GPR30 activation decreases anxiety in the open field test but not in the elevated plus maze test in female mice

Selective estrogen receptor activation prior to global cerebral ischemia in female rats impacts microglial activation and anxiety-like behaviors without effects on CA1 neuronal injury

Estrogen receptor (ER) activation by 17-ß estradiol (E2) can attenuate neuronal injury and behavioral impairments following global cerebral ischemia (GCI) in rodents. This study sought to further examine the discrete roles of ERs through characterization of the effects of selective ER activation on post-ischemic pro-inflammatory microglial activation, hippocampal neuronal injury, and anxiety-like behaviors. Forty-six ovariectomized (OVX) adult female Wistar rats received daily s.c injections (100 μg/kg/day) of propylpyrazole triol (PPT; ERα agonist), diarylpropionitrile (DPN; ERβ agonist), G-1 (G-protein coupled ER agonist; GPER), E2 (activating all receptors), or vehicle solution (VEH) for 21 days. After final injection, rats underwent GCI via 4-vessel occlusion (n=8 per group) or sham surgery (n=6, vehicle injections). The Open Field Test (OFT), Elevated Plus Maze (EPM), and Hole Board Test (HBT) assessed anxiety-like behaviors. Microglial activation (Iba1, CD68, CD86) in the basolateral amygdala (BLA), CA1 of the hippocampus, and paraventricular nucleus of the hypothalamus (PVN) was determined 8 days post-ischemia. Compared to sham rats, Iba1 activation and CA1 neuronal injury were increased in all ischemic groups except DPN-treated rats, with PPT-treated ischemic rats also showing increased PVN Iba1-ir expression. Behaviorally, VEH ischemic rats showed slightly elevated anxiety in the EPM compared to sham counterparts, with no significant effects of agonists. While no changes were observed in the OFT, emotion regulation via grooming in the HBT was increased in G-1 rats compared to E2 rats. Our findings support selective ER activation to regulate post-ischemic microglial activation and coping strategies in the HBT, despite minimal impact on hippocampal injury.

The role of mGluR5 on the therapeutic effects of ketamine in Wistar rats

RATIONALE

Ketamine produces dissociative, psychomimetic, anxiolytic, antidepressant, and anesthetic effects in a dose dependent manner. It has a complex mechanism of action that involve alterations in other glutamate receptors. The metabotropic glutamate receptor 5 (mGluR5) has been investigated in relation to the psychotic and anesthetic properties of ketamine, while its role in mediating the therapeutic effects of ketamine remains unknown.

OBJECTIVES

We investigated the role of mGluR5 on the antidepressant, anxiolytic and fear memory-related effects of ketamine in adult male Wistar rats.

METHODS

Two sets of experiments were conducted. We first utilized the positive allosteric modulator CDPPB to investigate how acute mGluR5 activation regulates the therapeutic effects of ketamine (10 mg/kg). We then tested the synergistic antidepressant effect of mGluR5 antagonism and ketamine by combining MTEP with a sub-effective dose of ketamine (1 mg/kg). Behavioral despair, locomotor activity, anxiety-like behavior, and fear memory were respectively assessed in the forced swim test (FST), open field test (OFT), elevated plus maze (EPM), and auditory fear conditioning.

RESULTS

Enhancing mGluR5 activity via CDPPB occluded the antidepressant effect of ketamine without changing locomotor activity. Furthermore, concomitant administration of MTEP and ketamine exhibited a robust synergistic antidepressant effect. The MTEP + ketamine treatment, however, blocked the anxiolytic effect observed by sole administration of MTEP or the low dose ketamine.

CONCLUSIONS

These findings suggest that suppressed mGluR5 activity is required for the antidepressant effects of ketamine. Consequently, the antagonism of mGluR5 enhances the antidepressant effectiveness of low dose ketamine, but eliminates its anxiolytic effects.

Estrogen deficiency affects synchronized neural connectivity in the olfactory bulb-nucleus accumbens circuit: A local field potential study in ovariectomized mouse model

Estrogen plays a crucial role in regulating various brain functions, including cognitive, emotional, and social behaviors. Menopausal women face a decline in estrogen levels, which has been linked to several physical and mental health issues. However, the impact of estrogen on the olfactory bulb-nucleus accumbens (OB-NAc) circuit, which is essential for regulating emotions and cognitive behaviors, remains poorly understood. To test the hypothesis that estrogen deficiency affects signal processing, we recorded local field potentials (LFPs) using intracranial electrodes implanted in four-week-old ovariectomized (OVX) mice during an open-field test (OFT). The results showed a decrease in locomotor activity and increase in anxiety-like behaviors in OVX mice. Furthermore, we found a decrease in high-gamma power in the OB. We analyzed coherence and inter-region phase-amplitude coupling (ir-PAC) to explore the connectivity between the OB and NAc. We observed a decrease in low-gamma and high-gamma coherence in OVX mice. Additionally, we found that the direction of connectivity from the NAc to the OB was disrupted in OVX mice. In summary, our study provides evidence that estrogen deficiency is linked to synchronized neural connectivity changes in the OB-NAc circuit. These findings have implications for our understanding of the roles played by the OB-NAc neural circuit and estrogen in the regulation of general exploratory behavior and anxiety-like behavior.

Upregulation of MAOA in the hippocampus results in delayed depressive-like behaviors in burn mice

OBJECTIVE

To observe depressive-like behavior and hippocampus monoamine oxidase A (MAOA) changes in burned mice.

METHODS

We tested depression and anxiety like behaviors of burn C57 mice with the sucrose preference test, forced swimming test (FST), open field test and elevated plus maze test and then detected the MAOA content and MAOA gene transcriptional levels in the hippocampus with western blot analysis and real-time quantitative PCR analysis. We then sought to reverse depressive-like behavior of burned mice with an MAOA inhibitor.

RESULTS

(1) Mice showed depressive and anxiety like behaviors one week after they were burned; (2) The content of MAOA in the hippocampus of burned mice was significantly higher than that in control mice (P<0.05); (3) MAOA gene transcription in the hippocampus of burned mice was significantly increased (MAOA mRNA was increased, P<0.05); (4) treatment with a MAOA inhibitor (phenelzine) significantly increased the sucrose preference rate and decreased FST immobility time in burned mice, and also decreased elevated expression of MAOA in the hippocampus of burned mice.

CONCLUSION

Burned mice showed "delayed" depressive-like behavior combined with a degree of anxiety; this phenomenon is likely associated with the increase in MAOA expression in the hippocampus.

Acute repeated cage exchange stress modifies urinary stress and plasma metabolic profiles in male mice

Exposure to a novel environment is psychologically and physically stressful for humans and animals. The response has been reported to involve enhanced sympathetic nervous system activity, but changes in nutrient levels under stress are not fully understood. As a form of exposure to a novel environment, repeated cage exchange (CE, four times at 2-h intervals for 8 h from 08:00 h) during the light phase with no restraint on movement was applied to A/J mice, a strain particularly prone to stress. Body temperature was measured with a temperature-sensing microchip implanted in the interscapular region. The stress conditions and anxiety level were evaluated by measuring urinary catecholamines and corticosterone and by performing an anxiety-like behavior test, respectively. Major nutrients such as glucose, fatty acids, and amino acids in the plasma were also examined. CE mice showed a significant increase in body temperature with each CE. They also showed a significantly greater reduction of body weight change, more water intake, and higher levels of urinary catecholamines and corticosterone and anxiety-like behavior score than control mice. The model revealed a significantly lower plasma glucose level and higher levels of several essential amino acids, such as branched-chain amino acids and phenylalanine, than those of control mice. Meanwhile, free fatty acids and several amino acids such as arginine, aspartic acid, proline, threonine, and tryptophan in both sets of mice were significantly decreased from the corresponding levels at 08:00 h, while similar plasma levels were exhibited between mice with and without CE. In conclusion, repeated CE stress was associated with changes in glucose and amino acids in plasma. Although further study is needed to clarify how these changes are specifically linked to anxiety-like behavior, this study suggests the potential for nutritional intervention to counter stress in humans exposed to novel environments.

Prenatal lipopolysaccharide exposure induces anxiety-like behaviour in male mouse offspring and aberrant glial differentiation of embryonic neural stem cells

BACKGROUND

Prenatal infection has been implicated in the development of neuropsychiatric disorders in children. We hypothesised that exposure to lipopolysaccharide during prenatal development could induce anxiety-like behaviour and sensorineural hearing loss in offspring, as well as disrupt neural differentiation during embryonic neural development.

