Anxiety-related Behavior In Mice Research Articles

Amygdala-hippocampus somatostatin interneuron beta-synchrony underlies a cross-species biomarker of emotional state

Emotional responses arise from limbic circuits including the hippocampus and amygdala. In the human brain, beta-frequency communication between these structures correlates with self-reported mood and anxiety. However, both the mechanism and significance of this biomarker as a readout vs. driver of emotional state remain unknown. Here, we show that beta-frequency communication between ventral hippocampus and basolateral amygdala also predicts anxiety-related behavior in mice, both on long timescales (∼30min) and immediately preceding behavioral choices. Genetically encoded voltage indicators reveal that this biomarker reflects synchronization between somatostatin interneurons across both structures. Indeed, synchrony between these neurons dynamically predicts approach-avoidance decisions, and optogenetically shifting the phase of synchronization by just 25ms is sufficient to bidirectionally modulate anxiety-related behaviors. Thus, back-translation establishes a human biomarker as a causal determinant (not just predictor) of emotional state, revealing a novel mechanism whereby interregional synchronization that is frequency, phase, and cell type specific controls emotional processing.

Nano polystyrene induced changes in anxiety and learning behaviour are mediated through oxidative stress and gene disturbance in mouse brain regions

It is widely reported now that nanoplastic particles have potential neurotoxic effects and may disturb central nervous system (CNS) function. However, the mechanism behind these toxic effects still needs to be elucidated. In the current study, we investigated the effects of polystyrene nanoplastics (PS-NPs) on changes in learning, memory, and anxiety-related behavior in mice based on some selected biochemical, molecular, and histopathological changes in three important brain regions (Cortex, Hypothalamus, and Hippocampus). Male mice were orally administered daily with two doses of 50 nm PS-NPs (0.2 mg/ml and 1 mg/ml) for 8 weeks. We observed decreased expression of neurotransmitter-related genes (VAChT, GAD, and SYP) in the cortex, hypothalamus, and hippocampus areas of the mouse brain. Other biochemical variables including, antioxidant enzymes, biomarkers for oxidative stress, and acetylcholinesterase activity showed significant alterations in all three brain regions. Molecular and neurochemical data thus suggest significant neurobehavioral changes following sub-chronic exposure to PS-NPs which may lead to enhanced anxiety-related and spatial learning and memory-related impairments by affecting limbic areas of the brain.

Oxytocin receptors in the prefrontal cortex play important roles in short-term social recognition in mice

We examined the roles of oxytocin (OT) receptors in the prefrontal cortex (PFC) in short- and long-term social recognition and anxiety-related behaviors in mice. Mice injected with high or low doses of an OT receptor antagonist (OTA) or vehicle performed the social recognition test, the open-field test, and the light–dark transition test. In the social recognition test, with three daily trials over three consecutive days, control mice showed short-term recognition of a conspecific on all three days. In contrast, a high-dose injection of OTA impaired short-term social recognition on the second and third days, and it was impaired by a low-dose injection of OTA on the third day. These results suggested that OTA injection into the PFC dose-dependently inhibited short-term social recognition within each day. All three groups did not show any long-term social recognition across three days. OTA injection did not affect anxiety related behavior in the open-field and light–dark transition tests. Our findings demonstrated that OT receptors in the PFC played important roles in short-term social recognition.

Paraventricular Thalamic MC3R Circuits Link Energy Homeostasis with Anxiety-Related Behavior.

