Use of the Open Field Maze to measure locomotor and anxiety-like behavior in mice

Optimization of behavioral testing in a long-term rat model of hypoxic ischemic brain injury

BACKGROUND

Hypoxic ischemic (HI) brain injury is a significant cause of childhood neurological deficits. Preclinical rodent models are often used to study these deficits; however, no preclinical study has determined which behavioral tests are most appropriate for long-term follow up after neonatal HI.

METHODS

HI brain injury was induced in postnatal day (PND) 10 rat pups using the Rice-Vannucci method of unilateral carotid artery ligation. Rats underwent long-term behavioral testing to assess motor and cognitive outcomes between PND11-50. Behavioral scores were transformed into Z-scores and combined to create composite behavioral scores.

RESULTS

HI rats showed a significant deficit in three out of eight behavioral tests: negative geotaxis analysis, the cylinder test and the novel object recognition test. These individual test outcomes were transformed into Z-scores and combined to create a composite Z-score. This composite z-score showed that HI rats had a significantly increased behavioral burden over the course of the experiment.

CONCLUSION

In this study we have identified tests that highlight specific cognitive and motor deficits in a rat model of neonatal HI. Due to the high variability in this model of neonatal HI brain injury, significant impairment is not always observed in individual behavioral tests, but by combining outcomes from these individual tests, long-term behavioral burden can be measured.

Differential effects by sex with Kmt5b loss

Lysine methyl transferase 5B (KMT5B) has been recently highlighted as a risk gene in genetic studies of neurodevelopmental disorders (NDDs), specifically, autism spectrum disorder (ASD) and intellectual disability (ID); yet, its role in the brain is not known. The goal of this work was to neurodevelopmentally characterize the effect(s) of KMT5B haploinsufficiency using a mouse model. A Kmt5b gene-trap mouse line was obtained from the Knockout Mouse Project. Wild type (WT) and heterozygous (HET) mice were subjected to a comprehensive neurodevelopmental test battery to assess reflexes, motor behavior, learning/memory, social behavior, repetitive movement, and common ASD comorbidities (obsessive compulsion, depression, and anxiety). Given the strong sex bias observed in the ASD patient population, we tested both a male and female cohort of animals and compared differences between genotypes and sexes. HET mice were significantly smaller than WT littermates starting at postnatal day 10 through young adulthood which was correlated with smaller brain size (i.e., microcephaly). This was more severe in males than females. HET male neonates also had delayed eye opening and significantly weaker reflexes than WT littermates. In young adults, significant differences between genotypes relative to anxiety, depression, fear, and extinction learning were observed. Interestingly, several sexually dimorphic differences were noted including increased repetitive grooming behavior in HET females and an increased latency to hot plate response in HET females versus a decreased latency in HET males. LAY SUMMARY: Lysine methyl transferase 5B (KMT5B) has been recently highlighted as a risk gene in neurodevelopmental disorders (NDDs), specifically, autism spectrum disorder (ASD) and intellectual disability (ID); yet its role in the brain is not known. Our study indicates that mice lacking one genomic copy of Kmt5b show deficits in neonatal reflexes, sociability, repetitive stress-induced grooming, changes in thermal pain sensing, decreased depression and anxiety, increased fear, slower extinction learning, and lower body weight, length, and brain size. Furthermore, several outcomes differed by sex, perhaps mirroring the sex bias in ASD.

Contribution of growth hormone secretagogue receptor (GHSR) signaling in the ventral tegmental area (VTA) to the regulation of social motivation in male mice

Most psychiatric disorders are characterized by deficits in the ability to interact socially with others. Ghrelin, a hormone normally associated with the regulation of glucose utilization and appetite, is also implicated in the modulation of motivated behaviors including those associated with food and sex rewards. Here we hypothesized that deficits in ghrelin receptor (growth hormone secretagogue receptor; GHSR) signaling are also associated with deficits in social motivation in male mice. To test this hypothesis, we compared social motivation in male mice lacking GHSR or mice treated with the GHSR antagonist JMV2959 with that of WT or vehicle-treated mice. GHSR signaling in dopamine cells of the ventral tegmental area (VTA) has been implicated in the control of sexual behavior, thus we further hypothesized that GHSR signaling in the VTA is important for social motivation. Thus, we conducted studies where we delivered JMV2959 to block GHSR in the VTA of mice, and studies where we rescued the expression of GHSR in the VTA of GHSR knockout (KO) mice. Mice lacking GHSR or injected with JMV2959 peripherally for 3 consecutive days displayed lower social motivation as reflected by a longer latency to approach a novel conspecific and shorter interaction time compared to WT or vehicle-treated controls. Furthermore, intra-VTA infusion of JMV2959 resulted in longer latencies to approach a novel conspecific, whereas GHSR KO mice with partial rescue of the GHSR showed decreased latencies to begin a novel social interaction. Together, these data suggest that GHSR in the VTA facilitate social approach in male mice, and GHSR-signaling deficits within the VTA result in reduced motivation to interact socially.

Complement mediates neuroinflammation and cognitive decline at extended chronic time points after traumatic brain injury

Traumatic brain injury (TBI) can result in progressive cognitive decline occurring for years after the initial insult, and for which there is currently no pharmacological treatment. An ongoing chronic inflammatory response after TBI is thought to be an important factor in driving this cognitive decline. Here, we investigate the role of complement in neuroinflammation and cognitive decline for up to 6 months after murine TBI. Male C57BL/6 mice were subjected to open head injury using a controlled cortical impact device. At 2 months post TBI, mice were moved to large cages with an enriched environment to simulate rehabilitation therapy, and assigned to one of three treatment groups: 1. vehicle (PBS), 2. CR2Crry (3 doses over 1 week), 3. CR2Crry (continuous weekly dose until the end of the study). The study was terminated at 6 months post-TBI for all groups. Motor and cognitive function was analyzed, with histopathological analysis of brain tissue. Measured at 6 months after TBI, neither of the complement inhibition paradigms improved motor performance. However, mice receiving continuous CR2Crry treatment showed improved spatial learning and memory compared to both mice receiving only 3 doses and to mice receiving vehicle control. Analysis of brain sections at 6 months after injury revealed ongoing complement activation in the control group, with reduced complement activation and C3 deposition in the continuous CR2Crry treatment group. The ipsilateral hemisphere of continuously treated animals also showed a decrease in microglia/macrophage and astrocyte activation compared to vehicle. There was also increased astrocytosis in the contralateral hippocampus of vehicle treated vs. naïve mice, which was reduced in mice continuously treated with CR2Crry. This study demonstrates continued complement mediated neuroinflammation at extended chronic time points after TBI, and extends the potential treatment window for complement inhibition, which has previously been shown to improve outcomes after murine TBI.

Pharmacological inhibition of nSMase2 reduces brain exosome release and α-synuclein pathology in a Parkinson's disease model

Aim

We have previously reported that cambinol (DDL-112), a known inhibitor of neutral sphingomyelinase-2 (nSMase2), suppressed extracellular vesicle (EV)/exosome production in vitro in a cell model and reduced tau seed propagation. The enzyme nSMase2 is involved in the production of exosomes carrying proteopathic seeds and could contribute to cell-to-cell transmission of pathological protein aggregates implicated in neurodegenerative diseases such as Parkinson’s disease (PD). Here, we performed in vivo studies to determine if DDL-112 can reduce brain EV/exosome production and proteopathic alpha synuclein (αSyn) spread in a PD mouse model.

Methods

The acute effects of single-dose treatment with DDL-112 on interleukin-1β-induced extracellular vesicle (EV) release in brain tissue of Thy1-αSyn PD model mice and chronic effects of 5 week DDL-112 treatment on behavioral/motor function and proteinase K-resistant αSyn aggregates in the PD model were determined.

Results/discussion

In the acute study, pre-treatment with DDL-112 reduced EV/exosome biogenesis and in the chronic study, treatment with DDL-112 was associated with a reduction in αSyn aggregates in the substantia nigra and improvement in motor function. Inhibition of nSMase2 thus offers a new approach to therapeutic development for neurodegenerative diseases with the potential to reduce the spread of disease-specific proteopathic proteins.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13041-021-00776-9.

Neurobehavioral, neurochemical and synaptic plasticity perturbations during postnatal life of rats exposed to chloroquine in-utero

Despite reports that quinoline antimalarials including chloroquine (Chq) exhibit idiosyncratic neuropsychiatric effects even at low doses, the drug continues to be in widespread use during pregnancy. Surprisingly, very few studies have examined the potential neurotoxic action of Chq exposure at different points of gestation or how this phenomenon may affect neurophysiological well-being in later life. We therefore studied behavior, and the expression of specific genes and neurochemicals modulating crucial neural processes in offspring of rats exposed to prophylactic dose of Chq during different stages of gestation. Pregnant rats were injected 5 mg/kg/day (3 times) of Chq either during early- (first week), mid- (second week), late- (third week), or throughout- (all weeks) gestation, while controls received PBS injection. Behavioral characterization of offspring between postnatal days 15-20 in the open field, Y-maze, elevated plus and elevated zero mazes revealed that Chq evoked anxiogenic responses and perturbed spatial memory in rats, although locomotor activity was generally unaltered. In the prefrontal cortex (PFC), hippocampus and cerebellum of rats prenatally exposed to Chq, RT-qPCR analysis revealed decreased mRNA expression of presynaptic marker synaptophysin, which was accompanied by downregulation of postsynaptic marker PSD95. Synaptic marker PICK1 expression was also downregulated in the hippocampus but was unperturbed in the PFC and cerebellum. In addition to recorded SOD downregulation in cortical and hippocampal lysates, induction of oxidative stress in rats prenatally exposed to Chq was corroborated by lipid peroxidation as evinced by increased MDA levels. Offspring of rats infused with Chq at mid-gestation and weekly treatment throughout gestation were particularly susceptible to neurotoxic changes, especially in the hippocampus. Interestingly, Chq did not cause histopathological changes in any of the brain areas. Taken together, our findings causally link intrauterine exposure to Chq with postnatal behavioral impairment and neurotoxic changes in rats.