METHODS

We simulated prenatal infection in FVB mice and mouse embryonic stem cell (ESC) lines, specifically 46C and E14Tg2a, through lipopolysaccharide treatment. Gene expression profiling analyses and behavioural tests were utilized to study the effects of lipopolysaccharide on the offspring and alterations in toll-like receptor (TLR) 2-positive and TLR4-positive cells during neural differentiation in the ESCs.

RESULTS

Exposure to lipopolysaccharide (25 µg/kg) on gestation day 9 resulted in anxiety-like behaviour specifically in male offspring, while no effects were detected in female offspring. We also found significant increases in the expression of GFAP and CNPase, as well as higher numbers of GFAP + astrocytes and O4+ oligodendrocytes in the prefrontal cortex of male offspring. Furthermore, increased scores for genes related to oligodendrocyte and lipid metabolism, particularly ApoE, were observed in the prefrontal cortex regions. Upon exposure to lipopolysaccharide during the ESC-to-neural stem cell (NSC) transition, Tuj1, Map2, Gfap, O4, and Oligo2 mRNA levels increased in the differentiated neural cells on day 14. In vitro experiments demonstrated that lipopolysaccharide exposure induced inflammatory responses, as evidenced by increased expression of IL1b and ApoB mRNA.

CONCLUSIONS

Our findings suggest that prenatal infection at different stages of neural differentiation may result in distinct disturbances in neural differentiation during ESC-NSC transitions. Furthermore, early prenatal challenges with lipopolysaccharide selectively induce anxiety-like behaviour in male offspring. This behaviour may be attributed to the abnormal differentiation of astrocytes and oligodendrocytes in the brain, potentially mediated by ApoB/E signalling pathways in response to inflammatory stimuli.

Enhanced neuronal activity by suffruticosol A extracted from Paeonia lactiflora via partly BDNF signaling in scopolamine-induced memory-impaired mice

Neurodegenerative diseases are explained by progressive defects of cognitive function and memory. These defects of cognition and memory dysfunction can be induced by the loss of brain-derived neurotrophic factors (BDNF) signaling. Paeonia lactiflora is a traditionally used medicinal herb in Asian countries and some beneficial effects have been reported, including anti-oxidative, anti-inflammatory, anti-cancer activity, and potential neuroprotective effects recently. In this study, we found that suffruticosol A is a major compound in seeds of Paeonia lactiflora. When treated in a SH-SY5 cell line for measuring cell viability and cell survival, suffruticosol A increased cell viability (at 20 µM) and recovered scopolamine-induced neurodegenerative characteristics in the cells. To further confirm its neural amelioration effects in the animals, suffruticosol A (4 or 15 ng, twice a week) was administered into the third ventricle beside the brain of C57BL/6 mice for one month then the scopolamine was intraperitoneally injected into these mice to induce impairments of cognition and memory before conducting behavioral experiments. Central administration of suffruticosol A into the brain restored the memory and cognition behaviors in mice that received the scopolamine. Consistently, the central treatments of suffruticosol A showed rescued cholinergic deficits and BDNF signaling in the hippocampus of mice. Finally, we measured the long-term potentiation (LTP) in the hippocampal CA3-CA1 synapse to figure out the restoration of the synaptic mechanism of learning and memory. Bath application of suffruticosol A (40 µM) improved LTP impairment induced by scopolamine in hippocampal slices. In conclusion, the central administration of suffruticosol A ameliorated neuronal effects partly through elevated BDNF signaling.

Chemical analysis of calabash chalk and its effect on locomotor activities and behavior in Swiss albino mice

Continuous exposure of young women to calabash chalk, especially at child-bearing age, necessitated this study to analyze the chemical constituents of calabash chalk and to evaluate its effect on locomotor activities and behavior in Swiss albino mice. Dried cubes of calabash chalk were purchased and analyzed by atomic and flame atomic absorption spectrophotometer. Twenty-four Swiss-albino mice were taken and divided into four groups: control (1 ml distilled water) and three treated groups with the doses of 200 mg/kg, 400 mg/kg, and 600 mg/kg of calabash chalk suspension, respectively, by oral gavage. Hole Cross, Hole Board, and Open Field tests were performed to evaluate the locomotor activities, behavior, and anxiety along with measurement of body weight. The data were analyzed by SPSS-software. Chemical analysis of calabash chalk showed the presence of trace elements along with some heavy metals such as lead (19.26 ppm), Chromium (34.73 ppm), and arsenic (4.57 ppm). After 21 days of oral administration of calabash chalk, the study showed a significant decrease in body weight in the treated groups of mice (p < 0.01). Decreased locomotor activities were also observed in all three experiments. Significantly decreased locomotion and behaviors were also observed in the hole crossing, line crossing, head dipping, grooming, rearing, stretch attend, central square entry, central square duration, defecation, and urination, in a dose-dependent manner (p < 0.01). These effects also prove the anxiogenic behavior of calabash chalk in albino mice. Heavy metals are believed to be harmful to the brain and responsible for cognitive dysfunction and elevated anxiety. In this study, decreased body weight in mice may occur due to disorders in hunger and thirst centers of the brain by heavy metals. Therefore, heavy metals may be responsible for muscle weakness, decreased locomotor activities, and axiogenic effects of mice.

Prepubertal ovariectomy confers resilience to stress-induced anxiety in adult female mice

The increased vulnerability to stress-induced neuropsychiatric disorders in women, including anxiety disorders, does not emerge until pubertal onset, suggesting a role for ovarian hormones in organizing sex-specific vulnerability to anxiety. Parvalbumin (PV) interneurons in the prefrontal cortex are a potential target for these ovarian hormones. PV+ interneurons undergo maturation during the adolescent period and have been shown to be sensitive to stress and to mediate stress-induced anxiety in female mice. To test the idea that ovarian hormones at puberty are necessary for the acquisition of sensitivity to stress, hypothetically driving the response of PV+ interneurons to stress, we performed ovariectomy or sham surgery before pubertal onset in female mice. These mice then were exposed to four weeks of unpredictable chronic mild stress in adulthood. We then assessed anxiety-like behavior and PV/FosB colocalization in the medial PFC. Additionally, we assessed stress-induced anxiety-like behavior in female mice following ovariectomy in adulthood to determine if puberty is a sensitive period for ovarian hormones in mediating vulnerability to stress. We found that prepubertal ovariectomy protects against the development of anxiety-like behavior in adulthood, an effect not found following ovariectomy in adulthood. This effect may be independent of ovarian hormones on prefrontal PV+ interneurons response to stress.

Tachykinin receptor 3 in the lateral habenula alleviates pain and anxiety comorbidity in mice

The coexistence of chronic pain and anxiety is a common clinical phenomenon. Here, the role of tachykinin receptor 3 (NK3R) in the lateral habenula (LHb) in trigeminal neuralgia and in pain-associated anxiety was systematically investigated. First, electrophysiological recording showed that bilateral LHb neurons are hyperactive in a mouse model of trigeminal neuralgia made by partial transection of the infraorbital nerve (pT-ION). Chemicogenetic activation of bilateral LHb glutamatergic neurons in naive mice induced orofacial allodynia and anxiety-like behaviors, and pharmacological activation of NK3R in the LHb attenuated allodynia and anxiety-like behaviors induced by pT-ION. Electrophysiological recording showed that pharmacological activation of NK3R suppressed the abnormal excitation of LHb neurons. In parallel, pharmacological inhibition of NK3R induced orofacial allodynia and anxiety-like behavior in naive mice. The electrophysiological recording showed that pharmacological inhibition of NK3R activates LHb neurons. Neurokinin B (NKB) is an endogenous high-affinity ligand of NK3R, which binds NK3R and activates it to perform physiological functions, and further neuron projection tracing showed that the front section of the periaqueductal gray (fPAG) projects NKB-positive nerve fibers to the LHb. Optogenetics combined with electrophysiology recordings characterize the functional connections in this fPAG ^NKB → LHb pathway. In addition, electrophysiological recording showed that NKB-positive neurons in the fPAG were more active than NKB-negative neurons in pT-ION mice. Finally, inhibition of NKB release from the fPAG reversed the analgesic and anxiolytic effects of LHb Tacr3 overexpression in pT-ION mice, indicating that fPAG ^NKB → LHb regulates orofacial allodynia and pain-induced anxious behaviors. These findings for NK3R suggest the cellular mechanism behind pT-ION in the LHb and suggest that the fPAG ^NKB → LHb circuit is involved in pain and anxiety comorbidity. This previously unrecognized pathway might provide a potential approach for relieving the pain and anxiety associated with trigeminal neuralgia by targeting NK3R.