The hypothalamic melanocortin system is critically involved in sensing stored energy and communicating this information throughout the brain, including to brain regions controlling motivation and emotion. This system consists of first-order agouti-related peptide (AgRP) and pro-opiomelanocortin (POMC) neurons located in the hypothalamic arcuate nucleus and downstream neurons containing the melanocortin-3 (MC3R) and melanocortin-4 receptor (MC4R). Although extensive work has characterized the function of downstream MC4R neurons, the identity and function of MC3R-containing neurons are poorly understood. Here, we used neuroanatomical and circuit manipulation approaches in mice to identify a novel pathway linking hypothalamic melanocortin neurons to melanocortin-3 receptor neurons located in the paraventricular thalamus (PVT) in male and female mice. MC3R neurons in PVT are innervated by hypothalamic AgRP and POMC neurons and are activated by anorexigenic and aversive stimuli. Consistently, chemogenetic activation of PVT MC3R neurons increases anxiety-related behavior and reduces feeding in hungry mice, whereas inhibition of PVT MC3R neurons reduces anxiety-related behavior. These studies position PVT MC3R neurons as important cellular substrates linking energy status with neural circuitry regulating anxiety-related behavior and represent a promising potential target for diseases at the intersection of metabolism and anxiety-related behavior such as anorexia nervosa.SIGNIFICANCE STATEMENT Animals must constantly adapt their behavior to changing internal and external challenges, and impairments in appropriately responding to these challenges are a hallmark of many neuropsychiatric disorders. Here, we demonstrate that paraventricular thalamic neurons containing the melanocortin-3 receptor respond to energy-state-related information and external challenges to regulate anxiety-related behavior in mice. Thus, these neurons represent a potential target for understanding the neurobiology of disorders at the intersection of metabolism and psychiatry such as anorexia nervosa.

Genetic modulation of the HTR2A gene reduces anxiety-related behavior in mice.

The expanding field of precision gene editing using CRISPR/Cas9 has demonstrated its potential as a transformative technology in the treatment of various diseases. However, whether this genome-editing tool could be used to modify neural circuits in the central nervous system (CNS), which are implicated in complex behavioral traits, remains uncertain. In this study, we demonstrate the feasibility of noninvasive, intranasal delivery of adeno-associated virus serotype 9 (AAV9) vectors containing CRISPR/Cas9 cargo within the CNS resulting in modification of the HTR2A receptor gene. In vitro, exposure to primary mouse cortical neurons to AAV9 vectors targeting the HT2RA gene led to a concentration-dependent decrease in spontaneous electrical activity following multielectrode array (MEA) analysis. In vivo, at 5 weeks postintranasal delivery in mice, analysis of brain samples revealed single base pair deletions and nonsense mutations, leading to an 8.46-fold reduction in mRNA expression and a corresponding 68% decrease in the 5HT-2A receptor staining. Our findings also demonstrate a significant decrease in anxiety-like behavior in treated mice. This study constitutes the first successful demonstration of a noninvasive CRISPR/Cas9 delivery platform, capable of bypassing the blood-brain barrier and enabling modulation of neuronal 5HT-2A receptor pathways. The results of this study targeting the HTR2A gene provide a foundation for the development of innovative therapeutic strategies for a broad range of neurological disorders, including anxiety, depression, attentional deficits, and cognitive dysfunction.

Diet, sex, and genetic predisposition to obesity and type 2 diabetes modulate motor and anxiety-related behaviors in mice, and alter cerebellar gene expression

Obesity and type 2 diabetes (T2D) are serious health problems linked to neurobehavioral alterations. We compared motor function, anxiety-related behavior, and cerebellar gene expression in TALLYHO/Jng (TH), a polygenic model prone to insulin resistance, obesity, and T2D, and normal C57BL/6 J (B6) mice. Male and female mice were weaned onto chow or high fat (HF) diet at 4 weeks of age (wk), and experiments conducted at young (5 wk) and old (14 – 20 wk) ages. In the open field, distance traveled was significantly lower in TH (vs. B6). For old mice, anxiety-like behavior (time in edge zone) was significantly increased for TH (vs B6), females (vs males), and for both ages HF diet (vs chow). In Rota-Rod testing, latency to fall was significantly shorter in TH (vs B6). For young mice, longer latencies to fall were observed for females (vs males) and HF (vs chow). Grip strength in young mice was greater in TH (vs B6), and there was a diet-strain interaction, with TH on HF showing increased strength, whereas B6 on HF showed decreased strength. For older mice, there was a strain-sex interaction, with B6 males (but not TH males) showing increased strength compared to the same strain females. There were significant sex differences in cerebellar mRNA levels, with Tnfα higher, and Glut4 and Irs2 lower in females (vs males). There were significant strain effects for Gfap and Igf1 mRNA levels with lower in TH (vs B6). Altered cerebellar gene expression may contribute to strain differences in coordination and locomotion.

Uncoupling Protein-1 Modulates Anxiety-Like Behavior in a Temperature-Dependent Manner.

