The ameliorating effect of the extract of the flower of Prunella vulgaris var.lilacina on drug-induced memory impairments in mice

Prunella vulgaris var. lilacina is widely distributed in Korea, Japan, China, and Europe, and its flowers are used to treat inflammation in traditional Chinese medicine. In the present study, we studied the effects of the ethanolic extract of the flower of P. vulgaris var. lilacina (EEPV) on drug-induced learning and memory impairment using the passive avoidance, the Y-maze, and the Morris water maze tasks in mice. EEPV (25 or 50 mg/kg, p.o.) significantly ameliorated scopolamine-induced cognitive impairments in the passive avoidance and Y-maze tasks (P < 0.05). In the Morris water maze task, EEPV (25 mg/kg, p.o.) significantly shortened escape latencies in training-trials. Furthermore, swimming times within the target zone during the probe-trial were significantly increased as compared with scopolamine-treated mice (P < 0.05). In addition, the reduced latency induced by MK-801 treatment in the passive avoidance task was ameliorated by EEPV (25 mg/kg, p.o.) (P < 0.05). Additionally, the ameliorating effect of EEPV on scopolamine-induced memory dysfunction was antagonized by a sub-effective dose of MK-801. These results suggest that EEPV would be useful for treating cognitive impairments induced by cholinergic dysfunction, and that it exerts its effects via NMDA receptor signaling.     

The seed extract of Cassia obtusifolia ameliorates learning and memory impairments induced by scopolamine or transient cerebral hypoperfusion in mice

In the present study, we assessed the effect of the ethanolic extract of the seeds of Cassia obtusifolia (COE) on the learning and memory impairments induced by scopolamine or transient bilateral common carotid artery occlusion (2VO). In a study of the cholinergic dysfunction induced by scopolamine, single COE (25, 50, or 100 mg/kg, p.o.) administration significantly attenuated scopolamine-induced cognitive impairments as determined by the passive avoidance and Y-maze tasks (P<0.05) and also reduced escape-latency on the Morris water maze task (P<0.05). In the 2VO study, COE (50 mg/kg, p.o.) significantly reversed 2VO-induced cognitive impairments in mice by the passive avoidance and the Y-maze tasks (P<0.05). Moreover, COE (50 mg/kg, p.o.) also reduced escape-latency and prolonged swimming time in the target quadrant during a probe trial of the Morris water maze task (P<0.05). In an in vitro study, COE was found to inhibit acetylcholinesterase activity in a dose-dependent manner (IC(50) value: 81.6 microg/ml). Furthermore, COE also inhibited acetylcholinesterase activity in an ex vivo study. These results suggest that COE attenuates memory impairment induced by scopolamine or 2VO and that these effects are mediated by enhancing the cholinergic nervous system via acetylcholinesterase inhibition.     

Effect of the flavonoid, oroxylin A, on transient cerebral hypoperfusion-induced memory impairment in mice

Oroxylin A is a flavonoid compound that is found in the root of Scutellaria baicalensis Georgi. The aim of this study was to determine the effects of oroxylin A on memory impairment induced by transient bilateral common carotid artery occlusion (2VO) in mice. The ameliorating effect of oroxylin A on memory impairment was investigated using a passive avoidance task, the Y-maze task, and the Morris water maze task in mice. Oroxylin A was found to significantly reverse 2VO-induced cognitive impairments in the passive avoidance and Y-maze tasks in a dose dependant manner (P<0.05). Moreover, oroxylin A (5 mg/kg, p.o.) shortened the escape-latency and prolonged swimming times in the target quadrant during the probe trial in the Morris water maze task (P<0.05). Histochemical and immunohistochemical studies showed that the number of Nissl bodies and OX-42 positive cells in the hippocampal CA1 and dentate gyrus regions were attenuated by oroxylin A. Moreover, phosphorylated cAMP response element-binding protein (CREB) and brain derived neurotrophic factor (BDNF) positive cell numbers were markedly increased in animals treated with oroxylin A than in untreated 2VO controls. These results suggest that oroxylin A dramatically attenuates the memory impairment induced by 2VO, and that this effect may be mediated by the neuroprotective effects of oroxylin A as supported oroxylin A induced reductions in activated microglia and increases in BDNF expression and CREB phosphorylation.     

