Role of GABA and glutamate circuitry in hypothalamo-pituitary-adrenocortical stress integration

Ketogenic diet has a positive association with mental and emotional well-being in the general population

OBJECTIVES

A ketogenic diet reduces pathologic stress and improves mood in neurodegenerative and neurodevelopmental disorders. However, the effects of a ketogenic diet for people from the general population have largely been unexplored. A ketogenic diet is increasingly used for weight loss. Research in healthy individuals primarily focuses on the physical implications of a ketogenic diet. It is important to understand the holistic effects of a ketogenic diet, not only the physiological but also the psychological effects, in non-clinical samples. The aim of this cross-sectional study with multiple cohorts was to investigate the association of a ketogenic diet with different aspects of mental health, including calmness, contentedness, alertness, cognitive and emotional stress, depression, anxiety, and loneliness, in a general healthy population.

METHODS

Two online surveys were distributed: cohort 1 used Bond-Lader visual analog scales and Perceived Stress Scale (n = 147) and cohort 2 the Depression Anxiety Stress Scale and revised UCLA Loneliness Scale (n = 276).

RESULTS

A ketogenic diet was associated with higher self-reported mental and emotional well-being behaviors, including calmness, contentedness, alertness, cognitive and emotional stress, depression, anxiety, and loneliness, compared with individuals on a non-specific diet in a general population.

CONCLUSION

This research found that a ketogenic diet has potential psychological benefits in the general population.

Fibromyalgia pathogenesis explained by a neuroendocrine multistable model

Fibromyalgia (FM) is a central disorder characterized by chronic pain, fatigue, insomnia, depression, and other minor symptoms. Knowledge about pathogenesis is lacking, diagnosis difficult, clinical approach puzzling, and patient management disappointing. We conducted a theoretical study based on literature data and computational analysis, aimed at developing a comprehensive model of FM pathogenesis and addressing suitable therapeutic targets. We started from the evidence that FM must involve a dysregulation of central pain processing, is female prevalent, suggesting a role for the hypothalamus-pituitary-gonadal (HPG) axis, and is stress-related, suggesting a role for the HP-adrenocortical (HPA) axis. Central pathogenesis was supposed to involve a pain processing loop system including the thalamic ventroposterolateral nucleus (VPL), the primary somatosensory cortex (SSC), and the thalamic reticular nucleus (TRN). For decreasing GABAergic and/or increasing glutamatergic transmission, the loop system crosses a bifurcation point, switching from monostable to bistable, and converging on a high-firing-rate steady state supposed to be the pathogenic condition. Thereafter, we showed that GABAergic transmission is positively correlated with gonadal-hormone-derived neurosteroids, notably allopregnanolone, whereas glutamatergic transmission is positively correlated with stress-induced glucocorticoids, notably cortisol. Finally, we built a dynamic model describing a multistable, double-inhibitory loop between HPG and HPA axes. This system has a high-HPA/low-HPG steady state, allegedly reached in females under combined premenstrual/postpartum brain allopregnanolone withdrawal and stress condition, driving the thalamocortical loop to the high-firing-rate steady state, and explaining the connection between endocrine and neural mechanisms in FM pathogenesis. Our model accounts for FM female prevalence and stress correlation, suggesting the use of neurosteroid drugs as a possible solution to currently unsolved problems in the clinical treatment of the disease.

Impacts of thyme and/or garlic oils on growth, immunity, antioxidant and net farm income in Damascus goats

This study aimed to evaluate the impact of thyme and/or garlic oil administration on growth performance, immunity, antioxidant, biochemical parameters, and net farm income of Damascus goats. Forty weaned Damascus goats were allocated into four groups. The first group was the control without oral administration, while the 2nd (Th), 3rd (Gr), and 4th (ThGr) groups were orally administrated by (2 ml/goat/day) of thyme oil, garlic oil and their mixture (1:1), respectively during the whole experiment period. The final body weight of goats orally administered oil mixture was the heaviest group, it was 10, 4.5 and 3.5% than the control, Th. and Gr. groups, respectively with better feed conversion ratio and high net farm income. Goats of ThGr. group revealed the best immunity, antioxidant and general health condition than the control group with 50% reduction of MDA. Liver (AST, 33% and ALT, 38%) and kidney (creatinine, 88%) functions improved by oils mixtures orally administration compared with the control group. LDL, triglyceride and cholesterol were reduced by 47, 33 and 21% compared with the control group, respectively. Thus, mixture oil administration (thyme and garlic at the ratio of 1:1, 2 ml/goat/day) improved growth (10%), antioxidant status (MDA 50%), liver (AST, 33% and ALT, 38%), kidney function (creatinine, 88%), the FCR (17.4%) and net farm income (21%), of Damascus goats.

Glutamate Spillover Dynamically Strengthens Gabaergic Synaptic Inhibition of the Hypothalamic Paraventricular Nucleus

The hypothalamic paraventricular nucleus (PVN) is strongly inhibited by γ-aminobutyric acid (GABA) from the surrounding peri-nuclear zone (PNZ). Because glutamate mediates fast excitatory transmission and is substrate for GABA synthesis, we tested its capacity to dynamically strengthen GABA inhibition. In PVN slices from male mice, bath glutamate applied during ionotropic glutamate receptor blockade increased PNZ-evoked inhibitory postsynaptic currents (eIPSCs) without affecting GABA-A receptor agonist currents or single-channel conductance, implicating a presynaptic mechanism(s). Consistent with this interpretation, bath glutamate failed to strengthen IPSCs during pharmacological saturation of GABA-A receptors. Presynaptic analyses revealed that glutamate did not affect paired-pulse ratio, peak eIPSC variability, GABA vesicle recycling speed, or readily releasable pool (RRP) size. Notably, glutamate-GABA strengthening (GGS) was unaffected by metabotropic glutamate receptor blockade and graded external Ca2+ when normalized to baseline amplitude. GGS was prevented by pan- but not glial-specific inhibition of glutamate uptake and by inhibition of glutamic acid decarboxylase (GAD), indicating reliance on glutamate uptake by neuronal excitatory amino acid transporter 3 (EAAT3) and enzymatic conversion of glutamate to GABA. EAAT3 immunoreactivity was strongly localized to presumptive PVN GABA terminals. High bath K+ also induced GGS, which was prevented by glutamate vesicle depletion, indicating that synaptic glutamate release strengthens PVN GABA inhibition. GGS suppressed PVN cell firing, indicating its functional significance. In sum, PVN GGS buffers neuronal excitation by apparent "over-filling" of vesicles with GABA synthesized from synaptically released glutamate. We posit that GGS protects against sustained PVN excitation and excitotoxicity while potentially aiding stress adaptation and habituation.

Evidence for an association between allostatic load and multisensory integration in middle-aged and older adults

Multisensory integration, the ability of the brain to integrate information from different sensory modalities, is critical for responding to environmental stimuli. While older adults show changes in multisensory integration with age, the impact of allostatic load (AL) (i.e., the effect of exposure to chronic stress, which can accelerate ageing) on multisensory perception remains understudied. We explored the relationship between multisensory integration and AL in 1,358 adults aged 50+ from The Irish Longitudinal Study on Ageing by performing a Sound Induced Flash Illusion (SIFI) task at multiple audio-visual temporal asynchronies. The AL score was created using a battery of biomarkers representing the activity of four major physiological systems: immunological, cardiovascular, metabolic, and renal. The number of biomarkers for which a participant was categorised in the highest risk quartile using sex-specific cutoffs was used to produce an overall AL score. We accounted for medication use when calculating our AL score. We analysed the accuracy of illusion trials on a SIFI task using generalised logistic mixed effects regression models adjusted for a number of covariates. Observation of cross-sectional and longitudinal results revealed that lower accuracy in integration (i.e., higher SIFI susceptibility with larger temporal asynchronies) was associated with higher AL. This confirmed the distinct patterns of multisensory integration in ageing.