Carnosic Acid Mitigates Depression-Like Behavior in Ovariectomized Mice via Activation of Nrf2/HO-1 Pathway

The peri- and post-menopausal periods have been described as the "window of vulnerability" for the development of depressive symptoms that impair women activities and quality of life. The etiopathogenesis of these symptoms is multifactorial and may confer resistance to traditional antidepressants. Attention is now directed toward phytochemicals for their pleiotropic functions and safer profiles. This study investigated the possible perturbation of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways as an underlying mechanism of post-ovariectomy depression and highlighted the potential benefits of carnosic acid (CA) on the associated behavioral, biochemical, and histopathological alterations. Female Balb/c mice were randomly assigned to be sham-operated or ovariectomized (OVX). After 3 weeks, OVX mice received either a vehicle, CA (20 mg/kg/day), or tin protoporphyrin IX (SnPP-IX; a heme oxygenase-1 (HO-1) inhibitor; 50 μmol/kg/day) for 3 weeks. Our findings revealed that OVX mice had depressive but not anxiety-like behavior. Suppressed Nrf2 and its downstream signaling, and augmented proinflammatory markers were observed in both the hippocampus and prefrontal cortex. CA treatment alleviated depressive behavior, induced the expression of Nrf2, HO-1, thioredoxin-1, and brain-derived neurotrophic factor, and enhanced serotonin levels. CA also suppressed oxidative stress, reduced TNF-α, IL-1β, and iNOS mRNA expression, and ameliorated OVX-induced histopathological changes. SnPP-IX aggravated post-OVX behavioral, neurobiochemical, and histological deteriorations, and reduced CA-protective effects. In conclusion, Nrf2/HO-1 signaling suppression and the associated proinflammatory state are key mechanisms in post-OVX depression. CA exerts multifaceted neuroprotection in OVX mice and represents a promising candidate for clinical evaluation as an antidepressant.

The live biotherapeutic Blautia stercoris MRx0006 attenuates social deficits, repetitive behaviour, and anxiety-like behaviour in a mouse model relevant to autism

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterised by deficits in social behaviour, increased repetitive behaviour, anxiety and gastrointestinal symptoms. The aetiology of ASD is complex and involves an interplay of genetic and environmental factors. Emerging pre-clinical and clinical studies have documented a potential role for the gut microbiome in ASD, and consequently, the microbiota represents a potential target in the development of novel therapeutics for this neurodevelopmental disorder. In this study, we investigate the efficacy of the live biotherapeutic strain, Blautia stercoris MRx0006, in attenuating some of the behavioural deficits in the autism-relevant, genetic mouse model, BTBR T+ Itpr3tf/J (BTBR). We demonstrate that daily oral administration with MRx0006 attenuates social deficits while also decreasing repetitive and anxiety-like behaviour. MRx0006 administration increases the gene expression of oxytocin and its receptor in hypothalamic cells in vitro and increases the expression of hypothalamic arginine vasopressin and oxytocin mRNA in BTBR mice. Additionally at the microbiome level, we observed that MRx0006 administration decreases the abundance of Alistipes putredinis, and modulates the faecal microbial metabolite profile. This alteration in the metabolite profile possibly underlies the observed increase in expression of oxytocin, arginine vasopressin and its receptors, and the consequent improvements in behavioural outcomes. Taken together, these findings suggest that the live biotherapeutic MRx0006 may represent a viable and efficacious treatment option for the management of physiological and behavioural deficits associated with ASD.

Effects of estrogen receptor β or G protein-coupled receptor 30 activation on anxiety-like behaviors in relation to GABAergic transmission in stress-ovariectomized rats

For mental disorders such as anxiety and depression, stress and stressful events are considered as precipitating causes that may be enhanced by estrogen variability. This condition is proven by the higher vulnerability of women than men. Despite the complexity of underlying mechanisms, the gamma-aminobutyric acid (GABA) system piques interest as its receptor contains multiple psychoactive modulatory sites including neurosteroids. Moreover, according to clinical and experimental reports, GABA-associated genes can be altered by stress and hormonal status. Therefore, this study investigated the effects of estrogen receptor β (ERβ) or G protein-coupled receptor 30 (GPR30) activation on anxiety/depression-like behaviors and the alterations in the GABA-associated gene of ovariectomized rats under chronic mild stress (CMS). Mild stressors were focused on because they represent a realistic simulation of daily life stress. In this study, ovariectomized rats were treated with vehicle, estradiol (E2), diarylpropionitrile (DPN; ERβ agonist) or G1 (GPR30 agonist) and exposed to 4-week CMS. The results showed that E2, DPN, and G1 treatments reduced anxiety-like behaviors without affecting depression-like behaviors. Concurrently, the GABA level and most GABA- and neurosteroid-associated mRNAs were altered by E2. Similar mRNA profiles were observed in DPN- and E2-administrations but not in G1 treatment. Collectively, these data suggest that estrogen exerts an anxiolytic-like action through either ERβ and/or GPR30 activation, and the modulatory effects of estrogen on GABAergic system are likely to be modulated through ERβ. The findings of this study therefore further provide insights into the roles of estrogen and daily mild stressors in GABA-related activity and behavioral responses, especially anxiety.

Examining sex disparities in risk/reward trade-offs in Smith's zokors, Eospalax smithii

Risk taking is imperative for the survival and fitness of animals since they are constantly facing innumerable threats from various sources. Indeed, the ability of the individual to balance the costs and benefits of various options and adopt a wise decision is critical for the animal well-being. We modified several traditionally used anxiety tests [The modified light-dark box (mLDB), the modified open field test (mOFT) and the modified defensive withdrawal apparatus (mDWA)] by adding a palatable food reward within the anxiogenic zone which granted us to assess the sex differences in risk-taking behavior in Smith's zokors (Eospalax smithii), a typical subterranean rodent species endemic to the Qinghai-Tibetan Plateau. Concomitant with our working hypothesis, female zokors showed strong aversion and avoidance behavioral responses when tested in the mOFT and mDWA while there were no apparent sexually dimorphic behavioral changes when they were tested in the mLDB (Except for the percentage of food consumed and the latency till start feeding). Furthermore, comparison between the three behavioral paradigms revealed that both sexes showed different behavioral responses toward the different behavioral tests. Sex differences in repeatable behaviors were more profound in females than males. This might reflect different degrees of risk perception and emotionality that may differ considerably between the different models of anxiety. Our results highlighted the functional significance of a trade-off between risk and incentives in natural environment that both male and female zokors differ in the processing of risk assessment in the presence of a food reward.

Cognitive profile of male mice exposed to a Ketogenic Diet

In recent years, nutritional interventions for different psychiatric diseases have gained increasing attention, such as the ketogenic diet (KD). This has led to positive effects in neurological disorders such as Parkinson's disease, addiction, autism or epilepsy. The neurobiological mechanisms through which these effects are induced and the effects in cognition still warrant investigation, and considering that other high-fat diets (HFD) can lead to cognitive disturbances that may affect the results achieved, the main aim of the present work was to evaluate the effects of a KD to determine whether it can induce such cognitive effects. A total of 30 OF1 male mice were employed to establish the behavioral profile of mice fed a KD by testing anxiety behavior (Elevated Plus Maze), locomotor activity (Open Field), learning (Hebb Williams Maze), and memory (Passive Avoidance Test). The results revealed that the KD did not affect locomotor activity, memory or hippocampal-dependent learning, as similar results were obtained with mice on a standard diet, albeit with increased anxiety behavior. We conclude that a KD is a promising nutritional approach to apply in research studies, given that it does not cause cognitive alterations.

Mouse hybrid genome mediates diverse brain phenotypes with the specificity of reciprocal crosses

Hybrid species have more genetic diversity than their parents. However, the impact of the hybrid genome of reciprocal crosses on brain function remains largely unknown. We performed behavioral, molecular, and neuronal analyses on C57BL/6J mice (B6), CAST/EiJ mice (CAST), and hybrid mice resulting from reciprocal crosses of the two strains, B6/CAST F1i and B6/CAST F1r, respectively. Hybrid mice displayed greater motor strength and coordination, food grinding, social dominance, and less sociability compared to their parental strains. Parental origin influenced body weight, locomotor speed, and heat nociception of hybrid mice. Parental origin, cell type, and the interaction of both affected expression patterns of hybrid genomes including imprinted genes. There was a correlation between affected genes and corresponding behavioral phenotypes. Hybrid genomes mediated neuronal activity in the locus coeruleus, a brain region implicated in arousal, adaptive behaviors, and sleep-wake cycle due to its norepinephrine projections throughout the central nervous system. The comprehensive brain phenotypes in these hybrid mice reveal important functional readouts associated with interactions of hybrid genomes and impacts of parental genomes.

