Learning large-scale spatial relationships in a maze and effects of MK-801 on retrieval in the rhesus monkey

Monkeys have strong abilities to remember the visual properties of potential food sources for survival in the nature. The present study demonstrated the first observations of rhesus monkeys learning to solve complex spatial mazes in which routes were guid

A novel physiological property of snake bradykinin-potentiating peptides-Reversion of MK-801 inhibition of nicotinic acetylcholine receptors

The first naturally occurring angiotensin-converting enzyme (ACE) inhibitors described are pyroglutamyl proline-rich oligopeptides, found in the venom of the viper Bothrops jararaca, and named as bradykinin-potentiating peptides (BPPs). Biochemical and pharmacological properties of these peptides were essential for the development of Captopril, the first active site-directed inhibitor of ACE, currently used for the treatment of human hypertension. However, a number of data have suggested that the pharmacological activity of BPPs could not only be explained by their inhibitory action on enzymatic activity of somatic ACE. In fact, we showed recently that the strong and long-lasting anti-hypertensive effect of BPP-10c [MK-801-induced inhibition of nicotinic acetylcholine receptor activity. Although more data are needed for understanding the mechanism of the BPP-10c effect on nicotinic receptor activity and its relationship with the anti-hypertensive activity, this work reveals possible therapeutic applications for BPP-10c in establishing normal acetylcholine receptor activity. (C) 2008 Elsevier Inc. All rights reserved.

Sensitivity to MK-801 in phospholipase C-β1 knockout mice reveals a specific NMDA receptor deficit

Phospholipase C-β1 (PLC-β1) is a critical component of multiple signalling pathways downstream of neurotransmitter receptors. Mice lacking this enzyme display a striking behavioural phenotype with relevance to human psychiatric disease. Glutamatergic dysfunction is strongly associated with several abnormal behavioural states and may underlie part of the phenotype of the phospholipase C-β1 knockout (KO) mouse. A heightened response to glutamatergic psychotomimetic drugs is a critical psychosis-related endophenotype, and in this study it was employed as a correlate of glutamatergic dysfunction. Control (n=8) and PLC-β1 KO mice (n=6) were treated with MK-801, a NMDA receptor (NMDAR) antagonist, following either standard housing or environmental enrichment, and the motor function and locomotor activity thus evoked was assessed. In addition, MK-801 binding to the NMDAR was evaluated through radioligand autoradiography in post-mortem tissue (on a drug-naive cohort). We have demonstrated a significantly increased sensitivity to the effects of the NMDA antagonist MK-801 in the PLC-β1 KO mouse. In addition, we found that this mouse line displays reduced hippocampal NMDAR expression, as measured by radioligand binding. We previously documented a reversal of specific phenotypes in this mouse line following housing in an enriched environment. Enrichment did not alter this heightened MK-801 response, nor NMDAR expression, indicating that this therapeutic intervention works on specific pathways only. These findings demonstrate the critical role of the glutamatergic system in the phenotype of the PLC-β1 KO mouse and highlight the role of these interconnected signalling pathways in schizophrenia-like behavioural disruption. These results also shed further light on the capacity of environmental factors to modulate subsets of these phenotypes.

Electrophysiological effects of guanosine and MK-801 in a quinolinic acid-induced seizure model

TORRES, F ; FILHO, M.S. ; ANTUNES, C. ; KALININE, E. ; ANTONIOLLI, E. ; PORTELA, Luis Valmor ; SOUZA, Diogo Onofre ; TORT, A. B. L. . Electrophysiological effects of guanosine and MK-801 in a quinolinic acid-induced seizure model. Experimental Neurology , v. 221, p. 296-306, 2010

Effects of MK-801 and amphetamine treatments on allergic lung inflammatory response in mice