Emphasizing the Crosstalk Between Inflammatory and Neural Signaling in Post-traumatic Stress Disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a chronic incapacitating condition with recurrent experience of trauma-related memories, negative mood, altered cognition, and hypervigilance. Agglomeration of preclinical and clinical evidence in recent years specified that alterations in neural networks favor certain characteristics of PTSD. Besides the disruption of hypothalamus-pituitary-axis (HPA) axis, intensified immune status with elevated pro-inflammatory cytokines and arachidonic metabolites of COX-2 such as PGE2 creates a putative scenario in worsening the neurobehavioral facet of PTSD. This review aims to link the Diagnostic and Statistical Manual of mental disorders (DSM-V) symptomology to major neural mechanisms that are supposed to underpin the transition from acute stress reactions to the development of PTSD. Also, to demonstrate how these intertwined processes can be applied to probable early intervention strategies followed by a description of the evidence supporting the proposed mechanisms. Hence in this review, several neural network mechanisms were postulated concerning the HPA axis, COX-2, PGE2, NLRP3, and sirtuins to unravel possible complex neuroinflammatory mechanisms that are obscured in PTSD condition.

The amygdala connectivity with depression and suicide ideation with suicide behavior: A meta-analysis of structural MRI, resting-state fMRI and task fMRI

In recent decades, the primary intention of neuroscientists and psychiatrics is to evaluate the connectivity between brain regions and psychiatric disorders. The amygdala has central immersion in memory alliance, stress response, emotional perception, and automatic responses to emotional stimuli. This paper uses a meta-analysis approach to establish the relationship between structural resting state and functional amygdala connectivity with depression and suicide ideation with suicide behavior. In addition, this study explores the moderating effect of patients' demographic characteristics (gender and age) based on 30 studies. The results show that structural amygdala connectivity is positively related to the instability of depression, while for resting and task functional connectivity amygdala shows a significant negative connection with depression. Furthermore, the amygdala showed a partial activation for non-suicide self-injuries and suicide ideation. From structural and functional magnetic imaging, the current findings also support the moderating effect of the age of the participants on the amygdala connectivity with psychiatric conditions. Generally, amygdala connectivity with psychiatric disorders was not significantly moderate with the role of gender, however, this study enhances the existing hypothetical review articles and confirms the connectivity of the psychological condition with the amygdala region. It concludes that the amygdala plays a vital role in regulating and responding to emotions.

Anxiolytic effects of vestibular stimulation: an update

The vestibular system inhibits both HPA and SAM axis and contributes to the management of anxiety. Both direct and indirect pathways exist in the inhibition of the HPA and SAM axis. In this review article, the authors describe various pathways through which the vestibular system can regulate the HPA and SAM axis activity. Lastly, the authors highlight the need of starting translational research work in this field. Rocking is soothing and this is a universal fact that babies in the swing will calm down and sleep. These soothing effects of vestibular stimulation may be due to the inhibition of cortical and subcortical structures. Vestibular stimulation may be able to manage anxiety through its connections with multiple brain areas. There is a need to undertake translational research in this area to establish strong scientific evidence and recommend implementation of the vestibular stimulation in the management of anxiety.

Probiotics for the treatment of depression and its comorbidities: A systemic review

Depression is one of the most common psychiatric conditions, characterized by significant and persistent depressed mood and diminished interest, and often coexists with various comorbidities. The underlying mechanism of depression remain elusive, evidenced by the lack of an appreciate therapy. Recent abundant clinical trials and animal studies support the new notion that the gut microbiota has emerged as a novel actor in the pathophysiology of depression, which partakes in bidirectional communication between the gut and the brain through the neuroendocrine, nervous, and immune signaling pathways, collectively known as the microbiota-gut-brain (MGB) axis. Alterations in the gut microbiota can trigger the changes in neurotransmitters, neuroinflammation, and behaviors. With the transition of human microbiome research from studying associations to investigating mechanistic causality, the MGB axis has emerged as a novel therapeutic target in depression and its comorbidities. These novel insights have fueled idea that targeting on the gut microbiota may open new windows for efficient treatment of depression and its comorbidities. Probiotics, live beneficial microorganisms, can be used to modulate gut dysbiosis into a new eubiosis and modify the occurrence and development of depression and its comorbidities. In present review, we summarize recent findings regarding the MGB axis in depression and discuss the potential therapeutic effects of probiotics on depression and its comorbidities.

Nutrient-sensing AgRP neurons relay control of liver autophagy during energy deprivation

Autophagy represents a key regulator of aging and metabolism in sensing energy deprivation. We find that fasting in mice activates autophagy in the liver paralleled by activation of hypothalamic AgRP neurons. Optogenetic and chemogenetic activation of AgRP neurons induces autophagy, alters phosphorylation of autophagy regulators, and promotes ketogenesis. AgRP neuron-dependent induction of liver autophagy relies on NPY release in the paraventricular nucleus of the hypothalamus (PVH) via presynaptic inhibition of NPY1R-expressing neurons to activate PVH^CRH neurons. Conversely, inhibiting AgRP neurons during energy deprivation abrogates induction of hepatic autophagy and rewiring of metabolism. AgRP neuron activation increases circulating corticosterone concentrations, and reduction of hepatic glucocorticoid receptor expression attenuates AgRP neuron-dependent activation of hepatic autophagy. Collectively, our study reveals a fundamental regulatory principle of liver autophagy in control of metabolic adaptation during nutrient deprivation.

Methylmercury effects on avian brains

Methylmercury (MeHg) is a concerning contaminant due to its ubiquity and harmful effects on organisms. Although birds are important models in the neurobiology of vocal learning and adult neuroplasticity, the neurotoxic effects of MeHg are less understood in birds than mammals. We surveyed the literature on MeHg effects on biochemical changes in the avian brain. Publication rates of papers related to neurology and/or birds and/or MeHg increased with time and can be linked with historical events, regulations, and increased understanding of MeHg cycling in the environment. However, publications on MeHg effects on the avian brain remain relatively low across time. The neural effects measured to evaluate MeHg neurotoxicity in birds changed with time and researcher interest. The measures most consistently affected by MeHg exposure in birds were markers of oxidative stress. NMDA, acetylcholinesterase, and Purkinje cells also seem sensitive to some extent. MeHg exposure has the potential to affect most neurotransmitter systems but more studies are needed for validation in birds. We also review the main mechanisms of MeHg-induced neurotoxicity in mammals and compare it to what is known in birds. The literature on MeHg effects on the avian brain is limited, preventing full construction of an adverse outcome pathway. We identify research gaps for taxonomic groups such as songbirds, and age- and life-stage groups such as immature fledgling stage and adult non-reproductive life stage. In addition, results are often inconsistent between experimental and field studies. We conclude that future neurotoxicological studies of MeHg impacts on birds need to better connect the numerous aspects of exposure from molecular physiological effects to behavioural outcomes that would be ecologically or biologically relevant for birds, especially under challenging conditions.

Maternal separation in mice leads to anxiety-like/aggressive behavior and increases immunoreactivity for glutamic acid decarboxylase and parvalbumin in the adolescence ventral hippocampus

It has been reported that stressful events in early life influence behavior in adulthood and are associated with different psychiatric disorders, such as major depression, post-traumatic stress disorder, bipolar disorder, and anxiety disorder. Maternal separation (MS) is a representative animal model for reproducing childhood stress. It is used as an animal model for depression, and has well-known effects, such as increasing anxiety behavior and causing abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis. This study investigated the effect of MS on anxiety or aggression-like behavior and the number of GABAergic neurons in the hippocampus. Mice were separated from their dams for four hours per day for 19 d from postnatal day two. Elevated plus maze (EPM) test, resident-intruder (RI) test, and counted glutamic acid decarboxylase 67 (GAD67) or parvalbumin (PV) positive cells in the hippocampus were executed using immunohistochemistry. The maternal segregation group exhibited increased anxiety and aggression in the EPM test and the RI test. GAD67-positive neurons were increased in the hippocampal regions we observed: dentate gyrus (DG), CA3, CA1, subiculum, presubiculum, and parasubiculum. PV-positive neurons were increased in the DG, CA3, presubiculum, and parasubiculum. Consistent with behavioral changes, corticosterone was increased in the MS group, suggesting that the behavioral changes induced by MS were expressed through the effect on the HPA axis. Altogether, MS alters anxiety and aggression levels, possibly through alteration of cytoarchitecture and output of the ventral hippocampus that induces the dysfunction of the HPA axis.