Structural, functional, and behavioral significance of sex and gonadal hormones in the basolateral amygdala: A review of preclinical literature

The basolateral amygdala (BLA) is intimately involved in the development of neuropsychiatric disorders such as anxiety and alcohol use disorder (AUD). These disorders have clear sex biases, with women more likely to develop an anxiety disorder and men more likely to develop AUD. Preclinical models have largely confirmed these sex-specific vulnerabilities and emphasize the effects of sex hormones on behaviors influenced by the BLA. This review will discuss sex differences in BLA-related behaviors and highlight potential mechanisms mediated by altered BLA structure and function, including the composition of GABAergic interneuron subpopulations, glutamatergic pyramidal neuron morphology, glutamate/GABA neurotransmission, and neuromodulators. Further, sex hormones differentially organize dimorphic circuits during sensitive developmental periods (organizational effects) and initiate more transient effects throughout adulthood (activational effects). Current literature indicates that estradiol and allopregnanolone, a neuroactive progestogen, generally reduce BLA-related behaviors through a variety of mechanisms, including activation of estrogen receptors or facilitation of GABA_A-mediated inhibition, respectively. This enhanced GABAergic inhibition may protect BLA pyramidal neurons from the excitability associated with anxiety and alcohol withdrawal. Understanding sex differences and the effects of sex hormones on BLA structure and function may help explain sex-specific vulnerabilities in BLA-related behaviors and ultimately improve treatments for anxiety and AUD.

Membrane-initiated actions of sex steroids and reproductive behavior: A historical account

It was assumed for a long time that sex steroids are activating reproductive behaviors by the same mechanisms that produce their morphological and physiological effects in the periphery. However during the last few decades an increasing number of examples were identified where behavioral effects of steroids were just too fast to be mediated via changes in DNA transcription. This progressively forced behavioral neuroendocrinologists to recognize that part of the effects of steroids on behavior are mediated by membrane-initiated events. In this review we present a selection of these early data that changed the conceptual landscape and we provide a summary the different types of membrane-associated receptors (estrogens, androgens and progestagens receptors) that are playing the most important role in the control of reproductive behaviors. Then we finally describe in more detail three separate behavioral systems in which membrane-initiated events have clearly been established to contribute to behavior control.

β-Arrestin-dependent ERK signaling reduces anxiety-like and conditioned fear-related behaviors in mice

G protein-coupled receptors (GPCRs) are implicated in the regulation of fear and anxiety. GPCR signaling involves canonical G protein pathways but can also engage downstream kinases and effectors through scaffolding interactions mediated by β-arrestin. Here, we investigated whether β-arrestin signaling regulates anxiety-like and fear-related behavior in mice in response to activation of the GPCR δ-opioid receptor (δOR or DOR). Administration of β-arrestin-biased δOR agonists to male C57BL/6 mice revealed β-arrestin 2-dependent activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) in the dorsal hippocampus and amygdala and β-arrestin 1-dependent activation of ERK1/2 in the nucleus accumbens. In mice, β-arrestin-biased agonist treatment was associated with reduced anxiety-like and fear-related behaviors, with some overlapping and isoform-specific input. In contrast, applying a G protein-biased δOR agonist decreased ERK1/2 activity in all three regions as well as the dorsal striatum and was associated with increased fear-related behavior without effects on baseline anxiety. Our results indicate a complex picture of δOR neuromodulation in which β-arrestin 1- and 2-dependent ERK signaling in specific brain subregions suppresses behaviors associated with anxiety and fear and opposes the effects of G protein-biased signaling. Overall, our findings highlight the importance of noncanonical β-arrestin-dependent GPCR signaling in the regulation of these interrelated emotions.

Ex vivo and in vitro inhibitory potential of Kava extract on monoamine oxidase B activity in mice

Background and aim

Experimental procedure

Results

Conclusion

•

Kava extract confirmed anxiolytic-like effect in mice.

•

Kava extract reduced MAO-B activity in cortex and in the region containing substantia nigra in mice.

•

Kava extract inhibited reversibly the MAO-B activity in vitro.

Central Administration of Ampelopsin A Isolated from Vitis vinifera Ameliorates Cognitive and Memory Function in a Scopolamine-Induced Dementia Model

Neurodegenerative diseases are characterized by the progressive degeneration of the function of the central nervous system or peripheral nervous system and the decline of cognition and memory abilities. The dysfunctions of the cognitive and memory battery are closely related to inhibitions of neurotrophic factor (BDNF) and brain-derived cAMP response element-binding protein (CREB) to associate with the cholinergic system and long-term potentiation. Vitis vinifera, the common grapevine, is viewed as the important dietary source of stilbenoids, particularly the widely-studied monomeric resveratrol to be used as a natural compound with wide-ranging therapeutic benefits on neurodegenerative diseases. Here we found that ampelopsin A is a major compound in V. vinifera and it has neuroprotective effects on experimental animals. Bath application of ampelopsin A (10 ng/µL) restores the long-term potentiation (LTP) impairment induced by scopolamine (100 μM) in hippocampal CA3-CA1 synapses. Based on these results, we administered the ampelopsin A (10 ng/µL, three times a week) into the third ventricle of the brain in C57BL/6 mice for a month. Chronic administration of ampelopsin A into the brain ameliorated cognitive memory-behaviors in mice given scopolamine (0.8 mg/kg, i.p.). Studies of mice’s hippocampi showed that the response of ampelopsin A was responsible for the restoration of the cholinergic deficits and molecular signal cascades via BDNF/CREB pathways. In conclusion, the central administration of ampelopsin A contributes to increasing neurocognitive and neuroprotective effects on intrinsic neuronal excitability and behaviors, partly through elevated BDNF/CREB-related signaling.

Chronic Voluntary Alcohol Drinking Causes Anxiety-like Behavior, Thiamine Deficiency, and Brain Damage of Female Crossed High Alcohol Preferring Mice

The central nervous system is vulnerable to chronic alcohol abuse, and alcohol dependence is a chronically relapsing disorder which causes a variety of physical and mental disorders. Appropriate animal models are important for investigating the underlying cellular and molecular mechanisms. The crossed High Alcohol Preferring mice prefer alcohol to water when given free access. In the present study, we used female cHAP mice as a model of chronic voluntary drinking to evaluate the effects of alcohol on neurobehavioral and neuropathological changes. The female cHAP mice had free-choice access to 10% ethanol and water, while control mice had access to water alone at the age of 60-day-old. The mice were exposed to alcohol for 7 months then subjected to neurobehavioral tests including open field (OF), elevated plus maze (EPM), and Morris water maze (MWM). Results from OF and EPM tests suggested that chronic voluntary drinking caused anxiety-like behaviors. After behavior tests, mice were sacrificed, and brain tissues were processed for biochemical analyses. Alcohol altered the levels of several neurotransmitters and neurotrophic factors in the brain including gamma-Aminobutyric acid (GABA), corticotropin-releasing factor, cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor. Alcohol increased the expression of neuroinflammation markers including interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and C-C chemokine receptor 2 (CCR2). Alcohol also induced cleaved caspase-3 and glial fibrillary acidic protein, indicative of neurodegeneration and gliosis. In addition, alcohol inhibited the expression of thiamine transporters in the brain and reduced thiamine levels in the blood. Alcohol also caused oxidative stress and endoplasmic reticulum (ER) stress, and stimulated neurogenesis.

Kava decreases the stereotyped behavior induced by amphetamine in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Kava extract (Piper methysticum) is a phytotherapic mainly used for the treatment of anxiety. Although the reported effects of Kava drinking improving psychotic symptoms of patients when it was introduced to relieve anxiety in aboriginal communities, its effects on models of psychosis-like symptoms are not investigated.

AIM OF THE STUDY

To investigate the effects of Kava extract on behavioral changes induced by amphetamine (AMPH) and its possible relation with alterations in monoamine oxidase (MAO) activity.

