摘要:

GENETICALLY identical mouse embryos were transferred into same-strain uteri (transfer controls) or into hybrid uteri. A third group was not transferred. When adult, the mice were given a series of behavioral tests. In-strain transfer controls differed from non-transfer mice only on two activity measures, and did not differ on any cognitive variable. In contrast, mice reared in hybrid uteri were found to be superior to in-strain transfer mice on discrimination learning, Lashley maze learning and Morris maze learning; they also showed better adaptation in an avoidance learning shuttlebox. To our knowledge this is the first study showing that the uterine environment can have a general enhancing effect upon cognitive competence across a broad range of behaviors.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

SOMATO-DENDRITIC subthreshold transient potassium current (ISA) was measured in acutely isolated rat hippocampal CA1 pyramidal neurons. The inactivation of this current was insensitive to externally applied H2O2(20 mM) which causes cysteine oxidation. This result suggests that Shal-channels not Shaker Kv1.4 channels underlie the somato-dendritic ISAin rat CA1 pyramidal neurons. The kinetics of the ISAinactivation was measured at various [K+]out. Increase in [K+]outleads to acceleration of Shal-channel inactivation. Thus, the shift in [K+]outfrom 1 to 50 mM results in decreased inactivation time constant from 37 to 91ms. This effect of [K+]outon the ISAis opposite to the previously described action of [K+]outon the inactivation of Shaker K+channels.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ACUTE incubation of NMDA with neuroblastom a × glioma hybrid (NG108–15) cells or neuroblastoma SK-N-SH cells produced significant attenuation of nociceptin/orphanin FQ (N/OFQ)-induced activation of G protein and inhibition of adenylyl cyclase. The attenuation of N/OFQ signaling by NMDA was dose-dependent, blockable by NMDA antagonists, and not observed in cells lacking NMDA receptors, indicating that the effect of NMDA is mediated by the NMDA receptor. Furthermore, NMDA antagonist pretreatment greatly attenuated N/OFQ-induced acute homologous desensitization of ORL1. Interestingly, the signaling induced by etorphine, an opioid agonist of wide spectrum, was sensitive to NMDA treatment in NG108–15 but insensitive in SK-N-SH cells, suggesting differential modulation of opioid signaling by NMDA. The attenuation effects of NMDA on μ opioid receptor-mediated signaling were also observed.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE evaluated the incentive motivational properties of MK-801 by determining its priming effect on drug-seeking behaviour following extinction of cocaine self-administration, an animal model for drug craving. Rats were allowed to self-adminstrate cocaine (0.5mg/kg) or saline during 10 daily sessions. MK-801 (0.1–0.52mg/kg, i.p.) dose-dependently reinstated responding for cocaine following an extinction period of 3 weeks. Responding was selectively enhanced in the previously drug-paired hole and was completely absent in rats with a history of saline self-administration. These data provide evidence for a possible role of NMDA receptors in the incentive motivation underlying cocaine-seeking behaviour. In addition, the ability of MK-801 to elicit drug-seeking behaviour may prove to be a serious drawback for the proposed use of NMDA antagonists in the treatment of drug addiction.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

TO investigate the possible role of 5HT1Band/or 5HT1Dreceptors in controlling neurogenic inflammation, we performed a co-localization study of the mRNA for 5HT1Band 5HT1Dreceptors and of substance P or calcitonin gene-related peptide (CGRP) mRNA in the guinea pig trigeminal ganglion using double labellingin situhybridization techniques. The 5HT1Dreceptor mRNA is abundant whereas 5HT1Breceptor mRNA is scarce. The vast majority of cells containing substance P mRNA also contained 5HT1Breceptor mRNA, but very few cells expressed substance P mRNA and 5HT1Dreceptor mRNA. Both receptor mRNAs were co-localized with CGRP mRNA. Hence, 5HT1Dreceptors may control the release of CGRP only, whereas 5HT1Breceptors may control the release of both substance P and CGRP. The question remains whether selective 5HT1Dagonists will have migraine abortive properties.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