Effects of olanzapine, sertindole and clozapine on learning and memory in the Morris water maze test in naive and MK-801-treated mice

Cognitive dysfunction in schizophrenia is associated with functional disease symptoms. The beneficial effects of second generation antipsychotic drugs on cognitive function in schizophrenic patients are controversial. In this study, we investigated the effects of the second generation antipsychotics olanzapine, sertindole and clozapine on cognitive function in the Morris water maze task in naive or MK-801-treated animals. Male balb-c mice were treated subchronically with olanzapine (1.25, 2.5 and 5 mg/kg, i.p.), sertindole (0.63, 1.3, 2.5 mg/kg, s.c.) or clozapine (0.5 and 1 mg/kg, i.p.), and cognitive deficits were induced by MK-801 (0.2 mg/kg, i.p.) administration. Water maze performance was expressed as escape latency to find the hidden platform, the time spent in target quadrant, the mean distance to platform and the swim speed. In naive mice olanzapine impaired water maze performance, whereas sertindole and clozapine had no effect while the MK-801-induced cognitive impairment was reversed by the second generation antipsychotics — olanzapine, sertindole and clozapine at the doses used. These results revealed that while olanzapine had some disturbing effects on cognitive functions in naive animals; olanzapine, sertindole and clozapine might improve cognitive deficits in schizophrenic patients.     

The effects of acute and repeated oroxylin A treatments on Abeta(25-35)-induced memory impairment in mice

Oroxylin A is a flavonoid that is found in the roots of Scutellaria baicalensis Georgi. The aim of this study was to characterize the effects of oroxylin A on the memory impairments and pathological changes induced by Aβ_25-35 peptide in mice. The ameliorating effect of oroxylin A on memory impairment was investigated using passive avoidance and Y-maze tasks and pathological changes were identified by immunostaining and western blotting. Aβ_25-35 peptide (5 nmol) was administered by intracerebroventricular injection. In the acute treatment study, a single dose of oroxylin A (5 mg/kg, p.o.) treated 1 h before behavioral tests was found to significantly reverse Aβ_25-35-induced cognitive impairments based on passive avoidance and Y-maze task findings (P < 0.05). Moreover, these acute effects of oroxylin A were blocked by diazepam (1 mg/kg, i.p.), a GABA_A/benzodiazepine binding site agonist (P < 0.05). On the other hand, our subchronic studies revealed that oroxylin A (1 or 5 mg/kg/day, p.o.) for 7 days ameliorated the memory impairment induced by Aβ_25-35 peptide. Moreover, Aβ_25-35-induced increases in GFAP (an astroglia marker) and OX-42 (a microglia marker), and increases in iNOS positive cells in the hippocampus were found to be attenuated by subchronic oroxylin A (1 or 5 mg/kg/day, i.p., P < 0.05). In addition, reductions in the immunoreactivity and protein level of ChAT (a cholinergic neuronal cell marker) in the CA3 hippocampal area induced by Aβ_25-35 peptide were also attenuated by oroxylin A. Furthermore, lipid peroxidation induced by Aβ_25-35 was also reduced by oroxylin A. These results suggest that the amelioration of Aβ_25-35 peptide-induced memory impairment by oroxylin A is mediated via the GABAergic neurotransmitter system after a single administration, or by reductions in Aβ_25-35 peptide-induced astrocyte and microglia activations, iNOS expression, lipid peroxidation, and increased cholinergic neurotransmission after subchronic administration.     