MATERIALS AND METHODS

Mice received vehicle or Kava extract by gavage and, 2 h after vehicle or AMPH intraperitoneally. Twenty-five minutes after AMPH administration, behavioral (elevated plus maze, open field, stereotyped behavior, social interaction and Y maze) and biochemical tests (MAO-A and MAO-B activity in cortex, hippocampus and striatum) were sequentially evaluated.

RESULTS

Kava extract exhibited anxiolytic effects in plus maze test, increased the locomotor activity of mice in open field test and decreased MAO-A (in cortex) and MAO-B (in hippocampus) activity of mice. Kava extract prevented the effects of AMPH on stereotyped behavior and, the association between Kava/AMPH increased the number of entries into arms in Y maze test as well as MAO-B activity in striatum. However, Kava extract did not prevent hyperlocomotion induced by AMPH in open field test. The social interaction was not modified by Kava extract and/or AMPH.

CONCLUSION

The results showed that Kava extract decreased the stereotyped behavior induced by AMPH at the same dose that promotes anxiolytic effects, which could be useful to minimize the psychotic symptoms in patients.

Targeting Oxidative Stress Reduction and Inhibition of HDAC1, MECP2, and NF-kB Pathways in Rats With Experimentally Induced Hyperglycemia by Administration of Thymus marshallianus Willd. Extracts

The effects of two lyophilized extracts obtained from the aerial parts of Thymus marschallianus Willd. and harvested from wild flora (TMW) and obtained from culture (TMC) were evaluated in Wistar rats with experimentally induced hyperglycemia. The hyperglycemia was induced by streptozotocin (STZ) administration and the obtained results were evaluated in comparison for TMW and TMC. The polyphenolic composition of extracts was evaluated by spectrophotometrical and LC-MS methods. In vitro antioxidant capacity assays (DPPH, FRAP, EPR) were performed in order to preliminary establish the ability of tested samples to protect against free radical induced damage. Afterwards, the effects of these extracts were assessed in vivo on rats with experimental-induced hyperglycemia. Oxidative stress biomarkers (e.g. malondialdehyde-MDA), phosphorylated transcription factor subunit of nuclear kappaB (NF-kB) p65, methyl CpG binding protein (MECP) 2 and histone deacetylase 1 (HDAC1) expressions in hippocampus and frontal lobe were assessed. Open Field Test (OFT) and Elevated Plus Maze (EPM) were conducted on tested animals. Malondialdehyde (MDA) levels and HDAC1and MeCP2 expressions increased significantly in hippocampus (p<0.05) and frontal lobe (p<0.001) of diabetes group compared to the control group in parallel with decreasing of GSH/GSSG ratio. TMW and TMC administration reduced blood glucose levels and diminished lipid peroxidation, HDAC1 expression and enhanced antioxidant capacity in frontal lobe. TMW improved central locomotion of rats, increased phospho-NFkB p65 and diminished MECP2 expressions in hippocampus. Both tested samples exerted a beneficial effect by increasing the antioxidant defense. Our findings indicate that the administration of these extracts might represent a good option in the treatment of diabetes and its complications.

Blast-induced hearing loss suppresses hippocampal neurogenesis and disrupts long term spatial memory

Acoustic information transduced by cochlear hair cells is continuously relayed from the auditory pathway to other sensory, motor, emotional and cognitive centers in the central nervous system. Human epidemiological studies have suggested that hearing loss is a risk factor for dementia and cognitive decline, but the mechanisms contributing to these memory and cognitive impairments are poorly understood. To explore these issues in a controlled experimental setting, we exposed adult rats to a series of intense blast wave exposures that significantly reduced the neural output of the cochlea. Several weeks later, we used the Morris Water Maze test, a hippocampal-dependent memory task, to assess the ability of Blast Wave and Control rats to learn a spatial navigation task (memory acquisition) and to remember what they had learned (spatial memory retention) several weeks earlier. The elevated plus maze and open field arena were used to test for anxiety-like behaviors. Afterwards, hippocampal cell proliferation and neurogenesis were evaluated using bromodeoxyuridine (BrdU), doublecortin (DCX), and Neuronal Nuclei (NeuN) immunolabeling. The Blast Wave and Control rats learned the spatial navigation task equally well and showed no differences on tests of anxiety. However, the Blast Wave rats performed significantly worse on the spatial memory retention task, i.e., remembering where they had been two weeks earlier. Deficits on the spatial memory retention task were associated with significant decreases in hippocampal cell proliferation and neurogenesis. Our blast wave results are consistent with other experimental manipulations that link spatial memory retention deficits (long term memory) with decreased cell proliferation and neurogenesis in the hippocampus. These results add to the growing body of knowledge linking blast-induced cochlear hearing loss with the cognitive deficits often seen in combat personnel and provide mechanistic insights into these extra auditory disorders that could lead to therapeutic interventions.

D1 receptors in the anterior cingulate cortex modulate basal mechanical sensitivity threshold and glutamatergic synaptic transmission

The release of dopamine (DA) into target brain areas is considered an essential event for the modulation of many physiological effects. While the anterior cingulate cortex (ACC) has been implicated in pain related behavioral processes, DA modulation of synaptic transmission within the ACC and pain related phenotypes remains unclear. Here we characterized a Crispr/Cas9 mediated somatic knockout of the D1 receptor (D1R) in all neuronal subtypes of the ACC and find reduced mechanical thresholds, without affecting locomotion and anxiety. Further, the D1R high-efficacy agonist SKF 81297 and low efficacy agonist (±)-SKF-38393 inhibit α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptor (AMPAR) currents in the ACC. Paradoxically, the D1R antagonists SCH-23390 and SCH 33961 when co-applied with D1R agonists produced a robust short-term synergistic depression of AMPAR currents in the ACC, demonstrating an overall inhibitory role for D1R ligands. Overall, our data indicate that absence of D1Rs in the ACC enhanced peripheral sensitivity to mechanical stimuli and D1R activation decreased glutamatergic synaptic transmission in ACC neurons.

The Modulatory Effect of Metformin on Ethanol-Induced Anxiety, Redox Imbalance, and Extracellular Matrix Levels in the Brains of Wistar Rats

The study investigated the potential neuroprotective effects of metformin (MET) on alcohol-induced neurotoxicity in adult Wistar rats. The animals were randomized in four groups (n = 10): control, alcohol (ALC), ALC + MET, and MET. ALC (2 g/kg b.w.) and MET (200 mg/kg b.w.) were orally administered for 21 days, once daily. For the ALC + MET group, MET was administered 2 h after ALC treatment. On day 22, the open field test (OFT) and elevated plus maze (EPM) were performed. MET improved global activity and increased the time spent in unprotected open arms, decreased oxidative stress, both in the frontal lobe and in the hippocampus, and increased neuroglobin expression in the frontal cortex. Histopathologically, an increased neurosecretory activity in the frontal cortex in the ALC + MET group was noticed. Thus, our findings suggest that metformin has antioxidant and anxiolytic effects and may partially reverse the neurotoxic effects induced by ethanol.

Rapid membrane effect of estrogens on stimulation of corticotropin-releasing hormone

BACKGROUND

Classic nuclear-initiated estrogen signaling stimulates corticotropin-releasing hormone (CRH) gene expression as a transcription factor. However, the possible mechanism by which membrane-initiated estrogen signaling (MIES) influences CRH expression remains unclear. There are indications that MIES may upregulate nitric oxide (NO) production through the phosphatidylinositol 3-hydroxy kinase (PI3K) and potentially through the mitogen-activated protein kinase (MAPK) pathway.

OBJECTIVES

We investigated the effect of MIES-mediated kinase pathways on CRH expression with or without NO synthesis.

METHOD

In SK-N-SH cell culture, estradiol-bovine serum albumin (E2-BSA) was used as the specific membrane estrogen receptor activator, with a specific NO donor, and/or inhibitors for NO synthase (NOS), PI3K, MAPK, protein kinase A (PKA), and protein kinase C (PKC).

RESULTS

E2-BSA significantly increased NO and CRH levels in the medium and NOS1-mRNA levels in the cells. In addition, NO donor up-regulated CRH expression, while NOS-inhibitor down-regulated it. When the inhibitor of MAPK and/or the inhibitor of PI3K was added to the medium, only the latter appeared to significantly block the stimulating effect of E2-BSA on NO synthesis, and this was accompanied by an increased CRH expression in the medium. We further studied the effect of the MIES-PKC-mediated pathway on CRH expression, with or without NOS-inhibitor, while the MIES-PKA(-PI3K) pathway served as a control. We found that MIES-PKC upregulated CRH expression independent of NO synthesis.