Pregnenolone effects on provoked alcohol craving, anxiety, HPA axis, and autonomic arousal in individuals with alcohol use disorder

RATIONALE

Chronic alcohol intake down-regulates GABAergic transmission and reduces levels of neuroactive steroids. These changes are associated with greater stress dysregulation and high alcohol craving which in turn increases relapse risk.

OBJECTIVES

This study tested whether potentiation of the neurosteroid system with pregnenolone (PREG), a precursor to neuroactive steroids and known to increase GABAergic transmission, will normalize chronic alcohol-related stress adaptations in the hypothalamic-pituitary-adrenal (HPA) axis and autonomic responses and reduce alcohol craving to significantly impact relapse risk.

METHODS

Forty-three treatment-seeking individuals with alcohol use disorder (AUD) were randomized to placebo (PBO) or supraphysiologic pregnenolone doses of 300 mg or 500 mg treatment using a parallel-between subject design as part of a larger 8-week pilot clinical trial. In week 2, they participated in a 3-day laboratory experiment where on each day they self-administered the assigned study drug in the laboratory and were then exposed to 5-min personalized guided imagery provocation of stress, alcohol, or neutral/relaxing cues, one condition per day on separate days, in a random, counterbalanced order. Repeated assessments of alcohol craving, anxiety, HPA axis, heart rate (HR), systolic (SBP), and diastolic blood pressure (DBP) and serum pregnenolone levels were made on each day.

RESULTS

Pregnenolone levels were significantly increased in the PREG groups versus PBO. PREG treatment decreased stress- and alcohol cue- induced craving and dose-specifically reduced stress-induced anxiety in the 300 mg/day group. Both PREG doses compared to PBO also normalized CORT/ACTH and increased stress-induced HR, stress- and cue-induced SBP, and in the 300 mg PREG group cue-induced DBP responses relative to neutral condition.

CONCLUSIONS

Findings indicate that pregnenolone decreases stress- and alcohol cue-provoked craving and normalizes HPA axis and autonomic arousal in individuals with AUD, thereby supporting the need for further assessment of pregnenolone in the treatment of AUD.

A molecular framework for autistic experiences: Mitochondrial allostatic load as a mediator between autism and psychopathology

Molecular autism research is evolving toward a biopsychosocial framework that is more informed by autistic experiences. In this context, research aims are moving away from correcting external autistic behaviors and toward alleviating internal distress. Autism Spectrum Conditions (ASCs) are associated with high rates of depression, suicidality and other comorbid psychopathologies, but this relationship is poorly understood. Here, we integrate emerging characterizations of internal autistic experiences within a molecular framework to yield insight into the prevalence of psychopathology in ASC. We demonstrate that descriptions of social camouflaging and autistic burnout resonate closely with the accepted definitions for early life stress (ELS) and chronic adolescent stress (CAS). We propose that social camouflaging could be considered a distinct form of CAS that contributes to allostatic overload, culminating in a pathophysiological state that is experienced as autistic burnout. Autistic burnout is thought to contribute to psychopathology via psychological and physiological mechanisms, but these remain largely unexplored by molecular researchers. Building on converging fields in molecular neuroscience, we discuss the substantial evidence implicating mitochondrial dysfunction in ASC to propose a novel role for mitochondrial allostatic load in the relationship between autism and psychopathology. An interplay between mitochondrial, neuroimmune and neuroendocrine signaling is increasingly implicated in stress-related psychopathologies, and these molecular players are also associated with neurodevelopmental, neurophysiological and neurochemical aspects of ASC. Together, this suggests an increased exposure and underlying molecular susceptibility to ELS that increases the risk of psychopathology in ASC. This article describes an integrative framework shaped by autistic experiences that highlights novel avenues for molecular research into mechanisms that directly affect the quality of life and wellbeing of autistic individuals. Moreover, this framework emphasizes the need for increased access to diagnoses, accommodations, and resources to improve mental health outcomes in autism.

Raw and Wine Processed Schisandra chinensis Regulate NREM-Sleep and Alleviate Cardiovascular Dysfunction Associated with Insomnia by Modulating HPA Axis

Clinical studies have shown that insomnia and anxiety are usually accompanied by cardiovascular dysfunction. In traditional Chinese medicine, Schisandra chinensis (SC) and wine processed Schisandra chinensis (WSC) are mainly used for the treatment of dysphoria, palpitation and insomnia. However, little attention was paid to its mechanism. In this study, we monitored the effect of SC and WSC on the nervous system and cardiovascular system of free-moving rats in the real-time. Our results show that SC and WSC can alleviate cardiovascular dysfunction while promoting sleep, and we further explored their potential mechanisms. HPLC-QTOF-MS was used for the quality control of chemical components in SC and WSC. Data sciences international (DSI) physiological telemetry system was applied to collect the electroencephalogram (EEG), electrocardiogram (ECG) and other parameters of free-moving rats to understand the effects of long-term intake of SC and WSC on rats. The content of Cortisol (CORT), neurotransmitters and amino acids in rat pituitary and hypothalamus were analyzed by UPLC-MS to determine the activity of HPA axis. The expression of melatonin receptor MT1 was analyzed by immunofluorescence technique. Our results suggested that SC and WSC may play the role of promoting sleep by increasing the expression level of melatonin receptor MT1 in hypothalamus, and modulate the activity of HPA axis by regulating the levels of the related neurotransmitters and amino acid, so as to improve the abnormal cardiovascular system of rats. This study may provide theoretical support for explicating the advantages of SC and other phytomedicines in the treatment of insomnia.

Dexmedetomidine Diminishes, but Does Not Prevent, Developmental Effects of Sevoflurane in Neonatal Rats

BACKGROUND

Sevoflurane (SEVO) increases neuronal excitation in neonatal rodent brains through alteration of gamma aminobutyric acid (GABA)(A) receptor signaling and increases corticosterone release. These actions may contribute to mechanisms that initiate the anesthetic's long-term neuroendocrine and neurobehavioral effects. Dexmedetomidine (DEX), a non-GABAergic α2-adrenergic receptor agonist, is likely to counteract SEVO-induced neuronal excitation. We investigated how DEX pretreatment may alter the neurodevelopmental effects induced by SEVO in neonatal rats.

METHODS

Postnatal day (P) 5 Sprague-Dawley male rats received DEX (25 µg/kg, intraperitoneal) or vehicle before exposure to 2.1% SEVO for 6 hours (the DEX + SEVO and SEVO groups, respectively). Rats in the DEX-only group received DEX without exposure to SEVO. A subcohort of P5 rats was used for electroencephalographic and serum corticosterone measurements. The remaining rats were sequentially evaluated in the elevated plus maze on P80, prepulse inhibition of the acoustic startle response on P90, Morris water maze (MWM) starting on P100, and for corticosterone responses to physical restraint for 30 minutes on P120, followed by assessment of epigenomic DNA methylation patterns in the hippocampus.

RESULTS

Acutely, DEX depressed SEVO-induced electroencephalogram-detectable seizure-like activity (mean ± SEM, SEVO versus DEX + SEVO, 33.1 ± 5.3 vs 3.9 ± 5.3 seconds, P < .001), but it exacerbated corticosterone release (SEVO versus DEX + SEVO, 169.935 ± 20.995 versus 280.853 ± 40.963 ng/mL, P = .043). DEX diminished, but did not fully abolish, SEVO-induced corticosterone responses to restraint (control: 11625.230 ± 877.513, SEVO: 19363.555 ± 751.325, DEX + SEVO: 15012.216 ± 901.706, DEX-only: 12497.051 ± 999.816; F[3,31] = 16.878, P < .001) and behavioral deficiencies (time spent in the target quadrant of the MWM: control: 31.283% ± 1.722%, SEVO: 21.888% ± 2.187%, DEX + SEVO: 28.617% ± 1.501%, DEX-only: 31.339% ± 3.087%; F[3,67] = 3.944, P = .012) in adulthood. Of the 391 differentially methylated genes in the SEVO group, 303 genes in the DEX + SEVO group had DNA methylation patterns that were not different from those in the control group (ie, they were normal). DEX alone did not cause acute or long-term functional abnormalities.