Hydrogen sulfide attenuates lipopolysaccharide-induced cognitive impairment: A pro-inflammatory pathway in rats

The present study investigated the effect of sodium hydrosulfide (NaHS), a H₂S donor, on cognitive impairment and neuroinflammatory changes induced by bilateral intracerebroventricular injections of LPS at a dose of 10 μg/rat. Rats received 5 mg/kg NaHS or volume-matched vehicle administration by intraperitoneal injection 3 days before LPS injection then for 9 days once daily. Morris water maze was used to detect the cognitive function. Compared to the sham-treated rats, LPS injection significantly prolonged the mean escape latency in the navigation test (P < 0.05) and shortened the adjusted escape latency by approximately 30% (P < 0.05). Meanwhile, LPS injection decreased H₂S level but increased pro-inflammatory mediators (i.e., TNF-α, TNFR1, degradation of IκB-α and thereafter activation of NF-κB) in hippocampus. However, these effects of LPS were significantly ameliorated with NaHS treatment (P < 0.05 vs vehicle-treated group). The present data suggest that H₂S attenuates LPS-induced cognitive impairment through reducing the overproduction of pro-inflammatory mediators via inhibition of NF-κB pathways in rats. This study sets the stage for exploring a novel H₂S releasing agent for preventing or retarding the development or progression of neurological disorders such as Alzheimer's disease.     

Protective effect of N-acetylcysteine on bisphenol A-induced cognitive dysfunction and oxidative stress in rats

Bisphenol A (BPA) is commonly used as a monomer in polycarbonate plastics. The present study was designed to investigate the effect of BPA on cognitive functions and oxidative stress in the brain tissue of rats and if co-administration of N-acetylcysteine (NAC), an antioxidant, can modulate the effect of BPA on cognitive functions and prevent any possible oxidative stress. The BPA was administered per orally (p.o) in two doses 2 and 20 μg/kg for 28 days. Cognitive functions were assessed using step-down latency (SDL) on a passive avoidance apparatus and spatial navigation task on Morris water maze. Oxidative stress was assessed by examining brain malondialdehyde (MDA) and reduced glutathione (GSH) levels. A significant reduction in SDL, and prolongation of latency in spatial navigation task were observed in BPA (2 and 20 μg/kg) treated group as compared to control group. The co-administration of NAC (100 mg/kg, p.o) antagonized the effect of BPA on SDL and spatial navigation test. NAC treatment also attenuated the BPA-induced increased MDA levels and decreased GSH levels in brain. Results of the present study show that NAC has potential to reverse cognitive dysfunction and oxidative stress induced by BPA exposure in rats.     

SAR110894, a potent histamine H₃-receptor antagonist, displays procognitive effects in rodents

SAR110894 is a novel histamine H₃-R ligand, displaying high and selective affinity for human, rat or mouse H₃-Rs. SAR110894 is a potent H₃-R antagonist at native receptors, reversing R-α-methylhistamine-induced inhibition of electrical field stimulation contraction in the guinea-pig ileum. Additionally, SAR110894 inhibited constitutive GTPγS binding at human H₃-Rs demonstrating inverse agonist properties. In behavioral models addressing certain aspects of cognitive impairment associated with schizophrenia (CIAS) and attention deficit/hyperactivity disorder (ADHD), SAR110894 improved memory performances in several variants of the object recognition task in mice (0.3-3 mg/kg, p.o.) or rats (0.3-1 mg/kg, p.o.). Moreover, SAR110894 (1 mg/kg, p.o.) reversed a deficit in working memory in the Y-maze test, following an acute low dose of phencyclidine (PCP) (0.5 mg/kg, i.p.) in mice sensitized by repeated treatment with a high dose of PCP (10 mg/kg, i.p.). In the latent inhibition (LI) model, SAR110894 potentiated LI in saline-treated rats (1 and 3 mg/kg, i.p.) and reversed abnormally persistent LI induced by neonatal nitric oxide synthase (NOS) inhibition in rodents (0.3-3 mg/kg, i.p.). In a social novelty discrimination task in rats, SAR110894 attenuated selective attention deficit induced by neonatal PCP treatment (3 and 10 mg/kg, p.o.) or a parametric modification of the procedure (3 and 10 mg/kg, p.o.). SAR110894 showed efficacy in several animal models related to the cognitive deficits in Alzheimer's disease (AD). It prevented the occurrence of episodic memory deficit induced by scopolamine in rats (0.01-10 mg/kg, p.o.) or by the central infusion of the toxic amyloid fragment β_25-35 in the object recognition test in mice (1 and 3 mg/kg, p.o.). Altogether, these findings suggest that SAR110894 may be of therapeutic interest for the treatment of the cognitive symptoms of AD, schizophrenia and certain aspects of ADHD.     

