Interaction of stress, corticotropin-releasing factor, arginine vasopressin and behaviour

Severe PTSD is marked by reduced oxytocin and elevated vasopressin

Neuroendocrine analyses of posttraumatic stress disorder (PTSD) have generally focused on hypothalamic-pituitary-adrenal (HPA) axis alterations. In the present analyses, we examine two additional neuroendocrine factors that have been previously implicated in biological stress responses: oxytocin (OT) and arginine vasopressin (AVP). Here we examined basal neuropeptide status in military veterans clinically diagnosed with PTSD (n = 29) and in two non-traumatized comparison groups with previous stress exposure (n = 11 SWAT trainees and n = 21 ultramarathon runners). PTSD patients showed low levels of plasma OT and high levels of AVP. The ratio of AVP/OT robustly related to PTSD status, and emerged as a statistically plausible mediator of relationships between the number of personal traumatic experiences and subsequent PTSD symptom burden. Over the course of behavioral therapy for PTSD, measures of OT showed a significant but modest normalization. Plasma cortisol levels were not statistically different among the three groups. This study suggests that AVP/OT ratios may represent a neuroendocrine predictor of severe PTSD, as well as a potential treatment response biomarker.

Identification of moderate effect size genes in autism spectrum disorder through a novel gene pairing approach

Autism Spectrum Disorder (ASD) arises from complex genetic and environmental factors, with inherited genetic variation playing a substantial role. This study introduces a novel approach to uncover moderate effect size (MES) genes in ASD, which individually do not meet the ASD liability threshold but collectively contribute when paired with specific other MES genes. Analyzing 10,795 families from the SPARK dataset, we identified 97 MES genes forming 50 significant gene pairs, demonstrating a substantial association with ASD when considered in tandem, but not individually. Our method leverages familial inheritance patterns and statistical analyses, refined by comparisons against control cohorts, to elucidate these gene pairs' contribution to ASD liability. Furthermore, expression profile analyses of these genes in brain tissues underscore their relevance to ASD pathology. This study underscores the complexity of ASD's genetic landscape, suggesting that gene combinations, beyond high impact single-gene mutations, significantly contribute to the disorder's etiology and heterogeneity. Our findings pave the way for new avenues in understanding ASD's genetic underpinnings and developing targeted therapeutic strategies.

Review of the direct and indirect effects of hyperglycemia on the HPA axis in T2DM and the co-occurrence of depression

Type 2 diabetes mellitus (T2DM) is characterized by persistent hyperglycemia which is further associated with hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. Several studies have shown that HPA axis hyperactivity is heightened in the chronic hyperglycemic state with severe hyperglycemic events more likely to result in a depressive disorder. The HPA axis is also regulated by the immune system. Upon stress, under homeostatic conditions, the immune system is activated via the sympatho-adrenal-medullary axis resulting in an immune response which secretes proinflammatory cytokines. These cytokines aid in the activation of the HPA axis during stress. However, in T2DM, where there is persistent hyperglycemia, the immune system is dysregulated resulting in the elevated concentrations of these cytokines. The HPA axis, already activated by the hyperglycemia, is further activated by the cytokines which all contribute to a diagnosis of depression in patients with T2DM. However, the onset of T2DM is often preceded by pre-diabetes, a reversible state of moderate hyperglycemia and insulin resistance. Complications often seen in T2DM have been reported to begin in the pre-diabetic state. While the current management strategies have been shown to ameliorate the moderate hyperglycemic state and decrease the risk of developing T2DM, research is necessary for clinical studies to profile these direct effects of moderate hyperglycemia in pre-diabetes on the HPA axis and the indirect effects moderate hyperglycemia may have on the HPA axis by investigating the components of the immune system that play a role in regulating this pathway.

Xinghamide A, a New Cyclic Nonapeptide Found in Streptomyces xinghaiensis

Xinghamide A (1), a new nonapeptide, was discovered in Streptomyces xinghaiensis isolated from a halophyte, Suaeda maritima (L.) Dumort. Based on high-resolution mass and NMR spectroscopic data, the planar structure of 1 was established, and, in particular, the sequence of nine amino acids was determined with ROESY and HMBC NMR spectra. The absolute configurations of the α-carbon of each amino acid residue were determined with 1-fluoro-2,4-dinitrophenyl-l-and -d-leucine amide (Marfey's reagents) and 2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl isothiocyanate, followed by LC-MS analysis. The anti-inflammatory activity of xinghamide A (1) was evaluated by inhibitory abilities against the nitric oxide (NO) secretion and cyclooxygenase-2 (COX-2) expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells.