CONCLUSIONS

This study suggests that the ability of DEX to depress SEVO-induced neuronal excitation, despite increasing corticosterone release, is sufficient to weaken mechanisms leading to long-term neuroendocrine/neurobehavioral abnormalities. DEX may prevent changes in DNA methylation in the majority of genes affected by SEVO, epigenetic modifications that could predict abnormalities in a wide range of functions.

The circadian rhythm of blood pressure in patients with panic disorder and generalized anxiety disorder

BACKGROUND

Anxiety disorders affect blood pressure both during the day and at night. Little is known about the effect of individual anxiety disorders on the circadian rhythm of blood pressure.

OBJECTIVES

The purpose of this study is to compare the nocturnal drop in blood pressure in patients with panic disorder (PD), generalized anxiety disorder (GAD), and healthy individuals.

METHODS

The study was conducted on fifty consecutive outpatients with anxiety disorders and personality disorders who participated in intensive group psychotherapy. Diagnoses were made according to DSM-IV-TR criteria using the PSE-10 questionnaire. Out of 50 patients under study, 17 were diagnosed with PD and 21 with GAD. The control group consisted of 40 healthy people recruited in the course of other studies. The resulting three groups were compared in terms of circadian blood pressure using the ABPM method.

RESULTS

Mean nocturnal falls in systolic and diastolic blood pressure were the following: 2% and 3% (PD), 11% and 12% (GAD), 27% and 23% (control). Four people out of PD group had higher systolic and diastolic blood pressure at night than during the day. The ratios between non-dippers/dippers were: 0/15 (PD), 8/21 (38% - GAD) and 40/40 (100% - control).

CONCLUSIONS

The patients with PD were characterized by an almost flat course of circadian blood pressure. The patients with GAD had a lower mean nocturnal fall in blood pressure than the control group, but significantly higher than the patients with PD. The differences in the circadian course of blood pressure between PD and GAD are so large that the impact of these disorders should be investigated separately.

A subpopulation of agouti-related peptide neurons exciting corticotropin-releasing hormone axon terminals in median eminence led to hypothalamic-pituitary-adrenal axis activation in response to food restriction

The excitatory action of gamma-aminobutyric-acid (GABA) in the median-eminence (ME) led to the steady-state release of corticotropin-releasing hormone (CRH) from CRH axon terminals, which modulates the hypothalamic-pituitary-adrenal (HPA) axis. However, in ME, the source of excitatory GABAergic input is unknown. We examined agouti-related peptide (AgRP) expressing neurons in the arcuate nucleus as a possible source for excitatory GABAergic input. Here, we show that a subpopulation of activated AgRP neurons directly project to the CRH axon terminals in ME elevates serum corticosterone levels in 60% food-restricted mice. This increase in serum corticosterone is not dependent on activation of CRH neuronal soma in the paraventricular nucleus. Furthermore, conditional deletion of Na⁺-K⁺-2Cl^– cotransporter-1 (NKCC1), which promotes depolarizing GABA action, from the CRH axon terminals results in significantly lower corticosterone levels in response to food restriction. These findings highlight the important role of a subset of AgRP neurons in HPA axis modulation via NKCC1-dependent GABAergic excitation in ME.

Hypothalamic Neurochemical Changes in Long-Term Recovered Bilateral Subdiaphragmatic Vagotomized Rats

Background

Vagus nerve is one of the crucial routes in communication between the immune and central nervous systems. The impaired vagal nerve function may intensify peripheral inflammatory processes. This effect subsides along with prolonged recovery after permanent nerve injury. One of the results of such compensation is a normalized plasma concentration of stress hormone corticosterone – a marker of hypothalamic-pituitary-adrenal (HPA) axis activity. In this work, we strive to explain this corticosterone normalization by studying the mechanisms responsible for compensation-related neurochemical alterations in the hypothalamus.

Materials and Methods

Using microarrays and high performance liquid chromatography (HPLC), we measured genome-wide gene expression and major amino acid neurotransmitters content in the hypothalamus of bilaterally vagotomized rats, 1 month after surgery.

Results

Our results show that, in the long term, vagotomy affects hypothalamic amino acids concentration but not mRNA expression of tested genes.

Discussion

We propose an alternative pathway of immune to CNS communication after vagotomy, leading to activation of the HPA axis, by influencing central amino acids and subsequent monoaminergic neurotransmission.

Caloric Vestibular Stimulation Induced Enhancement of Behavior and Neurotrophic Factors in Chronic Mild Stress Induced Rats

Background: Caloric Vestibular Stimulation (CVS) is a non-invasive technique for stimulating the vestibular system. The vestibular system maintains equilibrium and acts as a moderator of mood, emotional control, and stress levels. Stress is a disruption of psychological, behavioral, and physiological homeostasis that affects people of all ages in today's world. Thus, modest therapeutic procedures like vestibular stimulation can be practiced to effectively reduce stress. Hence, the purpose of the study was to determine the effect of vestibular stimulation on improving behavioral alterations and neurotrophic factors in rats exposed to Chronic Mild Stress (CMS). Methodology: The study employed 24 healthy male Sprague Dawley rats divided into four groups (n = 6). CMS was induced for 28 days with a variety of stimuli. Bilateral CVS with hot water (temperature ≈40°C) was started on Day 14 of CMS and continued for 15 days. On days 1, 15, and 28, locomotor activity (LA), wire grip strength (WGS), fall off time (FT), and immobilization time (IT) were measured, and the data were analyzed statistically. Additionally, neurotrophic factors such as Brain Derived Neurotrophic Factor (BDNF) and Glial cell line-Derived Neurotrophic Factor (GDNF) were observed in rats' hippocampus. Results: On days 15 and 28, the CMS-induced group showed a significant reduction in LA, WGS, FT and IT in comparison to the control group. On day 28, the CVS-induced group demonstrated a significant increase in WGS, FT and IT when compared to the CMS group. Immunohistochemical analysis revealed that animals subjected to CMS had decreased BDNF and GDNF expression compared to the control group, indicating neuronal dysfunction in the hippocampus in response to stress. However, therapy with CVS increased BDNF and GDNF expression, thereby regenerating damaged hippocampus nerve terminals. Conclusion: The findings of the current study revealed that CVS is a safe and simple neuroprotective treatment against stress and a promising non-invasive technique for overcoming the motor symptoms associated with it. The findings may pave the way for future research and therapeutic applications of CVS for stress management.

Allopregnanolone: An overview on its synthesis and effects

Allopregnanolone, a 3α,5α-progesterone metabolite, acts as a potent allosteric modulator of the γ-aminobutyric acid type A receptor. In the present review, the synthesis of this neuroactive steroid occurring in the nervous system is discussed with respect to physiological and pathological conditions. In addition, its physiological and neuroprotective effects are also reported. Interestingly, the levels of this neuroactive steroid, as well as its effects, are sex-dimorphic, suggesting a possible gender medicine based on this neuroactive steroid for neurological disorders. However, allopregnanolone presents low bioavailability and extensive hepatic metabolism, limiting its use as a drug. Therefore, synthetic analogues or a different therapeutic strategy able to increase allopregnanolone levels have been proposed to overcome any pharmacokinetic issues.

GABRB2, a key player in neuropsychiatric disorders and beyond

The GABA receptors represent the main inhibitory system in the central nervous system that ensure synaptogenesis, neurogenesis, and the regulation of neuronal plasticity and learning. GABAA receptors are pentameric in structure and belong to the Cys-loop superfamily. The GABRB2 gene, located on chromosome 5q34, encodes the β2 subunit that combines with the α and γ subunits to form the major subtype of GABAA receptors, which account for 43% of all GABAA receptors in the mammalian brain. Each subunit probably consists of an extracellular N-terminal domain, four membrane-spanning segments, a large intracellular loop between TM3 and TM4, and an extracellular C-terminal domain. Alternative splicing of the RNA transcript of the GABRB2 gene gives rise at least to four long and short isoforms with dissimilar electrophysiological properties. Furthermore, GABRB2 is imprinted and subjected to epigenetic regulation and positive selection. It has been associated with schizophrenia first in Han Chinese, and subsequently validated in other populations. Gabrb2 knockout mice also exhibited schizophrenia-like behavior and neuroinflammation that were ameliorated by the antipsychotic drug risperidone. GABRB2 was also associated with other neuropsychiatric disorders including bipolar disorder, epilepsy, autism spectrum disorder, Alzheimer's disease, frontotemporal dementia, substance dependence, depression, internet gaming disorder, and premenstrual dysphoric disorder. Recently, it has been postulated that GABRB2 might be a potential marker for different cancer types. As GABRB2 has a pivotal role in the central nervous system and is increasingly recognized to contribute to human diseases, further understanding of its structure and function may expedite the generation of new therapeutic approaches.