The selective phosphodiesterase 9 (PDE9) inhibitor PF-04447943 (6-[(3S,4S)-4-methyl-1-(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-1-(tetrahydro-2H-pyran-4-yl)-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one) enhances synaptic plasticity and cognitive function in rodents

Inhibition of phosphodiesterase 9 (PDE9) has been reported to enhance rodent cognitive function and may represent a potential novel approach to improving cognitive dysfunction in Alzheimer’s disease. PF-04447943, (6-[(3S,4S)-4-methyl-1-(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-1-(tetrahydro-2H-pyran-4-yl)-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one), a recently described PDE9 inhibitor, was found to have high affinity (Ki of 2.8, 4.5 and 18 nM) for human, rhesus and rat recombinant PDE9 respectively and high selectivity for PDE9 versus PDEs1-8 and 10-11. PF-04447943 significantly increased neurite outgrowth and synapse formation (as indicated by increased synapsin 1 expression) in cultured hippocampal neurons at low (30-100 nM) but not high (300-1000 nM) concentrations. PF-04447943 significantly facilitated hippocampal slice LTP evoked by a weak tetanic stimulus at a concentration of 100 nM but failed to affect response to the weak tetanus at either 30 or 300 nM, or the LTP produced by a theta burst stimulus. Systemic administration of PF-04447943 (1-30 mg/kg p.o.) dose-dependently increased cGMP in the cerebrospinal fluid 30 min after administration indicating target engagement in the CNS of rats. PF-04447943 (1-3 mg/kg p.o.) significantly improved cognitive performance in three rodent cognition assays (mouse Y maze spatial recognition memory model of natural forgetting, mouse social recognition memory model of natural forgetting and rat novel object recognition with a scopolamine deficit). When administered at a dose of 3 mg/kg p.o., which improved performance in novel object recognition, PF-04447943 significantly increased phosphorylated but not total GluR1 expression in rat hippocampal membranes. Collectively these data indicate that PF-04447943 is a potent, selective brain penetrant PDE9 inhibitor that increased indicators of hippocampal synaptic plasticity and improved cognitive function in a variety of cognition models in both rats and mice. Results with PF-04447943 are consistent with previously published findings using a structurally diverse PDE9 inhibitor, BAY73-6199, and further support the suggestion that PDE9 inhibition may represent a novel approach to the palliative remediation of cognitive dysfunction.     

Protective effect of Z-ligustilide against amyloid β-induced neurotoxicity is associated with decreased pro-inflammatory markers in rat brains