The protective effect of olanzapine on ketamine induced cognitive deficit and increased NR1 expression in rat model of schizophrenia

BACKGROUND

Impaired cognitive flexibility is the core manifestation of schizophrenia (SZ). Previous literature raised a claim against the effect of atypical antipsychotic drugs (AAD) on cognitive and executive functions whose cause needs further investigation. Attention set-shifting task (ASST) tests the prefrontal cortex's (PFC) executive and flexibility functions.

GOALS

To examine Olanzapine (OLZ) effect on ASST, expression of N-methyl-D-aspartate receptor 1 (NMDR-NR1) in prefrontal cortex (PFC), and metabolic comorbidity in ketamine (KET) model of SZ.

METHODS

Sixty-two male rats were divided into three groups: 8 for ASST and 30 for open field, ELISA and immunohistochemistry sub-chronic study, and 24 for regular serological and histopathological examination. Rats treated with V: vehicle; K: KET and KO: OLZ plus KET.

RESULTS

KET caused significant increase in time, trials, and errors to reach criterion. OLZ co-administration reversed effects of KET in ASST with no reduction of locomotor activity. OLZ normalized KET-induced rise of NR1 expression and protected against KET-induced degenerative changes in hippocampus and PFC. Significant increase in serum liver enzymes, total bilirubin, and lipids with chronic compared to sub-chronic OLZ administration. In contrast, insignificant difference between sub-chronic OLZ and vehicle was found.

CONCLUSIONS

Current study demonstrated the efficacy of OLZ to reverse KET-induced cognitive deficits in ASST with neither reduction in NR1 expression in PFC nor metabolic malfunction in the sub-chronic study. It also showed the protective effect of OLZ on KET induced neuronal degeneration and necrosis. We suggest that chronic OLZ treatment-induced-metabolic malfunction might be the cause of time-dependent cognitive deterioration.

Rosuvastatin revert memory impairment and anxiogenic-like effect in mice infected with the chronic ME-49 strain of Toxoplasma gondii

The aim of this study was to investigate the effect of rosuvastatin treatment on memory impairment, and anxiogenic-like effects in mice chronically infected with Toxoplasma gondii. For this, Balb/c mice were infected orally with chronic ME-49 strain of Toxoplasma gondii. Oral treatment with rosuvastatin (40mg/kg/day) started on the 51^st day post-infection and was performed daily for 21 days. After completion of treatment, anxiety-like effects and locomotion were investigated in the open field (OF) test, whereas novel object recognition (NOR) test was used for evaluation of short- and long-term memory. At the end of the experiments, the brain was collected for Toxoplasma gondii DNA quantification and histopathological analysis. Infection with ME-49 strain decreased the time spent in the center of OF, indicating an anxiogenic effect, without affecting total and peripheral locomotion. Rosuvastatin treatment inhibited the change in the center time. Besides, pharmacological treatment increased total and central locomotion in both non-infected and infected animals. Infection also impaired both short- and long-term memory in the NOR test, and these effects were reverted by rosuvastatin treatment. In addition to effects in behavioral changes, rosuvastatin also reduced parasite load in the brain and attenuated signs of brain inflammation such as perivascular cuffs, inflammatory cell infiltration and tissue damage. These findings indicate for the first time the efficacy of rosuvastatin in treatment of memory impairment and anxiogenic effect evoked by infection with Toxoplasma gondii. These effects might be mediated by reduced cyst load, which in turn decrease inflammation and damage in the brain.

A Need for Consistency in Behavioral Phenotyping for ASD: Analysis of the Valproic Acid Model

Autism spectrum disorder (ASD) is a highly prevalent and impairing neurodevelopmental disorder that affects 1 : 54 persons. Over the last several decades, the reported incidence of ASD in the US has increased potentially due to increased awareness and improved diagnostic measurement. Although ASD prevalence is increasing, the etiology of ASD remains relatively unknown. To better understand the neurological basis of ASD, rodent models of ASD have been developed for research. Currently, there is not a standardized set of behavioral tests to quantify ASD-like behavior in rodents. The goal of this review is to present an overview of the methodologies used to analyze ASD-like behaviors in rodents, focusing on the valproic acid (VPA) model, and illustrate inconsistencies between different approaches. Despite that the in utero VPA rodent model for ASD is widely used and extensively characterized, behaviors vary substantially between different researchers. Moving forward, consistency in behavioral method analytics would benefit progress in evaluating interventions for all models of ASD and help to uncover unique qualities underlying mechanisms causing ASD signs and symptoms.

Hsp90 co-chaperones, FKBP52 and Aha1, promote tau pathogenesis in aged wild-type mice

The microtubule associated protein tau is an intrinsically disordered phosphoprotein that accumulates under pathological conditions leading to formation of neurofibrillary tangles, a hallmark of Alzheimer's disease (AD). The mechanisms that initiate the accumulation of phospho-tau aggregates and filamentous deposits are largely unknown. In the past, our work and others' have shown that molecular chaperones play a crucial role in maintaining protein homeostasis and that imbalance in their levels or activity can drive tau pathogenesis. We have found two co-chaperones of the 90 kDa heat shock protein (Hsp90), FK506-binding protein 52 (FKBP52) and the activator of Hsp90 ATPase homolog 1 (Aha1), promote tau aggregation in vitro and in the brains of tau transgenic mice. Based on this, we hypothesized that increased levels of these chaperones could promote tau misfolding and accumulation in the brains of aged wild-type mice. We tested this hypothesis by overexpressing Aha1, FKBP52, or mCherry (control) proteins in the hippocampus of 9-month-old wild-type mice. After 7 months of expression, mice were evaluated for cognitive and pathological changes. Our results show that FKBP52 overexpression impaired spatial reversal learning, while Aha1 overexpression impaired associative learning in aged wild-type mice. FKBP52 and Aha1 overexpression promoted phosphorylation of distinct AD-relevant tau species. Furthermore, FKBP52 activated gliosis and promoted neuronal loss leading to a reduction in hippocampal volume. Glial activation and phospho-tau accumulation were also detected in areas adjacent to the hippocampus, including the entorhinal cortex, suggesting that after initiation these pathologies can propagate through other brain regions. Overall, our findings suggest a role for chaperone imbalance in the initiation of tau accumulation in the aging brain.

The orphan nuclear receptor Nurr1 agonist amodiaquine mediates neuroprotective effects in 6-OHDA Parkinson's disease animal model by enhancing the phosphorylation of P38 mitogen-activated kinase but not PI3K/AKT signaling pathway

Recent studies implicate the defects or altered expression of the orphan nuclear receptor Nurr1 gene in the substantia nigra in Parkinson's disease pathogenesis. In an attempt to corroborate the treatment-modifying disease that would replicate the effect of Nurr1, it has been found that amodiaquine and Nurr1 had the same chemical scaffolding, indicating a crucial structure-activity relationship. Interestingly, amodiaquine stimulate the transcriptional function of Nurr1 by physical interaction with its ligand-binding domain (LBD). However, the signaling route by which Nurr1 is activated by amodiaquine to cause the protective effect remains to be elucidated. We first demonstrated that amodiaquine treatment ameliorated behavioural deficits in 6-OHDA Parkinson's disease mouse model, and it promoted dopaminergic neurons protection signified by Tyrosine hydroxylase (TH) and dopamine transporter (DAT) mRNA; Tyrosine hydroxylase (TH) protein expression level and the immunoreactivity in the substantia nigra compacta. Subsequently, we used inhibitors to ascertain the effect of amodiaquine on Akt and P38 Mapk as crucial signaling pathways for neuroprotection. Wortmannin (Akt Inhibitor) induced a significant reduction of Akt mRNA; however, there was no statistical difference between the amodiaquine-treated group and the control group suggesting that amodiaquine may not be the active stimulant of Akt. Western blot analysis confirmed that the phosphorylated Akt decreased significantly in the amodiaquine group compared to the control group. In the same vein, we found that amodiaquine substantially increased the level of phosphorylated P38 Mapk. When P38 Mapk inhibited by SB203580 (P38-Mapk Inhibitor), the total P38 Mapk but not the phosphorylated P38 Mapk decreased significantly, while tyrosine hydroxylase significantly increased. These results collectively suggest that amodiaquine can augment tyrosine hydroxylase expression via phosphorylated P38 Mapk while negatively regulating the phosphorylated Akt in protein expression.

Antipsychotic potential of the type 1 cannabinoid receptor positive allosteric modulator GAT211: preclinical in vitro and in vivo studies

RATIONALE

Antipsychotics help alleviate the positive symptoms associated with schizophrenia; however, their debilitating side effects have spurred the search for better treatment options. Novel compounds can be screened for antipsychotic potential in neuronal cell cultures and following acute N-methyl-D-aspartate (NMDA) receptor blockade with non-competitive antagonists such as MK-801 in rodent behavioral models. Given the known interactions between NMDA receptors and type 1 cannabinoid receptors (CB1R), compounds that modulate CB1Rs may have therapeutic potential for schizophrenia.

OBJECTIVES

This study assessed whether the CB1R positive allosteric modulator GAT211, when compared to ∆⁹-tetrahydrocannabinol (THC), has potential to reduce psychiatric behavioral phenotypes following acute MK-801 treatment in rats, and block hyperdopaminergic signalling associated with those behaviors.

METHODS

The effects of GAT211 and THC on cellular signaling were compared in Neuro2a cells, and behavioral effects of GAT211 and THC on altered locomotor activity and prepulse inhibition of the acoustic startle response caused by acute MK-801 treatment were assessed in male, Long Evans rats.

RESULTS

GAT211 limited dopamine D2 receptor-mediated extracellular regulated kinase (ERK) phosphorylation in Neuro2a cells, whereas THC did not. As expected, acute MK-801 (0.15 mg/kg) produced a significant increase in locomotor activity and impaired PPI. GAT211 treatment alone (0.3-3.0 mg/kg) dose-dependently reduced locomotor activity and the acoustic startle response. GAT211 (3.0 mg/kg) also prevented hyperlocomotion caused by MK-801 but did not significantly affect PPI impairments.

CONCLUSION

Taken together, these findings support continued preclinical research regarding the usefulness of CB1R positive allosteric modulators as antipsychotics.

Co-administration of nalbuphine attenuates the morphine-induced anxiety and dopaminergic alterations in morphine-withdrawn rats

INTRODUCTION

The classical effects of exogenous opioids, such as morphine, are predominantly mediated through μ-opioid receptors. The chronic use of morphine induces anxiety-like behavior causing functional changes in the mesolimbic dopaminergic system. The mixed μ/κ-agonist, nalbuphine, used either as an analgesic or as an adjuvant with morphine, produces different and opposite effects. However, whether nalbuphine can be used to antagonize morphine-induced anxiety and dopaminergic alterations is not fully known.