Age Effects Aggressive Behavior: RNA-Seq Analysis in Cattle with Implications for Studying Neoteny Under Domestication

The reactive type of aggression is regulated mostly by the brain's prefrontal cortex; however, the molecular changes underlying aggressiveness in adults have not been fully characterized. We used an RNA-seq approach to investigate differential gene expression in the prefrontal cortex of bovines from the aggressive Lidia breed at different ages: young three-year old and adult four-year-old bulls. A total of 50 up and 193 down-regulated genes in the adult group were identified. Furthermore, a cross-species comparative analysis retrieved 29 genes in common with previous studies on aggressive behaviors, representing an above-chance overlap with the differentially expressed genes in adult bulls. We detected changes in the regulation of networks such as synaptogenesis, involved in maintenance and refinement of synapses, and the glutamate receptor pathway, which acts as excitatory driver in aggressive responses. The reduced reactive aggression typical of domestication has been proposed to form part of a retention of juvenile traits as adults (neoteny).

Precision Medicine in Alzheimer's Disease: Investigating Comorbid Common Biological Substrates in the Rat Model of Amyloid Beta-Induced Toxicity

Alzheimer's disease (AD), one of the most widespread neurodegenerative disorder, is a fatal global burden for the elder population. Although many efforts have been made, the search of a curative therapy is still ongoing. Individuating phenotypic traits that might help in investigating treatment response is of growing interest in AD research. AD is a complex pathology characterized by many comorbidities, such as depression and increased susceptibility to pain perception, leading to postulate that these conditions may rely on common biological substrates yet to be determined. In order to investigate those biological determinants to be associable with phenotypic traits, we used the rat model of amyloid beta-induced toxicity. This established model of early phase of AD is obtained by the intracerebroventricular injection of soluble amyloid beta1-42 (Aβ) peptide 7 days before performing experiments. In this model, we have previously reported increased immobility in the forced swimming test, reduced cortical serotonin levels and subtle alterations in the cognitive domain a depressive-like phenotype associated with subtle alteration in memory processes. In light of evaluating pain perception in this animal model, we performed two different behavioral tests commonly used, such as the paw pressure test and the cold plate test, to analyze mechanical hyperalgesia and thermal allodynia, respectively. Behavioural outcomes confirmed the memory impairment in the social recognition test and, compared to sham, Aβ-injected rats showed an increased selective susceptibility to mechanical but not to thermal stimulus. Behavioural data were then corroborated by neurochemical and biochemical biomarker analyses either at central or peripheral level. Data showed that the peptide injection evoked a significant increase in hypothalamic glutamate, kynurenine and dopamine content, while serotonin levels were reduced. Plasma Cystatin-C, a cysteine protease, was increased while serotonin and melatonin levels were decreased in Aβ-injected rats. Urinary levels paralleled plasma quantifications, indicating that Aβ-induced deficits in pain perception, mood and cognitive domain may also depend on these biomarkers. In conclusion, in the present study, we demonstrated that this animal model can mimic several comorbid conditions typical of the early phase of AD. Therefore, in the perspective of generating novel therapeutic strategies relevant to precision medicine in AD, this animal model and the biomarkers evaluated herein may represent an advantageous approach.

Voiding and storage symptoms in depression/anxiety

We here described the frequency and nature of voiding and storage bladder symptoms in depression/anxiety, for which we propose the name "bladder somatic symptom disorder (SSD)" because such symptoms most probably have brain mechanisms. SSD was formerly called as various terms including "somatoform disorder", "medically unexplained physical symptoms", "functional somatic syndrome" and "hysterical neurosis/hysteria". Bladder SSD has the following specific features that are distinguishable from "true" neurologic/organic bladder dysfunction: 1) situation-dependence (close association with life event in some), 2) urodynamically increased bladder sensation/hypersensitivity and 3) absence of neurologic/organic diseases, in addition to 4) other stress symptoms (insomnia, etc.), are key clues to the possibility of bladder SSD. Urodynamics in these patients showed, to a lesser extent, underactive bladder without post-void residual. These findings might reflect the biological changes of the depressive brain; e.g., decreases in serotonin and GABA, and possible increases in CRH. Treatment of bladder SSD can follow that of general depression/anxiety, with the potential addition of anticholinergic or selective beta3 bladder drugs.

Age- and sex-specific effects of stress on parvalbumin interneurons in preclinical models: Relevance to sex differences in clinical neuropsychiatric and neurodevelopmental disorders

Stress is a major risk factor for neurodevelopmental and neuropsychiatric disorders, with the capacity to impact susceptibility to disease as well as long-term neurobiological and behavioral outcomes. Parvalbumin (PV) interneurons, the most prominent subtype of GABAergic interneurons in the cortex, are uniquely responsive to stress due to their protracted development throughout the highly plastic neonatal period and into puberty and adolescence. Additionally, PV + interneurons appear to respond to stress in a sex-specific manner. This review aims to discuss existing preclinical studies that support our overall hypothesis that the sex-and age-specific impacts of stress on PV + interneurons contribute to differences in individual vulnerability to stress across the lifespan, particularly in regard to sex differences in the diagnostic rate of neurodevelopmental and neuropsychiatric diseases in clinical populations. We also emphasize the importance of studying sex as a biological variable to fully understand the mechanistic and behavioral differences between males and females in models of neuropsychiatric disease.

Dysfunction of the hypothalamic‑pituitary‑adrenal axis in male rat offspring with prenatal food restriction: Fetal programming of hypothalamic hyperexcitability and poor hippocampal feedback

Prenatal food restriction (PFR) induces dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis in the adult offspring. The aim of the present study was to identify the underlying mechanism of this process. Pregnant rats were placed on a restricted diet between gestational day 11 and 21. The offspring were fed with a high-fat diet and were subjected to unpredictable chronic stress (UCS) from postnatal week 17 to 20. A higher serum corticosterone (CORT) level was observed in the PFR fetuses. Although lower arginine vasopressin (AVP), hippocampal vesicular glutamate transporter 2 (vGLUT2) and glutamic acid decarboxylase 65 (GAD65) mRNA expression levels were detected in the hippocampi of PFR fetuses, the ratio of the mRNA expression levels of vGLUT2 and GAD65 was higher compared with that of the controls, which was accompanied by histopathological and ultrastructural abnormalities of both the hypothalamus and hippocampus. However, there were no marked changes in the hippocampal expression levels of glucocorticoids receptor (GR) and mineralocorticoids receptor (MR) or the ratio of MR/GR ratio. After the fetuses had matured, lower serum CORT and adrenocorticotropic hormone (ACTH) levels were observed in PFR rats without UCS when compared with the control. A higher rise rate of serum ACTH was also observed after UCS when compared with that in rats without UCS. Furthermore, the hypothalamic mRNA expression level of corticotrophin-releasing hormone (CRH) was lower in PFR rats without UCS, while expression levels of CRH, AVP, GAD65 and vGLUT2 were enhanced after UCS when compared with the control, accompanied by an increased vGLUT2/GAD65 expression ratio. MR mRNA expression was lower, and GR mRNA expression was higher in the hippocampus of the PFR rats without UCS when compared with the control. However, the mRNA expression levels of both MR and GR in the PFR rats were higher compared with those of the control after UCS, which was accompanied histopathological changes in the dentate gyrus, cornu ammonis (CA1) and CA3 areas. In summary, it was suggested that PFR induced fetal alterations of the HPA axis manifesting as hypothalamic hyperexcitability and poor hippocampal feedback, which persisted to adulthood and affected the behavior of the rat offspring.