The parabrachial nucleus elicits a vigorous corticosterone feedback response to the pro-inflammatory cytokine IL-1β

The central nervous system regulates systemic immune responses by integrating the physiological and behavioral constraints faced by an individual. Corticosterone (CS), the release of which is controlled in the hypothalamus by the paraventricular nucleus (PVN), is a potent negative regulator of immune responses. Using the mouse model, we report that the parabrachial nucleus (PB), an important hub linking interoceptive afferent information to autonomic and behavioral responses, also integrates the pro-inflammatory cytokine IL-1β signal to induce the CS response. A subpopulation of PB neurons, directly projecting to the PVN and receiving inputs from the vagal complex (VC), responds to IL-1β to drive the CS response. Pharmacogenetic reactivation of these IL-1β-activated PB neurons is sufficient to induce CS-mediated systemic immunosuppression. Our findings demonstrate an efficient brainstem-encoded modality for the central sensing of cytokines and the regulation of systemic immune responses.

Limosilactobacillus reuteri administration alters the gut-brain-behavior axis in a sex-dependent manner in socially monogamous prairie voles

Research on the role of gut microbiota in behavior has grown dramatically. The probiotic L. reuteri can alter social and stress-related behaviors - yet, the underlying mechanisms remain largely unknown. Although traditional laboratory rodents provide a foundation for examining the role of L. reuteri on the gut-brain axis, they do not naturally display a wide variety of social behaviors. Using the highly-social, monogamous prairie vole (Microtus ochrogaster), we examined the effects of L. reuteri administration on behaviors, neurochemical marker expression, and gut-microbiome composition. Females, but not males, treated with live L. reuteri displayed lower levels of social affiliation compared to those treated with heat-killed L. reuteri. Overall, females displayed a lower level of anxiety-like behaviors than males. Live L. reuteri-treated females had lower expression of corticotrophin releasing factor (CRF) and CRF type-2-receptor in the nucleus accumbens, and lower vasopressin 1a-receptor in the paraventricular nucleus of the hypothalamus (PVN), but increased CRF in the PVN. There were both baseline sex differences and sex-by-treatment differences in gut microbiome composition. Live L. reuteri increased the abundance of several taxa, including Enterobacteriaceae, Lachnospiraceae NK4A136, and Treponema. Interestingly, heat-killed L. reuteri increased abundance of the beneficial taxa Bifidobacteriaceae and Blautia. There were significant correlations between changes in microbiota, brain neurochemical markers, and behaviors. Our data indicate that L. reuteri impacts gut microbiota, gut-brain axis and behaviors in a sex-specific manner in socially-monogamous prairie voles. This demonstrates the utility of the prairie vole model for further examining causal impacts of microbiome on brain and behavior.

Vasopressin neurons in the paraventricular hypothalamus promote wakefulness via lateral hypothalamic orexin neurons

The sleep-wakefulness cycle is regulated by complicated neural networks that include many different populations of neurons throughout the brain. Arginine vasopressin neurons in the paraventricular nucleus of the hypothalamus (PVH^AVP) regulate various physiological events and behaviors, such as body-fluid homeostasis, blood pressure, stress response, social interaction, and feeding. Changes in arousal level often accompany these PVH^AVP-mediated adaptive responses. However, the contribution of PVH^AVP neurons to sleep-wakefulness regulation has remained unknown. Here, we report the involvement of PVH^AVP neurons in arousal promotion. Optogenetic stimulation of PVH^AVP neurons rapidly induced transitions to wakefulness from both NREM and REM sleep. This arousal effect was dependent on AVP expression in these neurons. Similarly, chemogenetic activation of PVH^AVP neurons increased wakefulness and reduced NREM and REM sleep, whereas chemogenetic inhibition of these neurons significantly reduced wakefulness and increased NREM sleep. We observed dense projections of PVH^AVP neurons in the lateral hypothalamus with potential connections to orexin/hypocretin (LH^Orx) neurons. Optogenetic stimulation of PVH^AVP neuronal fibers in the LH immediately induced wakefulness, whereas blocking orexin receptors attenuated the arousal effect of PVH^AVP neuronal activation drastically. Monosynaptic rabies-virus tracing revealed that PVH^AVP neurons receive inputs from multiple brain regions involved in sleep-wakefulness regulation, as well as those involved in stress response and energy metabolism. Moreover, PVH^AVP neurons mediated the arousal induced by novelty stress and a melanocortin receptor agonist melanotan-II. Thus, our data suggested that PVH^AVP neurons promote wakefulness via LH^Orx neurons in the basal sleep-wakefulness and some stressful conditions.