Neuroinflammatory responses induced by accumulation and aggregation of β-amyloid (Aβ) peptide are mainly involved in Alzheimer's disease (AD) pathogenesis. Z-ligustilide (LIG), a novel neuroprotectant against ischemic stroke, was reported to have significant anti-inflammatory effects via inhibition of TNF-α production and bioactivity. The present study investigated the effect of LIG on AD-like cognitive impairment and neuropathological and neuroinflammatory changes induced by bilateral intracerebroventricular injections of Aβ_25-35 at a dose of 50 nmol/rat. Rats received oral administration of 40 mg/kg LIG or volume-matched vehicle 1 h before Aβ_25-35 treatment then once daily for 15 days. Morris water maze was used to detect the cognitive dysfunction induced by Aβ_25-35. Compared to the sham-operated rats, Aβ_25-35 injection significantly prolonged the mean escape latency in vehicle-treated rats in the Morris water maze test (p < 0.01) and increased both AD-related neuropathological signs (i.e., Aβ, amyloid precursor protein, and phosphorylated Tau immunoreactivity) and pro-inflammatory mediators (i.e., TNF-α and activated NF-кB) in the prefrontal cortex and CA1 subregion of the hippocampus. And these neurotoxic effects of Aβ_25-35 were significantly ameliorated with LIG treatment (p < 0.01 vs. vehicle-treated group). The present data suggest that LIG modulates TNF-α-activated NF-кB signaling pathway with respect to its protective effect against Aβ_25-35-induced neurotoxicity. LIG would be a potential candidate for further preclinical study aimed at the prevention and treatment of cognitive deficits in AD.     

Single high dose treatment with methotrexate causes long-lasting cognitive dysfunction in laboratory rodents

Clinical studies have suggested that cognitive impairment due to chemotherapy persists long after treatment cessation. While animal studies have similarly found impairments in cognition due to chemotherapy, these studies are limited as they only assess the acute or extremely short-term effects of chemotherapy on cognition (e.g. within 1 month of treatment). Male hooded Wistar rats (N = 22) received either a high dose of methotrexate (MTX: 250 mg/kg i.p.) or physiological saline. Cognitive performance was evaluated acutely at 2 weeks, and up to 8 months post injection using the Morris water maze, Novel object recognition task, and an instrumental go/no-go task to assess discrimination learning. MTX-treated rats displayed impaired novel object recognition compared to controls at 11, 95, and 255 days after treatment. MTX rats were able to learn the hidden spatial location of a platform 22 days after treatment. When tested again after a 95-day retention interval, MTX rats showed impaired spatial memory compared to controls, but were subsequently able to re-learn the task. Finally, MTX-treated rats showed considerable difficulty learning to inhibit their behaviour in an instrumental discrimination task. These results show that chemotherapy produces persistent but subtle cognitive deficits in laboratory rodents that vary with time post treatment.     

Action of (R)-sila-venlafaxine and reboxetine to antagonize cisplatin-induced acute and delayed emesis in the ferret

The chemotherapeutic drug cisplatin is associated with severe gastrointestinal toxicity that can last for several days. A recent strategy to treat the nausea and emesis includes the combination of a 5-HT₃ receptor antagonist, a glucocorticoid, and an NK₁ receptor antagonist. The present studies explore the use of the selective noradrenaline reuptake inhibitors, (R)-sila-venlafaxine, (R,R)-reboxetine and (S,S)-reboxetine to prevent cisplatin (5 mg/kg, i.p.)-induced acute (0-24 h) and delayed (24-72 h) emesis in ferrets. The positive control regimen of ondansetron and dexamethasone, both at 1 mg/kg/8 h, reduced acute and delayed emesis by 100 (P < 0.001) and 61% (P < 0.05). (R)-sila-venlafaxine at 5 and 15 mg/kg/4 h reduced acute emesis by 86 (P < 0.01) and 66% (P < 0.05), respectively and both enantiomers of reboxetine at 1 mg/kg/12 h also reduced the response by ∼ 70-90% (P < 0.05). Out of the reuptake inhibitors, only (R)-sila-venlafaxine at 15 mg/kg/4 h was active to reduce delayed emesis (a 57% reduction was observed (P < 0.05)); its terminal plasma levels were positively correlated with an inhibition of emesis during the delayed phase (P < 0.05). (R)-sila-venlafaxine was also examined against a higher dose of cisplatin 10 mg/kg, i.p. (3 h test) and it dose-dependently antagonized the response (maximum reduction was 94% at 10 mg/kg, p.o.; P < 0.01) but it was ineffective against apomorphine (0.125 mg/kg, s.c.) and ipecacuanha (2 mg/kg, p.o.)-induced emesis (P > 0.05). In conclusion, the studies provide the first evidence for an anti-emetic potential of noradrenaline reuptake inhibitors to reduce chemotherapy-induced acute and delayed emesis.     