OBJECTIVE

This study aimed to compare acute and chronic effects of nalbuphine on morphine-induced anxiety and dopaminergic alterations in rats.

METHODS

Male adult Wistar albino rats were made opioid-dependent by administering increasing doses of morphine (5-25 mg/kg; i.p.; b.i.d.). Withdrawal was induced by naloxone (1 mg/kg, i.p.), 4 h after the last morphine injection. Anxiety-like behavior was measured using Activity Monitor (Coulbourn Instruments, Inc. USA). Thereafter, the animals were sacrificed and the brain dissected out and the level of cAMP and the transcriptional and translational expression of TH was measured. Nalbuphine was co-administered with morphine, acutely and chronically, at various doses (0.1, 0.3, 1.0, 3.0 mg/kg, i.p.).

RESULTS

Morphine-dependent rats showed a significant higher anxiety and cAMP levels and a significant decrease in the expression of TH. Co-administration of chronic doses of nalbuphine attenuates the higher anxiety, cAMP levels, and upregulates the TH expressions; however, the acute nalbuphine treatment does not attenuate the morphine-induced side effects.

CONCLUSION

Therefore, nalbuphine might have an important role in attenuating the anxiety and the effects of the dopaminergic pathway and may have potential in the treatment of opioid addiction.

Gut microbiota determines the social behavior of mice and induces metabolic and inflammatory changes in their adipose tissue

The link between the gut microbiota and social behavior has been demonstrated, however the translational impact of a certain microbiota composition on stable behavioral patterns is yet to be elucidated. Here we employed an established social behavior mouse model of dominance (Dom) or submissiveness (Sub). A comprehensive 16S rRNA gene sequence analysis of Dom and Sub mice revealed a significantly different gut microbiota composition that clearly distinguishes between the two behavioral modes. Sub mice gut microbiota is significantly less diverse than that of Dom mice, and their taxa composition uniquely comprised the genera Mycoplasma and Anaeroplasma of the Tenericutes phylum, in addition to the Rikenellaceae and Clostridiaceae families. Conversely, the gut microbiota of Dom mice includes the genus Prevotella of the Bacteriodetes phylum, significantly less abundant in Sub mice. In addition, Sub mice show lower body weight from the age of 2 weeks and throughout their life span, accompanied with lower epididymis white adipose tissue (eWAT) mass and smaller adipocytes together with substantially elevated expression of inflammation and metabolic-related eWAT adipokines. Finally, fecal microbiota transplantation into germ-free mice show that Sub-transplanted mice acquired Sub microbiota and adopted their behavioral and physiological features, including depressive-like and anti-social behaviors alongside reduced eWAT mass, smaller adipocytes, and a Sub-like eWAT adipokine profile. Our findings demonstrate the critical role of the gut microbiome in determining dominance vs. submissiveness and suggest an association between gut microbiota, the eWAT metabolic and inflammatory profile, and the social behavior mode.

Acute MDPV Binge Paradigm on Mice Emotional Behavior and Glial Signature

3,4-Methylenedioxypyrovalerone (MDPV), a widely available synthetic cathinone, is a popular substitute for classical controlled drugs of abuse, such as methamphetamine (METH). Although MDPV poses public health risks, its neuropharmacological profile remains poorly explored. This study aimed to provide evidence on that direction. Accordingly, C57BL/6J mice were exposed to a binge MDPV or METH regimen (four intraperitoneal injections every 2 h, 10 mg/kg). Locomotor, exploratory, and emotional behavior, in addition to striatal neurotoxicity and glial signature, were assessed within 18–24 h, a known time-window encompassing classical amphetamine dopaminergic neurotoxicity. MDPV resulted in unchanged locomotor activity (open field test) and emotional behavior (elevated plus maze, splash test, tail suspension test). Additionally, striatal TH (METH neurotoxicity hallmark), Iba-1 (microglia), GFAP (astrocyte), RAGE, and TLR2/4/7 (immune modulators) protein densities remained unchanged after MDPV-exposure. Expectedly, and in sheer contrast with MDPV, METH resulted in decrease general locomotor activity paralleled by a significant striatal TH depletion, astrogliosis, and microglia arborization alterations (Sholl analysis). This comparative study newly highlights that binge MDPV-exposure comes without evident behavioral, neurochemical, and glial changes at a time-point where METH-induced striatal neurotoxicity is clearly evident. Nevertheless, neuropharmacological MDPV signature needs further profiling at different time-points, regimens, and brain regions.

Maternal antibodies facilitate Amyloid-β clearance by activating Fc-receptor-Syk-mediated phagocytosis

Maternal antibodies (MAbs) protect against infections in immunologically-immature neonates. Maternally transferred immunity may also be harnessed to target diseases associated with endogenous protein misfolding and aggregation, such as Alzheimer's disease (AD) and AD-pathology in Down syndrome (DS). While familial early-onset AD (fEOAD) is associated with autosomal dominant mutations in the APP, PSEN1,2 genes, promoting cerebral Amyloid-β (Aβ) deposition, DS features a life-long overexpression of the APP and DYRK1A genes, leading to a cognitive decline mediated by Aβ overproduction and tau hyperphosphorylation. Although no prenatal screening for fEOAD-related mutations is in clinical practice, DS can be diagnosed in utero. We hypothesized that anti-Aβ MAbs might promote the removal of early Aβ accumulation in the central nervous system of human APP-expressing mice. To this end, a DNA-vaccine expressing Aβ1-11 was delivered to wild-type female mice, followed by mating with 5xFAD males, which exhibit early Aβ plaque formation. MAbs reduce the offspring's cortical Aβ levels 4 months after antibodies were undetectable, along with alleviating short-term memory deficits. MAbs elicit a long-term shift in microglial phenotype in a mechanism involving activation of the FcγR1/Syk/Cofilin pathway. These data suggest that maternal immunization can alleviate cognitive decline mediated by early Aβ deposition, as occurs in EOAD and DS.

Therapeutic effects of sertraline on improvement of Ovariectomy-induced decreased spontaneous activity in mice

We have already reported that ovariectomized (OVX) rats reduced the spontaneous activity during the dark period due to the decease of serotonin release in the amygdala. In this study, we examined the potential of sertraline, a selective serotonin reuptake inhibitor, on the recovery of less spontaneous activity seen in mice with OVX-induced despair-like behaviors. Female 9-week old ICR mice were underwent either OVX or sham surgery. Sertraline (10 mg/kg/day, s.c.) or saline were started to administer to each group for 8 weeks (6 times/week) from the 8th week after OVX. Each spontaneous activity of mouse was evaluated during the dark period (19:00-07:00) using an infrared sensor. Moreover, mRNA expression levels of tryptophan hydroxylase (TPH) and X-box binding protein 1 (XBP1) were measured in the hippocampus and prefrontal cortex using by a real-time PCR method. We found out that the OVX-induced despair-like behaviors were improved by the continuous administration of sertraline. After treatment of OVX, our real-time PCR data showed that sertraline significantly suppressed the upregulation of XBP1 expression levels in both hippocampus and prefrontal cortex, although this suppression of the downregulation of TPH expression levels was seen in only hippocampus. These results suggest that sertraline improves the decrease in spontaneous activity induced by OVX assessed by the hippocampus suppressing decreased serotonin synthesis in the serotonergic neuron.

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.

Polygala sabulosa A.W. Bennett extract mitigates motor and cognitive deficits in a mouse model of acute ischemia

Stroke is considered one of the leading causes of death worldwide. The treatment is limited; however, the Brazilian flora has a great source of natural products with therapeutic potentials. Studies with the medicinal plant Polygala sabulosa W. Bennett provided evidence for its use as an anti-inflammatory and neuroprotective drug. In the case of ischemic stroke due to lack of oxygen, both acute and chronic inflammatory processes are activated. Thus, we hypothesized that P. sabulosa (HEPs) has the potential to treat the motor and cognitive deficits generated by ischemic stroke. Male mice were subjected to global ischemia for 60 min, followed by reperfusion and orally treated with HEPs (100 mg/kg in saline + 3% tween 20) twice a day (12 h apart) for 48 h starting 3 h after surgery. Motor skills were assessed using grip force and open field tasks. Hippocampi were then collected for mRNA quantification of the cytokines IL-1-β and TNF-α levels. After 48 h of acute treatment, spatial reference memory was evaluated in a Morris water maze test for another group of animals. We show that HEPs treatment significantly prevented motor weakness induced by ischemia. Brain infarct area was reduced by 22.25% with downregulation of the levels of IL-1β and TNF-α mRNA. Learning performance and memory ability on Morris water maze task were similar to the sham group. Our data demonstrates the neuroprotective properties of HEPs through its anti-inflammatory activities, which prevent motor and cognitive impairments, suggesting that HEPs may be an effective therapy for ischemic stroke.

Tetragonia tetragonioides Relieves Depressive-Like Behavior through the Restoration of Glial Loss in the Prefrontal Cortex

Tetragonia tetragonioides, which is a halophyte and grows widely in Asian-Pacific regions, has been used for the treatment of digestive disorders in traditional oriental medicine. This study examined the potential antidepressant effect of Tetragonia tetragonioides in an astroglial degeneration model of depression, which was established based on the postmortem study of depressive patients' brain presenting diminished astrocytes in the prefrontal cortex. C57BL/6 male mice were exposed to glial ablation in the prefrontal cortex by the administration of the gliotoxin, L-alpha-aminoadipic acid (L-AAA) to induce depression. Tetragonia tetragonioides at doses of 100 mg/kg and 300 mg/kg, imipramine at a dose of 15 mg/kg, and distilled water were orally administrated to mice for 18 days. Behavioral tests including the open field test (OFT), sucrose preference test (SPT), forced swimming test (FST), and tail suspension test (TST) were carried out after 2 days of L-AAA injection. The expression levels of GFAP and NeuN in the prefrontal cortex were determined by immunohistochemistry. Mice subjected to glial ablation in the prefrontal cortex displayed decreased sucrose consumption in SPT and increased immobility time in FST and TST. Treatment with imipramine and Tetragonia tetragonioides remarkably ameliorated the behavioral despair induced by L-AAA. In addition, immunohistochemistry analysis showed that treatment with Tetragonia tetragonioides significantly restored the glial loss as indicated by the elevated GFAP expression level. These findings suggest that Tetragonia tetragonioides exerts an antidepressant effect through the restoration of glial loss under conditions of depression and can be a candidate for an antidepressant agent.