Paraventricular hypothalamic vasopressin neurons induce self-grooming in mice

Self-grooming plays an essential role in hygiene maintenance, thermoregulation, and stress response. However, the neural populations involved in self-grooming remain largely unknown. The paraventricular hypothalamic nucleus (PVH) has been implicated in the regulation of self-grooming. Arginine vasopressin-producing neurons are among the major neuronal populations in the PVH (PVH^AVP), which play important roles in water homeostasis, blood pressure regulation, feeding, and stress response. Here, we report the critical role of PVH^AVP neurons in the induction of self-grooming. Optogenetic activation of PVH^AVP neurons immediately induced self-grooming in freely moving mice. Chemogenetic activation of these neurons also increased time spent self-grooming. In contrast, their chemogenetic inhibition significantly reduced naturally occurring self-grooming, suggesting that PVH^AVP-induced grooming has physiological relevance. Notably, optogenetic activation of PVH^AVP neurons triggered self-grooming over other adaptive behaviors, such as voracious feeding induced by fasting and social interaction with female mice. Thus, our study proposes the novel role of PVH^AVP neurons in regulating self-grooming behavior and, consequently, hygiene maintenance and stress response. Furthermore, uncontrolled activation of these neurons may be potentially relevant to diseases characterized by compulsive behaviors and impaired social interaction, such as autism, obsessive–compulsive disorder, and anorexia nervosa.

Stress and central autonomic network

The central autonomic network (CAN) plays a critical role in the stress response, which is triggered by challenges on the homeostasis (physiological stressors) or unpleasant social or environmental situations. This review focuses on the role of areas of the CAN including the insular and anterior cingulate cortices, extended amygdala, hypothalamus, periaqueductal gray and locus coeruleus in the stress response. These areas are interconnected and affect sympathetic or parasympathetic output via their influence on premotor or preganglionic autonomic neurons in the lower brainstem and spinal cord. The insula integrates multiple inputs to create a sense of the physiological state of the body, whereas the anterior cingulate initiates predictive visceromotor commands. The amygdala and bed nucleus of the stria terminalis provide automatic emotional tagging and trigger automatic survival responses to threat via their outputs to the hypothalamus, periaqueductal gray, and lower brainstem. Several regions of the hypothalamus, including the paraventricular nucleus, dorsomedial nucleus and lateral hypothalamic area participate in different patterns of stress response according to the type of stimulus and projections to premotor and preganglionic autonomic neurons. The periaqueductal gray initiates different patterns of autonomic, pain modulatory, and motor responses, including the "fight or flight" or "playing dead" responses. The locus coeruleus promotes emotional learning in the amygdala associated with states of anxiety. Neurons of the C1 area of the rostral ventrolateral medulla elicit sympathoexcitatory responses to internal stressors such as hypoxia and inflammation. The ventromedial medulla, including the nucleus raphe pallidus, initiates sympathoexcitatory responses to social and other external stressors.

Enhancing oxygenation of patients with coronavirus disease 2019: Effects on immunity and other health-related conditions

Coronavirus disease 2019 (COVID-19) distresses the pulmonary system causing acute respiratory distress syndrome, which might lead to death. There is no cure for COVID-19 infection. COVID-19 is a self-limited infection, and the methods that can enhance immunity are strongly required. Enhancing oxygenation is one safe and effective intervention to enhance immunity and pulmonary functions. This review deliberates the probable influences of enhancing oxygenation on immunity and other health-connected conditions in patients with COVID-19. An extensive search was conducted through Web of Science, Scopus, Medline databases, and EBSCO for the influence of enhancing oxygenation on immunity, pulmonary functions, psycho-immune hormones, and COVID-19 risk factors. This search included clinical trials and literature and systematic reviews. This search revealed that enhancing oxygenation has a strong effect on improving immunity and pulmonary functions and psycho-immune hormones. Also, enhancing oxygenation has a self-protective role counter to COVID-19 risk factors. Lastly, this search revealed the recommended safe and effective exercise protocol to enhance oxygenation in patients with COVID-19. Enhancing oxygenation should be involved in managing patients with COVID-19 because of its significant effects on immunity, pulmonary functions, and COVID-19 risk factors. A mild to moderate cycling or walking with 60%-80% Vo2max for 20-60 min performed 2-3 times per week could be a safe and effective aerobic exercise program in patients with COVID-19 to enhance their immunity and pulmonary functions.

Association of Copeptin With Sense of Coherence in Individuals With Varying Degrees of Glucose Intolerance

OBJECTIVE

This study aimed to examine the association of serum copeptin levels, a surrogate marker of arginine-vasopressin secretion with sense of coherence (SOC) among individuals with varying degrees of glucose intolerance.

METHODS

The study was conducted in 120 age- and sex-matched individuals who were divided equally into three groups. Group A included individuals with normal glucose tolerance; group B, individuals with prediabetes (impaired glucose tolerance and/or impaired fasting glucose); and group C, individuals with newly detected diabetes mellitus (NDDM). SOC, perceived stress scale (PSS), copeptin, anthropometry, glycated hemoglobin, insulin, and salivary cortisol were measured in all study participants.