CONCLUSION

MIES can efficiently upregulate CRH expression via various intracellular kinase pathways and may thus be a crucial component in the stress response.

A blastocyst biopsy approach for preimplantation genetic diagnosis technique that affects the expression of SNAP-α in mice

Preimplantation genetic diagnosis (PGD) is a technique that is commonly used during assisted reproduction in the clinics to eliminate genetically abnormal embryos before implantation. The blastomere biopsy technique has risks related to the embryo, but blastocyst biopsy has not been systematically evaluated in relation to effects after birth, and the resulting offspring have not been followed up on. We designed a series of experiments to evaluate the risk of blastocyst biopsy on the resulting progeny. Mice were divided into a PGD group and a control group. The former was the progeny of mice that underwent blastocyst biopsy and the latter was delivered through a normal pregnancy without blastocyst biopsy. Each group consisted of 15 animals. We found no effects of blastocyst biopsy on reproductive capacities and weight gain. As for neurobehavioral evaluation between both groups, there were no significant differences in tail suspension test, sucrose preference test, the open field test and the elevated plus maze. Western blotting, immunohistochemistry and quantitative RT-PCR results showed that the expression levels of MBP, PRDX5 and UCHL1 in the PGD group were not significantly different compared to the control group, but SNAP-α expression in the PGD group was lower than that in control group. In summary, we concluded that blastocyst biopsy had no adverse effect on the general growth and behavior in mice. However, blastocyst biopsy effected the expression of SNAP-α. Therefore, the safety of blastocyst biopsy requires further evaluation.

Anesthesia and surgery induce age-dependent changes in behaviors and microbiota

The neuropathogenesis of postoperative delirium remains mostly unknown. The gut microbiota is implicated in the pathogenesis of neurological disorders. We, therefore, set out to determine whether anesthesia/surgery causes age-dependent gut microbiota dysbiosis, changes in brain IL-6 level and mitochondrial function, leading to postoperative delirium-like behavior in mice. Female 9 or 18 months old mice received abdominal surgery under 1.4% isoflurane for two hours. The postoperative delirium-like behavior, gut microbiota, levels of brain IL-6, PSD-95 and synaptophysin, and mitochondrial function were determined by a battery of behavioral tests, 16s rRNA sequencing, ELISA, Western blot and Seahorse XFp Extracellular Flux Analyzer. Intragastric administration of Lactobacillus (10 days) and probiotic (20 days) were used to mitigate the anesthesia/surgery-induced changes. Anesthesia/surgery caused different alterations in gut microbiota, including change rate of reduction in the levels of gut lactobacillus, between the 18 and 9 months old mice. The anesthesia/surgery induced greater postoperative delirium-like behavior, increased brain IL-6 levels, decreased PSD-95 and synaptophysin levels, and mitochondrial dysfunction in 18 than 9 months old mice. Treatments with Lactobacillus and probiotic mitigated the anesthesia/surgery-induced changes. These data suggest that microbiota dysbiosis may contribute to neuropathogenesis of postoperative delirium and treatment with Lactobacillus or a probiotic could mitigate postoperative delirium.

Surgery/Anesthesia disturbs mitochondrial fission/fusion dynamics in the brain of aged mice with postoperative delirium

Postoperative delirium (POD) is a common complication following surgery and anesthesia (Surgery/Anesthesia). Mitochondrial dysfunction, which is demonstrated by energy deficits and excessively activated oxidative stress, has been reported to contribute to POD. The dynamic balance between mitochondrial fusion and fission processes is critical in regulating mitochondrial function. However, the impact of Surgery/Anesthesia on mitochondrial fusion/fission dynamics remains unclear. Here, we evaluate the effects of laparotomy under 1.4% isoflurane anesthesia for 2 hours on mitochondrial fission/fusion dynamics in the brain of aged mice. Mice in Surgery/Anesthesia group showed unbalanced fission/fusion dynamics, with decreased DISC1 expression and increased expression of Drp1 and Mfn2 in the mitochondrial fraction, leading to excessive mitochondrial fission and disturbed mitochondrial morphogenesis in the hippocampus and prefrontal cortex. In addition, surgical mice presented mitochondrial dysfunction, demonstrated by abnormally activated oxidative stress (increased ROS level, decreased SOD level) and energy deficits (decreased levels of ATP and MMP). Surgery/Anesthesia also decreased the expression of neuronal/synaptic plasticity-related proteins such as PSD-95 and BDNF. Furthermore, Surgery/Anesthesia induced delirium-like behavior in aged mice. In conclusion, Surgery/Anesthesia disturbed mitochondrial fission/fusion dynamics and then impaired mitochondrial function in the brain of aged mice; these effects may be involved in the underlying mechanism of POD.

Does GPER1 Play a Role in Sexual Dimorphism?

Estrogens are critical in driving sex-typical social behaviours that are ethologically relevant in mammals. This is due to both production of local estrogens and signaling by these ligands, particularly in an interconnected set of nuclei called the social behavioural network (SBN). The SBN is a sexually dimorphic network studied predominantly in rodents that is thought to underlie the display of social behaviour in mammals. Signalling by the predominant endogenous estrogen, 17β-estradiol, can be either via the classical genomic or non-classical rapid pathway. In the classical genomic pathway, 17β-estradiol binds the intracellular estrogen receptors (ER) α and β which act as ligand-dependent transcription factors to regulate transcription. In the non-genomic pathway, 17β-estradiol binds a putative plasma membrane ER (mER) such as GPR30/GPER1 to rapidly signal via kinases or calcium flux. Though GPER1's role in sexual dimorphism has been explored to a greater extent in cardiovascular physiology, less is known about its role in the brain. In the last decade, activation of GPER1 has been shown to be important for lordosis and social cognition in females. In this review we will focus on several mechanisms that may contribute to sexually dimorphic behaviors including the colocalization of these estrogen receptors in the SBN, interplay between the signaling pathways activated by these different estrogen receptors, and the role of these receptors in development and the maintenance of the SBN, all of which remain underexplored.

Dorsal Hippocampus ERK2 Signaling Mediates Anxiolytic-Related Behavior in Male Rats

Background

Anxiety disorders are the most common neuropathologies worldwide, but the precise neuronal mechanisms that underlie these disorders remain unknown. The hippocampus plays a role in mediating anxiety-related responses, which can be modeled in rodents using behavioral assays, such as the elevated plus maze. Yet, the molecular markers that underlie affect-related behavior on the elevated plus maze are not well understood.

Methods

We used herpes simplex virus vector delivery to overexpress extracellular signal-regulated kinase-2, a signaling molecule known to be involved in depression and anxiety, within the dorsal hippocampus of adult Sprague-Dawley male rats. Three days post virus delivery, we assessed anxiety-like responses on the elevated plus maze or general locomotor activity on the open field test.

Results

When compared to controls, rats overexpressing extracellular signal-regulated kinase-2 in the dorsal hippocampus displayed an anxiolytic-like phenotype, per increases in time spent in the open arms, and less time in the closed arms, of the elevated plus maze. Furthermore, no changes in locomotor activity as a function of virus infusion were observed on the open field test between the experimental groups.

Conclusion

This investigation demonstrates that virus-mediated increases of extracellular signal-regulated kinase-2 signaling, within the hippocampus, plays a critical role in decreasing anxiogenic responses on the rat elevated plus maze. As such, our data provide construct validity, at least in part, to the molecular mechanisms that mediate anxiolytic-like behavior in rodent models for the study of anxiety.

The role of G protein-coupled estrogen receptor 1 on neurological disorders

G protein-coupled estrogen receptor 1 (GPER) is a membrane-associated estrogen receptor (ER) associated with rapid estrogen-mediated effects. Over recent years GPER emerged has a potential therapeutic target to induce neuroprotection, avoiding the side effects elicited by the activation of classical ERs. The putative neuroprotection triggered by GPER selective activation was demonstrated in mood disorders, Alzheimer's disease or Parkinson's disease of male and female in vivo rodent models. In others, like ischemic stroke, the results are contradictory and currently there is no consensus on the role played by this receptor. However, it seems clear that sex is a biological variable that may impact the results. The major objective of this review is to provide an overview about the physiological effects of GPER in the brain and its putative contribution in neurodegenerative disorders, discussing the data about the signaling pathways involved, as well as, the diverse effects observed.