A strong bidirectional link between metabolic and psychiatric disorders exists; yet, the molecular basis underlying this interaction remains unresolved. Here we explored the role of the brown adipose tissue (BAT) as modulatory interface, focusing on the involvement of uncoupling protein 1 (UCP-1), a key metabolic regulator highly expressed in BAT, in the control of emotional behavior. Male and female constitutive UCP-1 knock-out (KO) mice were used to investigate the consequences of UCP-1 deficiency on anxiety-related and depression-related behaviors under mild thermogenic (23°C) and thermoneutral (29°C) conditions. UCP-1 KO mice displayed a selective enhancement of anxiety-related behavior exclusively under thermogenic conditions, but not at thermoneutrality. Neural and endocrine stress mediators were not affected in UCP-1 KO mice, which showed an activation of the integrated stress response alongside enhanced fibroblast-growth factor-21 (FGF-21) levels. However, viral-mediated overexpression of FGF-21 did not phenocopy the behavioral alterations of UCP-1 KO mice and blocking FGF-21 activity did not rescue the anxiogenic phenotype of UCP-1 KO mice. No effects of surgical removal of the intrascapular BAT on anxiety-like behavior or FGF-21 levels were observed in either UCP-1 KO or WT mice. We provide evidence for a novel role of UCP-1 in the regulation of emotions that manifests as inhibitory constraint on anxiety-related behavior, exclusively under thermogenic conditions. We propose this function of UCP-1 to be independent of its activity in the BAT and likely mediated through a central role of UCP-1 in brain regions with converging involvement in energy and emotional control.SIGNIFICANCE STATEMENT In this first description of a temperature-dependent phenotype of emotional behavior, we propose uncoupling protein-1 (UCP-1), the key component of the thermogenic function of the brown adipose tissue, as molecular break controlling anxiety-related behavior in mice. We suggest the involvement of UCP-1 in fear regulation to be mediated through its expression in brain regions with converging roles in energy and emotional control. These data are important and relevant in light of the largely unexplored bidirectional link between metabolic and psychiatric disorders, which has the potential for providing insight into novel therapeutic strategies for the management of both conditions.

Age, Sex, and Genetic Predisposition to Obesity and Type 2 Diabetes Modulate Motor and Anxiety-Related Behaviors in Mice Fed Chow or High Fat Diet, and Alter Cerebellar Gene Expression

Age, Sex, and Genetic Predisposition to Obesity and Type 2 Diabetes Modulate Motor and Anxiety-Related Behaviors in Mice Fed Chow or High Fat Diet, and Alter Cerebellar Gene Expression

Monoclonal Antibodies From Anti-NMDA Receptor Encephalitis Patient as a Tool to Study Autoimmune Seizures.

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis manifests with precipitous cognitive decline, abnormal movements, and severe seizures that can be challenging to control with conventional anti-seizure medications. We previously demonstrated that intracerebroventricular (i.c.v.) administration of cerebrospinal fluid from affected patients, or purified NMDA receptor antibodies from encephalitis patients to mice precipitated seizures, thereby confirming that antibodies are directly pathogenic for seizures. Although different repertoires of anti-NMDA receptor antibodies could contribute to the distinct clinical manifestations in encephalitis patients, the role of specific antibodies in the expression of seizure, motor, and cognitive phenotypes remains unclear. Using three different patient-derived monoclonal antibodies with distinct epitopes within the N-terminal domain (NTD) of the NMDA receptor, we characterized the seizure burden, motor activity and anxiety-related behavior in mice. We found that continuous administration of 5F5, 2G6 or 3C11 antibodies for 2 weeks precipitated seizures, as measured with continuous EEG using cortical screw electrodes. The seizure burden was comparable in all three antibody-treated groups. The seizures were accompanied by increased hippocampal C-C chemokine ligand 2 (CCL2) mRNA expression 3 days after antibody infusion had stopped. Antibodies did not affect the motor performance or anxiety scores in mice. These findings suggest that neuronal antibodies targeting different epitopes within the NMDA receptor may result in a similar seizure phenotype.

The Cannabis Constituent Cannabigerol Does Not Disrupt Fear Memory Processes or Stress-Induced Anxiety in Mice.