Glutamate acts as a neurotransmitter within the Central Nervous System (CNS) and modifies immune cell activity. In lymphocytes, NMDA glutamate receptors regulate intracellular calcium, the production of reactive oxygen species and cytokine synthesis. MK-801, a NMDA receptor open-channel blocker, inhibits calcium entry into mast cells, thereby preventing mast cell degranulation. Several lines of evidence have shown the involvement of NMDA glutamate receptors in amphetamine (AMPH)-induced effects. AMPH treatment has been reported to modify allergic lung inflammation. This study evaluated the effects of MK-801 (0.25mg/kg) and AMPH (2.0mg/kg), given alone or in combination, on allergic lung inflammation in mice and the possible involvement of NMDA receptors in this process. In OVA-sensitized and challenged mice, AMPH and MK-801 given alone decreased cellular migration into the lung, reduced IL-13 and IL10 levels in BAL supernatant, reduced ICAM-1 and L-selectin expression in granulocytes in the BAL and decreased mast cell degranulation. AMPH treatment also decreased IL-5 levels. When both drugs were administered, treatment with MK-801 reversed the decrease in the number of eosinophils and neutrophils induced by AMPH in the BAL of OVA-sensitized and challenged mice as well as the effects on the expression of L-selectin and ICAM-1 in granulocytes, the IL-10, IL-5 and IL-13 levels in BAL supernatants and increased mast cell degranulation. At the same time, treatment with MK-801, AMPH or with MK-801+AMPH increased corticosterone serum levels in allergic mice. These results are discussed in light of possible indirect effects of AMPH and MK-801 via endocrine outflow from the CNS (i.e., HPA-axis activity) to the periphery and/or as a consequence of the direct action of these drugs on immune cell activity, with emphasis given to mast cell participation in the allergic lung response of mice.

Effects of lamotrigine alone and in combination with MK-801, phenobarbital, or phenytoin on cell death in the neonatal rat brain

The neonatal rat brain is vulnerable to neuronal apoptosis induced by antiepileptic drugs (AEDs), especially when given in combination. This study evaluated lamotrigine alone or in combination with phenobarbital, phenytoin, or the glutamate antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) for a proapoptotic action in the developing rat brain. Cell death was assessed in brain regions (striatum, thalamus, and cortical areas) of rat pups (postnatal day 8) by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, 24 h after acute drug treatment. Lamotrigine alone did not increase neuronal apoptosis when given in doses up to 50 mg/kg; a significant increase in cell death occurred after 100 mg/kg. Combination of 20 mg/kg lamotrigine with 0.5 mg/kg MK-801 or 75 mg/kg phenobarbital resulted in a significant increase in TUNEL-positive cells, compared with MK-801 or phenobarbital treatment alone. A similar enhancement of phenytoin-induced cell death occurred after 30 mg/kg lamotrigine. In contrast, 20 mg/kg lamotrigine significantly attenuated phenytoin-induced cell death. Lamotrigine at 10 mg/kg was without effect on apoptosis induced by phenytoin. Although the functional and clinical implications of AED-induced developmental neuronal apoptosis remain to be elucidated, our finding that lamotrigine alone is devoid of this effect makes this drug attractive as monotherapy for the treatment of women during pregnancy, and for preterm or neonatal infants. However, because AEDs are often introduced as add-on medication, careful selection of drug combinations and doses may be required to avoid developmental neurotoxicity when lamotrigine is used in polytherapy.

Electrophysiological effects of guanosine and MK-801 in a quinolinic acid-induced seizure model

TORRES, F ; FILHO, M.S. ; ANTUNES, C. ; KALININE, E. ; ANTONIOLLI, E. ; PORTELA, Luis Valmor ; SOUZA, Diogo Onofre ; TORT, A. B. L. . Electrophysiological effects of guanosine and MK-801 in a quinolinic acid-induced seizure model. Experimental Neurology , v. 221, p. 296-306, 2010

Electrophysiological effects of guanosine and MK-801 in a quinolinic acid-induced seizure model

TORRES, F ; FILHO, M.S. ; ANTUNES, C. ; KALININE, E. ; ANTONIOLLI, E. ; PORTELA, Luis Valmor ; SOUZA, Diogo Onofre ; TORT, A. B. L. . Electrophysiological effects of guanosine and MK-801 in a quinolinic acid-induced seizure model. Experimental Neurology , v. 221, p. 296-306, 2010