RESULTS

The SOC score was found to be significantly lower in group C compared with group A (p < .001) and group B (p = .006). The PSS score was found to be significantly higher in group C compared with group A (p = .002). No significant difference was found between PSS scores of groups B and C (p = .25). Copeptin levels were found to be significantly higher in group C compared with group A (p = .016). Copeptin levels in group C did not differ significantly from those in group B (p = .056). There was a significant negative correlation between serum copeptin levels and SOC in the NDDM group C (r = 0.31, p = .048) and overall (r = 0.19, p = .037). In multiple regression analysis, SOC emerged as the variable with the strongest association with 2-hour postprandial plasma glucose and glycated hemoglobin.

CONCLUSION

Individuals with NDDM displayed significantly higher serum copeptin levels that inversely correlated with SOC, a global measure of stress coping ability.

Neuroendocrine Response to Psychosocial Stressors, Inflammation Mediators and Brain-periphery Pathways of Adaptation

Threats, challenging events, adverse experiences, predictable or unpredictable, namely stressors, characterize life, being unavoidable for humans. The hypothalamus-pituitary-adrenal axis (HPA) and the sympathetic nervous system (SNS) are well-known to underlie adaptation to psychosocial stress in the context of other interacting systems, signals and mediators. However, much more effort is necessary to elucidate these modulatory cues for a better understanding of how and why the "brain-body axis" acts for resilience or, on the contrary, cannot cope with stress from a biochemical and biological point of view. Indeed, failure to adapt increases the risk of developing and/or relapsing mental illnesses such as burnout, post-traumatic stress disorder (PTSD), and at least some types of depression, even favoring/worsening neurodegenerative and somatic comorbidities, especially in the elderly. We will review here the current knowledge on this area, focusing on works presenting the main brain centers responsible for stressor interpretation and processing, together with those underscoring the physiology/biochemistry of endogenous stress responses. Autonomic and HPA patterns, inflammatory cascades and energy/redox metabolic arrays will be presented as allostasis promoters, leading towards adaptation to psychosocial stress and homeostasis, but also as possible vulnerability factors for allostatic overload and non-adaptive reactions. Besides, the existence of allostasis buffering systems will be treated. Finally, we will suggest promising lines of future research, particularly the use of animal and cell culture models together with human studies by means of high-throughput multi-omics technologies, which could entangle the biochemical signature of resilience or stress-related illness, a considerably helpful facet for improving patients' treatment and monitoring.

Neuroplasticity in cognitive and psychological mechanisms of depression: an integrative model

Chronic stress and depressive-like behaviors in basic neuroscience research have been associated with impairments of neuroplasticity, such as neuronal atrophy and synaptic loss in the medial prefrontal cortex (mPFC) and hippocampus. The current review presents a novel integrative model of neuroplasticity as a multi-domain neurobiological, cognitive, and psychological construct relevant in depression and other related disorders of negative affect (e.g., anxiety). We delineate a working conceptual model in which synaptic plasticity deficits described in animal models are integrated and conceptually linked with human patient findings from cognitive science and clinical psychology. We review relevant reports including neuroimaging findings (e.g., decreased functional connectivity in prefrontal-limbic circuits), cognitive deficits (e.g., executive function and memory impairments), affective information processing patterns (e.g., rigid, negative biases in attention, memory, interpretations, and self-associations), and patient-reported symptoms (perseverative, inflexible thought patterns; inflexible and maladaptive behaviors). Finally, we incorporate discussion of integrative research methods capable of building additional direct empirical support, including using rapid-acting treatments (e.g., ketamine) as a means to test this integrative model by attempting to simultaneously reverse these deficits across levels of analysis.

Increased protein and mRNA expression of corticotropin-releasing factor (CRF), decreased CRF receptors and CRF binding protein in specific postmortem brain areas of teenage suicide subjects

Overactivity of hypothalamic-pituitary-adrenal (HPA) axis function has been implicated in depression and suicidal behavior. This is based on the observation of an abnormal dexamethasone (DEX) and DEX-adrenocorticotropic hormone (ACTH) test in patients with depression and suicidal behavior. Recently, some studies have also found abnormalities of glucocorticoid receptors (GR), mineralocorticoid receptors (MR), corticotropin releasing factor (CRF), CRF receptors (CRF-R) and CRF binding protein (CRF-BP) in depressed and suicidal patients. Some investigators have also observed increased levels of CRF in the cerebrospinal fluid (CSF) and altered levels of MR, GR and CRF in the postmortem brain of depressed and suicidal subjects. We have earlier reported decreased protein and mRNA expression of GR and GILZ, a chaperone protein, in the postmortem brain of teenage suicide subjects. We have further studied CRF and its receptors in different areas of the postmortem brain of suicide subjects, i.e., the prefrontal cortex (PFC), hippocampus (HIPPO), subiculum and amygdala (AMY) from teenage suicide subjects. The CRF and its receptors were determined in the PFC (Brodmann area 9), HIPPO, subiculum and different amygdaloid nuclei from 24 normal control subjects and 24 teenage suicide subjects. Protein expression of CRF, its receptors and CRF-BP was determined by immunolabeling using the Western blot technique and mRNA expression was determined by real-time PCR (qPCR) technique. We found that the mRNA levels of CRF were significantly increased in the PFC, in the central amygdaloid nucleus (CeAMY) and in the subiculum. mRNA levels of CRF-R1 and CRF-BP were significantly decreased in the PFC. We did not find any changes in the HIPPO of any of the CRF components we studied. When we compared the protein expression of CRF components we found that CRF was significantly increased and CRF-R1, CRF-R2 and CRF-BP significantly decreased in the PFC. On the other hand, there were no changes in the protein expression of CRF components in the HIPPO. Our results in the postmortem brain suggest that, as found by clinical studies in the CSF, there are significant alterations of CRF and its receptors in the postmortem brain of teenage suicide subjects. These alterations of CRF and its components were region-specific, as changes were not generally observed in the HIPPO.