Taurine Partially Improves Abnormal Anxiety in Taurine-Deficient Mice

Taurine is abundant in various tissues including the brain, muscle, heart, spleen, liver and kidney with various physiological functions. Since taurine is produced by cysteine sulfinic acid decarboxylase (CSAD) in the liver and kidney, taurine-deficient mice without CSAD have been investigated for abnormal physiological functions such as retinal development, immune, pancreatic and liver function. In this study, the behavioral effects and abnormal brain development caused by low taurine in the developing brain were examined. In neonatal brains of homozygous CSAD knockout mice (HO), taurine was reduced by 85%, compared to wild-type mice (WT). Taurine was reduced by 35% in the brains of 2 month-old HO, compared to WT. Anxiety, motor coordination and autistic-like behaviors were evaluated at 2 months of age using five behavioral tests: elevated plus maze, open field, social approach, marble burying and accelerating rotarod. Mice were tested from 3 groups including WT, HO and HO with oral treatment of 0.2% taurine in the drinking water (HOT). HOT were born from HO dams treated with taurine from before pregnancy and were continuously treated with taurine in the drinking water after weaning. The taurine levels in the brain and plasma of HOT were restored to WT at 2 months of age. Taurine-deficiency did not lead to changes in autistic-like behaviors as the HO were not significantly different from WT in marble burying and social approach. However, taurine-deficiency increased anxiety-like behavior in HO in the elevated plus maze and open field, compared to WT. Taurine treatment significantly restored the HOT to WT levels of anxiety-like behavior in the elevated plus maze. However, changes in exploratory activity in the open field were not improved with taurine treatment. There was a slight difference in motor ability as the WT mice stayed on the accelerating rotarod longer that the HO and HOT, but the difference was significant in the HOT during the first trial only, compared to WT.These data support hypothesis that taurine is essential for the emotional development of the brain. First, taurine is remarkably low in the neonatal brain of HO, compared to the adult brain of HO. Second, taurine treatment in HO partially improves anxiety-like behavior to WT.

Gender-dependent regulation of anxiety-like behavior by δ subunit-containing GABAA receptor during postnatal development

The δ subunit-containing GABAA receptor [GABAA(δ)R], which is exclusively situated in the extrasynaptic space, has considerable influence on emotion and behavior. Although the expression of this receptor experiences dramatic fluctuation during postnatal development, it remains unknown whether it regulates emotion in a development-dependent manner. Here, by using mice with genetic deletion of GABAA(δ)R (knockout) and their wild-type littermates, we examined the role of GABAA(δ)R in regulating anxiety-like behavior, as measured with open field test (OFT) and elevated plus maze during the transition from puberty to adulthood. We observed that for female mice, the knockout ones at puberty but not adulthood showed increased anxiety-like behavior in the OFT relative to their wild-type littermates. However, such increase was not observed in elevated plus maze. For male mice, no between-genotype differences were observed in both tests at the above two developmental stages. Our results suggest that GABAA(δ)R preferentially affects the anxiety-like behavior in OFT in a development-dependent manner, but only in female mice.

Transient Anosmia Induces Depressive-like and Anxiolytic-like Behavior and Reduces Amygdalar Corticotropin-Releasing Hormone in a ZnSO4-Induced Mouse Model

Olfactory loss is known to affect both mood and quality of life. Transient anosmia was induced in mice to study the resulting changes in mood, behavior, and on a molecular level. Transient anosmia was induced by a single intranasal instillation of ZnSO4 in BALB/c mice. Hematoxylin and eosin (HE) staining, and potato chip finding test were performed to confirm olfactory loss. Tail suspension, forced swim, and splash tests were performed to evaluate depression-related behavior; while the open field, and elevated plus maze tests were used to evaluate anxiety-related behavior. The mRNA levels of amygdalar corticotropin-releasing hormone (CRH) and hypothalamic glucocorticoid receptor (GR) were quantified using real-time PCR to confirm relevant molecular change. Olfactory loss was confirmed 1-2.5 weeks after induction, and this loss was subsequently reversed over time. The results of the behavioral tests indicated increased depression-like and reduced anxiety-like behavior at week 1. Accordingly, PCR data identified decreased amygdalar CRH expression at week 1. These results suggest that transient anosmia induces both depressive and anxiolytic behavior as a result of decreased amygdalar CRH in a mouse model of anosmia.

Electroacupuncture and Moxibustion Improved Anxiety Behavior in DSS-Induced Colitis Mice

Background and Aims

Psychological disorders are prevalent in patients with inflammatory bowel disease, but the underlying mechanisms remain unknown. The aim of this study was to study whether electroacupuncture (EA) and moxibustion (MB) can improve anxiety behavior in DSS-induced colitis mice and to investigate whether this effect is related to hypothalamic-pituitary-adrenocortical (HPA) axis.

Methods

The colitis model was established by drinking 2.5% dextran sodium sulfate (DSS). DSS-induced colitis mice were treated by EA or MB. Disease activity index (DAI) was scored; intestinal morphological and pathological structure was observed; anxiety behavior was tested by the elevated plus maze and open field. The concentration of corticotropin-releasing hormone (CRH) and cortisol (CORT) in serum was measured by enzyme-linked immunosorbent assay (ELISA). The protein expression of CRH in the colon and hypothalamus was detected by Western blot (WB).

Results

Both EA and MB treatments can improvethe morphology of their distal colonic mucosal epithelia, as well as the disease activity index. Meanwhile, anxiety behavior in colitis mice was improved slightly after EA and MB treatment. In addition, the levels of CRH and CORT in the serum were slightly improved after EA and MB treatment. These effects are further supported by WB results. The expression of CRH in the colon and hypothalamus was increased significantly after treatment, compared with the model group.

Conclusion

EA and MB were able to regulate the concentration of CRH in serum and protein expression in the peripheral and central at different levels and promote the recovery of the HPA axis that may be the basis for EA and MB to improve colonic pathology and alleviate anxiety behavior in DSS-induced colitis.

GPR30-mediated estrogenic regulation of actin polymerization and spatial memory involves SRC-1 and PI3K-mTORC2 in the hippocampus of female mice

AIMS

The G-protein-coupled estrogen receptor GPR30 (also referred to as GPER) has been implicated in the estrogenic regulation of hippocampal plasticity and spatial memory; however, the molecular mechanisms are largely unclear.

METHODS

In this study, we initially examined the levels of GPR30 in the hippocampus of postnatal, ovariectomy (OVX)- and letrozole (LET)-treated female mice. Under G1, G15, and/or OVX treatment, the spatial memory, spine density, levels of ERα, ERβ, and SRC-1, selected synaptic proteins, mTORC2 signals (Rictor and p-AKT Ser473), and actin polymerization dynamics were subsequently evaluated. Furthermore, G1, G15, and/or E2 combined with SRC-1 and/or PI3K inhibitors, actin cytoskeleton polymerization modulator JPK, and CytoD treatments were used to address the mechanisms that underlie GPR30 regulation in vitro. Finally, mTORC2 activator A-443654 (A4) was used to explore the role of mTORC2 in GPR30 regulation of spatial memory.

RESULTS

The results showed that high levels of GPR30 were detected in the adult hippocampus and the levels were downregulated by OVX and LET. OVX induced an impairment of spatial memory, and changes in other parameters previously described were reversed by G1 and mimicked by G15. Furthermore, the E2 effects on SRC-1 and mTORC2 signals, synaptic proteins, and actin polymerization were inhibited by G15, whereas G1 effects on these parameters were inhibited by the blockade of SRC-1 or PI3K; the levels of synaptic proteins were regulated by JPK and CytoD. Importantly, G15-induced actin depolymerization and spatial memory impairment were rescued by mTORC2 activation with A4.

CONCLUSIONS

Taking together, these results demonstrated that decreased GPR30 induces actin depolymerization through SRC-1 and PI3K/mTORC2 pathways and ultimately impairs learning and memory, indicating its potential role as a therapeutic target against hippocampus-based, E2-related memory impairments.