Introduction: Medicinal cannabis has proliferated around the world and there is increasing interest in the therapeutic potential of individual plant-derived cannabinoids (phytocannabinoids). Preclinical evidence suggests the phytocannabinoid cannabigerol (CBG) could be useful in treating brain disorders, including stress and anxiety-related disorders. In this study, we aimed to explore whether CBG disrupts various contextually conditioned fear memory processes and trauma-induced anxiety-related behavior in a mouse model of post-traumatic stress disorder (PTSD). Materials and Methods: All mice underwent contextual fear conditioning. CBG was administered between 1 and 60 mg/kg intraperitoneally (i.p.). We first assessed the effects of repeated CBG exposure on long-term fear memories. We also examined whether acute CBG affected various fear memory processes, namely expression, acquisition, consolidation, and reconsolidation of conditioned fear. Finally, the effect of acute CBG administration on stress-induced anxiety in the light/dark test was assessed. Results: Repeated CBG exposure did not affect long-term conditioned fear that was observed 24 days after the conditioning session. Moreover, acute CBG administration did not influence the acquisition, consolidation, reconsolidation, or expression of contextually conditioned fear. Acute CBG treatment also did not affect stress-induced anxiety-related behaviors in the light/dark test. Conclusions: CBG was ineffective in disrupting long-term fear memories, various conditioned fear memory processes, or stress-induced anxiety-related behavior in mice. These preclinical data suggest CBG may have limited scope in the treatment of PTSD and stress-related anxiety.

A Behavioral Study of Anxiety-Related Behavior in Mice

A Behavioral Study of Anxiety-Related Behavior in Mice

Naringenin improves depressive- and anxiety-like behaviors in mice exposed to repeated hypoxic stress through modulation of oxido-inflammatory mediators and NF-kB/BDNF expressions

Oxidative and inflammatory signaling pathways have been identified as important targets for mitigating hypoxic stress-induced neurological complications. Thus, the effects of naringenin, a potent antioxidant, anti-inflammatory and neuroprotective bioflavonoid on hypoxic stress-induced depressive-like and anxiety-related behaviors in mice, and the underlying molecular mechanisms were evaluated in this study. Thirty-five male Swiss mice were distributed into 5 groups (n = 7). Mice in group I (non-stress control) and group 2 (stress-control) both had vehicle (5 % DMSO), while groups 3–5 received naringenin (10, 25 and 50 mg/kg), intraperitonally. Thirty minutes later, mice in groups 2–5 were subjected to 15 min hypoxic stress, daily for 14 days. Locomotor activity, anxiety and depression were evaluated on day 15. The mice brains were processed for malondialdehyde, glutathione, superoxide-dismutase (SOD), catalase, tumor necrosis factor-alpha (TNF-α) and interleukin-1β assays. The serum corticosterone concentration and expressions of the brain immunopositive cells of inducible nitric oxide synthase (iNOS), nuclear factor kappa-B (NF-kB) and brain derived neurotrophic factor (BDNF) as well as histomorphological changes of the amygdala were also determined. Naringenin (25−50 mg/kg) ameliorated the hypolocomotion, depressive- and anxiety-like behaviors in hypoxic mice. The increased brain contents of malondialdehyde, TNF-α, interleukin-1β, and decreased antioxidant (glutathione and SOD) status were attenuated by naringenin. Naringenin (10 mg/kg) increases BDNF expression but did not significantly (p < 0.05) alter corticosterone and catalase contents. The increased expressions of iNOS and NF-kB as well as loss of amygdala neuronal cells were reduced by naringenin (10 mg/kg). Overall, these findings suggest that naringenin improves depressive- and anxiety-like behaviors in mice exposed to hypoxic stress by modulating oxido-inflammatory insults and NF-kB/BDNF expressions.