Exploring the involvement of Tac2 in the mouse hippocampal stress response through gene networking

Tachykinin 2 (Tac2) is expressed in a number of areas throughout the brain, including the hippocampus. However, knowledge about its function has been only well explored in the hypothalamus in the context of reproductive health. In this study, we identified and validated increased hippocampal Tac2 mRNA expression in response to chronic mild stress in mice. Expression quantitative trait locus (eQTL) analysis showed Tac2 is cis-regulated in the hippocampus. Using a systems genetics approach, we constructed a Tac2 co-expression network to better understand the relationship between Tac2 and the hippocampal stress response. Our network identified 69 total genes associated with Tac2, several of which encode major neuropeptides involved in hippocampal stress signaling as well as critical genes for producing neural plasticity, indicating that Tac2 is involved in these processes. Pathway analysis for the member of Tac2 gene network revealed a strong connection between Tac2 and neuroactive ligand-receptor interaction, calcium signaling pathway, as well as cardiac muscle contraction. In addition, we also identified 46 stress-related phenotypes, specifically fear conditioning response, that were significantly correlated with Tac2 expression. Our results provide evidence for Tac2 as a strong candidate gene who likely plays a role in hippocampal stress processing and neural plasticity.

Sleep and circadian rhythm disruption and stress intersect in Alzheimer's disease

Alzheimer's disease (AD) was discovered and the pathological hallmarks were revealed more than a century ago. Subsequently, many remarkable discoveries and breakthroughs provided us with mechanistic insights into the pathogenesis of AD. The identification of the molecular underpinning of the disease not only provided the framework of AD pathogenesis but also targets for therapeutic inventions. Despite all the initial successes, no effective treatment for AD has emerged yet as all the late stages of clinical trials have failed. Many factors ranging from genetic to environmental factors have been critically appraised as the potential causes of AD. In particular, the role of stress on AD has been intensively studied while the relationship between sleep and circadian rhythm disruption (SCRD) and AD have recently emerged. SCRD has always been thought to be a corollary of AD pathologies until recently, multiple lines of evidence converge on the notion that SCRD might be a contributing factor in AD pathogenesis. More importantly, how stress and SCRD intersect and make their concerted contributions to AD phenotypes has not been reviewed. The goal of this literature review is to examine at multiple levels - molecular, cellular (e.g. microglia, gut microbiota) and holistic - how the interaction between stress and SCRD bi-directionally and synergistically exacerbate AD pathologies and cognitive impairment. AD, in turn, worsens stress and SCRD and forms the vicious cycle that perpetuates and amplifies AD.

ACTH and cortisol responses to CRH in acute, subacute, and prolonged critical illness: a randomized, double-blind, placebo-controlled, crossover cohort study

Purpose

Low plasma ACTH in critically ill patients may be explained by shock/inflammation-induced hypothalamus-pituitary damage or by feedback inhibition exerted by elevated plasma free cortisol. One can expect augmented/prolonged ACTH-responses to CRH injection with hypothalamic damage, immediately suppressed responses with pituitary damage, and delayed decreased responses in prolonged critical illness with feedback inhibition.

Methods

This randomized, double-blind, placebo-controlled crossover cohort study, compared ACTH responses to 100 µg IV CRH and placebo in 3 cohorts of 40 matched patients in the acute (ICU-day 3–6), subacute (ICU-day 7–16) or prolonged phase (ICU-day 17–28) of critical illness, with 20 demographically matched healthy subjects. CRH or placebo was injected in random order on two consecutive days. Blood was sampled repeatedly over 135 min and AUC responses to placebo were subtracted from those to CRH.