Early death of ALS-linked CHCHD10-R15L transgenic mice with central nervous system, skeletal muscle, and cardiac pathology

Mutations in coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10) have been identified in patients suffering from various degenerative diseases including mitochondrial myopathy, spinal muscular atrophy Jokela type, frontotemporal dementia, and/or amyotrophic lateral sclerosis (ALS). The pathogenic mechanism underlying CHCHD10-linked divergent disorders remains largely unknown. Here we show that transgenic mice overexpressing an ALS-linked CHCHD10 p.R15L mutation leads to an abbreviated lifespan compared with CHCHD10-WT transgenic mice. The occurrence and severity of the phenotype correlates to transgene copy number. Central nervous system (CNS), skeletal muscle, and cardiac pathology is apparent in CHCHD10-R15L transgenic mice. Despite the pathology, CHCHD10-R15L transgenic mice perform comparably to control mice in motor behavioral tasks until very close to death. Although paralysis is not observed, these models provide insight into the pleiotropic nature of CHCHD10 and suggest a contribution of CNS, skeletal muscle, and cardiac pathology to CHCHD10 p.R15L-ALS pathogenesis.

The cage test as an easy way to screen and evaluate spontaneous activity in preclinical neuroscience studies

Within behavioral neuroscience, subjects used to be randomly assigned to the experimental groups based on the premise that interindividual variability will be homogeneously distributed. However, the equivalence offered by randomization diminishes in small samples, which is the case for most experiments in the field. In rodents, it is well-recognized that individual differences in psychomotor reactivity, risk-assessment behaviors, and emotional responsiveness modulate the effects of different pharmacological and non-pharmacological treatments. For that reason, knowing such differences before the experiment provides highly valuable information for balancing the groups so that the interindividual variability is equally distributed within the groups without excluding subjects as far as possible. Because unconditioned anxiety tests such as the open-field (OF) and the elevated plus-maze are commonly used within experimental procedures, we developed a strategy to explore the rat's behavioral phenotype by assessing it in a very innocuous testing context: a housing cage.•We offer a very straightforward protocol for assessing spontaneous, novelty-induced reactivity in rodents.•We describe its implementation, analysis, and use, as well as some suggestions about key behavioral readouts for the group allocation procedure.•The current protocol provides an alternative strategy to assess a reasonably wide range of behavioral outcomes, most of which are of great interest in modeling different neuropsychiatric disorders.

Effects of quercetin on exercise performance, physical activity and blood supply in a novel model of sustained hind-limb ischaemia

BACKGROUND

There are currently few effective drugs to treat the leg symptoms of peripheral arterial disease (PAD). Previous studies have suggested that the nutraceutical, quercetin, can improve exercise performance and reduce pain sensitivity in healthy mice and improve blood supply in a rodent model of acute hind-limb ischaemia. These models may not be relevant to people with PAD. The aim of this study was to examine the effect of quercetin on exercise performance, physical activity and blood supply in a novel mouse model of sustained hind-limb ischaemia.

METHODS

Hind-limb ischaemia was induced in 6-month-old male apolipoprotein E-deficient mice using a novel two-stage surgical procedure. Five days after induction of ischaemia, mice were allocated to commence dietary quercetin or a control diet for 4 weeks. The primary outcome was exercise performance evaluated using a treadmill test. Other outcomes included physical activity, estimated by an open field test, and hind-limb blood supply, assessed by laser Doppler monitoring.

RESULTS

A sustained reduction in relative limb blood supply (P < 0.001) was achieved consistently in all 48 mice before allocation to a control (n = 24) or quercetin (n = 24) diet. Quercetin did not improve exercise performance (P = 0.785), physical activity (P = 0.151) or relative limb blood supply (P = 0.954) over the 4-week assessment period.

CONCLUSION

These data suggest that quercetin does not improve exercise performance, physical activity or limb blood supply in mice with sustained hind-limb ischaemia, and therefore is unlikely be an effective treatment for PAD.

Chronic modafinil therapy ameliorates depressive-like behavior, spatial memory and hippocampal plasticity impairments, and sleep-wake changes in a surgical mouse model of menopause

Depression, cognitive deficits, and sleep disturbances are common and often severe in menopausal women. Hormone replacement cannot effectively alleviate these symptoms and sometimes elicits life-threatening adverse reactions. Exploring effective therapies to target psychological problems is urgently needed. In this work, we developed a mouse model of menopause by bilateral ovariectomies (OVXs) and investigated whether menopausal mental symptoms can be ameliorated by psychostimulant modafinil (MOD) as well as explored the underlying mechanisms. At ~3 weeks after OVXs, mice got daily intraperitoneal administrations of MOD at the beginning of the active phase. Several behavioral tests and electroencephalogram (EEG) recordings were conducted. Electrophysiological and immunohistochemical experiments were carried out to evaluate the synaptic plasticity and neurogenesis, respectively. We found that chronic MOD administration in OVX mice significantly decreased immobility time. The spatial memory performance of OVX mice improved significantly in response to MOD administration in the Morris water-maze test. The OVX mice were characterized by an attenuation of hippocampal synaptic transmission and synaptic long-term potentiation and had fewer 5-ethynyl-2'-deoxyuridine-labeled cells in the dentate gyrus, which were restored after MOD administration. Antagonists of dopamine D₁ and D₂ receptors and GABA_A receptor agonists were involved in MOD-exerted anti-depressant actions and augments of hippocampal neurogenesis in OVX mice. Moreover, night-dosed MOD therapy significantly promoted the night-time delta-band EEG power during wakefulness and the day-time rapid eye movement sleep amount, which were significantly reduced by OVXs. Collectively, these findings suggest that MOD is a promising therapeutic candidate for menopausal women.

Preservation of dendritic spine morphology and postsynaptic signaling markers after treatment with solid lipid curcumin particles in the 5xFAD mouse model of Alzheimer's amyloidosis

BACKGROUND

Synaptic failure is one of the principal events associated with cognitive dysfunction in Alzheimer's disease (AD). Preservation of existing synapses and prevention of synaptic loss are promising strategies to preserve cognitive function in AD patients. As a potent natural anti-oxidant, anti-amyloid, and anti-inflammatory polyphenol, curcumin (Cur) shows great promise as a therapy for AD. However, hydrophobicity of natural Cur limits its solubility, stability, bioavailability, and clinical utility for AD therapy. We have demonstrated that solid lipid curcumin particles (SLCP) have greater therapeutic potential than natural Cur in vitro and in vivo models of AD. In the present study, we have investigated whether SLCP has any preservative role on affected dendritic spines and synaptic markers in 5xFAD mice.

METHODS

Six- and 12-month-old 5xFAD and age-matched wild-type mice received oral administration of SLCP (100 mg/kg body weight) or equivalent amounts of vehicle for 2 months. Neuronal morphology, neurodegeneration, and amyloid plaque load were investigated from prefrontal cortex (PFC), entorhinal cortex (EC), CA1, CA3, and the subicular complex (SC). In addition, the dendritic spine density from apical and basal branches was studied by Golgi-Cox stain. Further, synaptic markers, such as synaptophysin, PSD95, Shank, Homer, Drebrin, Kalirin-7, CREB, and phosphorylated CREB (pCREB) were studied using Western blots. Finally, cognitive and motor functions were assessed using open-field, novel object recognition (NOR) and Morris water maze (MWM) tasks after treatment with SLCP.

RESULTS

We observed an increased number of pyknotic and degenerated cells in all these brain areas in 5xFAD mice and SLCP treatment partially protected against those losses. Decrease in dendritic arborization and dendritic spine density from primary, secondary, and tertiary apical and basal branches were observed in PFC, EC, CA1, and CA3 in both 6- and 12-month-old 5xFAD mice, and SLCP treatments partially preserved the normal morphology of these dendritic spines. In addition, pre- and postsynaptic protein markers were also restored by SLCP treatment. Furthermore, SLCP treatment improved NOR and cognitive function in 5xFAD mice.

CONCLUSIONS

Overall, these findings indicate that use of SLCP exerts neuroprotective properties by decreasing amyloid plaque burden, preventing neuronal death, and preserving dendritic spine density and synaptic markers in the 5xFAD mice.

Neuromodulatory effect of cinnamon oil on behavioural disturbance, CYP1A1, iNOStranscripts and neurochemical alterations induced by deltamethrin in rat brain

The objective of this study was to investigate the influence of deltamethrin (DLM)on brain function and to find whether DLM-induced neurotoxicity is prevented by the treatment with cinnamon oil. Four groups of ten Wistar albino male rats each were used. Group I (control) received saline only. Group II received cinnamon oil alone at 0.5 mg/kg B.W. intraperitonally, whereas Group III received orally DLM alone at 6 mg/kg B.W. Groups IV was treated with cinnamon oil plus DLM for 21 days to induce neurotoxicity. Rat behaviour, brain acetylcholine esterase (AChE), serotonin, oxidative stress profile were assessed. Serum sampling for the assessment of corticosterone concentration was also carried out. Finally, we demonstrate the gene expression of CYP1A1 and iNOS and the histological picture of the brain. Considering the behaviour assessment, DLM administration alone caused neurobehavioral deficits manifested by anxiety-like behavior which represented ina marked decrease in the sleeping frequency and duration, and marked increase the digging frequency and a wake non-active behavior duration. Moreover, the open field result showed a significant decrease in central square entries and duration. The neurochemical analysis revealed that DLM significantly suppressed AChE activity and elevated serotonin and corticosterone concentrations. Furthermore, results revealed thatthe brain reduced glutathione (GSH) content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration were significantly altered in DLM treated rats. Neurochemical disturbances were confirmed by histopathological changes in the brain. Furthermore, DLM up-regulates the mRNA expression of brain CYP1A1 and iNOS. Co-treatment with cinnamon oil exhibited significant improvement in behavioural performance and the brain antioxidant capacities with an increase in AChE activity and diminished the concentration of serotonin, serum corticosterone and MDA. Cinnamon oil treatment resulted in down-regulation of CYP1A1 and iNOS and improve the histologically picture. In conclusion, cinnamon oil ameliorated DLM-induced neurotoxicity through preventing oxidative stress-induced genotoxicity and apoptosis of brain in rats.