Glutamatergic Modulation of Cue-Induced Drug-Seeking Behavior in the Rat

The characteristics of drug addiction include compulsive drug use despite negative consequences and re-occurring relapses, returns to drug use after a period of abstinence. Therefore, relapse prevention is one of the major challenges for the treatment of drug addiction. There are three main factors capable of inducing craving for drugs and triggering relapse long after cessation of drug use and dissipation of physical withdrawal signs: stress, re-exposure to the drug, and environmental stimuli (cues) that have been previously associated with drug use. The neurotransmitters dopamine and glutamate have been implicated in the modulation of drug-seeking behavior. The aim of this project was to examine the role of glutamatergic neurotransmission in relapse triggered by conditioned drug-associated stimuli. The focus was on clarifying whether relapse to drug seeking can be attenuated by blockade of glutamate receptors. In addition, as the nucleus accumbens has been proposed to participate in the modulation of drug-seeking behavior, the effects of glutamate receptor blockade in this brain structure on cue-induced relapse were investigated. The studies employed animals models in which rats were trained to press a lever in a test cage to obtain alcohol or intravenous cocaine. Drug availability was paired with distinct olfactory, auditory, or visual stimuli. This phase was followed by extinction training, during which lever presses did not result in the presentation of the drug or the drug-associated stimuli. Extinction training led to a gradual decrease in the number of lever presses during test sessions. Relapse was triggered by presenting the rats with the drug-associated stimuli in the absence of alcohol or cocaine. The drug-associated stimuli were alone capable of inducing resumption of lever pressing and maintaining this behavior during repeated testing. The number of lever presses during a session represented the intensity of drug-seeking and relapse behavior. The results suggest that glutamatergic neurotransmission is involved in the modulation of drug-seeking behavior. Both alcohol and cocaine relapse were attenuated by systemic pretreatment with glutamate receptor antagonists. However, differences were found in the ability of ionotropic AMPA/kainate and NMDA receptor antagonists to regulate drug-seeking behavior. The AMPA/kainate antagonists CNQX and NBQX, and L-701,324, an antagonist with affinity for the glycine site of the NMDA receptor, attenuated cue-induced drug seeking, whereas the competitive NMDA antagonist CGP39551 and the NMDA channel blocker MK-801 were without effect. MPEP, an antagonist at metabotropic mGlu5 glutamate receptors, also decreased drug seeking, but its administration was found to lead to conditioned suppression of behavior during subsequent treatment sessions, suggesting that MPEP may have undesirable side effects. The mGluR2/3 agonist LY379268 and the mGluR8 agonist (S)-3,4-DCPG decreased both cue-induced relapse to alcohol drinking and alcohol consumption. Control experiments showed however that administration of the agonists was accompanied by motor suppression limiting their usefulness. Administration of the AMPA/kainate antagonist CNQX, the NMDA antagonist D-AP5, and the mGluR5 antagonist MPEP into the nucleus accumbens resulted also in a decrease in drug-seeking behavior, suggesting that the nucleus accumbens is at least one of the anatomical sites regulating drug seeking and mediating the effects of glutamate receptor antagonists on this behavior.

Kirjallisuusosa: Alzheimerin taudin rottamallien vastaavuus tautiin ihmisessä ja mallien käyttökelpoisuus