Results

Patients had normal mean ± SEM plasma ACTH concentrations (25.5 ± 1.6 versus 24.8 ± 3.6 pg/ml in healthy subjects, P = 0.54) but elevated free cortisol concentrations (3.11 ± 0.27 versus 0.58 ± 0.05 µg/dl in healthy subjects, P < 0.0001). The order of the CRH/placebo injections did not affect the ACTH responses, hence results were pooled. Patients in the acute phase of illness had normal mean ± SEM ACTH responses (5149 ± 848 pg/mL min versus 4120 ± 688 pg/mL min in healthy subjects; P = 0.77), whereas those in the subacute (2333 ± 387 pg/mL min, P = 0.01) and prolonged phases (2441 ± 685 pg/mL min, P = 0.001) were low, irrespective of sepsis/septic shock or risk of death.

Conclusions

Suppressed ACTH responses to CRH in the more prolonged phases, but not acute phase, of critical illness are compatible with feedback inhibition exerted by elevated free cortisol, rather than by cellular damage to hypothalamus and/or pituitary.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5427-y) contains supplementary material, which is available to authorized users.

Rapid nonapeptide synthesis during a critical period of development in the prairie vole: plasticity of the paraventricular nucleus of the hypothalamus

Vasopressin (VP) and oxytocin (OT) are involved in modulating basic physiology and numerous social behaviors. Although the anatomical distributions of nonapeptide neurons throughout development have been described, the functional roles of VP and OT neurons during development are surprisingly understudied, and it is unknown whether they exhibit functional changes throughout early development. We utilized an acute social isolation paradigm to determine if VP and OT neural responses in eight nonapeptide cell groups differ at three different stages of early development in prairie voles. We tested pups at ages that are representative of the three rapid growth stages of the developing brain: postnatal day (PND)2 (closed eyes; poor locomotion), PND9 (eye opening; locomotion; peak brain growth spurt), and PND21 (weaning). Neural responses were examined in pups that (1) were under normal family conditions with their parents and siblings, (2) were isolated from their parents and siblings and then reunited, and (3) were isolated from their parents and siblings. We found that VP and OT neural activity (as assessed via Fos co-localization) did not differ in response to social condition across development. However, remarkably rapid VP and OT synthesis in response to social isolation was observed only in the paraventricular nucleus of the hypothalamus (PVN) and only in PND9 pups. These results suggest that PVN nonapeptide neurons exhibit distinct cellular properties during a critical period of development, allowing nonapeptide neurons to rapidly upregulate peptide production in response to stressors on a much shorter timescale than has been observed in adult animals.

Tectal corticotropin-releasing factor (CRF) neurons respond to fasting and a reactive stressor in the African Clawed Frog, Xenopus laevis

It is well established that hypothalamic neurons producing the peptide corticotropin-releasing factor (CRF) play a key role in stress adaptation, including reduction of food intake when a threat or stressor is present. We have previously reported on the presence of an intrinsic CRF signaling system within the optic tectum (OT), a brain area that plays a key role in visually guided prey capture/predator avoidance decisions. To better understand the potential role of tectal CRF neurons in regulating adaptive behavior and energy balance during stress we examined evidence for modulation of tectal CRF neuronal activity after stressor exposure and food deprivation in the African clawed frog Xenopus laevis. We tested two predictions, 1) that exposure to categorically distinct stressors (ether vapors and shaking) will reduce food intake and modulate the activity of tectal CRF cells, and 2) that food deprivation will modulate the activity of tectal CRF cells. Exposure to ether increased tectal content of CRF and CRF transcript, but lowed CRFR1 transcript abundance. Two weeks of food deprivation reduced total fat stores in frogs and decreased tectal content of CRF content while having no effect on CRF and CRFR1 transcript abundance. Our data are consistent with a role for tectal CRF neurons in modulating food intake in response to certain stressors.

Activation of CRF/CRFR1 signaling in the basolateral nucleus of the amygdala contributes to chronic forced swim-induced depressive-like behaviors in rats

The basolateral nucleus of the amygdala (BLA) plays a key role in processing stressful events and affective disorders. Previously we have documented that exposure of chronic forced swim (FS) to rats produces a depressive-like behavior and that sensitization of BLA neurons is involved in this process. In the present study, we demonstrated that chronic FS stress (CFSS) could activate corticotropin-releasing factor (CRF)/CRF receptor type 1 (CRFR1) signaling in the BLA, and blockade of CRF/CRFR1 signaling by intra-BLA injection of NBI27914 (NBI), a selective CRFR1 antagonist, could prevent the CFSS-induced depressive-like behaviors in rats, indicating that activation of CRF/CRFR1 signaling in the BLA is required for CFSS-induced depression. Furthermore, we discovered that exposure of chronic FS to rats could reinforce long-term potentiation (LTP) at the external capsule (EC)-BLA synapse and increase BLA neuronal excitability, and that all these alterations were inhibited by CRFR1 antagonist NBI. Moreover, we found that application of exogenous CRF also may facilitate LTP at the EC-BLA synapse and sensitize BLA neuronal excitability in normal rats via the activation of CRFR1. We conclude that activation of CRF/CRFR1 signaling in the BLA contributes to chronic FS-induced depressive-like behaviors in rats through potentiating synaptic efficiency at the EC-BLA pathway and sensitizing BLA neuronal excitability.