Targeting increased levels of APP in Down syndrome: Posiphen-mediated reductions in APP and its products reverse endosomal phenotypes in the Ts65Dn mouse model

OBJECTIVE

Recent clinical trials targeting amyloid beta (Aβ) and tau in Alzheimer's disease (AD) have yet to demonstrate efficacy. Reviewing the hypotheses for AD pathogenesis and defining possible links between them may enhance insights into both upstream initiating events and downstream mechanisms, thereby promoting discovery of novel treatments. Evidence that in Down syndrome (DS), a population markedly predisposed to develop early onset AD, increased APP gene dose is necessary for both AD neuropathology and dementia points to normalization of the levels of the amyloid precursor protein (APP) and its products as a route to further define AD pathogenesis and discovering novel treatments.

BACKGROUND

AD and DS share several characteristic manifestations. DS is caused by trisomy of whole or part of chromosome 21; this chromosome contains about 233 protein-coding genes, including APP. Recent evidence points to a defining role for increased expression of the gene for APP and for its 99 amino acid C-terminal fragment (C99, also known as β-CTF) in dysregulating the endosomal/lysosomal system. The latter is critical for normal cellular function and in neurons for transmitting neurotrophic signals.

NEW/UPDATED HYPOTHESIS

We hypothesize that the increase in APP gene dose in DS initiates a process in which increased levels of full-length APP (fl-APP) and its products, including β-CTF and possibly Aβ peptides (Aβ42 and Aβ40), drive AD pathogenesis through an endosome-dependent mechanism(s), which compromises transport of neurotrophic signals. To test this hypothesis, we carried out studies in the Ts65Dn mouse model of DS and examined the effects of Posiphen, an orally available small molecule shown in prior studies to reduce fl-APP. In vitro, Posiphen lowered fl-APP and its C-terminal fragments, reversed Rab5 hyperactivation and early endosome enlargement, and restored retrograde transport of neurotrophin signaling. In vivo, Posiphen treatment (50 mg/kg/d, 26 days, intraperitoneal [i.p.]) of Ts65Dn mice was well tolerated and demonstrated no adverse effects in behavior. Treatment resulted in normalization of the levels of fl-APP, C-terminal fragments and small reductions in Aβ species, restoration to normal levels of Rab5 activity, reduced phosphorylated tau (p-tau), and reversed deficits in TrkB (tropomyosin receptor kinase B) activation and in the Akt (protein kinase B [PKB]), ERK (extracellular signal-regulated kinase), and CREB (cAMP response element-binding protein) signaling pathways. Remarkably, Posiphen treatment also restored the level of choline acetyltransferase protein to 2N levels. These findings support the APP gene dose hypothesis, point to the need for additional studies to explore the mechanisms by which increased APP gene expression acts to increase the risk for AD in DS, and to possible utility of treatments to normalize the levels of APP and its products for preventing AD in those with DS.

MAJOR CHALLENGES FOR THE HYPOTHESIS

Important unanswered questions are: (1) When should one intervene in those with DS; (2) would an APP-based strategy have untoward consequences on possible adaptive changes induced by chronically increased APP gene dose; (3) do other genes present on chromosome 21, or on other chromosomes whose expression is dysregulated in DS, contribute to AD pathogenesis; and (4) can one model strategies that combine the use of an APP-based treatment with those directed at other AD phenotypes including p-tau and inflammation.

LINKAGE TO OTHER MAJOR THEORIES

The APP gene dose hypothesis interfaces with the amyloid cascade hypothesis of AD as well as with the genetic and cell biological observations that support it. Moreover, upregulation of fl-APP protein and products may drive downstream events that dysregulate tau homeostasis and inflammatory responses that contribute to propagation of AD pathogenesis.

Lamin B1 decline underlies age-related loss of adult hippocampal neurogenesis

Neurogenesis in the adult hippocampus declines with age, a process that has been implicated in cognitive and emotional impairments. However, the mechanisms underlying this decline have remained elusive. Here, we show that the age-dependent downregulation of lamin B1, one of the nuclear lamins in adult neural stem/progenitor cells (ANSPCs), underlies age-related alterations in adult hippocampal neurogenesis. Our results indicate that higher levels of lamin B1 in ANSPCs safeguard against premature differentiation and regulate the maintenance of ANSPCs. However, the level of lamin B1 in ANSPCs declines during aging. Precocious loss of lamin B1 in ANSPCs transiently promotes neurogenesis but eventually depletes it. Furthermore, the reduction of lamin B1 in ANSPCs recapitulates age-related anxiety-like behavior in mice. Our results indicate that the decline in lamin B1 underlies stem cell aging and impacts the homeostasis of adult neurogenesis and mood regulation.

Evaluation of the effects of the T-type calcium channel enhancer SAK3 in a rat model of TAF1 deficiency

The TATA-box binding protein associated factor 1 (TAF1) is part of the TFIID complex that plays a key role during the initiation of transcription. Variants of TAF1 are associated with neurodevelopmental disorders. Previously, we found that CRISPR/Cas9 based editing of the TAF1 gene disrupts the morphology of the cerebral cortex and blunts the expression as well as the function of the CaV3.1 (T-type) voltage gated calcium channel. Here, we tested the efficacy of SAK3 (ethyl 8'-methyl-2', 4-dioxo-2-(piperidin-1-yl)-2'H-spiro [cyclopentane-1, 3'-imidazo [1, 2-a] pyridine]-2-ene-3-carboxylate), a T-type calcium channel enhancer, in an animal model of TAF1 intellectual disability (ID) syndrome. At post-natal day 3, rat pups were subjected to intracerebroventricular (ICV) injection of either gRNA-control or gRNA-TAF1 CRISPR/Cas9 viruses. At post-natal day 21, the rat pups were given SAK3 (0.25 mg/kg, p.o.) or vehicle for 14 days (i.e. till post-natal day 35) and then subjected to behavioral, morphological, and molecular studies. Oral administration of SAK3 (0.25 mg/kg, p.o.) significantly rescued locomotion abnormalities associated with TAF1 gene editing. SAK3 treatment prevented the loss of cortical neurons and GFAP-positive astrocytes observed after TAF1 gene editing. In addition, SAK3 protected cells from apoptosis. SAK3 also restored the Brain-derived neurotrophic factor/protein kinase B/Glycogen Synthase Kinase 3 Beta (BDNF/AKT/GSK3β) signaling axis in TAF1 edited animals. Finally, SAK3 normalized the levels of three GSK3β substrates - CaV3.1, FOXP2, and CRMP2. We conclude that the T-type calcium channel enhancer SAK3 is beneficial against the deleterious effects of TAF1 gene-editing, in part, by stimulating the BDNF/AKT/GSK3β signaling pathway.

Kisspeptin-8 Induces Anxiety-Like Behavior and Hypolocomotion by Activating the HPA Axis and Increasing GABA Release in the Nucleus Accumbens in Rats

Kisspeptins (Kp) are RF-amide neuropeptide regulators of the reproductive axis that also influence anxiety, locomotion, and metabolism. We aimed to investigate the effects of intracerebroventricular Kp-8 (an N-terminally truncated octapeptide) treatment in Wistar rats. Elevated plus maze (EPM), computerized open field (OF), and marble burying (MB) tests were performed for the assessment of behavior. Serum LH and corticosterone levels were determined to assess kisspeptin1 receptor (Kiss1r) activation and hypothalamic-pituitary-adrenal axis (HPA) stimulation, respectively. GABA release from the nucleus accumbens (NAc) and dopamine release from the ventral tegmental area (VTA) and NAc were measured via ex vivo superfusion. Kp-8 decreased open arm time and entries in EPM, and also raised corticosterone concentration, pointing to an anxiogenic effect. Moreover, the decrease in arm entries in EPM, the delayed increase in immobility accompanied by reduced ambulatory activity in OF, and the reduction in interactions with marbles show that Kp-8 suppressed exploratory and spontaneous locomotion. The increase in GABA release from the NAc might be in the background of hypolocomotion by inhibiting the VTA-NAc dopaminergic circuitry. As Kp-8 raised LH concentration, it could activate Kiss1r and stimulate the reproductive axis. As Kiss1r is associated with hyperlocomotion, it is more likely that neuropeptide FF receptor activation is involved in the suppression of locomotor activity.

The potential neuroprotective role of Amphora coffeaeformis algae against monosodium glutamate-induced neurotoxicity in adult albino rats

Monosodium glutamate (MSG) is a neurotoxin found in most processed and infant formulas. Amphora coffeaeformis (AC) has neuroprotective properties. We investigated, for the first time, the potential neuroprotective role of AC on MSG-induced neurotoxicity in brain using a unique procedural approach. The AC extract was characterized via high performance liquid chromatography (HPLC). Animals were assigned into six groups; a control group, low dose MSG (LD-MSG), high dose MSG (HD-MSG), combined groups (LD-MSG + AC) (HD-MSG + AC) and AC only group for eight weeks. Assessment of the cognitive and mood domains was done via Barnes maze and an open field. Gene expression of Bdnf, TrkB, NMDA-B2 and mGlur5 in the hippocampus was obtained via real-time PCR. The hippocampi of the animals were assessed for structural changes. Oxidative stress was assessed in the cerebrum. The results revealed that omega-6 and β-coumaric acid represented the highest percentage among the constituents in the AC extract. The NO level was decreased in the LD-MSG + AC compared to LD-MSG. SOD was diminished in both treated groups compared to the untreated group. HD-MSG + AC exhibited an increase in the number of wrongly visited quadrants compared to the HD-MSG group. HD-MSG + AC showed decreased anxiety-like behavior compared to HD-MSG. LD-MSG + AC and AC groups revealed enhanced anxiety-like behavior. HD-MSG + AC showed under expressed NMDA-B2 and over expressed Bdnf and TrkB genes, compared to HD-MSG. LD-MSG + AC revealed under expression of Bdnf gene compared to LD-MSG. The AC group revealed under expressed TrkB gene compared to the control group. Overall, the results refer to the potential neuroprotective properties of AC alga against MSG neurotoxicity.