The effect of pectin of tansy, Tanacetum vulgare L., on anxiety and overeating food rich in fats and sugars in mice in modelling binge eating

Binge eating is repeated episodes of eating large amounts of sweet and fatty food in short periods. Dietary fibers, including pectin, significantly reduce the subjective ratings of hunger, and the amount of food eaten. However, studies showing the effect of dietary fibers on satiety use juices or yoghurts with added dietary fiber, or a kissel-like food. Thus, there is a lack of data on the effect of dietary fibres on binge eating of palatable food. The aim of the study was to assess the effect of tansy pectin on anxiety and the binge eating of palatable food in mice. Material and methods. 64 mice weighing 33.3±0.6 g were divided into two groups. Binge eating was induced in forty mice of the first group by consumption of sunflower halva (SH) in addition to regular chow for 24 h once a week. The total energy intake and separately the consumption of regular chow (RC) and SH were monitored. Tansy pectin in the form of an aqueous solution was administered to the mice using a gastric feeding tube (50 mg/kg body weight) before the last presentation of SH. Blood was obtained by cardiac puncture at the end of the last 24 h SH access period. The concentration of insulin and ghrelin in plasma samples were determined by the enzyme immunoassay. In animals of the second group, 24 hours after the administration of pectin, the level of anxiety and depression of mice was assayed with an open field test, a light-dark box test, an elevated plus-maze test, and a forced swim test. Throughout the study, water was used as a negative control, and imipramine at a dose of 20 mg/kg was used as a positive control. Results. Mice treated with tansy pectin ate 2.6 fold less SH within 3 h and 1.4 fold less within 24 h after oral administration of tansy pectin compared to control (water administration). Consumption of RC did not differ within 3 or 24 h. The total energy intake was 1.9 fold lower within 3 h in mice treated with tansy pectin. Within 24 h after pectin oral administration the total energy intake did not differ from control. Insulin plasma level was 2.5 fold lower and ghrelin plasma concentration was 25% higher in the mice that received pectin compared to control, at the end of the 24 h SH access period. The administration of tansy pectin was found to decrease anxietyrelated behaviour in mice. Its administration significantly increased the time spent in the central sector of the open field apparatus by 87%, the time spent in the light area of the light-dark box by 31%, and the time spent on the open arms of the elevated plus maze by 22% compared with the control. Conclusion. Overall, tansy pectin reduced the binge eating of SH representing highly palatable, sweet, and fatty food. Reduced intake SH lead to a decrease in insulin concentration. Blood level of ghrelin was increased in mice treated with tansy pectin at the end of the sweet and fatty food presentation period. Tansy pectin reduced the level of anxiety in mice.

Familiarization effects on the behavioral disinhibition of the cerebellar Lurcher mutant mice: use of the innovative Dual Maze

Anxiety-related behaviors in mice are often assessed over short periods starting immediately after introducing the animals in a dedicated apparatus. In these usual conditions (5−10 min periods), the cerebellar Lurcher mutants showed disinhibited behaviors characterized by abnormally high exploration of the aversive areas in the elevated plus-maze test. We nevertheless observed that this disinhibition sharply weakened after 10 min. We therefore decided to further investigate the influence of the disinhibition on the intrinsic and anxiety-related exploratory behaviors in Lurcher mice, with a special focus on familiarization effects. To this end, we used an innovative apparatus, the Dual Maze, permitting to tune the familiarization level of animals to the experimental context before they are faced with more (open configuration of the device) or less (closed configuration of the device) aversive areas. Chlordiazepoxide administration in BALB/c mice in a preliminary experiment confirmed both the face and the predictive validity of our device as anxiety test and its ability to measure exploratory motivation. The results obtained with the Lurcher mice in the open configuration revealed that 20 min of familiarization to the experimental context abolished the behavioral abnormalities they exhibited when not familiarized with it. In addition, their exploratory motivation, as measured in the closed configuration, was comparable to that of their non-mutant littermates, whatever the level of familiarization applied. Exemplifying the interest of this innovative device, the results we obtained in the Lurcher mutants permitted to differentiate between the roles played by the cerebellum in exploratory motivation and stress-related behaviors.

Cannabidiol disrupts conditioned fear expression and cannabidiolic acid reduces trauma-induced anxiety-related behaviour in mice.