Potential impact of stocking density on growth, carcass traits, indicators of biochemical and oxidative stress and meat quality of different broiler breeds

The aim of the current study to investigate the potential impact of different stocking densities on growth performance, carcass traits, indicators of biochemical and oxidative stress and meat quality of Arbor Acres and Ross-308 broiler breeds to recommend the better stocking density with low production cost simultaneously with high quality. A total of 312 one-day old of each Arbor Acres broiler and Ross-308 were randomly classified into 3 experimental groups with different stocking density, each of 6 replicates. The first group (SD1) was 14 birds/m2 (28 kg/m2), while the second group (SD2) was 18 birds/m2 (36 kg/m2) and the third group (SD3) was 20 birds/m2 (40 kg/m2). The growth performance, carcass traits, meat quality hematological and biochemical parameters were measured. SD3 group possessed the lowest body weight. Alanine transaminase in Arbor Acres was 15 and 14% higher in SD3 when compared with SD1 and SD2, respectively. While, was 21 and 20% of Ross-308, respectively. SD3 revealed the highest values of cholesterol, TG, MDA, and LDL of both breeds when compared with SD1 and SD2, with the lowest levels of HDL, GPX, and IGG. Birds of SD3 was the nastiest carcass weight 873 (P = 0.000) and 1,411.60 g (P = 0.000); dressing percentage 63.07 (P = 0.000) and 75.83% (P = 0.000); breast weight 513.10 g (P = 0.000) and 885.50g (P = 0.000); thigh weight 359.90 g (P = 0.000) and 526.08 g (P = 0.000) when compared with SD1 and SD2 of Arbor Acres and Ross-308, respectively. The dressing % of SD1 and SD2 was approximately 19% better than that of SD3 of Arbor Acres, while it was 4% of Ross-308. The cooking loss and drip loss of breast and thigh muscles were higher in SD3 of both breeds. Moreover, SD3 possessed the highest bacterial count. In conclusion birds reared in medium stocking density revealed better performance and welfare than high density but similar to low density. Therefore, from the economic point, medium density was the best.

Exploring the link between adolescent inhalant misuse and suicidal behaviour: a behavioural toxicology perspective

Adolescent inhalant misuse has a known association with suicidal thoughts and behaviour. This association persists even after inhalant misuse has ceased. Previous studies have hypothesised that this association may derive from socioeconomic disadvantage or vulnerability, and potentially mediated by impulsivity. This association may also be due to the central nervous system depressant effects of inhalants. This review takes a behavioural toxicology perspective, focussed particularly on the serotonergic system and the Hypothalamic-Pituitary-Adrenal (HPA) axis, as potential links between adolescent inhalant misuse and suicidal behaviour. The challenges of bridging the pre-clinical and clinical literature in this area are discussed, along with promising avenues for future research; ultimately aimed at reducing suicide risk in a vulnerable adolescent population group.

Gut Microbiota-Induced Changes in β-Hydroxybutyrate Metabolism Are Linked to Altered Sociability and Depression in Alcohol Use Disorder

Patients with alcohol use disorder (AUD) present with important emotional, cognitive, and social impairments. The gut microbiota has been recently shown to regulate brain functions and behavior but convincing evidence of its role in AUD is lacking. Here, we show that gut dysbiosis is associated with metabolic alterations that affect behavioral (depression, sociability) and neurobiological (myelination, neurotransmission, inflammation) processes involved in alcohol addiction. By transplanting the gut microbiota from AUD patients to mice, we point out that the production of ethanol by specific bacterial genera and the reduction of lipolysis are associated with a lower hepatic synthesis of β-hydroxybutyrate (BHB), which thereby prevents the neuroprotective effect of BHB. We confirm these results in detoxified AUD patients, in which we observe a persisting ethanol production in the feces as well as correlations among low plasma BHB levels and social impairments, depression, or brain white matter alterations.

The effect of gamma-aminobutyric acid supplementation on growth performances, immune responses, and blood parameters of chickens reared under stressful environment: a meta-analysis

Gamma-aminobutyric acid (GABA) is a well-known feed supplement for its capability of reducing the adverse effect of stress in chickens. Several studies using GABA supplementation as a mitigatory measure have been published. However, it remains difficult to draw a general conclusion since these studies have been done under different experimental conditions. Therefore, the objective of this study was to quantify the response (growth performances, immune responses, and blood biochemical parameters) of chickens to GABA supplementation under various stressful conditions through a meta-analysis approach. A total of 19 articles published from 2011 to 2020, including 30 treatments, were used. A mixed-model ANOVA was used to assess how the growth parameters varied based on the GABA mode of supplementation. Linear mixed models and general linear models were used to evaluate the effects of the GABA doses and the duration of the supplementation on the growth performances and the immune parameters. Results indicated that supplementation of GABA via drinking water was more effective than dietary supplementation for reducing the feed conversion ratio in heat-stressed birds (P < 0.01). In addition, an increase in the GABA doses resulted in an augmentation (P < 0.01) of the body weight gain while a longer duration of supplementation resulted in increasing (P<0.01) the feed intake. Furthermore, increasing the duration of the supplementation reduced the immunoglobulin (P < 0.0001) and bursa's relative weight (P < 0.0001), while increasing blood CD8+ count (P < 0.001) and spleen's relative weight (P < 0.0001). Finally, blood total protein content was increased (P < 0.0001) by a longer duration of supplementation. This study showed that the doses and the duration of the GABA supplementation can affect the growth performances of chickens under stressful conditions. However, the effect of GABA on immune responses and blood parameters is perceived with a relatively longer supplementation duration.

Drugs and bugs: Negative affect, psychostimulant use and withdrawal, and the microbiome

BACKGROUND AND OBJECTIVES

A growing body of literature demonstrates that the human microbiota plays a crucial role in health and disease states, as well as in the body's response to stress. In addition, the microbiome plays a role in psychological well-being and regulating negative affect. Regulation of negative affect is a factor in psychostimulant abuse disorders. We propose a risk chain in which stress leads to negative affect that places an individual at risk to develop or relapse to psychostimulant abuse disorder. Stress, negative affect, and psychostimulant use all alter the gut microbiome.

METHODS

This review brings together the literature on affective disorders, stress, and psychostimulant abuse disorders to assess possible modulatory actions of the gut-brain axis to regulate these conditions.

RESULTS

Studies reviewed across the various disciplines suggest that the dysbiosis resulting from drug use, drug withdrawal, or stress may cause an individual to be more susceptible to addiction and relapse. Probiotics and prebiotics reduce stress and negative affect.

SCIENTIFIC SIGNIFICANCE

Treatment during the withdrawal phase of psychostimulant abuse disorder, when the microbiome is altered, may ameliorate the symptoms of stress and negative affect leading to a reduced risk of relapse to psychostimulant use.

Capturing the Effects of Domestication on Vocal Learning Complexity

Domesticated and vocal learning species can serve as informative model organisms for the reduction of reactive aggression and emergence of speech in our lineage. Amidst mounting evidence that domestication modifies vocal repertoires across different species, we focus on the domesticated Bengalese finch, which has a more complex song than the wild-type white-rumped munia. Our explanation for this effect revolves around the glutamate neurotransmitter system. Glutamate signaling (i) is implicated in birdsong learning, (ii) controls dopamine activity in neural circuits crucial for vocal learning, (iii) is disproportionately targeted in the evolution of domesticates, and (iv) regulates stress responses and aggressive behaviors attenuated under domestication. We propose that attenuated excitation of stress-related neural circuits potentiates vocal learning via altered dopaminergic signaling.

Drug addiction co-morbidity with alcohol: Neurobiological insights

Addiction is a chronic disorder that consists of a three-stage cycle of binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. These stages involve, respectively, neuroadaptations in brain circuits involved in incentive salience and habit formation, stress surfeit and reward deficit, and executive function. Much research on addiction focuses on the neurobiology underlying single drug use. However, alcohol use disorder (AUD) can be co-morbid with substance use disorder (SUD), called dual dependence. The limited epidemiological data on dual dependence indicates that there is a large population of individuals suffering from addiction who are dependent on more than one drug and/or alcohol, yet dual dependence remains understudied in addiction research. Here, we review neurobiological data on neurotransmitter and neuropeptide systems that are known to contribute to addiction pathology and how the involvement of these systems is consistent or divergent across drug classes. In particular, we highlight the dopamine, opioid, corticotropin-releasing factor, norepinephrine, hypocretin/orexin, glucocorticoid, neuroimmune signaling, endocannabinoid, glutamate, and GABA systems. We also discuss the limited research on these systems in dual dependence. Collectively, these studies demonstrate that the use of multiple drugs can produce neuroadaptations that are distinct from single drug use. Further investigation into the neurobiology of dual dependence is necessary to develop effective treatments for addiction to multiple drugs.