Individual variation in plasma oxytocin and vasopressin levels in relation to the development of combat-related PTSD in a large military cohort

In an attempt to decrease the risk of developing mental health problems after military deployment, it is important to find biological markers to identify those at risk. Oxytocin (OT) and arginine vasopressin (AVP) are potential biomarkers for the development of posttraumatic stress disorder (PTSD) because they are involved in the regulation of stress and anxiety. Therefore, the aim was to examine whether plasma OT (pOT) and AVP (pAVP) levels before and after deployment are biomarkers for the development of posttraumatic stress symptoms over time in addition to other known risk factors. This study is part of a large prospective cohort study on candidate markers for stress-related mental health symptoms and resiliency after deployment to a combat zone; Prospective Research in Stress-related Military Operations (PRISMO; N = 907). Data was collected prior to deployment and follow-ups were performed at 1 and 6 months, and 1, 2, and 5 years post-deployment. Blood samples were collected in the first three assessments. The levels of pOT and pAVP were not significantly related to the development of PTSD symptoms over time. The results confirm that age, the experience of early life trauma, combat-related stressors and the presence of depressive symptoms are predictive for the development of PTSD symptoms over time. These findings showed that peripherally measured OT and AVP currently do not qualify as useful susceptibility biomarkers for the development of PTSD symptoms over time in military men after combat.

Endocrinology and the brain: corticotropin-releasing hormone signaling

Corticotropin-releasing hormone (CRH) is a key player of basal and stress-activated responses in the hypothalamic-pituitary-adrenal axis (HPA) and in extrahypothalamic circuits, where it functions as a neuromodulator to orchestrate humoral and behavioral adaptive responses to stress. This review describes molecular components and cellular mechanisms involved in CRH signaling downstream of its G protein-coupled receptors (GPCRs) CRHR1 and CRHR2 and summarizes recent findings that challenge the classical view of GPCR signaling and impact on our understanding of CRHRs function. Special emphasis is placed on recent studies of CRH signaling that revealed new mechanistic aspects of cAMP generation and ERK1/2 activation in physiologically relevant contexts of the neurohormone action. In addition, we present an overview of the pathophysiological role of the CRH system, which highlights the need for a precise definition of CRHRs signaling at molecular level to identify novel targets for pharmacological intervention in neuroendocrine tissues and specific brain areas involved in CRH-related disorders.

Early Life Stress Alters Adult Inflammatory Responses in a Mouse Model for Depression

Increased levels of pro-inflammatory cytokines and hypothalamic pituitary axis (HPA) activity are strongly associated with depression. Childhood stress and trauma predispose individuals for increased inflammatory tone and major depression in later life, suggesting that early life reprogramming of the stress/immune axis may be involved in the pathogenesis of depression. In this study, we are using a short duration neonatal maternal separation stress (MS) paradigm in mice to test if early life stress can impact plasma and brain inflammatory tone into adulthood. We use ELISA assays to investigate levels of the pro-inflammatory cytokines IL-1beta, IL-2, IL-6 and TNF-alpha, in both plasma and brain tissue of mice exposed to MS (STR), their unseparated littermates (LMC) and unhandled age matched controls (AMC). Cytokine levels are assessed in male and female adult mice with and without a bacterial lipopolysaccharide (LPS) induced immune challenge. We present evidence that stress exposure, during the first week of life, predisposes both male and female mice for increased inflammatory cytokine secretion, peripherally and in brain tissue, upon adult exposure to lipopolysaccharide (LPS).

Differential contributions of vasopressin V1A and oxytocin receptors in the amygdala to pain-related behaviors in rats

Neuroplastic changes in the amygdala account for emotional-affective aspects of pain and involve neuropeptides such as calcitonin gene-related peptide and corticotropin-releasing factor. Another neuropeptide system, central arginine vasopressin, has been implicated in neuropsychiatric disorders, but its role in pain-related emotional expression and neuroplasticity remains to be determined. Here, we tested the hypothesis that arginine vasopressin in the amygdala contributes to pain-related emotional-affective responses, using stereotaxic applications of arginine vasopressin and antagonists for G-protein coupled vasopressin V1A and oxytocin receptors in adult male Sprague-Dawley rats. In normal animals, arginine vasopressin increased audible and ultrasonic vocalizations and anxiety-like behavior (decreased open-arm preference in the elevated plus maze). The facilitatory effects were blocked by a selective V1A antagonist (SR 49059, Relcovaptan) but not by an oxytocin receptor antagonist (L-371,257). L-371,257 had some facilitatory effects on vocalizations. Arginine vasopressin had no effect in arthritic rats (kaolin/carrageenan knee joint pain model). SR 49059 inhibited vocalizations and anxiety-like behavior (elevated plus maze) in arthritic, but not normal, rats and conveyed anxiolytic properties to arginine vasopressin. Arginine vasopressin, SR 49059, and L-371,257 had no significant effects on spinal reflexes. We interpret the data to suggest that arginine vasopressin through V1A in the amygdala contributes to emotional-affective aspects of pain (arthritis model), whereas oxytocin receptors may mediate some inhibitory effects of the vasopressin system.