The major phytocannabinoid cannabidiol (CBD) has anxiolytic properties and lacks tetrahydrocannabinol-like psychoactivity. Cannabidiolic acid (CBDA) is the acidic precursor to CBD, and this compound appears more potent than CBD in animal models of emesis, pain and epilepsy. In this short report, we aimed to examine whether CBDA is more potent than CBD in disrupting expression of conditioned fear and generalised anxiety-related behaviour induced by Pavlovian fear conditioning. Mice underwent fear conditioning and 24 h later were administered CBD and CBDA before testing for fear expression and generalized anxiety-like behaviour. We found that CBD and CBDA had dissociable effects; while CBD but not CBDA disrupted cued fear memory expression, CBDA but not CBD normalized trauma-induced generalized anxiety-related behaviour. Neither phytocannabinoid affected contextual fear expression. Our findings form the basis for future experiments examining whether phytocannabinoids, alone and in combination, are effective in these mouse models of fear and anxiety.

Blockade of NOP receptor modulates anxiety-related behaviors in mice exposed to inescapable stress.

Depression and anxiety frequently co-occur, and this has important clinical implications. Previous studies showed that activation of the nociceptin/orphanin FQ receptor (NOP) elicits anxiolytic effects, while its blockade promotes consistent antidepressant actions. NOP antagonists are effective in reversing footshock-induced depressive-like behaviors, but their effects on stress-induced anxiety are still unclear. This study aimed to investigate the effects of the NOP antagonist SB-612111 on footshock stress-induced anxiety behaviors. Male Swiss mice were exposed to inescapable electric footshock stress, and behavioral phenotype was screened based on the ability to escape from footshock (i.e., helpless or non-helpless). Animals were then treated with diazepam (1mg/kg) and SB-612111 (0.1-10mg/kg), and their behavior was assessed in the elevated plus-maze (EPM) and open field test. When compared with non-stressed mice, helpless, but not non-helpless, animals displayed significant reductions in the time spent in and entries into open arms in the EPM. Diazepam significantly increased open arms exploration in helpless, non-helpless, and non-stressed mice. However, treatment with the NOP antagonist SB-612111 was inactive in naive mice, while it reversed anxiogenic-related behaviors in helpless mice and increased anxiety states in non-helpless mice. No effects on locomotion were observed. Helpless mice displayed increased anxiety compared to non-stressed and non-helpless animals, thus supporting use of this approach as an animal model to investigate anxiety/depression comorbidity. Additionally, SB-612111 modulated anxiety-like behaviors in male mice depending on individual stress susceptibility. Ultimately, NOP antagonists could be useful for treating anxiety in depressed patients.

Increased anxiety-related behavior in mice following β-citronellol inhalation

ABSTRACT β-Citronellol is a monoterpene alcohol found in essential oils of various aromatic plant species. The physiological effects of β-citronellol inhalation on the central nervous system remain unclear. We investigated the effects of β-citronellol inhalation on mouse behavior. First, we examined whether the odor of β-citronellol was attractive or repellent to mice. Then, following 30 minutes of β-citronellol inhalation, a series of behavioral tests (elevated plus maze, open field, Y-maze, tail suspension, and forced swim tests) were performed. Mice were neither attracted to nor repelled by β-citronellol. Mice that inhaled β-citronellol showed an increase in anxiety-like behavior in the elevated plus maze and open field tests. Performance in the Y-maze and forced swim tests was not affected. These results indicate that β-citronellol acts on the central nervous system of mice following inhalation and increases anxiety. Essential oils and cosmetics containing β-citronellol should be used with caution.

Low-dose alcohol ameliorated homocysteine-induced anxiety-related behavior via attenuating oxidative stress in mice

Recent studies showed that homocysteine (Hcy) levels were obviously elevated in patients with anxiety, furthermore, oxidative stress and inflammation were closely linked with Hcy-related damage. Despite alcohol exposure has differential effects on different forms of anxiety, the role of alcohol on anxiety-related behavior induced by high Hcy levels is still not entirely clear. The present study investigated the protective potential of low-dose alcohol against homocysteine-induced anxiety-related behavior and explored the possible underlying mechanisms. Mice were administered intragastrically with methionine (2.0 g/kg/day) or alcohol (0.6 g/kg/day). After 21 days of administration, the anxiety-related behavior was evaluated through open field (OF) and elevated plus maze (EPM) tests, and the variations of oxidative stress and inflammation levels were measured. The results of OF and EPM tests showed that the anxiety-related behavior in mice was prevented by alcohol treatment. Alcohol lowered the elevated serum Hcy levels and alleviated the damage of hippocampal tissues in hyperhomocysteinemia (HHcy) mice. Meanwhile, the superoxide dismutase (SOD) activity of the hippocampal tissues enhanced, and the malondialdehyde (MDA) concentration of the hippocampal tissues and the serum interleukin-1β (IL-1β) level decreased. In addition, after administering alcohol, the increase of superoxide dismutase 1 (SOD1), heme oxygenase 1 (HO-1) protein expression and the decrease of IL-1β protein expression were also detected in HHcy mice hippocampal tissues. Taken together, low-dose alcohol significantly ameliorated the Hcy-induced anxiety-related behavior in mice, which might be related to SOD1 and HO-1 upregulation and IL-1β downregulation.