NON-STEROIDAL anti-inflammatory drugs inhibit constitutive (COX-1) and induced cyclooxygenase (COX-2), blocking prostaglandin production. We have compared the effects on nociceptive reflexes of meloxicam, which is COX-2 selective, with indomethacin, which is non-selective, using anin vitrospinal cord preparation. Cords were taken from naive rats, and from rats with carrageenan-induced hyperalgesia of one hindpaw. Reflex thresholds were lower in carrageenan preparations. Superfusion with meloxicam (10–100 μM) dose-dependently inhibited baseline reflexes and wind-up in normal and carrageenan preparations, whereas indomethacin (100–300 μM) had no effect. Thus meloxicam inhibits spinal reflexes, whereas indomethacin does not, despite its high affinity for both COX isoforms. We conclude that meloxicam has spinal antinociceptive actions which cannot be explained by the current concept of COX inhibition.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

SUSTAINED iontophoresis of NMDA potentiated visual responses for minutes after the application in 16 of 38 cells (42%), peaking 3 min after the end of the application and declining to control levels within 12min. Potentiation was also seen after application of ACPD (36%,n= 14) and AMPA (29%,n= 14), but not after application of ACh (n= 20). ACh also excites dLGN cells, but does not interact with amino acid receptors, and ACh receptors are not directly involved in the transmission of visual information. We suggest that this modulation is a form of visually induced potentiation which permits dynamic modification of the strength of visual information to be relayed to the cortex depending upon the history of previous activity levels.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

A patient is presented who suffered a lateral brainstem infarction which selectively abolished pain and temperature sensitivity in the lower right limb. One year later central post-stroke pain had developed in the affected limb with touch and cold allodynia. P40m dipoles calculated from magnetoencephalographic fields after electrical stimulation of both tibial nerves were localized in SI as is seen in normal subjects. However, stimulation of the affected side caused deep pain sensations and elicited a large N80m component, best explained by an additionally active dipole in cingulate cortex. This early co-activation in a limbic structure suggests peripheral Aβ-fiber mediation and lemniscal projection. Abnormal link to the pain system may be due to sensitization and reorganization above the level of nociceptive deaf-ferentation.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE actin cytoskeleton is an important contributor to the integrity of cellular shape and responses in neurons. However, the molecular mechanisms associated with functional interactions between the actin cytoskeleton and neuronal ion channels are largely unknown. Wholecell and single channel recording techniques were thus applied to identified retinal bipolar neurons of the tiger salamander (Ambystoma tigrinu)mto assess the role of acute changes in actin-based cytoskeleton dynamics in the regulation of voltage-gated ion channels. Disruption of endogenous actin filaments after brief treatment (20–30 min) with cytochalasin D (CD) activated voltagegated K+currents in bipolar cells, which were largely prevented by intracellular perfusion with the actin filament-stabilizer agent, phalloidin. Either CD treatment under cell-attached conditions or direct addition of actin to excised, inside-out patches of bipolar cells activated and/or increased single K+channels. Thus, acute changes in actin-based cytoskeleton dynamics regulate voltagegated ion channel activity in bipolar cells.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WHOLE-CELL patch-clamp recordings were made from substantia nigra pars reticulata (SNR) neurones in rat midbrain slices to investigate the electrophysiological effects of cannabinoids. The cannabinoid receptor agonist WIN 55212-2 (10 μM) significantly reduced intranigrally evoked and spontaneous inhibitory post- synaptic currents (IPSCs) which were mediated by GABAAreceptors. The postsynaptic current induced by bath application of GABA was not affected by the presence of WIN 55212-2. The actions of WIN 55212-2 were not mimicked by the inactive enantiomer WIN 55212-3. WIN 55212-2 also hyperpolarized the membrane of SNR neurones in a tetrodotoxin/0–Ca2+-insensitive manner. These data suggest that cannabinoids modulate the activity of SNR neurones by presynaptic inhibition of GABA inputs. They may also exert a direct post-synaptic inhibition on these neurones.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID