Barnes Maze Test Research Articles

The role of dopamine D2-like receptors in a “depotentiation-like effect” of deep brain stimulation in kindled rats

The mechanisms involved in the anti-seizure effects of low-frequency stimulation (LFS) have not been completely determined. However, Gi-protein-coupled receptors, including D2-like receptors, may have a role in mediating these effects. In the present study, the role of D2-like receptors in LFS’ anti-seizure action was investigated. Rats were kindled with semi-rapid (6 stimulations per day), electrical stimulation of the hippocampal CA1 area. In LFS-treated groups, subjects received four trials of LFS at 5 min, 6 h, 24 h, and 30 h following the last kindling stimulation. Each LFS set occurred at 5 min intervals, and consisted of 4 trains. Each train contained 200, 0/1 ms long, monophasic square wave pulses at 1 Hz. Haloperidol (D2-like receptors antagonist, 2 µm) and/or bromocriptine (D2-like receptors agonist 2 µg/µlit) were microinjected into the lateral ventricle immediately after the last kindling, before applying LFS. Obtained results showed that applying LFS in fully-kindled subjects led to a depotentiation-like decrease in kindling-induced potentiation and reduced the amplitude and rise slope of excitatory and inhibitory post-synaptic currents in whole-cell recordings from CA1 pyramidal neurons. In addition, LFS restored the kindling-induced, spatial learning and memory impairments in the Barnes maze test. A D2-like receptor antagonist inhibited these effects of LFS, while a D2-like receptor agonist mimicked these effects. In conclusion, a depotentiation-like mechanism may be involved in restoring LFS’ effects on learning and memory, and synaptic plasticity. These effects depend on D2-like receptors activity.

Amplified Protein Kinase C Signaling in Alzheimer's Disease

Protein kinase C (PKC) isozymes are tightly regulated kinases that transduce signals from receptor‐mediated hydrolysis of membrane phospholipids. Whereas loss‐of‐function mutations in PKC are associated with cancer, germline mutations that enhance the activity of one isozyme, PKCα, are associated with Alzheimer’s Disease (AD). Here we show that introducing a highly penetrant AD‐associated variant of PKCα (M489V; increases catalytic activity by 30%) into a mouse model accelerates brain pathogenesis and results in a cognitive defect compared to wild‐type mice. Specifically, behavioral studies reveal a cognitive impairment in mice harboring this mutation compared to WT mice at 12 months of age, as assessed by performance on a Barnes Maze test, which measures spatial learning and memory. Additionally, the presence of the PKCα mutation in an AD mouse model overexpressing the amyloid precursor protein with the Swedish mutation, significantly exacerbated the cognitive decline as early as 6 months of age. To better understand the molecular basis for the cognitive defect, we analyzed the phosphoproteome and synapse morphology of mice harboring the PKCα M489V mutation. Analysis of the brain phosphoproteome of PKCα M489V mice vs wild‐type mice identified a variety of substrates with altered phosphorylation including known substrates of PKC involved in synaptic depression. Phosphorylation of one such protein, MARCKS, was increased both in mice harboring the PKCα mutation as well as human brains from patients with AD. Analysis of spine density revealed a modest (approximately 10%) but highly significant reduction in the number of spines per micron in the homozygous M489V mice compared to the wild‐type mice. Reduced spine density is consistent with the enhanced phosphorylation of MARCKS observed in brains from the M489V mice. In summary, this work reveals that a single amino acid change in the catalytic domain of PKCα is sufficient to cause increased phosphorylation of PKC substrates, neurite degeneration, and cognitive decline. These data strongly support inhibition of PKCα as a potential therapeutic target in AD.Support or Funding InformationCure Alzheimer's Fund