Nectandra grandiflora essential oil and its isolated sesquiterpenoids minimize anxiety-related behaviors in mice through GABAergic mechanisms

Nectandra grandiflora Ness (Lauraceae) essential oil (EO) main constituent, the sesquiterpenoid (+)-dehydrofukinone (DHF), has sedative and anticonvulsant effects through GABAergic mechanisms. Other DHF-related sesquiterpenoids have been identified in the EO, such as, dehydrofukinone epoxide (DFX), eremophil-11-en-10-ol (ERM) and selin-11-en-4-α-ol (SEL). However, the neuronal effects of these compounds in mammals remain unknown. Therefore, the aim of this study was to evaluate the anxiolytic potential of the N. grandiflora EO and the isolated compounds in in mice. For this purpose, mice were administered orally with vehicle, 10, 30 or 100 mg/kg EO, DHF, DFX, ERM or SEL or 1 mg/kg diazepam. Locomotion and ethological parameters in the open field (OF) and elevated plus maze (EPM) were recorded. We also examined the effect of DFX, ERM and SEL on the membrane potential and calcium influx in synaptosomes, and the presence of the compounds in the cortical tissue using gas chromatography. EOs and isolated compounds reduced anxiety-related parameters in the EPM (open arms time and entries, end activity, head dipping) and OF (center time and entries, total rearing, unprotected rearing, sniffing, grooming) without alter ambulation or induce sedation. Flumazenil (2 mg/kg, i.p.) altered the anxiolytic-like effect of all treatments and vanished the DFX, ERM and SEL-induced changes in membrane potential. However, FMZ did not blocked the DFX-, ERM- and SEL-induced inhibition of calcium influx. Therefore, our results suggest that N. grandiflora EO and isolated compounds induced anxiolytic-like effect in mice due to positive modulation of GABAa receptors and/or inhibition of neuronal calcium influx.

Cannabidiol (CBD) reduces anxiety-related behavior in mice via an FMRP-independent mechanism

Fragile X Syndrome is a neurodevelopmental disorder which affects intellectual, social and physical development due to mutation of the Fragile X mental retardation 1 (FMR1) gene. The resultant loss of Fragile X mental retardation protein can be modelled by Fmr1 gene knockout (KO) in mice. The current study investigated the behavioural effects of cannabidiol (CBD; a non-psychoactive phytocannabinoid) in male Fmr1 KO mice as a preclinical model for therapeutic discovery. Vehicle or CBD (5 or 20 mg/kg body weight) was administered to adult Fmr1 KO and wild type-like (WT) mice before they were tested in behavioural tasks including: open field (OF), elevated plus maze (EPM), spontaneous alternation, social preference, and passive avoidance tasks. Fmr1 KO mice were hyperlocomotive and hyperexplorative and habituated more slowly to a novel environment compared to control animals. Furthermore, Fmr1 KO mice showed fewer anxiety-related behaviours across tests. Effects of CBD were subtle and limited to the EPM, where CBD decreased the anxiety response of all mice tested. Acute CBD had no impact on locomotion or anxiety-related parameters in the OF. Cognitive performance of Fmr1 KO mice was equivalent to controls and not affected by CBD treatment. Brain concentrations of CBD were equivalent between genotypes, but in animals sacrificed 90 min post-administration, decreased plasma CBD in Fmr1 KO mice compared to WT suggested more rapid clearance of CBD by transgenic animals. Overall, acute CBD at the doses chosen did not selectively normalize behavioural abnormalities in Fmr1 KO mice, but reduced anxiety-like behaviour in both Fmr1 KO and WT mice.