Bidirectional Regulation of Cognitive and Anxiety-like Behaviors by Dentate Gyrus Mossy Cells in Male and Female Mice

The dentate gyrus (DG) of the hippocampus is important for cognition and behavior. However, the circuits underlying these functions are unclear. DG mossy cells (MCs) are potentially important because of their excitatory synapses on the primary cell type, granule cells (GCs). However, MCs also activate GABAergic neurons, which inhibit GCs. We used viral delivery of designer receptors exclusively activated by designer drugs (DREADDs) in mice to implement a gain- and loss-of-function study of MCs in diverse behaviors. Using this approach, manipulations of MCs could bidirectionally regulate behavior. The results suggest that inhibiting MCs can reduce anxiety-like behavior and improve cognitive performance. However, not all cognitive or anxiety-related behaviors were influenced, suggesting specific roles of MCs in some, but not all, types of cognition and anxiety. Notably, several behaviors showed sex-specific effects, with females often showing more pronounced effects than the males. We also used the immediate early gene c-Fos to address whether DREADDs bidirectionally regulated MC or GC activity. We confirmed excitatory DREADDs increased MC c-Fos. However, there was no change in GC c-Fos, consistent with MC activation leading to GABAergic inhibition of GCs. In contrast, inhibitory DREADDs led to a large increase in GC c-Fos, consistent with a reduction in MC excitation of GABAergic neurons, and reduced inhibition of GCs. Together, these results suggest that MCs regulate anxiety and cognition in specific ways. We also raise the possibility that cognitive performance may be improved by reducing anxiety.SIGNIFICANCE STATEMENT The dentate gyrus (DG) has many important cognitive roles as well as being associated with affective behavior. This study addressed how a glutamatergic DG cell type called mossy cells (MCs) contributes to diverse behaviors, which is timely because it is known that MCs regulate the activity of the primary DG cell type, granule cells (GCs), but how MC activity influences behavior is unclear. We show, surprisingly, that activating MCs can lead to adverse behavioral outcomes, and inhibiting MCs have an opposite effect. Importantly, the results appeared to be task-dependent and showed that testing both sexes was important. Additional experiments indicated what MC and GC circuitry was involved. Together, the results suggest how MCs influence behaviors that involve the DG.

High-Fat Diet-Induced Weight Gain, Behavioral Deficits, and Dopamine Changes in Young C57BL/6J Mice

Chronic exposure to a high-fat diet (HFD) may predispose individuals to neuropathologies and behavioral deficits. The objective of this study was to determine the temporal effects of a HFD on weight gain, behavioral deficits, and dopamine changes in young mice. One-month old C57BL/6J male and female mice were fed either a control diet (containing 10% calories from fat) or a HFD (containing 45% of calories from fat) for 5 months. Physiological measures such as food consumption, body weight, blood glucose, and behaviors such as motor activity, sensorimotor integration, and anxiety-like behaviors were evaluated monthly. Dopamine (DA), dopamine receptor D2 (DRD2), and dopamine transporter (DT) protein expression levels were measured in the midbrain after 5 months of dietary exposure. Results showed that body weight was significantly greater in the HFD-exposed group compared to the control-group at the end of the 4th month, while food consumption was similar in both groups. For behavioral effects, the HFD group exhibited a significant decrease in motor activity in the open field test after 3 months, and rearing frequency after 4 months of dietary exposure. The HFD group also showed deficits in sensorimotor integration after 3 months. Specifically, chronic HFD exposure increased contact time and time to remove the first adhesive tape in the adhesive-tape removal test (p < 0.05). Furthermore, the HFD group showed significant deficits in balance/coordination compared to the control group after 4 months of dietary exposure using the beam traverse test, and increased anxiety-like behavior tested by both the open field and light/dark box tests (p < 0.05). Neurochemical measurements showed that HFD-exposed mice had significantly higher midbrain DA and DRD2 protein levels compared to the control group after 5 months of dietary exposure (p < 0.05). These results indicate that the impact of HFD on the C57BL/6J mouse strain began at the 3^rd month of dietary exposure. Behavioral deficits occurred at a similar time point as increased body weight, at about 3–4 months. Overall, this study provides a critical understanding on how HFD-induced changes in weight gain and behavioral deficits in this strain occur over time. The behavioral changes support the idea that changes also occurred in neurochemical pathways such as dopamine dysregulation.

Grewia asiatica Berry Juice Diminishes Anxiety, Depression, and Scopolamine-Induced Learning and Memory Impairment in Behavioral Experimental Animal Models

Grewia asiatica L. fruit natively called phalsa is a popular berry of Pakistan and widely consumed in the form of fresh juices and carbonated drinks in the summer season. The berry is enriched with antioxidants such as phenols, flavonoids, anthocyanins, and vitamin C. Scientifically, it is the least explored berry in terms of neuromodulatory activities, and therefore, in the designed study, chronically fed rats with the different dilutions (5%-30%) of fruit juice were subjected to behavioral assessment for anxiety, depression, and cognition (spatial memory) followed by biochemical analysis of isolated brains. Results revealed a prominent impact of 20 and 30% dilutions of fruit exudate as treated animals showed anxiolytic behavior to central zone (P < 0.05) of open field test (OFT) and open arms of elevated plus maze (EPM) (P < 0.05) in anxiety models. Overall, immobility of rats treated with a higher concentration of exudate in forced swim test (FST) was reduced (P < 0.05) presenting antidepressant-like activity. Moreover, in learning and memory experimental models, the treated animals reversed scopolamine-induced amnesic effects as evident from improved step-through latencies (P < 0.05 vs. scopolamine; passive avoidance test), spontaneous alternation behavior (P < 0.05 vs. scopolamine; Y-maze test), discrimination index (P < 0.05 vs. scopolamine; novel object recognition test), and escape latencies (P < 0.05 vs. scopolamine; Morris water maze). Biochemical studies of isolated brains from treated rats demonstrated significantly elevated levels of superoxide dismutase and glutathione peroxidase (P < 0.05), whereas levels of acetylcholinesterase and malondialdehyde level (P < 0.05) were reduced, indicating its potential to reduce oxidative damage in the brain and modulation with the cholinergic system. The outcomes of studies support the benefits of phytoconstituents possessed by G. asiatica fruit in the amelioration of neurological disorders that could be due to their antioxidative capacity or due to interaction with GABAergic, serotonergic, and cholinergic systems in the brain.

Animal Models of Depression: What Can They Teach Us about the Human Disease?

Depression is apparently the most common psychiatric disease among the mood disorders affecting about 10% of the adult population. The etiology and pathogenesis of depression are still poorly understood. Hence, as for most human diseases, animal models can help us understand the pathogenesis of depression and, more importantly, may facilitate the search for therapy. In this review we first describe the more common tests used for the evaluation of depressive-like symptoms in rodents. Then we describe different models of depression and discuss their strengths and weaknesses. These models can be divided into several categories: genetic models, models induced by mental acute and chronic stressful situations caused by environmental manipulations (i.e., learned helplessness in rats/mice), models induced by changes in brain neuro-transmitters or by specific brain injuries and models induced by pharmacological tools. In spite of the fact that none of the models completely resembles human depression, most animal models are relevant since they mimic many of the features observed in the human situation and may serve as a powerful tool for the study of the etiology, pathogenesis and treatment of depression, especially since only few patients respond to acute treatment. Relevance increases by the fact that human depression also has different facets and many possible etiologies and therapies.

A Comprehensive Phenotype of Non-motor Impairments and Distribution of Alpha-Synuclein Deposition in Parkinsonism-Induced Mice by a Combination Injection of MPTP and Probenecid

Parkinson's disease (PD) is characterized by non-motor symptoms as well as motor deficits. The non-motor symptoms rarely appear individually and occur simultaneously with motor deficits or independently. However, a comprehensive research on the non-motor symptoms using an experimental model of PD remains poorly understood. The aim of the current study is to establish a chronic mouse model of PD mimicking the comprehensive non-motor symptoms of human PD by injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and probenecid (MPTP/p). The non-motor and motor symptoms were evaluated by performing buried food, short-term olfactory memory, hot plate, open field, tail suspension, Y maze, novel object recognition, bead expulsion, one-h stool collection, rotarod, rearing, catalepsy, and akinesia tests after 10 injections of MPTP/p into mice. The expression levels of α-synuclein, glial fibrillary acidic protein (GFAP), tyrosine hydroxylase (TH) or DJ-1 were analyzed by Western blotting or immunostaining. MPTP/p-treated mice achieved to reproduce the key features of non-motor symptoms including olfactory deficit, thermal hyperalgesia, anxiety, depression, cognitive decline, and gastrointestinal dysfunction in addition to motor deficits. The MPTP/p-treated mice also showed the high levels of α-synuclein and low levels of TH and DJ-1 in striatum, substantia nigra, olfactory bulb, hippocampus, amygdala, prefrontal cortex, locus coeruleus, or colon. In addition, the expression levels of phosphorylated-α-synuclein and GFAP were elevated in the striatum and substantia nigra in the MPTP/p-treated mice. Taken together, our study clarifies that the chronic MPTP/p-treated mice have a variety of non-motor dysfunctions as well as motor abnormalities by α-synuclein overexpression and dopaminergic depletion. Therefore, the study of comprehensive phenotypes of non-motor symptoms in one PD model would advance in-depth understandings of neuropathological alternations and contribute to future strategies for PD treatment.