Effects of the Gut Microbiome on Aged‐Related Cognitive Decline and Inflammation

IntroductionAging is associated with low level inflammation and cognitive decline. We tested the hypothesis that the gut microbiome has a major role in these age‐related changes and that this age‐related decline is transferrable through the gut microbiome in mice.MethodsFor this study we gavaged a suspension of fresh fecal contents from aged (~20 months) or young (~3 months) BL/6 mice into germ‐free BL/6 mice (N=10 per group). The absence of gut bacteria in germ‐free mice reduced competition and enhanced the colonization of the aged or young microbiomes. Gavages began in the germ‐free mice at 12 weeks of age and were repeated monthly for 3 months. Behavioral testing and collection of fecal samples occurred over the study period. After 3 months, mice were euthanized, and the brain and colon were harvested for assessing the inflammatory state using flow cytometry. Bacterial community structures and relative abundances were measured in fecal samples by sequencing the bacterial 16S rRNA gene. Short‐chain fatty acids (SCFA) were measured in feces using LC‐MS.ResultsMice with an aged microbiome demonstrated depressive‐like behavior, impaired short‐term memory, and impaired spatial memory for at least 3 months after the initial gavage using the tail‐suspension (P=0.008), the Novel Object Recognition (P<0.001), and the Barnes Maze (P=0.019) tests respectively. The aged microbiome increased inflammation as revealed by flow cytometry studies. In brain γΔ T cells were increased (P=0.017) with an aged microbiome. In the gut, leukocytes were increased (P<0.001) and Tregs were decreased (P=0.029) with an aged microbiome. Mice with aged and young microbiomes showed clear differences in bacterial α diversity (Simpsons and Fisher, P<0.001 for both) and β diversity (weighted and unweighted PCoA, P=0.001 for both). At 3 months after the initial gavage, the bacteria families, Defluviitaleaceae and Lactobacillaceae, were significantly decreased in mice with aged microbiomes (P<0.001 and P=0.01 respectively). Fecal SCFAs, including acetate, propionate, and butyrate (P<0.01 for each), were decreased in mice with an aged microbiome. These 3 SCFAs are gut protective and anti‐inflammatory. Of note, Lactobacillus, a SCFA‐producing genus, was decreased 3‐fold in mice with an aged microbiome (P=0.009).ConclusionWe conclude that the gut microbiome has a major role in aged‐related cognitive impairment and inflammation. Furthermore, cognitive decline and an enhanced inflammatory state associated with aging can be transferred via the gut microbiome. Thus, manipulating the gut microbiome can protect from the detrimental effects associated with aging.Support or Funding InformationRO1 AG058463 (RMB and LDM)RO1 NS103592 (LDM and RMB)

The Effect of Modified Curcumin Compounds on the Numbers and Morphology of Microglia

Chronic neuroinflammation is a promising therapeutic target in many neurodegenerative and age‐related brain disorders. In this study, we investigated two highly bioavailable curcumin preparations, Longvida (LC) and Meriva (MC) for their anti‐inflammatory properties, using the GFAP‐IL6 mouse model. We hypothesized that the highly bioavailable curcumin, as a potent cytokine‐suppressive anti‐inflammatory drug, will decrease microglial and astroglial activation measured by cell number and morphology, and consequently improve motor and cognitive functions.MethodsGFAP‐IL6 and wild type mice were fed with LC and MC for 1 and 5 months, respectively. LC fed mice were tested on the elevated walking beam, Rotarod, Barnes maze and Novel object recognition tests before all the mice were sacrificed. Immunohistological staining for microglia and astrocytes were carried out and unbiased stereological analysis was completed for all groups on microglia(labelled by Iba‐1 and TSPO) and astrocytes numbers (GFAP) as well as the morphology of the cells were analyzed using the MBF Biosciences system (StereoInvestigator and Neurolucida 360).ResultsShort term MC oral administration lead to a dose‐dependent reduction in neuroinflammatory markers. Moreover, MC decreased the number of activated microglia and astroglia, as well as changed the microglial morphology from activated to resting state. Long term LC treatment led to a significant decrease in the number of microglia in the hippocampus and cerebellum and in turn, led to significant improvement of both motor and cognitive function. Both short‐ and long‐term consumption of modified curcumin preparations significantly downregulated microglial activation GFAP‐IL6 mice. Spatial memory and recognition memory improvements were also found in mice fed with LC in comparison to control counterparts. Our results promise potential therapeutic applications of both Longvida and Meriva curcumin against brain inflammation and associated cognitive and motor decline.Support or Funding InformationThe present study was supported by a project grant (#P00023016) by Indena S.P.A, Italy to GM and EG. F.U has been supported by a postgraduate scholarship by Western Sydney University.

