine and relates them to the physiology of catecholamine systems and to the pathophysiology of catecholamine-related disorders. The applications to catecholamine systems exemplify how scientific integrative medicine links systems biology with integrative physiology. Concepts of scientific integrative medicine include (i) negative feedback regulation, maintaining stability of the body's monitored variables; (ii) homeostats, which compare information about monitored variables with algorithms for responding; (iii) multiple effectors, enabling compensatory activation of alternative effectors and primitive specificity of stress response patterns; (iv) effector sharing, accounting for interactions among homeostats and phenomena such as hyperglycemia attending gastrointestinal bleeding and hyponatremia attending congestive heart failure; (v) stress, applying a definition as a state rather than as an environmental stimulus or stereotyped response; (vi) distress, using a noncircular definition that does not presume pathology; (vii) allostasis, corresponding to adaptive plasticity of feedback-regulated systems; and (viii) allostatic load, explaining chronic degenerative diseases in terms of effects of cumulative wear and tear. From computer models one can predict mathematically the effects of stress and allostatic load on the transition from wellness to symptomatic disease. The review describes acute and chronic clinical disorders involving catecholamine systems-especially Parkinson disease-and how these concepts relate to pathophysiology, early detection, and treatment and prevention strategies in the post-genome era.

Sex differences in corticotropin-releasing factor receptor-1 action within the dorsal raphe nucleus in stress responsivity

BACKGROUND

Women are twice as likely as men to suffer from stress-related affective disorders. Corticotropin-releasing factor (CRF) is an important link between stress and mood, in part through its signaling in the serotonergic dorsal raphe (DR). Development of CRF receptor-1 (CRFr1) antagonists has been a focus of numerous clinical trials but has not yet been proven efficacious. We hypothesized that sex differences in CRFr1 modulation of DR circuits might be key determinants in predicting therapeutic responses and affective disorder vulnerability.

METHODS

Male and female mice received DR infusions of the CRFr1 antagonist, NBI 35965, or CRF and were evaluated for stress responsivity. Sex differences in indices of neural activation (cFos) and colocalization of CRFr1 throughout the DR were examined. Whole-cell patch-clamp electrophysiology assessed sex differences in serotonin neuron membrane characteristics and responsivity to CRF.

RESULTS

Males showed robust behavioral and hypothalamic-pituitary-adrenal axis responses to DR infusion of NBI 35965 and CRF, whereas females were minimally responsive. Sex differences were also found for both CRF-induced DR cFos and CRFr1 co-localization throughout the DR. Electrophysiologically, female serotonergic neurons showed blunted membrane excitability and divergent inhibitory postsynaptic current responses to CRF application.

CONCLUSIONS

These studies demonstrate convincing sex differences in CRFr1 activity in the DR, where blunted female responses to NBI 35965 and CRF suggest unique stress modulation of the DR. These sex differences might underlie affective disorder vulnerability and differential sensitivity to pharmacologic treatments developed to target the CRF system, thereby contributing to a current lack of CRFr1 antagonist efficacy in clinical trials.

The psyche and gastric functions

Although the idea that gastric problems are in some way related to mental activity dates back to the beginning of the last century, until now it has received scant attention by physiologists, general practitioners and gastroenterologists. The major breakthrough in understanding the interactions between the central nervous system and the gut was the discovery of the enteric nervous system (ENS) in the 19th century. ENS (also called 'little brain') plays a crucial role in the regulation of the physiological gut functions. Furthermore, the identification of corticotropin-releasing factor (CRF) and the development of specific CRF receptor antagonists have permitted to characterize the neurochemical basis of the stress response. The neurobiological response to stress in mammals involves three key mechanisms: (1) stress is perceived and processed by higher brain centers; (2) the brain mounts a neuroendocrine response by way of the hypothalamic-pituitary-adrenal axis (HPA) and the autonomic nervous system (ANS), and (3) the brain triggers feedback mechanisms by HPA and ANS stimulation to restore homeostasis. Various stressors such as anger, fear, painful stimuli, as well as life or social learning experiences affect both the individual's physiologic and gastric function, revealing a two-way interaction between brain and stomach. There is overwhelming experimental and clinical evidence that stress influences gastric function, thereby outlining the pathogenesis of gastric diseases such as functional dyspepsia, gastroesophageal reflux disease and peptic ulcer disease. A better understanding of the role of pathological stressors in the modulation of disease activity may have important pathogenetic and therapeutic implications.