Pyk2 in the amygdala modulates chronic stress sequelae via PSD-95-related micro-structural changes

Major depressive disorder (MDD) is a common disorder with a variety of symptoms including mood alterations, anhedonia, sleep and appetite disorders, and cognitive disturbances. Stressful life events are among the strongest risk factors for developing MDD. At the cellular level, chronic stress results in the modification of dendritic spine morphology and density. Here, we study the role of Pyk2 in the development of depressive-like symptoms induced by a model of chronic unpredictable mild stress (CUMS). Pyk2 is a non-receptor calcium-dependent protein-tyrosine kinase highly expressed in the forebrain principal neurons and involved in spine structure and density regulation. We show that Pyk2 knockout mice are less affected to anxiety-like and anhedonia-like phenotypes induced by the CUMS paradigm. Using region-specific knockout, we demonstrate that this phenotype is fully recapitulated by selective Pyk2 inactivation in the amygdala. We also show that in the absence of Pyk2 the spine alterations, PSD-95 clustering, and NMDA receptors changes induced by the CUMS paradigm are prevented. Our results reveal a possible role for Pyk2 in the response to stress and in synaptic markers expression and spine density regulation in the amygdala. We suggest that Pyk2 contributes to stress-induced responses through micro-structural changes and that its deficit may contribute to the resilience to chronic stress.

Radioprotective effect of epimedium on neurogenesis and cognition after acute radiation exposure

The radioprotective effect of herb epimedium (or yin yang huo) extract (5 g/kg, oral administration daily for 4 weeks) on neurogenesis and cognition after acute radiation exposure with 5.5 Gy was evaluated in Balb/c mice by behavioral tests and immunohistochemical study. The results indicated that epimedium extract could improve animal weight loss, locomotor activity and spatial learning and memory which are similar to pre-irradiation intraperitoneal injection (100 mg/kg) of amifostine phosphate, a well- known radioprotective drug. Immunohistochemical study showed that epimedium extract prevented the loss of proliferation cells, newly generated neurons, and interneurons in the hilus, in particular, the subgranular zone of the dentate gyrus. It suggests that herb epimedium may be a promising radio-neuro-protective drug to prevent radiation-induced neuropsychological disorders.

Intermittent fasting uncovers and rescues cognitive phenotypes in PTEN neuronal haploinsufficient mice

Phosphatase and tensin homolog (PTEN) is an important protein with key modulatory functions in cell growth and survival. PTEN is crucial during embryogenesis and plays a key role in the central nervous system (CNS), where it directly modulates neuronal development and synaptic plasticity. Loss of PTEN signaling function is associated with cognitive deficits and synaptic plasticity impairment. Accordingly, Pten mutations have a strong link with autism spectrum disorder. In this study, neuronal Pten haploinsufficient male mice were subjected to a long-term environmental intervention – intermittent fasting (IF) – and then evaluated for alterations in exploratory, anxiety and learning and memory behaviors. Although no significant effects on spatial memory were observed, mutant mice showed impaired contextual fear memory in the passive avoidance test – an outcome that was effectively rescued by IF. In this study, we demonstrated that IF modulation, in addition to its rescue of the memory deficit, was also required to uncover behavioral phenotypes otherwise hidden in this neuronal Pten haploinsufficiency model.

Evaluation of estrogen and G protein-coupled estrogen receptor 1 (GPER) levels in drug-naïve patients with attention deficit hyperactivity disorder (ADHD)

Estrogen has a crucial role in the regulation of reproductive and neuroendocrine function and exerts its effects through two classes of receptors, nuclear and membrane estrogen receptors (mERs). G protein-coupled estrogen receptor 1 (GPER) is a member of mERs, and despite limited research on the levels of GPER in patients with psychiatric diseases, a role of GPER in such conditions has been suggested. Here we evaluated serum estrogen and GPER levels in children with attention deficit hyperactivity disorder (ADHD) in relation to their age- and gender-matched healthy controls. A total of 82 children were included in the study, 47 drug- naïve patients with ADHD (age: 6-12 years; male/female: 34/13) and 35 healthy controls (age: 6-12 years; male/female: 19/16). The subgroups according to ADHD types were inattentive, hyperactive/impulsive, and combined. Serum estrogen was measured using an immunoassay system, while serum GPER was determined using a commercial sandwich enzyme-linked immunosorbent assay kit. Estrogen levels in children with ADHD were similar as in control group, while GPER levels were significantly lower in ADHD group compared to controls (p < 0.05). Logistic regression analysis showed a significant association between GPER levels and ADHD (p < 0.05), and no association between estrogen levels and ADHD (p > 0.05). No significant differences were found in GPER and estrogen levels between ADHD subgroups (p > 0.05). To the best of our knowledge, this study is the first to investigate estrogen and GPER levels in ADHD. Our preliminary findings suggest a relationship between serum GPER levels and ADHD, and this should be further investigated.

Establishment and Evaluation of a Rat Model of Sidestream Cigarette Smoke-Induced Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common cause of mortality worldwide. The current lack of an animal model that can be established within a certain time frame and imitate the unique features of the disease is a major limiting factor in its study. The present study established and evaluated an animal model of COPD that represents the early and advanced stage features using short-, middle-, and long-term sidestream cigarette smoke (CS) exposure. One hundred and nine Sprague-Dawley rats were randomly divided into 10 groups for different periods of sidestream CS exposure or no exposure (i.e., normal groups). The rats were exposed to CS from 3R4F cigarettes in an exposure chamber. Histological analysis was performed to determine pathological changes. We also conducted open-field tests, lung function evaluations, and cytokine analysis of the blood serum, bronchoalveolar lavage fluid, and lung tissue. The lung tissue protein levels, blood gases, and were also analyzed. As the CS exposure time increased, the indicators associated with oxidative stress, inflammatory responses, and airway remodeling were greater in the CS exposure groups than in the normal group. At 24 and 36 weeks, the COPD model rats displayed the middle- and advanced-stage features of COPD, respectively. In the 8-week CS exposure group, after the CS exposure was stopped for 4 weeks, inflammatory responses and oxidative responses were ameliorated and lung function exacerbation was reduced compared with the 12-week CS exposure group. Therefore, we established a more adequate rat model of sidestream CS induced COPD, which will have great significance for a better understanding of the pathogenesis of COPD and drug effectiveness evaluation.

GPER1/GPR30 in the brain: Crosstalk with classical estrogen receptors and implications for behavior

The GPER1/GPR30 is a membrane estrogen receptor (mER) that binds 17β-estradiol (17β-E) with high affinity and is thought to play a role in cancer progression and cardiovascular health. Though widespread in the central nervous system, less is known about this receptor's function in the brain. GPER1 has been shown to activate kinase cascades and calcium flux within cells rapidly, thus fitting in with the idea of being a mER that mediates non-genomic signaling by estrogens. Signaling from GPER1 has been shown to improve spatial memory, possibly via release of neurotransmitters and generation of new spines on neurons in the hippocampus. In addition, GPER1 activation contributes to behaviors that denote anxiety and to social behaviors such as social memory and lordosis behavior in mice. In the male hippocampus, GPER1 activation has also been shown to phosphorylate the classical intracellular estrogen receptor (ER)α, suggesting that crosstalk with ERα is important in the display of these behaviors, many of which are absent in ERα-null mice. In this review, we present a number of categories of such crosstalk, using examples from literature. The function of GPER1 as an ERα collaborator or as a mER in different tissues is relevant to understanding both normal physiology and abnormal pathology, mediated by estrogen signaling.

Zinc oxide nanoparticles in predicted environmentally relevant concentrations leading to behavioral impairments in male swiss mice

Although the potential neurotoxic effects from the exposure to zinc oxide nanoparticles (ZnO NPs) on humans and on experimental models have been reported in previous studies, the effects from the exposure to environmentally relevant concentrations of them remain unclear. Thus, the aim of the present study is to investigate the effects from the exposure to environmentally relevant concentrations of ZnO NPs on the behavior of male Swiss mice. The animals were daily exposed to environmentally relevant concentrations of ZnO NPs (5.625×10^-5mgkg^-1) at toxic level (300mgkg^-1) through intraperitoneal injection for five days; a control group was set for comparison purposes. Positive control groups (clonazepam and fluoxetine) and a baseline group were included in the experimental design to help analyzing the behavioral tests (open field, elevated plus maze and forced swim tests). Although we did not observe any behavioral change in the animals subjected to the elevated plus maze and forced swim tests, our data evidence the anxiogenic behavior of animals exposed to the two herein tested ZnO NPs concentrations in the open field test. The animals stayed in the central part of the apparatus and presented lower locomotion ratio in the central quadrants/total of locomotion during this test. It indicates that the anxiogenic behavior was induced by ZnO NP exposure, because it leads to Zn accumulation in the brain. Thus, the current study is the first to demonstrate that the predicted environmentally relevant ZnO NPs concentration induces behavioral changes in mammalian experimental models. Our results corroborate previous studies that have indicated the biological risks related to the water surface contamination by metal-based nanomaterials.