Attenuation of noisy environment-induced neuroinflammation and dysfunction of learning and memory by minocycline during perioperative period in mice

Noisy environment often occurs in hospitals. We set out to determine whether noisy environment induces neuroinflammation and impairment of learning and memory and whether the effects of noise contribute to the development of neuroinflammation and impairment of learning and memory during the perioperative period. Seven-week old CD-1 male mice were exposed to noisy environment in the presence or absence of surgery (right carotid artery exposure). Noisy environment was 75 db, 6 h/day, for 3 days or 5 days. Minocycline (40 mg/kg), an antibiotic with anti-inflammatory property, was administered intraperitoneally 1 h before surgery or each episode of noise. The learning and memory of mice were assessed by Barnes maze and fear conditioning tests. Brain was harvested for the determination of interleukin (IL)-1β and IL-6 and for immunohistochemical staining. We found that noise induced learning and memory impairment. Noise also increased IL-1β, IL-6 and ionized calcium binding adapter molecule 1 (Iba-1) in the hippocampus. The combination of noisy environment and surgery induced dysfunction of additional domains of learning and memory and a higher expression of Iba-1 in the hippocampus. The effects of noisy environment or the combination of noisy environment and surgery were attenuated by minocycline. These findings suggest that noisy environment induces neuroinflammation and impairment of learning and memory. These effects may contribute to the development of neuroinflammation and dysfunction of learning and memory during the perioperative period. Neuroinflammation may be an underlying pathophysiological process for cognitive dysfunction induced by noise or the combination of noise and surgery. Minocycline may be effective in attenuating these noise-induced effects.

Astaxanthin Ameliorated Parvalbumin-Positive Neuron Deficits and Alzheimer's Disease-Related Pathological Progression in the Hippocampus of AppNL-G-F/NL-G-F Mice.

Growing evidence suggests that oxidative stress due to amyloid β (Aβ) accumulation is involved in Alzheimer’s disease (AD) through the formation of amyloid plaque, which leads to hyperphosphorylation of tau, microglial activation, and cognitive deficits. The dysfunction or phenotypic loss of parvalbumin (PV)-positive neurons has been implicated in cognitive deficits. Astaxanthin is one of carotenoids and known as a highly potent antioxidant. We hypothesized that astaxanthin’s antioxidant effects may prevent the onset of cognitive deficits in AD by preventing AD pathological processes associated with oxidative stress. In the present study, we investigated the effects of astaxanthin intake on the cognitive and pathological progression of AD in a mouse model of AD. The AppNL-G-F/NL-G-F mice were fed with or without astaxanthin from 5-to-6 weeks old, and cognitive functions were evaluated using a Barnes maze test at 6 months old. PV-positive neurons were investigated in the hippocampus. Aβ42 deposits, accumulation of microglia, and phosphorylated tau (pTau) were immunohistochemically analyzed in the hippocampus. The hippocampal anti-oxidant status was also investigated. The Barnes maze test indicated that astaxanthin significantly ameliorated memory deficits. Astaxanthin reduced Aβ42 deposition and pTau-positive areal fraction, while it increased PV-positive neuron density and microglial accumulation per unit fraction of Aβ42 deposition in the hippocampus. Furthermore, astaxanthin increased total glutathione (GSH) levels, although 4-hydroxy-2,3-trans-nonenal (4-HNE) protein adduct levels (oxidative stress marker) remained high in the astaxanthin supplemented mice. The results indicated that astaxanthin ameliorated memory deficits and significantly reversed AD pathological processes (Aβ42 deposition, pTau formation, GSH decrease, and PV-positive neuronal deficits). The elevated GSH levels and resultant recovery of PV-positive neuron density, as well as microglial activation, may prevent these pathological processes.

Lead acetate- induced neurodegenerative changes in the dorsolateral prefrontal cortex of mice: the role of Vitexin.

This study was aimed at investigating the neuroprotective effect of Vitexin against lead (Pb) induced neurodegenerative changes in the dorsolateral prefrontal cortex (DLPFC) and working memory in mice. Thirty-two adolescent male albino mice were divided into four groups (n=8). Control group received 0.2 mL of normal saline; Pb group received 100 mg/kg of Pb acetate for 14 days, Vitexin group received 1mg/kg of Vitexin for 14 days, and Pb+Vitexin group received 100 mg/kg of Pb acetate and 1 mgkg of Vitexin for 14 days. Barnes maze test and novel object recognition test were done to ascertain working memory. Histoarchitectural assessment of DLPFC was done with haematoxylin and eosin (H&E), cresyl fast violet and congo red stains. Furthermore, cell count and other morphometric measurements were done. There was significant decline in working memory in the Pb group, but a combination of Pb+Vitexin improved the working memory. Vitexin significantly reduced neuronal death and chromatolysis caused by Pb. Amyloid aggregation was not observed in any of the groups. This study has shown that concurrent administration of Vitexin and Pb will significantly reduce neurodegeneration and improve working memory. However, Pb treatment or Pb+Vitexin treatment does not have any effect on intercellular distance, neuronal length and the cross-sectional area of neurons in layer III of DLPFC.