The Role of Hypothalamic Inflammation in Diet-Induced Obesity and Its Association with Cognitive and Mood Disorders

Obesity is often associated with cognitive and mood disorders. Recent evidence suggests that obesity may cause hypothalamic inflammation. Our aim was to investigate the hypothesis that there is a causal link between obesity-induced hypothalamic inflammation and cognitive and mood disorders. Inflammation may influence hypothalamic inter-connections with regions important for cognition and mood, while it may cause dysregulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis and influence monoaminergic systems. Exercise, healthy diet, and glucagon-like peptide receptor agonists, which can reduce hypothalamic inflammation in obese models, could improve the deleterious effects on cognition and mood.

Magnesium Status and Stress: The Vicious Circle Concept Revisited

Magnesium deficiency and stress are both common conditions among the general population, which, over time, can increase the risk of health consequences. Numerous studies, both in pre-clinical and clinical settings, have investigated the interaction of magnesium with key mediators of the physiological stress response, and demonstrated that magnesium plays an inhibitory key role in the regulation and neurotransmission of the normal stress response. Furthermore, low magnesium status has been reported in several studies assessing nutritional aspects in subjects suffering from psychological stress or associated symptoms. This overlap in the results suggests that stress could increase magnesium loss, causing a deficiency; and in turn, magnesium deficiency could enhance the body’s susceptibility to stress, resulting in a magnesium and stress vicious circle. This review revisits the magnesium and stress vicious circle concept, first introduced in the early 1990s, in light of recent available data.

GABA-mediated activated microglia induce neuroinflammation in the hippocampus of mice following cold exposure through the NLRP3 inflammasome and NF-κB signaling pathways

Chronic cold stress has long-term dramatic effects on the animal immune and neuroendocrine systems. As one of the important regions of the brain, the hippocampus is the main region involved in response to stressors. Nevertheless, the impact to the hippocampus following cold exposure and the underlying mechanism involved are not clear. To evaluate the response of the hippocampus during chronic cold stress, male C57BL/6 mice were exposed to 4 °C, 3 h per day for 1 week, after which neuroinflammation and the molecular and signaling pathways in the hippocampus response to cold stress were investigated. To confirm the potential mechanism, BV2 cells were treated with γ-aminobutyric acid (GABA) and BAY 11-7082 and MCC950, then the activation of microglia and key proteins involved in the regulation of inflammation were measured. We demonstrated that chronic cold stress induced the activation of microglia, the emergence of neuroinflammation, and the impairment of neurons in the hippocampus, which might be the result of GABA-mediated activation of nod-like receptor protein 3 (NLRP3) inflammasome and the nuclear factor kappa B (NF-κB) signaling pathway.

Astrocytes Amplify Neuronal Dendritic Volume Transmission Stimulated by Norepinephrine

In addition to their support role in neurotransmitter and ion buffering, astrocytes directly regulate neurotransmission at synapses via local bidirectional signaling with neurons. Here, we reveal a form of neuronal-astrocytic signaling that transmits retrograde dendritic signals to distal upstream neurons in order to activate recurrent synaptic circuits. Norepinephrine activates α₁ adrenoreceptors in hypothalamic corticotropin-releasing hormone (CRH) neurons to stimulate dendritic release, which triggers an astrocytic calcium response and release of ATP; ATP stimulates action potentials in upstream glutamate and GABA neurons to activate recurrent excitatory and inhibitory synaptic circuits to the CRH neurons. Thus, norepinephrine activates a retrograde signaling mechanism in CRH neurons that engages astrocytes in order to extend dendritic volume transmission to reach distal presynaptic glutamate and GABA neurons, thereby amplifying volume transmission mediated by dendritic release.

The effects of Topiramate on isolation-induced aggression: a behavioral and immunohistochemical study in mice

Topiramate, an antiepileptic drug, has been found to be useful for the treatment of aggression in clinical populations. Most preclinical studies related to Topiramate have been focused exclusively on the quantitative aspects of the aggressive behavior between mice. However, there is still limited knowledge regarding the effects of Topiramate on neuronal mechanisms occurring in aggressive mice. The present work aims to understand further the effects of the antiepileptic drug Topiramate on aggressive behaviors, and on the neural correlates underlying such behaviors. To achieve this, we combined the resident-intruder model of isolation-induced aggression in mice with two drug regimens of Topiramate administration (30.0 mg/kg; acute and sub-chronic treatments). Our data showed that both acute and subchronic treatments decreased the intensity of agonistic encounters and reinforced social behavior. By using C-fos immunoreactivity, we investigated the neuronal activation of several brain regions involved in aggressive behavior following subchronic treatment. We found that Topiramate produced activation in several cortical areas and in the lateral septum of resident brain mice compared with their controls. However, Topiramate induced inhibition in the medial nucleus of the amygdala, the dorsomedial nucleus of the periaqueductal gray, and especially in the anterior hypothalamic nucleus. Finally, we performed microinfusion of Topiramate (0.1 and 0.3 mM) into the lateral septum and anterior hypothalamus on offensive behaviors in isolation-induced-aggression paradigm. Interestingly, the microinfusion of Topiramate into the lateral septum has the capacity to alleviate aggressive behavior, without affecting social behavior. However, the microinfusion of Topiramate into the anterior hypothalamus decreased aggressive behavior and slightly reinforced social behavior. Our observations supported that the dose of 0.1 mM of Topiramate appeared more efficacy to treat aggression in adult mice. These pharmacological characteristics may account for Topiramate efficacy on aggressive symptoms in psychiatric patients.

Pharmacological Treatment of Anxiety Disorders: The Role of the HPA Axis

Stress in general, and early life stress in particular, has been associated with the development of anxiety and mood disorders. The molecular, biological and psychological links between stress exposure and the pathogenesis of anxiety and mood disorders have been extensively studied, resulting in the search of novel psychopharmacological strategies aimed at targets of the hypothalamic-pituitary-adrenal (HPA) axis. Hyperactivity of the HPA axis has been observed in certain subgroups of patients with anxiety and mood disorders. In addition, the effects of different anti-anxiety agents on various components of the HPA axis has been investigated, including benzodiazepines, tricyclic antidepressants (TCAs), and selective serotonin reuptake inhibitors (SSRIs). For example, benzodiazepines, including clonazepam and alprazolam, have been demonstrated to reduce the activity of corticotrophin releasing factor (CRF) neurons in the hypothalamus. TCAs and SSRIs are also effective anti-anxiety agents and these may act, in part, by modulating the HPA axis. In this regard, the SSRI escitalopram inhibits CRF release in the central nucleus of the amygdala, while increasing glucocorticoid receptor (GRs) density in the hippocampus and hypothalamus. The molecular effects of these anti-anxiety agents in the regulation of the HPA axis, taken together with their clinical efficacy, may provide further understanding about the role of the HPA axis in the pathophysiology of mood and anxiety disorders, paving the way for the development of novel therapeutic strategies.

Non-pharmacological and pharmacological approaches for psychiatric disorders: Re-appraisal and insights from zebrafish models

Acute and chronic stressors are common triggers of human mental illnesses. Experimental animal models and their cross-species translation to humans are critical for understanding of the pathogenesis of stress-related psychiatric disorders. Mounting evidence suggests that both pharmacological and non-pharmacological approaches can be efficient in treating these disorders. Here, we analyze human, rodent and zebrafish (Danio rerio) data to compare the impact of non-pharmacological and pharmacological therapies of stress-related psychopathologies. Emphasizing the likely synergism and interplay between pharmacological and environmental factors in mitigating daily stress both clinically and in experimental models, we argue that environmental enrichment emerges as a promising complementary therapy for stress-induced disorders across taxa. We also call for a broader use of novel model organisms, such as zebrafish, to study such treatments and their potential interplay.