CRF and urocortin peptides as modulators of energy balance and feeding behavior during stress

Early on, corticotropin-releasing factor (CRF), a hallmark brain peptide mediating many components of the stress response, was shown to affect food intake inducing a robust anorexigenic response when injected into the rodent brain. Subsequently, other members of the CRF signaling family have been identified, namely urocortin (Ucn) 1, Ucn 2, and Ucn 3 which were also shown to decrease food intake upon central or peripheral injection. However, the kinetics of feeding suppression was different with an early decrease following intracerebroventricular injection of CRF and a delayed action of Ucns contrasting with the early onset after systemic injection. CRF and Ucns bind to two distinct G-protein coupled membrane receptors, the CRF1 and CRF2. New pharmacological tools such as highly selective peptide CRF1 or CRF2 agonists or antagonists along with genetic knock-in or knock-out models have allowed delineating the primary role of CRF2 involved in the anorexic response to exogenous administration of CRF and Ucns. Several stressors trigger behavioral changes including suppression of feeding behavior which are mediated by brain CRF receptor activation. The present review will highlight the state-of-knowledge on the effects and mechanisms of action of CRF/Ucns-CRF1/2 signaling under basal conditions and the role in the alterations of food intake in response to stress.

Psychological reactivity to laboratory stress is associated with hormonal responses in postmenopausal women

OBJECTIVE

The present study examined associations between psychological reactivity and hormonal responses to a standardized laboratory stressor (Trier Social Stress Test, TSST) in postmenopausal women.

METHODS

Postmenopausal women aged 50-74 years undertook anxiety and mood assessments prior to and following the TSST. Blood samples were drawn at multiple timepoints for assessment of cortisol, adrenocorticotrophic hormone (ACTH) and dehydroepiandrosterone (DHEA).

RESULTS

Forty postmenopausal women completed the assessments. As expected, significant increases in anxiety and negative affect and decreases in positive affect were observed after the TSST; however, the magnitude of change in anxiety and mood varied considerably across individuals. Analyses indicated that greater increases in anxiety and negative affect after the TSST were associated with higher levels of cortisol, ACTH and DHEA after controlling for race, age, body mass index and smoking status. Changes in positive affect were not associated with cortisol, ACTH or DHEA.

CONCLUSIONS

These findings suggest that enhanced reactivity to stress is associated with higher hormone levels among postmenopausal women, which could have potential implications for health.

Behavioral responses to social separation stressor change across development and are dynamically related to HPA activity in marmosets

Psychosocial stressors activate two distinct stress-response systems, a central, behavioral response, and a peripheral, endocrine response. Both behavioral and endocrine responses to stressors are subject to individual and developmental variables, but it is not known whether stressor induced behaviors are stable across development, and how they correspond with changes in the endocrine component of the stress response. We characterized the development and stability of behavioral responses to a mild psychosocial stressor in marmosets (Callithrix geoffroyi), and assessed the degree to which the behavioral and endocrine stress-response systems were co-activated. The behavioral response to stressors was stable within individuals, but only some stressor-induced behaviors changed as the monkeys developed. Overall, there was more variability in the development of behavioral responses compared to stress-induced endocrine profiles found previously [French et al., 2012. Horm Behav 61:196-203]. In young marmosets, only increased alarm calling was correlated with increased cortisol reactivity, and in older marmosets increased cage manipulations and motor activity were associated with poorer post-stressor cortisol regulation. Because these relationships were so few, we conclude that while the behavioral and endocrine systems follow a similar developmental trajectory, each system maintains a level of independence. Furthermore, the relationship between stressor-induced behaviors and HPA activity changes across development.