Kirjallisuusosa: Alzheimerin taudin hoitoon olisi tarvetta uusille taudinkulkuun vaikuttaville lääkeaineille. Niiden kehittämiseksi tarvitaan eläinmalleja, joissa esiintyy taudin patofysiologisia piirteitä. Rottamalleista vanhemmat skopolamiini- tai MK-801-häirintä sekä ikääntyneiden rottien käyttö eivät kovin hyvin vastaa taudin patofysiologiaa, vaikka niissä eläimen muisti käyttäytymiskokeissa onkin heikentynyt. Uudemmat transgeeniset rottamallit ja mallit, joissa annetaan Aβ:a aivoihin, ilmentävät huomattavasti paremmin Alzheimerin taudin kaltaista tilaa aivoissa ainakin Aβ:n osalta. Taupatofysiologiaa ei silti kummassakaan näistä malleista juuri esiinny. Toisaalta Aβ:lla näyttäisi olevan huomattavasti tau:ta suurempi rooli taudissa, joten sen ilmeneminen mallissa onkin keskeisempi tekijä. Nämä mallit ilmentävät melko suurelti osin yhtä hyvin Alzheimerin taudin patofysiologiaa. Aβ:n antaminen on hieman yksinkertaisempi suorittaa käytännössä, sillä siinä ei tarvitse luoda transgeenista kantaa. Toisaalta transgeenisessa mallissa Aβ-patofysiologia syntyy enemmän Alzheimerin taudin kaltaisesti solujen sisällä eikä valmiita aggregoituvia Aβ-peptidejä anneta ulkopuolelta aivoihin. Molemmat mallit ovat kuitenkin käyttökelpoisia, ja soveltuvat erityisesti Aβ:an vaikuttavien lääkeaineiden kehittämiseen. Kokeellinen osa: Kokeen tarkoituksena oli validoida kohotettu ristikko-sokkelo (elevated plus-maze, EPM) hiirillä kognitiomallina. Kokeessa käytettiin kahden koekerran (trial, T) menetelmää, jossa koekertojen pituus oli viisi minuuttia. Näin saatiin useita oppimista kuvaavia parametreja. Hiirille yritettiin saada muistihäiriö aikaviiveen avulla (koekertojen väli 1-18 vrk) tai antamalla muskariinireseptoriantagonistia skopolamiinia (0,1-0,8 mg/kg i.p.) 30 minuuttia ennen T1:tä. Nämä kokeet suoritettiin sekä C57BL/6J- että ICR:(CD-1)-hiirillä. Aikaviivekokeissa ainut ryhmä, jolla oli viitettä unohtamisesta, oli ICR:(CD-1)-hiirien 18 vrk:n ryhmä. Tämän perusteella tutkittiin vielä 21 vuorokauden aikaväli, mutta selvää muistihäiriötä ei esiintynyt. Skopolamiini ei häirinnyt muistia ICR:(CD-1)-hiirillä, mutta C57BL/6J-hiirillä 0,2 mg/kg:n annoksesta ylöspäin merkitsevä muistihäiriö esiintyi. Näin ollen jatkokokeissa käytettäväksi valittiin skopolamiinin annos 0,2 mg/kg C57BL/6J-hiirillä, ja siinä tutkittiin donepetsiilin (0,3, 0,8 ja 1,5 mg/kg s.c), memantiinin (5,0 ja 10,0 mg/kg s.c) ja kokeellisen 5-HT6-antagonistin SB742457:n (1,5 ja 6,0 mg/kg s.c) muistia parantavia vaikutuksia. Tutkittavat lääkeaineet annettiin 40 minuuttia ennen T1:tä ja skopolamiini 30 minuuttia ennen. Memantiinilla (5,0 mg/kg) oli selkeä skopolamiinin heikentämää kognitiota parantava vaikutus ja donepetsiilillakin (1,5 mg/kg) suuntaus tähän. Tulosten perusteella malli näyttäisi soveltuvan muisti- ja oppimisvaikutusten tutkimiseen käytettäväksi malliksi.

Usage of substances and their dosage regimes in pharmacological animal models of schizophrenia

Background: Contrary to what is generally thought schizophrenia is a very common mental health issue. For this, several animal models are used to assess the illness in order to develop a definitive. The most widely spread paradigm is the use of pharmacological models. Aim: The aim of this review is to display which are the most used insults for the assessment of social behaviour related negative symptoms in animal models as well as to ascertain which is the most adequate regime. Design: Literature review. Methods: PubMed database was used for this article by the search of the indexed “schizophrenia”, “animal models”, “social behaviour” and “negative symptoms” descriptors. With the exception of a single article due to it value this review is based on articles from 10 years onwards. Besides, only clinical trials and reviews written in English or Spanish and that had laboratory rodents as target population were accepted. Results: The studies assessed agree that pharmacological models (specially those regarding the NMDA receptor antagonists) are a valuable means for the experimental investigation of negative symptoms in schizophrenia with the necessity to emphasise that only some negative symptoms (anhedonia and social interaction, mainly) can be experimentally assessed. Conclusions: There is not enough evidence regarding the fours aspects of this review. PCP, Ketamine or MK-801 in sub-acute dosage regimes are currently the most indicated insults to mimic schizophrenic symptoms in rodents, although further research in needed, albeit other substances are valuable as well. (In English language exclusively)