Dehydration Impairs Physical Growth and Cognitive Development in Young Mice

Infancy and childhood are periods of physical and cognitive development that are vulnerable to disruption by dehydration; however, the effects of dehydration on cognitive development during the periods have not yet been fully elucidated. Thus, the present study used a murine model to examine the effects of sustained dehydration on physical growth and cognitive development. Three-week-old C57BL/6J mice were provided either ad libitum (control group) or time-limited (15 min/day; dehydration group) access to water for 4 weeks. Physical growth was examined via a dual-energy X-ray absorptiometry whole-body scan, and cognitive development was assessed using the Barnes maze test. RNA-sequencing and qPCR analyses were carried out to assess the hippocampal transcriptome and the expression of key neurotrophic factors, respectively. These analyses showed that dehydrated mice exhibited a reduced body mass and tail length, and they spent four times longer completing the Barnes maze test than control mice. Moreover, dehydration significantly dysregulated long-term potentiation signaling and specifically decreased hippocampal brain-derived neurotrophic factor (Bdnf) expression. Collectively, these data confirm dehydration inhibits physical growth and suggest that it impairs cognitive development by altering the hippocampal transcriptional network in young mice; thus, they highlight the importance of water as a vital nutrient for optimal growth and development during infancy and childhood.

β-Lapachone attenuates cognitive impairment and neuroinflammation in beta-amyloid induced mouse model of Alzheimer's disease

Oxidative stress and neuroinflammation are critically involved in amyloid beta (Aβ) induced cognitive impairments. β-Lapachone (β-LAP) is a natural activator of NAD(P)H quinone oxidoreductase 1 (NQO1) which has antioxidant and anti-inflammatory properties.This study investigated the effect of β-LAP administration on Aβ-induced memory deficit, oxidative stress, neuroinflammation, and apoptosis cell death in the hippocampus. Forty BALB/c mice were allocated into control, sham, β-LAP (βL), Aβ, and Aβ + βL groups. Intracerebroventricular injection of Aβ1-42 was used to induce Alzheimer’s disease (AD) model. Mice in the βL and Aβ + βL groups were treated with β-LAP (10 mg/kg, i.p) for 4 days. Results revealed that β-LAP attenuated memory impairment in the Aβ-received mice, as measured in the novel object recognition (NOR) and Barnes maze tests. Moreover, Aβ resulted in inflammasome activation evident by enhanced caspase-1 immunoreactivity and interleukin-1 beta (IL-1β) protein levels. However, β-LAP could markedly reduce reactive oxygen species (ROS) production and down-regulate mRNA expression of NLRP3 inflammasome and protein levels of cleaved caspase 1 and IL-1β. Additionally, β-LAP-treated mice showed increased SIRT1 levels and NAD+/NADH ratio in the hippocampus. These results were followed by fewer number of TUNEL-positive cell, reduced hippocampal atrophy and neuronal loss in the hippocampal dentate gyrus (DG). These results indicated that the protective effect of β-LAP against AD-associated cognitive deficits is partially through its strong antioxidant and anti-inflammatory actions.

Effects of Coriandrum sativum Seed Extract on Aging-Induced Memory Impairment in Samp8 Mice.