Drug-induced suppression of ACTH secretion does not promote anti-depressive or anxiolytic effects

Mammals respond to a real or perceived stress in an integrated physiological and psychological fashion. Psychiatric disorders like major depression and anxiety have been associated to stressful events. In a previous study we demonstrated that the stress-induced ACTH secretion can be robustly inhibited by the concurrent use of CRF1 (CP154,526 - Pfizer) and V1B (SSR149415 - Sanofi-Aventis) non-peptide antagonists. A proof of mechanism was offered by substituting CP154,526 by SSR125543 and obtaining the same results on three stress models: forced swimming, ether vapor inhalation and restraint. SSR125543 effectively blocked only restraint stress-induced ACTH secretion. We then challenged the hypothesis that the concurrent use of both antagonists would have a potent effect on behavioral models of anxiety and depression. Decreasing doses (30-0.1 mg/kg s.c.) of both drugs were tested in three behavioral models: Porsolt forced swimming test, elevated plus maze and social interaction. Results showed that these drugs had no effect on anxiety models (plus maze and social interaction) but significantly reduced immobility time in the forced swimming test, suggesting anti-depressive action in a dose-range from 1 to 30 mg/kg, not different from the reported in the literature referring to one drug or the other. This negates the proposed hypothesis of summation/potentiation of effects as observed in stress-induced ACTH secretion. These results point toward the involvement of extra-hypothalamic sites for the anti-depressive effects. Recent Phase II clinical research on anti-depressive effects of these drugs has failed rising strong criticisms against the predictive value of behavioral tests currently employed.

Role of kappa-opioid receptors in stress and anxiety-related behavior

RATIONALE

Accumulating evidence indicates that brain kappa-opioid receptors (KORs) and dynorphin, the endogenous ligand that binds at these receptors, are involved in regulating states of motivation and emotion. These findings have stimulated interest in the development of KOR-targeted ligands as therapeutic agents. As one example, it has been suggested that KOR antagonists might have a wide range of indications, including the treatment of depressive, anxiety, and addictive disorders, as well as conditions characterized by co-morbidity of these disorders (e.g., post-traumatic stress disorder) A general effect of reducing the impact of stress may explain how KOR antagonists can have efficacy in such a variety of animal models that would appear to represent different disease states.

OBJECTIVE

Here, we review evidence that disruption of KOR function attenuates prominent effects of stress. We will describe behavioral and molecular endpoints including those from studies that characterize the effects of KOR antagonists and KOR ablation on the effects of stress itself, as well as on the effects of exogenously delivered corticotropin-releasing factor, a brain peptide that mediates key effects of stress.

CONCLUSION

Collectively, available data suggest that KOR disruption produces anti-stress effects and under some conditions can prevent the development of stress-induced adaptations. As such, KOR antagonists may have unique potential as therapeutic agents for the treatment and even prevention of stress-related psychiatric illness, a therapeutic niche that is currently unfilled.

Involvements of stress hormones in the restraint-induced conditioned place preference

The conditioned place preference (CPP) paradigm is widely used when examining the reinforcing effects of drugs. Some previous studies have shown that an acute stressor, such as restraint could also induce CPP. Although the modulating effects of stress hormones on various forms of learning are well known, the finding that a stressor has a potentially direct role in the reinforcement mechanism is novel. This study focused on the function of stress hormones in restraint-induced CPP in Wistar rats administered agonist or antagonist of 2 critical stress hormones prior to conditioning. Results showed that peripheral applications of corticosterone (CORT, 1, 3, 5, and 10 mg/kg, subcutaneously) failed to induce CPP. Furthermore, a glucocorticoid (GC) antagonist (mifepristone, 10, 40, or 100 mg/kg, sc) failed to block the restraint-induced CPP. Intracerebroventricular injection of a selective corticotropin-releasing factor receptor 1 (CRFR1) antagonist antalarmin (1 μg/5 μl), on the contrary, completely blocked the restraint-induced CPP. We concluded that CRFR1 plays an essential role in the neural mechanism of restraint-induced CPP. Negative feedback of CORT from peripheral sources may not be involved in this phenomenon.