1. 大鼠海马-前额叶回路在学习记忆中的作用2. 芬克罗酮改善恒河猴空间工作记忆的谷氨酸机制

一、大鼠海马-前额叶回路在学习记忆中的作用 解剖学研究证实大鼠和猴的海马结构（hippocampal formation, HF；本文‘海马 (hippocampus, Hip)’一词即指海马结构）和前额叶 (prefrontal cortex, PFC) 之间存在一条单向、同侧和单突触的神经回路，即海马-前额叶回路（Hip-PFC回路）。Hip和PFC均参与学习记忆等多种认知功能，PFC是工作记忆的关键脑区，而Hip是空间参考记忆的关键脑区。虽然人们已经对PFC和Hip进行了广泛深入的研究，但对Hip-PFC回路参与哪些认知功能还知之甚少。本研究的目的就是通过暂时阻断Hip-PFC回路，探讨其在学习和记忆中的作用。 在大鼠，Hip-PFC回路中的纤维主要从Hip腹部 (ventral hippocampus, VH)发出，投射到PFC的前边缘皮质(prelimbic cortex, PLC)、下边缘皮质 (infralimbic cortex, ILC) 和外侧前额叶 (lateral prefrontal cortex) 等亚区，其中PLC是Hip-PFC主要投射的区域。我们通过给动物安装慢性导管向脑内注射GABAA受体激动剂muscimol (MU) 阻断Hip-PFC回路。注射位点包括 ①双侧PLC，②双侧VH，③一侧VH和对侧PLC (VH-PLC)。我们首先观察了在PLC或VH局部注射MU对自由活动大鼠PLC和VH脑电功率的影响，并以此确定在行为实验中所用蝇蕈醇的剂量。然后采用T-迷宫空间交互延缓作业 (spatial delayed alternation task) 测试Hip-PFC回路被阻断的动物的空间工作记忆功能；采用被动回避作业 (passive avoidance task) 测试其情绪相关记忆的能力（训练前给药；24 h后重测试）；采用Morris水迷宫作业 (Morris water maze task) 测试其空间参考记忆的能力（每天训练前给药；训练期（3 d）结束24 h后重测试）。结果表明：在大鼠PLC或VH局部注射0.5 μg/0.25μl MU后30 min显著抑制VH 和PLC的脑电功率 (VH, p < 0.01; PLC, p < 0.05 vs. PBS/baseline)。注射MU (0.5 μg/0.25μl) 到 ①双侧PLC、②双侧VH、③VH-PLC均显著降低动物在空间交互延缓作业 (All p < 0.001, vs. PBS) 和空间Morris水迷宫作业中的成绩 (All p < 0.05, vs. PBS)，表明Hip-PFC回路在空间工作记忆（空间短时记忆）和在空间参考记忆（空间长时记忆）中均起重要作用。在空间交互延缓作业中，双侧PLC被抑制的大鼠的成绩显著低于双侧VH或VH-PLC被抑制的动物，说明PFC在空间工作记忆功能中占有主导地位。在被动回避作业中，双侧VH被抑制动物的回避反应的潜伏期显著短于对照动物 (p < 0.05 vs. PBS)，说明双侧VH被抑制动物的情绪记忆受损；而双侧PLC或VH-PLC被抑制的动物其回避反应的潜伏期与对照动物无显著差异 (PLC, p > 0.9; VH-PLC, p > 0.3 vs. PBS)，表明双侧PLC或VH-PLC被抑制的动物情绪记忆正常。