The purpose of this study was to investigate whether or not Coriandrum sativum seed extract (CSSE) can ameliorate memory impairment in senescence-accelerated mouse-prone 8 (SAMP8) mice. Sixteen 10-week-old male SAMP8 mice were divided into two groups, which were orally administrated water (SAMP8(−)) or CSSE (200 mg/kg/day; SAMP8(+)). Eight 10-week-old male Institute of Cancer Research (ICR) mice were used as a normal control group and were also orally administrated water. The mean escape time in the Barnes maze test of SAMP8(−) mice was significantly longer than that of ICR mice. However, SAMP8(+) mice showed a shorter mean escape time compared to that of SAMP8(−) mice. Neurofilament messenger (m)RNA levels significantly decreased in the frontal lobe of SAMP8(−) mice when compared with ICR mice, but significantly increased in SAMP8(+) mice relative to SAMP8(−) mice. In addition, mRNA levels of inducible nitric oxide synthase (iNOS) and neuronal (n)NOS significantly increased in the frontal lobe of SAMP8(−) mice, but only the mRNA level of nNOS significantly decreased in SAMP8(+) mice. These results indicated that continuous oral administration of CSSE for 12 weeks could ameliorate aging-induced memory declines in the senescence-accelerated SAMP8 mouse model.

G-protein-coupled estrogen receptor activation upregulates interleukin-1 receptor antagonist in the hippocampus after global cerebral ischemia: implications for neuronal self-defense

BackgroundG-protein-coupled estrogen receptor (GPER/GPR30) is a novel membrane-associated estrogen receptor that can induce rapid kinase signaling in various cells. Activation of GPER can prevent hippocampal neuronal cell death following transient global cerebral ischemia (GCI), although the mechanisms remain unclear. In the current study, we sought to address whether GPER activation exerts potent anti-inflammatory effects in the rat hippocampus after GCI as a potential mechanism to limit neuronal cell death.MethodsGCI was induced by four-vessel occlusion in ovariectomized female SD rats. Specific agonist G1 or antagonist G36 of GPER was administrated using minipump, and antisense oligonucleotide (AS) of interleukin-1β receptor antagonist (IL1RA) was administrated using brain infusion kit. Protein expression of IL1RA, NF-κB-P65, phosphorylation of CREB (p-CREB), Bcl2, cleaved caspase 3, and microglial markers Iba1, CD11b, as well as inflammasome components NLRP3, ASC, cleaved caspase 1, and Cle-IL1β in the hippocampal CA1 region were investigated by immunofluorescent staining and Western blot analysis. The Duolink II in situ proximity ligation assay (PLA) was performed to detect the interaction between NLRP3 and ASC. Immunofluorescent staining for NeuN and TUNEL analysis were used to analyze neuronal survival and apoptosis, respectively. We performed Barnes maze and Novel object tests to compare the cognitive function of the rats.ResultsThe results showed that G1 attenuated GCI-induced elevation of Iba1 and CD11b in the hippocampal CA1 region at 14 days of reperfusion, and this effect was blocked by G36. G1 treatment also markedly decreased expression of the NLRP3-ASC-caspase 1 inflammasome and IL1β activation, as well as downstream NF-κB signaling, the effects reversed by G36 administration. Intriguingly, G1 caused a robust elevation in neurons of a well-known endogenous anti-inflammatory factor IL1RA, which was reversed by G36 treatment. G1 also enhanced p-CREB level in the hippocampus, a transcription factor known to enhance expression of IL1RA. Finally, in vivo IL1RA-AS abolished the anti-inflammatory, neuroprotective, and anti-apoptotic effects of G1 after GCI and reversed the cognitive-enhancing effects of G1 at 14 days after GCI.ConclusionsTaken together, the current results suggest that GPER preserves cognitive function following GCI in part by exerting anti-inflammatory effects and enhancing the defense mechanism of neurons by upregulating IL1RA.

A Novel Knockout Mouse Model of the Noncoding Antisense  <i>Brain-Derived Neurotrophic Factor (Bdnf)</i> Gene Displays Increased Endogenous Bdnf Protein and Improved Memory Function Following Exercise

Brain-derived neurotrophic factor (Bdnf) expression is tightly controlled at the transcriptional and post-transcriptional levels. Previously, we showed that inhibition of noncoding Bdnf antisense (Bdnf-AS) RNA upregulates Bdnf protein. Here, we generated a Bdnf-antisense knockout (Bdnf-AS KO) mouse model by deleting 6 kilobases upstream of Bdnf-AS. After verifying suppression of Bdnf-AS, baseline behavioral tests indicated no significant difference in knockout and wild type mice, except for enhanced cognitive function in the knockout mice in the Y-maze. Following acute involuntary exercise, Bdnf-AS KO mice were re-assessed and a significant increase in Bdnf mRNA and protein as well as significant associated increases in nonspatial and spatial memory were observed in novel object recognition and Barnes maze tests in Bdnf-AS KO mice. Our data provides evidence for the beneficial effects of endogenous Bdnf upregulation and the synergistic effect of Bdnf-AS knockout on exercise and memory retention.