Propofol Causes Consciousness Loss by Affecting GABA-A Receptor in the Nucleus Basalis of Rats

Objective

Propofol is a classical anesthetic and induces consciousness loss, and gamma-aminobutyric-acid-type-A (GABA-A) receptor is its target. Righting reflex is associated with conscious response. The nucleus basalis (NB) acts as a major relay between the reticular activating system and the frontal cortex (FC). Propofol may mediate righting reflex by affecting GABA-A receptor in NB.

Methods

Fifty male SD rats (250-350 g) were divided into parts I and II. In part I, 20 male SD rats were randomly divided into control group (CG) and NB-lesion group (NG, ibotenic acid-induced NB lesion). In part II, 30 male SD rats were treated with saline (0.9% NaCl, SG group), muscimol (a GABA-A receptor agonist, MG group), and gabazine (a GABA-A receptor antagonist, GG group) in NB, respectively. Two weeks later, the activity of the rats was measured between CG and NG groups. The rats were intravenously injected with propofol (50 mg/kg/h) to test the time of loss of righting reflex (LORR) in all rats. When LORR occurred, the rats received single administration of propofol (12 mg/kg) to measure the time of return of righting reflex (RORR). Electroencephalogram (EEG) activity of the frontal cortex (FC) was recorded.

Results

The numbers of NB neurons were reduced by 44% in the NG group compared to the CG group (p < 0.05) whereas the activity of rats was reduced a little in the NG group when compared with the CG group, but the statistical difference was insignificant (p < 0.05) whereas the activity of rats was reduced a little in the NG group when compared with the CG group, but the statistical difference was insignificant (p < 0.05) whereas the activity of rats was reduced a little in the NG group when compared with the CG group, but the statistical difference was insignificant (p < 0.05) whereas the activity of rats was reduced a little in the NG group when compared with the CG group, but the statistical difference was insignificant (p < 0.05) whereas the activity of rats was reduced a little in the NG group when compared with the CG group, but the statistical difference was insignificant (p < 0.05) whereas the activity of rats was reduced a little in the NG group when compared with the CG group, but the statistical difference was insignificant (

Conclusions

The unilateral NB lesion increased the recovery time and FC delta power, and the NB region might be involved in the emergence after propofol administration. Propofol plays a crucial role for causing conscious loss by affecting GABA-A receptor in NB.

LPA1 receptor and chronic stress: Effects on behaviour and the genes involved in the hippocampal excitatory/inhibitory balance

The LPA₁ receptor, one of the six characterized G protein-coupled receptors (LPA_1-6) through which lysophosphatidic acid acts, is likely involved in promoting normal emotional behaviours. Current data suggest that the LPA-LPA_1-receptor pathway may be involved in mediating the negative consequences of stress on hippocampal function. However, to date, there is no available information regarding the mechanisms whereby the LPA₁ receptor mediates this adaptation. To gain further insight into how the LPA-LPA₁ pathway may prevent the negative consequences of chronic stress, we assessed the effects of the continuous delivery of LPA on depressive-like behaviours induced by a chronic restraint stress protocol. Because a proper excitatory/inhibitory balance seems to be key for controlling the stress response system, the gene expression of molecular markers of excitatory and inhibitory neurotransmission was also determined. In addition, the hippocampal expression of mineralocorticoid receptor genes and glucocorticoid receptor genes and proteins as well as plasma corticosterone levels were determined. Contrary to our expectations, the continuous delivery of LPA in chronically stressed animals potentiated rather than inhibited some (e.g., anhedonia, reduced latency to the first immobility period), though not all, behavioural effects of stress. Furthermore, this treatment led to an alteration in the genes coding for proteins involved in the excitatory/inhibitory balance in the ventral hippocampus and to changes in corticosterone levels. In conclusion, the results of this study reinforce the assumption that LPA is involved in emotional regulation, mainly through the LPA₁ receptor, and regulates the effects of stress on hippocampal gene expression and hippocampus-dependent behaviour.

Integration of energy homeostasis and stress by parvocellular neurons in rat hypothalamic paraventricular nucleus

KEY POINTS

Central regulation of energy homeostasis and stress are believed to be reciprocally regulated, i.e. excessive food intake suppresses, while prolonged hunger exacerbates, stress responses in vivo. This relationship may be mediated by neuroendocrine parvocellular corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus that receive both stress- and feeding-related input. We find that hunger strongly and selectively potentiates, while re-feeding suppresses, a cellular analogue of a stress response induced by acute glucopenia in CRH neurons in rat hypothalamic slices. Neuronal activation in response to glucopenia was mediated synaptically, via the relative enhancement of glutamate over GABA input. These results illustrate how acute stress responses may be initiated in vivo and show that it is reciprocally integrated with energy balance via local hypothalamic mechanisms acting at the level of CRH neurons and their afferent terminals.

ABSTRACT

Increased food intake is a common response to help cope with stress, implying the existence of a previously postulated but imperfectly understood, inverse relationship between the regulation of feeding and stress. We have identified components of the neural circuitry that can integrate these homeostatic responses. Prior fasting (∼24 h) potentiates, and re-feeding suppresses, excitatory responses to acute glucopenia in about half of the corticotropin releasing hormone (CRH)-expressing, putatively neurosecretory, stress-related neurons in the paraventricular nucleus of the hypothalamus studied. Glucoprivation stress ex vivo resulted from a preferential relative increase in excitatory (glutamatergic) over inhibitory (GABAergic) inputs. Putative preautonomic cells were less sensitive to fasting, and showed a predominant inhibition to acute glucopenia. We conclude that hunger may sensitize hypothalamic stress responses by acting via local mechanisms, at the level of CRH neurons and their presynaptic inputs. Those mechanisms involve neither presynaptic ATP-sensitive potassium channels nor postsynaptic ATP levels.

Sex differences in stress-related disorders: Major depressive disorder, bipolar disorder, and posttraumatic stress disorder

Stress-related disorders, such as mood disorders and posttraumatic stress disorder (PTSD), are more common in women than in men. This sex difference is at least partly due to the organizing effect of sex steroids during intrauterine development, while activating or inhibiting effects of circulating sex hormones in the postnatal period and adulthood also play a role. Such effects result in structural and functional changes in neuronal networks, neurotransmitters, and neuropeptides, which make the arousal- and stress-related brain systems more vulnerable to environmental stressful events in women. Certain brainstem nuclei, the amygdala, habenula, prefrontal cortex, and hypothalamus are important hubs in the stress-related neuronal network. Various hypothalamic nuclei play a central role in this sexually dimorphic network. This concerns not only the hypothalamus-pituitary-adrenal axis (HPA-axis), which integrates the neuro-endocrine-immune responses to stress, but also other hypothalamic nuclei and systems that play a key role in the symptoms of mood disorders, such as disordered day-night rhythm, lack of reward feelings, disturbed eating and sex, and disturbed cognitive functions. The present chapter focuses on the structural and functional sex differences that are present in the stress-related brain systems in mood disorders and PTSD, placing the HPA-axis in the center. The individual differences in the vulnerability of the discussed systems, caused by genetic and epigenetic developmental factors warrant further research to develop tailor-made therapeutic strategies.

GABA-A receptor modulating steroids in acute and chronic stress; relevance for cognition and dementia?

Cognitive dysfunction, dementia and Alzheimer's disease (AD) are increasing as the population worldwide ages. Therapeutics for these conditions is an unmet need. This review focuses on the role of the positive GABA-A receptor modulating steroid allopregnanolone (APα), it's role in underlying mechanisms for impaired cognition and of AD, and to determine options for therapy of AD. On one hand, APα given intermittently promotes neurogenesis, decreases AD-related pathology and improves cognition. On the other, continuous exposure of APα impairs cognition and deteriorates AD pathology. The disparity between these two outcomes led our groups to analyze the mechanisms underlying the difference. We conclude that the effects of APα depend on administration pattern and that chronic slightly increased APα exposure is harmful to cognitive function and worsens AD pathology whereas single administrations with longer intervals improve cognition and decrease AD pathology. These collaborative assessments provide insights for the therapeutic development of APα and APα antagonists for AD and provide a model for cross laboratory collaborations aimed at generating translatable data for human clinical trials.