Maternal Undernutrition Modulates Neonatal Rat Cerebrovascular Structure, Function, and Vulnerability to Mild Hypoxic-Ischemic Injury via Corticosteroid-Dependent and -Independent Mechanisms

The present study explored the hypothesis that an adverse intrauterine environment caused by maternal undernutrition (MUN) acted through corticosteroid-dependent and -independent mechanisms to program lasting functional changes in the neonatal cerebrovasculature and vulnerability to mild hypoxic-ischemic (HI) injury. From day 10 of gestation until term, MUN and MUN-metyrapone (MUN-MET) group rats consumed a diet restricted to 50% of calories consumed by a pair-fed control; and on gestational day 11 through term, MUN-MET groups received drinking water containing MET (0.5 mg/mL), a corticosteroid synthesis inhibitor. P9/P10 pups underwent unilateral carotid ligation followed 24 h later by 1.5 h exposure to 8% oxygen (HI treatment). An ELISA quantified MUN-, MET-, and HI-induced changes in circulating levels of corticosterone. In P11/P12 pups, MUN programming promoted contractile differentiation in cerebrovascular smooth muscle as determined by confocal microscopy, modulated calcium-dependent contractility as revealed by cerebral artery myography, enhanced vasogenic edema formation as indicated by T2 MRI, and worsened neurobehavior MUN unmasked HI-induced improvements in open-field locomotion and in edema resolution, alterations in calcium-dependent contractility and promotion of contractile differentiation. Overall, MUN imposed multiple interdependent effects on cerebrovascular smooth muscle differentiation, contractility, edema formation, flow-metabolism coupling and neurobehavior through pathways that both required, and were independent of, gestational corticosteroids. In light of growing global patterns of food insecurity, the present study emphasizes that infants born from undernourished mothers may experience greater risk for developing neonatal cerebral edema and sensorimotor impairments possibly through programmed changes in neonatal cerebrovascular function.

Plasmodium berghei-induced malaria decreases pain sensitivity in mice

Various types of pain were reported by people with Plasmodium falciparum and were mostly attributed to a symptom of malarial infection. Neural processes of pain sensation during malarial infection and their contributions to malaria-related death are poorly understood. Thus, these form the focus of this study. Swiss mice used for this study were randomly divided into two groups. Animals in the first group (Pb-infected group) were inoculated with Plasmodium berghei to induce malaria whilst the other group (intact group) was not infected. Formalin test was used to assess pain sensitivity in both groups and using various antagonists, the possible mechanism for deviation in pain sensitivity was probed. Also, plasma and brain samples collected from animals in both groups were subjected to biochemical and/or histological studies. The results showed that Pb-infected mice exhibited diminished pain-related behaviours to noxious chemical. The observed parasite-induced analgesia appeared to be synergistically mediated via µ-opioid, α2 and 5HT2A receptors. When varied drugs capable of decreasing pain threshold (pro-nociceptive drugs) were used, the survival rate was not significantly different in the Pb-infected mice. This showed little or no contribution of the pain processing system to malaria-related death. Also, using an anti-CD68 antibody, there was no immunopositive cell in the brain to attribute the observed effects to cerebral malaria. Although in the haematoxylin and eosin-stained tissues, there were mild morphological changes in the motor and anterior cingulate cortices. In conclusion, the pain symptom was remarkably decreased in the animal model for malaria, and thus, the model may not be appropriate for investigating malaria-linked pain as reported in humans. This is the first report showing that at a critical point, the malaria parasite caused pain-relieving effects in Swiss mice.

Aberrant regulation of a poison exon caused by a non-coding variant in a mouse model of Scn1a-associated epileptic encephalopathy

Dravet syndrome (DS) is a developmental and epileptic encephalopathy that results from mutations in the Nav1.1 sodium channel encoded by SCN1A. Most known DS-causing mutations are in coding regions of SCN1A, but we recently identified several disease-associated SCN1A mutations in intron 20 that are within or near to a cryptic and evolutionarily conserved "poison" exon, 20N, whose inclusion is predicted to lead to transcript degradation. However, it is not clear how these intron 20 variants alter SCN1A expression or DS pathophysiology in an organismal context, nor is it clear how exon 20N is regulated in a tissue-specific and developmental context. We address those questions here by generating an animal model of our index case, NM_006920.4(SCN1A):c.3969+2451G>C, using gene editing to create the orthologous mutation in laboratory mice. Scn1a heterozygous knock-in (+/KI) mice exhibited an ~50% reduction in brain Scn1a mRNA and Nav1.1 protein levels, together with characteristics observed in other DS mouse models, including premature mortality, seizures, and hyperactivity. In brain tissue from adult Scn1a +/+ animals, quantitative RT-PCR assays indicated that ~1% of Scn1a mRNA included exon 20N, while brain tissue from Scn1a +/KI mice exhibited an ~5-fold increase in the extent of exon 20N inclusion. We investigated the extent of exon 20N inclusion in brain during normal fetal development in RNA-seq data and discovered that levels of inclusion were ~70% at E14.5, declining progressively to ~10% postnatally. A similar pattern exists for the homologous sodium channel Nav1.6, encoded by Scn8a. For both genes, there is an inverse relationship between the level of functional transcript and the extent of poison exon inclusion. Taken together, our findings suggest that poison exon usage by Scn1a and Scn8a is a strategy to regulate channel expression during normal brain development, and that mutations recapitulating a fetal-like pattern of splicing cause reduced channel expression and epileptic encephalopathy.

A Highly Selective MNK Inhibitor Rescues Deficits Associated with Fragile X Syndrome in Mice

Fragile X syndrome (FXS) is the most common inherited source of intellectual disability in humans. FXS is caused by mutations that trigger epigenetic silencing of the Fmr1 gene. Loss of Fmr1 results in increased activity of the mitogen-activated protein kinase (MAPK) pathway. An important downstream consequence is activation of the mitogen-activated protein kinase interacting protein kinase (MNK). MNK phosphorylates the mRNA cap-binding protein, eukaryotic initiation factor 4E (eIF4E). Excessive phosphorylation of eIF4E has been directly implicated in the cognitive and behavioral deficits associated with FXS. Pharmacological reduction of eIF4E phosphorylation is one potential strategy for FXS treatment. We demonstrate that systemic dosing of a highly specific, orally available MNK inhibitor, eFT508, attenuates numerous deficits associated with loss of Fmr1 in mice. eFT508 resolves a range of phenotypic abnormalities associated with FXS including macroorchidism, aberrant spinogenesis, and alterations in synaptic plasticity. Key behavioral deficits related to anxiety, social interaction, obsessive and repetitive activities, and object recognition are ameliorated by eFT508. Collectively, this work establishes eFT508 as a potential means to reverse deficits associated with FXS.

Lung pathology due to hRSV infection impairs blood-brain barrier permeability enabling astrocyte infection and a long-lasting inflammation in the CNS

The human respiratory syncytial virus (hRSV) is the most common infectious agent that affects children before two years of age. hRSV outbreaks cause a significant increase in hospitalizations during the winter season associated with bronchiolitis and pneumonia. Recently, neurologic alterations have been associated with hRSV infection in children, which include seizures, central apnea, and encephalopathy. Also, hRSV RNA has been detected in cerebrospinal fluids (CSF) from patients with neurological symptoms after hRSV infection. Additionally, previous studies have shown that hRSV can be detected in the lungs and brains of mice exposed to the virus, yet the potential effects of hRSV infection within the central nervous system (CNS) remain unknown. Here, using a murine model for hRSV infection, we show a significant behavior alteration in these animals, up to two months after the virus exposure, as shown in marble-burying tests. hRSV infection also produced the expression of cytokines within the brain, such as IL-4, IL-10, and CCL2. We found that hRSV infection alters the permeability of the blood-brain barrier (BBB) in mice, allowing the trespassing of macromolecules and leading to increased infiltration of immune cells into the CNS together with an increased expression of pro-inflammatory cytokines in the brain. Finally, we show that hRSV infects murine astrocytes both, in vitro and in vivo. We identified the presence of hRSV in the brain cortex where it colocalizes with vWF, MAP-2, Iba-1, and GFAP, which are considered markers for endothelial cells, neurons, microglia, and astrocyte, respectively. hRSV-infected murine astrocytes displayed increased production of nitric oxide (NO) and TNF-α. Our results suggest that hRSV infection alters the BBB permeability to macromolecules and immune cells and induces CNS inflammation, which can contribute to the behavioral alterations shown by infected mice. A better understanding of the neuropathy caused by hRSV could help to reduce the potential detrimental effects on the CNS in hRSV-infected patients.

Motor Function Deficits in the Estrogen Receptor Beta Knockout Mouse: Role on Excitatory Neurotransmission and Myelination in the Motor Cortex

BACKGROUND

Male estrogen receptor beta (ERβ) knockout (BERKO) mice display anxiety and aggression linked to, among others, altered serotonergic signaling in the basolateral amygdala and dorsal raphe, impaired cortical radial glia migration, and reduced GABAergic signaling. The effects on primary motor cortex (M1 cortex) and locomotor activity as a consequence of ERβ loss have not been investigated.

OBJECTIVE

The aim of this study was to determine whether locomotor activity is altered as a consequence of the changes in the M1 cortex.

METHODS

The locomotor activity of male wild-type (WT) and BERKO mice was evaluated using the open-field and rotarod tests. Molecular changes in the M1 cortex were analyzed by RNA sequencing, electron microscopy, electrophysiology, and immunohistological techniques. In addition, we established oligodendrocyte (OL) cultures from WT and BERKO mouse embryonic stem cells to evaluate OL function.

RESULTS

Locomotor profiling revealed that BERKO mice were more active than WT mice but had impaired motor coordination. Analysis of the M1 cortex pointed out differences in synapse function and myelination. There was a reduction in GABAergic signaling resulting in imbalanced excitatory and inhibitory neurotransmission as well as a defective OL differentiation accompanied by myelin defects. The effects of ERβ loss on OL differentiation were confirmed in vitro.

CONCLUSION

ERβ is an important regulator of GABAergic interneurons and OL differentiation, which impacts on adult M1 cortex function and may be linked to increased locomotor activity and decreased motor coordination in BERKO mice.

Microbiota metabolites modulate the T helper 17 to regulatory T cell (Th17/Treg) imbalance promoting resilience to stress-induced anxiety- and depressive-like behaviors

Chronic stress disrupts immune homeostasis while gut microbiota-derived metabolites attenuate inflammation, thus promoting resilience to stress-induced immune and behavioral abnormalities. There are both peripheral and brain region-specific maladaptations of the immune response to chronic stress that produce interrelated mechanistic considerations required for the design of novel therapeutic strategies for prevention of stress-induced psychological impairment. This study shows that a combination of probiotics and polyphenol-rich prebiotics, a synbiotic, attenuates the chronic-stress induced inflammatory responses in the ileum and the prefrontal cortex promoting resilience to the consequent depressive- and anxiety-like behaviors in male mice. Pharmacokinetic studies revealed that this effect may be attributed to specific synbiotic-produced metabolites including 4-hydroxyphenylpropionic, 4-hydroxyphenylacetic acid and caffeic acid. Using a model of chronic unpredictable stress, behavioral abnormalities were associated to strong immune cell activation and recruitment in the ileum while inflammasome pathways were implicated in the prefrontal cortex and hippocampus. Chronic stress also upregulated the ratio of activated proinflammatory T helper 17 (Th17) to regulatory T cells (Treg) in the liver and ileum and it was predicted with ingenuity pathway analysis that the aryl hydrocarbon receptor (AHR) could be driving the synbiotic's effect on the ileum's inflammatory response to stress. Synbiotic treatment indiscriminately attenuated the stress-induced immune and behavioral aberrations in both the ileum and the brain while in a gut-immune co-culture model, the synbiotic-specific metabolites promoted anti-inflammatory activity through the AHR. Overall, this study characterizes a novel synbiotic treatment for chronic-stress induced behavioral impairments while defining a putative mechanism of gut-microbiota host interaction for modulating the peripheral and brain immune systems.