Polychlorinated biphenyls induced oxidative stress mediated neurodegeneration in hippocampus and behavioral changes of adult rats: Anxiolytic-like effects of quercetin

Polychlorinated biphenyls (PCBs) are extremely toxic environmental contaminant speculated to accelerate neurochemical and behavioral damages. Developmental and behavioral development relies on the proper functioning of the endogenous neurotransmitters that remain the pivotal target of neurotoxicants. This study intent to evidence the neuroprotective efficacy of quercetin against PCBs induced hippocampal degeneration. Animals were sorted into four (n = 6), Group I: received corn oil (vehicle) intraperitoneally (i.p.); Group II: received quercetin 50 mg/kg bwt (gavage); Group III: were induced with Aroclor 1254 (commercial mixture of PCB) at 2 mg/kg bwt (i.p); Group IV: received quercetin 50 mg/kg bwt (gavage) and along with PCBs 2 mg/kg bwt (i.p.) for 30 days. Cognitive behaviors such as learning and memory were assessed by 8-arm radial maze behavior test throughout the experimental period. Subsequently, anxiety and stress were studied by open field test at the termination of experiment. Hippocampal tissue and blood were collected after the intended experimental period to analyze the levels of oxidative stressors, antioxidants in tissue and estimation of neurotransmitters. Perhaps, PCBs evoke detrimental deterioration of the neurotransmitters and integrative antioxidant defense by elevation of reactive oxygen species (ROS). Concurrent treatment with quercetin prominently suppresses the oxidative stressors, improved the levels of enzymatic antioxidants and neurotransmitter levels significantly at the level of p < 0.05. Behavioral analysis claims drastic revitalization of cognitive functions like learning and memory on treatment with quercetin. The results coalesced depicts neurotoxicity stimulated by PCBs is augmented by simultaneous quercetin administration.     

Alaternin attenuates delayed neuronal cell death induced by transient cerebral hypoperfusion in mice

The aim of this study was to determine whether alaternin exhibits neuroprotective activity after transient cerebral hypoperfusion induced by bilateral common carotid artery occlusion (BCCAO). Mice were subjected to BCCAO, and circulation was restored after 20 min. Alaternin (10 mg/kg, p.o) treatment significantly prevented nitrotyrosine and lipid peroxidation, as well as BCCAO induced-inducible nitric oxide synthase (iNOS) expression. Alaternin also significantly reduced microglial activation (a marker of inflammation). The number of viable neurons detected by Nissl staining increased with alaternin (10 mg/kg, p.o) treatment at 7 days post-BCCAO. In the passive avoidance task, alaternin significantly ameliorated BCCAO-induced cognitive impairments (P < 0.05). These results suggest that the neuroprotective effects of alaternin are mediated by its anti-inflammatory and radical scavenging activities.     

Treatment of spatial memory impairment in hamsters infected with West Nile virus using a humanized monoclonal antibody MGAWN1