Combination of ellagic acid and trans-cinnamaldehyde alleviates aging-induced cognitive impairment via modulation of mitochondrial function and inflammatory and apoptotic mediators in the prefrontal cortex of aged rats.

Cognitive impairments are associated with advancing age. Trans-cinnamaldehyde (CIN) and ellagic acid (ELA) have multiplex activities to reduce various age-related cognitive disorders. In this study, we investigated the effects of these compounds separately or in combination on the cognitive outcomes, mitochondrial function, and inflammatory and apoptotic mediators in aged male Wistar rats. Thirty-two old (22 months old) and eight young (5 months old) rats were randomly allocated to five groups of young control, aged control, ELA-aged, CIN-aged, and ELA + CIN-aged. ELA (15 mg/kg, orally) and CIN (50 mg/kg, intraperitoneally) separately or in combination were administered for 1 month in aged animals. Spatial memory and cognitive activity were evaluated by the Barnes maze and novel object recognition tests. Mitochondrial function (its reactive oxygen species [ROS], mitochondrial membrane potential and ATP level), pro-inflammatory cytokines such as interleukin (IL)-1β and IL-6 and pro-apoptotic caspase 3 and Bax, and anti-apoptotic Bcl2 levels and their ratio were assessed in the prefrontal cortex. Behavioral results revealed that CIN separately or in combination with ELA significantly alleviates aging-induced memory impairment. Moreover, co-administration of agents effectively decreased inflammatory cytokines, cleaved-caspase 3, Bax and Bax/Bcl2 levels, mitochondrial ROS production, and mitochondrial membrane depolarization and increased Bcl2 and ATP level as compared with untreated aged control rats. Combination therapy was greater than those of individual treatments in all parameters. Therefore, combination therapy with CIN and ELA improved aging-induced cognitive impairment through anti-inflammatory, anti-apoptotic, and mitochondrial-boosting effects in aged rats.

Voluntary exercise modulates learning & memory and synaptic plasticity impairments in sleep deprived female rats

Previous studies have indicated that forced exercise plays a preventive role in synaptic plasticity deficits in the hippocampus and behavioral impairments in sleep-deprived male and female rats. The objective of the present study was to evaluate the effects of voluntary exercise on early long-term potentiation (E-LTP) at the Cornu Ammonis (CA1) area of the hippocampus and behavioral functions by barnes maze and novel location tests in sleep-deprived female rats.Intact female Wistar rats were used in the present study. The exercise protocol was four weeks wheel running and the multiple platform method was applied to induce 72 h Sleep deprivation (SD). We examine the effect of exercise and/or SD on synaptic plasticity using in vivo extracellular recording in the CA1 area of the hippocampus. Spatial learning and memory examined by Barnes maze and recognition memory assessed by novel location test.Field potential recording indicated that the induction and maintenance phase of E-LTP impaired in the sleep deprived animals compared to the other groups. After 72 h SD, LTP impairments were reduced by 4 weeks of voluntary exercise but do not go back to control values. SD impairs learning and memory and exercise could improve these deficits. In conclusion, the synaptic plasticity deficit in sleep-deprived female rats was improved by voluntary exercise. Further studies are suggested to evaluate the possible underlying mechanisms.

Cerebrolysin enhances the expression of the synaptogenic protein LRRTM4 in the hippocampus and improves learning and memory in senescent rats.