被动回避作业的结果说明VH参与情绪记忆的形成，但Hip-PFC回路在情绪记忆形成中不起重要作用。 以上结果表明，大鼠Hip-PFC回路参与空间工作记忆和空间参考记忆而不是情绪记忆功能。情绪记忆的关键脑结构是杏仁复合体 (amygdala complex, AMC)，VH与AMC有密切的纤维联系。VH被抑制的大鼠情绪记忆受损，说明情绪记忆可能与AMC-Hip回路有关。情绪记忆与空间记忆（参考记忆和工作记忆）在解剖上的分离说明，对于不同类型的记忆来说，其在脑内的信息加工过程是并行的。神经回路内部的信息加工过程则是串行的，回路上任何一个结构的破坏均可导致回路功能的损伤。本研究的结果为学习记忆的“多重记忆系统”理论和记忆信息加工的串行并行机制提供了新的实验证据。 二、芬克罗酮改善成年恒河猴空间工作记忆的谷氨酸机制 芬克罗酮是中科院昆明植物所郝小江等合成的取代吡咯烷酮类化合物。中科院昆明动物所蔡景霞等发现芬克罗酮能改善东莨菪碱、育亨宾等导致的多种动物的不同类型的学习记忆障碍，提高老年动物的学习记忆能力，尤其是老年猴的空间工作记忆。已证实芬克罗酮为部分钙激动剂，可使脑缺血沙土鼠脑内升高的谷氨酸降低，而使正常的沙土鼠海马胞外谷氨酸释放增加。那么芬克罗酮能否提高正常动物的学习记忆，其对正常动物学习记忆的提高是否与其增加谷氨酸的释放有关？本研究采用空间延缓反应作业和谷氨酸NMDA受体拮抗剂MK-801在正常成年猴恒河猴上探讨了以上问题。 结果表明，口服芬克罗酮可显著提高成年猴的空间工作记忆，其量效曲线呈倒‘U’形，符合许多促智药的量效特点。0.25 mg/kg和0.5 mg/kg为芬克罗酮的最佳有效剂量 (p < 0.05 vs. 安慰剂)。肌注MK-801 (0.1 mg/kg) 显著降低成年猴的空间工作记忆 (p < 0.01 vs. 安慰剂)，而口服2.0 mg/kg和4.0 mg/kg的芬克罗酮则显著改善MK-801导致的工作记忆障碍 (p < 0.05 vs. MK-801)。芬克罗酮的所有测试剂量不影响猴在作业中的反应时 (p > 0.05 vs. 安慰剂)，表明芬克罗酮在该剂量范围不影响动物的运动能力。 本研究结果提示，芬克罗酮可能通钙激动作用促进谷氨酸的释放，在一定剂量范围内提高胞外谷氨酸水平，提高正常动物的空间工作记忆等认知功能。 关键词：芬克罗酮，恒河猴，空间工作记忆，空间延缓反应作业，谷氨酸，MK-801

文冠果果壳提取物对学习记忆障碍的改善作用

目的研究文冠果果壳乙醇提取物、总皂苷及ST-n-2对学习记忆障碍的影响,并初步探讨其作用机制。方法采用跳台法观察东莨菪碱和亚硝酸钠所致学习记忆障碍小鼠的学习记忆能力,八臂放射状迷路法观察(+)-MK-801致学习记忆障碍大鼠的学习记忆能力。结果文冠果果壳乙醇提取物、总皂苷及ST-n-2均显著改善东莨菪碱所致的记忆获得障碍和亚硝酸钠所致的记忆巩固障碍,文冠果果壳乙醇提取物显著改善(+)-MK-801所致的工作记忆和参照记忆障碍。结论文冠果果壳乙醇提取物、总皂苷及ST-n-2对学习记忆障碍均有显著改善作用,其作用机制可能与增强中枢胆碱能神经系统及谷氨酸能神经系统功能、抗脑组织耗氧损伤有关;总皂苷是文冠果果壳改善记忆障碍的有效部位,ST-n-2是其主要有效成分之一。