In addition to functional disorders of paresis, paralysis, and cardiopulmonary complications, subsets of West Nile virus (WNV) patients may also experience neurocognitive deficits and memory disturbances. A previous hamster study has also demonstrated spatial memory impairment using the Morris water maze (MWM) paradigm. The discovery of an efficacious therapeutic antibody MGAWN1 from pre-clinical rodent studies raises the possibility of preventing or treating WNV-induced memory deficits. In the current study, hamsters were treated intraperitoneally (i.p.) with 32 mg/kg of MGAWN1 at 4.5 days after subcutaneously (s.c.) challenging with WNV. As expected, MGAWN1 prevented mortality, weight loss, and improved food consumption of WNV-infected hamsters. The criteria for entry of surviving hamsters into the study were that they needed to have normal motor function (forelimb grip strength, beam walking) and normal spatial reference memory in the MWM probe task. Twenty-eight days after the acute phase of the disease had passed, MGAWN1- and saline-treated infected hamsters were again trained in the MWM. Spatial memory was evaluated 48 h after this training in which the hamsters searched for the location where a submerged escape platform had been positioned. Only 56% of infected hamsters treated with saline spent more time in the correct quadrant than the other three quadrants, as compared to 92% of MGAWN1-treated hamsters (P ? 0.05). Overall these studies support the possibility that WNV can cause spatial memory impairment and that therapeutic intervention may be considered.     

Vitamin C reduces spatial learning deficits in middle-aged and very old APP/PSEN1 transgenic and wild-type mice

Alzheimer's disease is a progressive and fatal neurodegenerative disease characterized by a build up of amyloid β (Aβ) deposits, elevated oxidative stress, and deterioration of the cholinergic system. The present study investigated short-term cognitive-enhancing effects of acute intraperitoneal (i.p.) Vitamin C (ascorbate) treatment in APP/PSEN1 mice, a mouse model of Alzheimer's disease. Middle-aged (12 months) and very old (24 months) APP/PSEN1 bigenic and wild-type mice were treated with ascorbate (125 mg/kg i.p.) or the vehicle 1 h before testing on Y-maze spontaneous alternation and Morris water maze tasks. Very old mice performed more poorly on cognitive tasks than middle-aged mice. Ascorbate treatment improved Y-maze alternation rates and swim accuracy in the water maze in both wild-type and APP/PSEN1 mice. Aβ deposits and oxidative stress both increased with age, and acetylcholinesterase (AChE) activity was significantly reduced in APP/PSEN1 compared to wild-type mice. However, the short course of acute ascorbate treatment did not alter Alzheimer-like neuropathological features of plaque deposition, oxidative stress, or AChE activity. These data suggest that ascorbate may have noötropic functions when administered parenterally in high doses and that the mode of action is via an acute, pharmacological-like mechanism that likely modulates neurotransmitter function.     

The neurokinin NK2 antagonist, saredutant, ameliorates stress-induced conditions without impairing cognition

The current work extends our previous findings in stress-related disorders, but also addresses the impact of a neurokinin-2 (NK2) antagonist on cognition. Besides efficacy in mood disorders, an NK2 antagonist may have the potential to lack the disinhibitory components and adverse side effects associated with existing clinical treatments. Saredutant (3-30 mg/kg, per os, p.o.) was tested for anxiolytic-like potential in three mouse models: holeboard, stress-induced hyperthermia (SIH) and four-plate. In the holeboard model saredutant (30 mg/kg) showed a trend to increase head dipping without affecting general activity. In the SIH model, saredutant demonstrated a significant reduction in stress-induced temperature at 30 mg/kg, while the number of punished crossings in the four-plate was increased at all doses tested (3-30 mg/kg). While chlordiazepoxide (CDP) demonstrated anxiolytic-like effects in these models, the adverse side effects of benzodiazepines, such as sedation, disinhibition and cognitive deficits are well-documented. Saredutant produced no detrimental effect in three models of cognition: Morris Water Maze (MWM) in rats, spontaneous alternation in a Y-maze in mice and novel objection recognition in mice. In contrast, the benzodiazepine, diazepam (DZM), produced cognitive impairments. NK2 receptor antagonists like saredutant may therefore yield beneficial effects for mood disorders without the adverse effects of current treatments.     

