18,661 research outputs found
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Inhibition of alpha7 nicotinic receptors in the ventral hippocampus selectively attenuates reinstatement of morphineāconditioned place preference and associated changes in AMPA receptor binding
Recurrent relapse is a major problem in treating opiate addiction. Pavlovian conditioning plays a role in recurrent relapse whereby exposure to cues learned during drug intake can precipitate relapse to drug taking. Ī±7 nicotinic acetylcholine receptors (nAChRs) have been implicated in attentional aspects of cognition and mechanisms of learning and memory. In this study we have investigated the role of Ī±7 nAChRs in morphineāconditioned place preference (morphineāCPP). CPP provides a model of associative learning that is pertinent to associative aspects of drug dependence. The Ī±7 nAChR antagonist methyllycaconitine (MLA; 4 mg/kg s.c.) had no effect on the acquisition, maintenance, reconsolidation or extinction of morphineāCPP but selectively attenuated morphineāprimed reinstatement of CPP, in both mice and rats. Reinstatement of morphineāCPP in mice was accompanied by a selective increase in [3H]āAMPA binding (but not in [3H]āMK801 binding) in the ventral hippocampus that was prevented by prior treatment with MLA. Administration of MLA (6.7 Ī¼g) directly into the ventral hippocampus of rats prior to a systemic priming dose of morphine abolished reinstatement of morphineāCPP, whereas MLA delivered into the dorsal hippocampus or prefrontal cortex was without effect. These results suggest that Ī±7 nAChRs in the ventral hippocampus play a specific role in the retrieval of associative drug memories following a period of extinction, making them potential targets for the prevention of relapse
Projections from the brain to the spinal cord in the mouse
The cells that project from the brain to the spinal cord have previously been mapped in a wide range of mammalian species, but have not been comprehensively studied in the mouse. We have mapped these cells in the mouse using retrograde tracing after large unilateral Fluoro-Gold (FG) and horseradish peroxidase (HRP) injections in the C1 and C2 spinal cord segments. We have identified over 30 cell groups that project to the spinal cord, and have confirmed that the pattern of major projections from the cortex, diencephalon, midbrain, and hindbrain in the mouse is typically mammalian, and very similar to that found in the rat. However, we report two novel findings: we found labeled neurons in the precuneiform area (an area which has been associated with the midbrain locomotor center in other species), and the epirubrospinal nucleus. We also found labeled cells in the medial division of central nucleus of the amygdala in a small number of cases. Our findings should be of value to researchers engaged in evaluating the impact of spinal cord injury and other spinal cord pathologies on the centers which give rise to descending pathways
The spinal precerebellar nuclei: Calcium binding proteins and gene expression profile in the mouse
We have localized the spinocerebellar neuron groups in C57BL/6J mice by injecting the retrograde neuronal tracer Fluoro-Gold into the cerebellum and examined the distribution of SMI 32 and the calcium-binding proteins (CBPs), calbindin-D-28K (Cb), calretinin (Cr), and parvalbumin (Pv) in the spinal precerebellar nuclei. The spinal precerebellar neuron clusters identified were the dorsal nucleus, central cervical nucleus, lumbar border precerebellar nucleus, lumbar precerebellar nucleus, and sacral precerebellar nucleus. Some dispersed neurons in the deep dorsal horn and spinal laminae 6ā8 also projected to the cerebellum. Cb, Cr, Pv, and SMI 32 were present in all major spinal precerebellar nuclei and Pv was the most commonly observed CBP. A number of genes expressed in hindbrain precerebellar nuclei are also expressed in spinal precerebellar groups, but there were some differences in gene expression profile between the different spinal precerebellar nuclei, pointing to functional diversity amongst them
Technical aspects of an impact acceleration traumatic brain injury rat model with potential suitability for both microdialysis and PtiO2 monitoring
This report describes technical adaptations of a traumatic brain injury (TBI)
model-largely inspired by Marmarou-in order to monitor microdialysis data and
PtiO2 (brain tissue oxygen) before, during and after injury. We particularly
focalize on our model requirements which allows us to re-create some drastic
pathological characteristics experienced by severely head-injured patients:
impact on a closed skull, no ventilation immediately after impact, presence of
diffuse axonal injuries and secondary brain insults from systemic origin...We
notably give priority to minimize anaesthesia duration in order to tend to
banish any neuroprotection. Our new model will henceforth allow a better
understanding of neurochemical and biochemical alterations resulting from
traumatic brain injury, using microdialysis and PtiO2 techniques already
monitored in our Intensive Care Unit. Studies on efficiency and therapeutic
window of neuroprotective pharmacological molecules are now conceivable to
ameliorate severe head-injury treatment
On-Off Intermittency in Time Series of Spontaneous Paroxysmal Activity in Rats with Genetic Absence Epilepsy
Dynamic behavior of complex neuronal ensembles is a topic comprising a
streamline of current researches worldwide. In this article we study the
behavior manifested by epileptic brain, in the case of spontaneous
non-convulsive paroxysmal activity. For this purpose we analyzed archived
long-term recording of paroxysmal activity in animals genetically susceptible
to absence epilepsy, namely WAG/Rij rats. We first report that the brain
activity alternated between normal states and epilepsy paroxysms is the on-off
intermittency phenomenon which has been observed and studied earlier in the
different nonlinear systems.Comment: 11 pages, 6 figure
Using a Panel of Immunomarkers to Define Homologies in Mammalian Brains
Brain mapping has relied on a small number of routine chemical stains for many decades. The advent of immunomarkers has had a major impact on the ability to define homologous nuclei from one species to another. The first atlas to present a panel of immunomarkers was that of Paxinos et al. (1999a,b) in the adult rat brain. The markers used were parvalbumin, calbindin, calretinin, SMI32, tyrosine hydroxylase, and NADPH diaphorase (plus nissl and acetylcholinesterase). The āsignatureā of a nucleus of interest in a new species can be tested against the findings in the rat. Since the pattern of immunomarkers seems to be conserved in mammalian evolution, such extrapolations can be made with reasonable confidence. A marmoset brain stained with a comprehensive set of immunomarkers has recently been published on the internet (Tokuno et al., 2009) and we are in the process of defining nuclear homologies in this brain by comparison with the same markers in the rat. In this article, we present an example (mapping the amygdala in the marmoset) which demonstrates the application of this immunomarker panel in defining homologies. The technique is particularly valuable in situations where little data on hodology or electrophysiology are available
The Number of Stem Cells in the Subependymal Zone of the Adult Rodent Brain is Correlated with the Number of Ependymal Cells and Not with the Volume of the Niche
The mammalian subependymal zone (SEZ; often called subventricular) situated at the lateral walls of the lateral ventricles of the brain contains a pool of relatively quiescent adult neural stem cells whose neurogenic activity persists throughout life. These stem cells are positioned in close proximity both to the ependymal cells that provide the cerebrospinal fluid interface and to the blood vessel endothelial cells, but the relative contribution of these 2 cell types to stem cell regulation remains undetermined. Here, we address this question by analyzing a naturally occurring example of volumetric scaling of the SEZ in a comparison of the mouse SEZ with the larger rat SEZ. Our analysis reveals that the number of stem cells in the SEZ niche is correlated with the number of ependymal cells rather than with the volume, thereby indicating the importance of ependymal-derived factors in the formation and function of the SEZ. The elucidation of the factors generated by ependymal cells that regulate stem cell numbers within the SEZ is, therefore, of importance for stem cell biology and regenerative neuroscience
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