Aging reduces the efficiency of the organs and systems, including the cognitive functions. Brain aging is related to a decrease in the vascularity, neurogenesis, and synaptic plasticity. Cerebrolysin, a peptide and amino acid preparation, has been shown to improve the cognitive performance in animal models of Alzheimer's disease. Similarly, the leucine-rich repeat transmembrane 4 protein exhibits a strong synaptogenic activity in the hippocampal synapses. The aim of this study was to evaluate the effect of the cerebrolysin treatment on the learning and memory abilities, sensorimotor functions, and the leucine-rich repeat transmembrane 4 protein expression in the brain of 15-month-old rats. Cerebrolysin (1076 mg/kg) or vehicle was administered to Wistar rats intraperitoneally for 4 weeks. After the treatments, learning and memory were tested using the Barnes maze test, and the acoustic startle response, and its pre-pulse inhibition and habituation were measured. Finally, the leucine-rich repeat transmembrane 4 expression was measured in the brainstem, striatum, and hippocampus using a Western-blot assay. The 15-month-old vehicle-treated rats showed impairments in the habituation of the acoustic startle response and in learning and memory when compared to 3-month-old rats. These impairments were attenuated by the subchronic cerebrolysin treatment. The leucine-rich repeat transmembrane 4 protein expression was lower in the old vehicle-treated rats than in the young rats; the cerebrolysin treatment attenuated that decrease in the old rats. The leucine-rich repeat transmembrane 4 protein was not expressed in striatum or brainstem. These results suggest that the subchronic cerebrolysin treatment enhances the learning and memory abilities in aging by increasing the expression of the leucine-rich repeat transmembrane 4 protein in the hippocampus.

Inescapable exposure to the Barnes maze increases preference for alcohol over water in rats: Implications for depression and anxiety

Various sources of stress induce alcohol intake in rodents, including inescapable shocks, physical restraint, and reward loss. One hypothesis maintains that alcohol intake increases because its anxiolytic properties reduce negative emotion. A series of experiments explored this hypothesis using escapable vs. inescapable exposure to the well-lit circular platform of a Barnes maze in a master/yoked (M/Y) design, with pairs of rats matched in the amount of time on the lighted platform, but differing in terms of the presence vs. absence of an escape box. In Experiment 1 the M/Y design was validated as a means of producing rapid acquisition of escape behavior in master animals. In Experiment 2, immediate postsession access to a 2-h, 2-bottle preference test with 8 % alcohol and water resulted in a higher increase in preference for alcohol over water across sessions in yoked animals compared to master animals. Group differences were not observed when animals had access to water in both bottles. Higher preference for 8 % alcohol in yoked vs. master animals was also observed when the Barnes maze and preference test were separated by a 1-h interval (Experiment 3). However, voluntary alcohol consumption was similar in master and yoked animals when the order of exposure to the Barnes maze and fluid consumption was reversed (Experiment 4) or when the threat level was reduced by using a dim light over the Barnes maze (Experiment 5). Increased preference for alcohol after inescapable exposure to the Barnes maze is consistent with the hypothesis that alcohol alleviates negative mood and anxiety induced by an inescapable threat. This animal model is relevant to an understanding of the initial stages of co-morbidity between depression, anxiety, and alcohol use.

Pyrola incarnata demonstrates neuroprotective effects against β-amyloid-induced memory impairment in mice

This study aims to investigate the neuroprotective effects of Pyrola incarnata against β-amyloid-induced memory impairment in mice. Ethanol extract of Pyrola incarnata (EPI) was obtained and led to eleven phytochemicals successfully by isolation and purification, which were elucidated by spectroscopic analysis (1H NMR, 13C NMR and HR-ESI-MS). Thereinto, ursolic acid was gained as most abundant monomer. C57BL/6 mice were intracerebroventricular injected with aggregated Aβ25–35. Open-field test, Barnes maze test and Morris water maze were conducted for evaluating cognition processes of EPI and ursolic acid. EPI significantly improved learning and memory deficits, attenuated the Aβ25–35 level of deposition immunohistochemically. Further studies revealed that ursolic acid as bioactive phytochemical of P. incarnata improved spatial memory performance and ameliorated Aβ25–35 accumulation by activating microglia cells and up-regulating Iba1 level in the hippocampus. These findings suggest P. incarnata could improve the cognition of mice and be a promising natural source for the treatment of neurodegenerative disease.

Abstract 03: High-Dose Intranasal Insulin During CPR Improves Neurological Outcomes in a Rat Model of Cardiac Arrest