针刺疗法对AD大鼠的治疗作用及其机制的实验研究

目的探究针刺疗法是否可以减轻D-半乳糖(D-gal)联合三氯化铝(AlCl3)诱导的阿尔兹海默症(AD)大鼠的学习和记忆缺陷及其机制。方法本研究为动物实验。将体质量为240～270 g的雄性大鼠按照随机数字表法分为对照(A)组、模型(B)组、针刺(C)组、药物治疗对照(D)组, 每组5只。造模并治疗后, 通过Y-迷宫、跳台和莫里斯水迷宫实验对各组大鼠的认知功能进行评估;尼氏体亚甲蓝特殊染色评估神经元损伤情况;TUNEL染色检测大鼠海马组织中神经元凋亡情况;免疫组化检测海马组织中β-淀粉样蛋白(β-AP)和磷酸化tau水平。计量资料使用单因素方差分析进行多组比较, 然后选择Tukey检验进行多重比较。结果与A组相比, B组大鼠存在认知功能障碍, 出现神经元损伤和高神经元凋亡率, 且β-AP和磷酸化tau水平均明显更高(均P<0.05);与B组相比, C组和D组大鼠认知功能障碍得到缓解, 神经元损伤得到改善, 神经元凋亡率更低, β-AP和磷酸化tau水平均下调(均P<0.05)。结论针刺疗法可能通过降低海马组织中β-AP和磷酸化tau水平来改善AD大鼠的认知功能障碍。     

Spatial learning and morphine-rewarded place preference negatively correlates in mice

Accumulating evidence has indicated that there might exist some correlation between opiate reward and certain kinds of learning and memory processes. The present study attempted to investigate the correlation between individual differences in morphine reward and capacities in spatial learning and spontaneous alternation. In the present studies, good-response (GR) and poor-response (PR) mice were respectively selected according to their performance in a spatial learning test involving the Morris water maze or in a spontaneous alternation task using the Y-maze. In a place preference conditioning procedure, morphine (3.0 mg/kg) produced significant conditioned place preference (CPP) in both GR and PR mice selected by using either the Morris water maze or the Y-maze. The PR mice selected with the Morris water maze showed significantly more CPP induced by morphine than the GR mice. However, no detectable difference was observed in morphine-induced CPP between the GR and PR mice selected with the Y-maze. These results suggested that the variation in morphine-induced CPP in mice is somehow differentially related to that of spatial learning but unlikely to that of spontaneous alternation.     

Ethanolic Extract of the Seed of Zizyphus jujuba var. spinosa Ameliorates Cognitive Impairment Induced by Cholinergic Blockade in Mice

In the present study, we investigated the effect of ethanolic extract of the seed of Zizyphus jujuba var. spinosa (EEZS) on cholinergic blockade-induced memory impairment in mice. Male ICR mice were treated with EEZS. The behavioral tests were conducted using the passive avoidance, the Y-maze, and the Morris water maze tasks. EEZS (100 or 200 mg/kg, p.o.) significantly ameliorated the scopolamine-induced cognitive impairment in our present behavioral tasks without changes of locomotor activity. The ameliorating effect of EEZS on scopolamine-induced memory impairment was significantly reversed by a sub-effective dose of MK-801 (0.0125 mg/kg, s.c.). In addition, single administration of EEZS in normal naïve mouse enhanced latency time in the passive avoidance task. Western blot analysis was employed to confirm the mechanism of memory-ameliorating effect of EEZS. Administration of EEZS (200 mg/kg) increased the level of memory-related signaling molecules, including phosphorylation of extracellular signal-regulated kinase or cAMP response element-binding protein in the hippocampal region. Also, the time-dependent expression level of brain-derived neurotrophic factor by the administration of EEZS was markedly increased from 3 to 9 h. These results suggest that EEZS has memory-ameliorating effect on scopolamine-induced cognitive impairment, which is mediated by the enhancement of the cholinergic neurotransmitter system, in part, via NMDA receptor signaling, and that EEZS would be useful agent against cognitive dysfunction such as Alzheimer’s disease.