Deficient or Excess Folic Acid Supply During Pregnancy Alter Cortical Neurodevelopment in Mouse Offspring

Folate is an essential micronutrient required for both cellular proliferation through de novo nucleotide synthesis and epigenetic regulation of gene expression through methylation. This dual requirement places a particular demand on folate availability during pregnancy when both rapid cell generation and programmed differentiation of maternal, extraembryonic, and embryonic/fetal tissues are required. Accordingly, prenatal neurodevelopment is particularly susceptible to folate deficiency, which can predispose to neural tube defects, or when effective transport into the brain is impaired, cerebral folate deficiency. Consequently, adequate folate consumption, in the form of folic acid (FA) fortification and supplement use, is widely recommended and has led to a substantial increase in the amount of FA intake during pregnancy in some populations. Here, we show that either maternal folate deficiency or FA excess in mice results in disruptions in folate metabolism of the offspring, suggesting diversion of the folate cycle from methylation to DNA synthesis. Paradoxically, either intervention causes comparable neurodevelopmental changes by delaying prenatal cerebral cortical neurogenesis in favor of late-born neurons. These cytoarchitectural and biochemical alterations are accompanied by behavioral abnormalities in FA test groups compared with controls. Our findings point to overlooked potential neurodevelopmental risks associated with excessively high levels of prenatal FA intake.

Novel role for mineralocorticoid receptors in control of a neuronal phenotype

Mineralocorticoid receptors (MRs) in the brain play a role in learning and memory, neuronal differentiation, and regulation of the stress response. Within the hippocampus, the highest expression of MRs is in area CA2. CA2 pyramidal neurons have a distinct molecular makeup resulting in a plasticity-resistant phenotype, distinguishing them from neurons in CA1 and CA3. Thus, we asked whether MRs regulate CA2 neuron properties and CA2-related behaviors. Using three conditional knockout methods at different stages of development, we found a striking decrease in multiple molecular markers for CA2, an effect mimicked by chronic antagonism of MRs. Furthermore, embryonic deletion of MRs disrupted afferent inputs to CA2 and enabled synaptic potentiation of the normally LTP-resistant synaptic currents in CA2. We also found that CA2-targeted MR knockout was sufficient to disrupt social behavior and alter behavioral responses to novelty. Altogether, these results demonstrate an unappreciated role for MRs in controlling CA2 pyramidal cell identity and in facilitating CA2-dependent behaviors.

Effects of Acrylic Tunnel Enrichment on Anxiety-Like Behavior, Neurogenesis, and Physiology of C57BL/6J Mice

Environmental enrichment for mice lags behind the standard enrichment offered to other laboratory rodents due to concerns about environmental variability and, in specific contexts, aggression. Our objective in this study was to evaluate concerns that the introduction of structural enrichment in the form of a single red acrylic mouse tunnel into murine housing may confound study findings. We measured effects on anxiety-like behaviors (elevated zero maze and open field activity), hippocampal neurogenesis, body weight gain, and physiologic markers of stress (adrenal gland weight, plasma corticosterone concentration, and neutrophil:lymphocyte ratio). Male and female C57BL/6J mice were randomly assigned to one of 2 groups: a standard-housed control group with enrichment consisting of paper nesting material, or an enriched group that received a single acrylic tunnel in addition to nesting material. All results fell within biologically normal ranges regardless of treatment, and variability (standard deviation) was not significantly different between groups for any measure. Mice in the enriched group showed modest differences during open field testing suggestive of decreased anxiety, traveling farther and depositing fewer fecal boli than standard-housed mice. Male mice in the tunnel-enriched group gained more body weight than standard-housed male mice. No significant effects by treatment were found in neurogenic or physiologic parameters. These results indicate that provision of simple structural enrichment is unlikely to have confounding effects on murine anxiety-like behaviors, neurogenesis, body weight gain, or physiologic parameters. We therefore recommend the inclusion of simple structural enrichment, such as an acrylic tunnel, to the standard environmental enrichment of social housing and nesting material for mice.

Novel Derivatives of diphenyl-1,3,4-oxadiazol as Ligands of Benzodiazepine Receptors; Synthesize, Binding Assay and Pharmacological Evaluation

Benzodiazepines (BZD) are among the main classes of tranquilizing drugs, bearing much less toxicity compared to other drugs acting on the CNS. Considering the pharmacophore model of BZD binding to GABA-A receptor, novel diphenyl 1,3,4-oxadiazole compounds as BZD ligands were designed. The compounds were synthesized and structurally confirmed using LCMS, IR and NMR techniques. We investigated the affinity of the compounds to BZD receptors using radioligand [³H]-flumazenil by in-vitro studies. In addition, sedative-hypnotic, anxiety, anticonvulsant, muscle relaxant, memory impairment, and motor coordination activities of the synthesized compounds were evaluated using in-vivo studies. Based on in-vitro studies, compounds 7i and 7j were the most potent with IC₅₀ values of 1.54 and 1.66 nM respectively. In-vivo studies showed that compound 7i has the highest impact on increased sedation, muscle relaxation, and decreased anxiety and these observations were antagonized by flumazenil. Compounds 7e and 7i were the most potent anticonvulsant agents among synthesized compounds in both MES and PTZ induced seizure tests. All synthesized compounds significantly decreased latency to fall in the Rotarod test but none of them had a significant impact on the memory impairment test.

Neurobehavioural changes and morphological study of cerebellar purkinje cells in kaolin induced hydrocephalus

Cerebellar abnormalities are commonly associated with hydrocephalus. However, the effect of hydrocephalus on the otherwise normal cerebellum has been largely neglected. This study assesses the morphological changes in the Purkinje cells in relation to cerebellar dysfunction observed in juvenile hydrocephalic rats. Fifty-five three-week old albino Wistar rats were used, hydrocephalus was induced by intracisternal injection of kaolin (n = 35) and others served as controls (n = 20). Body weight measurements, hanging wire, negative geotaxis, and open field tests were carried out at the onset and then weekly for 4 weeks, rats were killed, and their cerebella processed for Hematoxylin and Eosin, Cresyl violet and Golgi staining. Qualitative and quantitative studies were carried out; quantitative data were analyzed using two-way ANOVA and independent T tests at p < 0.05. Hydrocephalic rats weighed less than controls (p = 0.0247) but their cerebellar weights were comparable. The hydrocephalic rats had a consistently shorter latency to fall in the hanging wire test (F(4,112) = 18.63; p < 0.0001), longer latency to turn in the negative geotaxis test (F(4,112) = 22.2; p < 0.0001), and decreased horizontal (F(4,112) = 4.172, p = 0.0035) and vertical movements (F(4,112) = 4.397; p = 0.0024) in the open field test than controls throughout the 4 weeks post-induction. Cellular compression in the granular layer, swelling of Purkinje cells with vacuolations, reduced dendritic arborization and increased number of pyknotic Purkinje cells were observed in hydrocephalic rats. Hydrocephalus caused functional and morphological changes in the cerebellar cortex. Purkinje cell loss, a major pathological feature of hydrocephalus, may be responsible for some of the motor deficits observed in this condition.

Cang-Ai Volatile Oil Ameliorates Depressive Behavior Induced by Chronic Stress Through IDO-Mediated Tryptophan Degradation Pathway

Background: Cang-ai volatile oil (CAVO) is a Chinese herbal volatile oil. Previous studies report that CAVO exhibits of anti-depressant and anti-inflammatory effects, and modulates activity of monoamine neurotransmitter. The current study sought to explore whether CAVO exhibits anti-depressant effects of CAVO through inhibition of inflammatory response and regulation of indoleamine 2 and 3-dioxygenase (IDO) mediated tryptophan degradation pathway. Methods: The study established chronic unpredictable mild stress (CUMS) depression-like model using rats. Body weight and food intake of animals were determined, and open field test (OFT), forced swim test (FST), and sucrose preference test (SPT) were performed to explored the behavioral changes of animals. Expression levels of interleukin-6 (IL-6), interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-4 (IL-4), interleukin-10 (IL-10), kynurenine (KYN), quinolinic acid (QUIN), tryptophan (Trp), kynurenic acid (KYNA), serotonin (5-HT), and 5-hydroxyindole acetic acid (5-HIAA) in the prefrontal cortex of CUMS rats were determined by ELISA. Co-localization of the microglia markers, Iba1 and IL-6 was determined by immunofluorescence. Western blotting was performed to determine the protein expression level of IDO1. Results: The findings of the current study showed that CAVO increased the body weight and food intake of rats and alleviated depression-like behaviors as shown in OFT, FST, and SPT analysis. ELISA assay showed that CAVO decreased IL-6, IL-1β, TNF-α, and IFN-γ levels and increased levels of IL-4 and IL-10 in the prefrontal cortex of CUMS rats. Analysis showed that CAVO significantly reduced KYN and QUIN levels and the ratio of KYN/Trp, whereas it increased the levels of Trp, KYNA, 5-HT, and 5-HIAA. Immunofluorescence analysis showed that CAVO reduced the number of positive cells with co-localization of microglia markers, Iba1 and IL-6. Western blot analysis showed that CAVO decreased the protein expression level of IDO1 in rats. Conclusion: The findings show that the anti-depressant effects of CAVO are mainly attributed to inhibition of the activation of microglia and downregulation of IDO expression, thus inhibiting the kynurenine pathway and reversing the effects exerted on the 5-HT system.