Introduction: Post-cardiac arrest brain injury is a major cause of mortality and morbidity. Insulin has well-established CNS neuroprotecive properties mediated by the AKT survival signaling pathway, and known transnasal transport mechanisms make it possible to rapidly achieve therapeutic brain insulin levels after intranasal delivery. Hypothesis: We hypothesize that high-dose intranasal insulin (HD-IN-I) administered during CPR, could improve neurologic outcomes in a rat model of asphyxial cardiac arrest. Methods: Male Long Evans rats were subjected to 8-minute asphyxial cardiac arrest then block randomized to HD-IN-I (1.92 U/g brain wet weight) or placebo (PL) given at the onset of CPR by an experimental operator blinded to treatment. Sham operated rats were used as uninjured controls. For the long-term outcome study (n = 14/group), rats with return of spontaneous circulation (ROSC) were maintained at 37.0 ±0.5 °C for 72 hours and neurologic function was assessed on days 7 - 10. For the mechanistic study (n = 6/group), rats with ROSC were euthanized 30 minutes after ROSC and regional brain homogenates were analyzed by western blot for AKT phosporylation. Results: HD-IN-I during CPR had no statistically significant effect on ROSC rate (93% (13/14) HD-IN-I vs. 86% (12/14) PL, p > 0.05) or 10-day survival (71% (10/14) HD-INI vs. 43% (6/14) PL, p > 0.05). HD-IN-I had no significant impact on serum glucose concentrations. At 10 days post-ROSC, rats in the HD-IN-I group had significantly improved performance on rotarod (latency to fall 87±27 sec HD-IN-I vs. 41±18 sec PL, p < 0.05), Barnes maze (latency to escape box 27±15 sec HD-IN-I vs. 298±5 sec PL, p < 0.05), and passive avoidance (latency to re-enter shock chamber 300±0 sec HD-IN-I vs. 142±46 sec PL, p < 0.05) testing. Hippocampal phosph-AKT/total AKT ratio increased 2-fold in the placebo group and 5.7-fold in the HD-IN-I group relative to shams (p < 0.05). Conclusions: HD-IN-I administered during CPR causes rapid activation of brain AKT survival signaling and improves recovery of neurologic function in a rat cardiac arrest model. Additional studies are warranted to determine dose optimization, therapeutic window and effectiveness in large animal models to advance this novel therapy toward clinical trials.

How does cognitive performance change in relation to seasonal and experimental changes in blood glucose levels?

In some species, cognition can change flexibly in response to environmental changes. These changes can be adaptive or can result from physiological constraints, such as when energy availability decreases seasonally. Here, we investigated: (1) how cognitive performance changes between seasons that differ significantly in food availability; (2) how these changes are related to environmentally induced physiological changes (blood glucose); and (3) whether experimental increase in blood glucose levels during the dry season impacts cognitive performance. We studied 93 free-ranging African striped mice, Rhabdomys pumilio, in the Succulent Karoo, South Africa during the hot summer dry season with low food availability, and the cold wet winter with high food availability. Striped mice had reduced blood glucose levels during the food-restricted dry season. We measured their attention using the standardized orientation response test and their spatial memory using the Barnes maze test. Neither attention nor spatial memory changed seasonally. However, high basal and experimentally increased blood glucose levels impaired cognition in most cases. We also found sex differences in cognitive performance. Even though food was restricted in the dry season and blood glucose levels were reduced, cognition was not affected by these changes, indicating cognitive resilience, which represents an evolved adaptation to cope with seasonally changing energy supply in striped mice.

Normobaric oxygen treatment improves neuronal survival functional recovery and axonal plasticity after newborn hypoxia-ischemia

BackgroundNewborn hypoxia ischemia (HI) is one of the most prevalent cases in the emergency and can result from fetal hypoxia during delivery. In HI, restricted blood supply to the fetal brain may cause epilepsy or mental disorders. MethodsIn the present study, seven-day-old pups were subjected HI and treated with different normobaric oxygen (NBO) concentrations (21%, 70% or 100%). In the acute phase, we analyzed infarct area, disseminate neuronal injury and surviving neurons. In addition, we studied the regulation of PTEN and MMP-9 proteins which were suggested to be activated by HI in the ischemic tissue. Moreover, long-term effects of NBO treatments were evaluated with open field, rotarod and Barnes maze tests. We also examined axonal plasticity with EGFP-AAV injection. ResultsHere, we demonstrate that hyperoxic NBO concentration causes an increase in cellular survival and a decrease in the number of apoptotic cells, meanwhile inhibiting the proteins involved in cellular death mechanisms. Moreover, we found that hyperoxia decreases anxiety, promotes motor coordination and improve spatial learning and memory. Notably that axonal sprouting was promoted by hyperoxia. ConclusionOur data suggest that NBO is a promising approach for the treatment of newborn HI, which encourage proof-of-concept studies in newborn.