The Preeminence of Early Life Trauma as a Risk Factor for Worsened Long-Term Health Outcomes in Women

Early life trauma (ELT) comprises an array of disturbingly common distressing experiences between conception and the beginning of adulthood with numerous and significant potential long-term, even transgenerational, health consequences of great public health concern, including depression, cardiovascular disease, and other psychiatric and medical disorders, and neurobiological, psychological, and behavioral effects which are sufficiently robust to confound many types of biomedical research. The impact of ELT on a woman's health trajectory appears to vary with the specific characteristics of the ELT (e.g., type, number of different types, severity, and timing), the individual (e.g., age, genetics, epigenetics, personality, and cognitive factors), and the individual's environment (e.g., level of social support and ongoing stressors) and to be mediated to a significant extent by persistent changes in a number of biological systems, dysregulation of those governing the stress response chief among them. Growing knowledge of the risk factors and pathophysiological mechanisms by which ELT confers diathesis to various poor health outcomes and the unique treatment-response profiles of women with ELT will lead to much needed improvements in prevention, diagnostic, and therapeutic efforts, including more effective psychotherapy and pharmacotherapy approaches, hopefully making strides toward improvements in the lives of women everywhere and ending countless cycles of intergenerational trauma-associated pathology. This article attempts to broadly summarize the current state of knowledge about the long-term sequelae of ELT for women's health.

Corticotropin-releasing factor mediates bone cancer induced pain through neuronal activation in rat spinal cord

Corticotropin-releasing factor (CRF) serves as a neuromodulator in the hypothalamic-pituitary-adrenal axis, playing an essential role in depression, anxiety, and pain regulation. However, its biological role in bone cancer induced pain has not been investigated. In the present study, we aimed to elucidate the expression and distribution of CRF in spinal cord using a rodent model of bone cancer pain. Our study showed that implantation of Walker 256 mammary gland carcinoma cells into the tibia of rats significantly increased CRF expression in the spinal cord in a time-dependent manner. The upregulated expression of CRF mainly expressed in the superficial dorsal horn of spinal cord. Moreover, immunofluorescence double staining showed that CRF was extensively colocalized with neurons, but hardly with astrocytes or microglia. In addition, intrathecal injection of CRF receptor antagonist (α-helical-CRF) significantly inhibited heat hyperalgesia, mechanical allodynia, and the expression of c-Fos in spinal dorsal horn of bone cancer pain rats. In summary, our study demonstrates that CRF plays an important role in the development and maintenance of bone cancer pain via activation of neurons.

Oxytocin and MDMA ('Ecstasy') enhance social reward in rats

RATIONALE

Oxytocin (OT), vasopressin (AVP) and 3,4 methylenedioxymethamphetamine (MDMA, 'Ecstasy') all increase social interaction in rats, perhaps by enhancing the rewarding value of social encounters.

OBJECTIVES

Here, we used the conditioned place preference (CPP) paradigm to assess the intrinsic rewarding effects of OT, AVP and MDMA, and whether these effects are enhanced by the presence of a conspecific, or a dynamic, tactile object (a tennis ball).

METHODS

Adult male rats received conditioning sessions in a CPP apparatus twice a day (vehicle at 10 a.m., drug at 3 p.m.). Experiment 1 involved conditioning with OT (0.5 mg/kg, intraperitoneal (i.p.)), AVP (0.005 mg/kg, i.p.) or MDMA (5 mg/kg, i.p.). Experiments 2 and 3 involved conditioning with the same treatments but in the presence of a conspecific receiving the same treatment (social-CPP) or in the presence of a tennis ball (object-CPP), respectively. Conditioned place preference was assessed 24 h, 2 weeks and 4 weeks later.

RESULTS

OT, AVP and MDMA did not produce a conventional CPP. However, when the conditioning environment also contained a conspecific both OT and MDMA induced a significant CPP lasting for at least 4 weeks. Rats given OT and MDMA also developed a more modest yet significant CPP for the environment where they encountered a tennis ball.

CONCLUSIONS

These results indicate that OT and MDMA can augment the rewarding effects of social interaction, but also interaction with a dynamic and tactile non-social object. AVP does not condition social- or object-CPPs and may promote social proximity by inducing generalized anxiety and defensive aggregation.