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Entire Hippocampus (entire + hippocampus)
Selected AbstractsSpontaneous recurrent network activity in organotypic rat hippocampal slicesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005Majid H. Mohajerani Abstract Organotypic hippocampal slices were prepared from postnatal day 4 rats and maintained in culture for >6 weeks. Cultured slices exhibited from 12 days in vitro spontaneous events which closely resembled giant depolarizing potentials (GDPs) recorded in neonatal hippocampal slices. GDP-like events occurred over the entire hippocampus with a delay of 30,60 ms between two adjacent regions as demonstrated by pair recordings from CA3,CA3, CA3,CA1 and interneurone,CA3 pyramidal cells. As in acute slices, spontaneous recurrent events were generated by the interplay of GABA and glutamate acting on AMPA receptors as they were reversibly blocked by bicuculline and 6,7-dinitroquinoxaline-2,3-dione but not by dl -2-amino-5-phosphonopentaoic acid. The equilibrium potentials for GABA measured in whole cell and gramicidin-perforated patch from interconnected interneurones,CA3 pyramidal cells were ,70 and ,56 mV, respectively. The resting membrane potential estimated from the reversal of N -methyl- d -aspartate-induced single-channel currents in cell-attach experiments was ,75 mV. In spite of its depolarizing action, in the majority of cases GABA was still inhibitory as it blocked the firing of principal cells. The increased level of glutamatergic connectivity certainly contributed to network synchronization and to the development of interictal discharges after prolonged exposure to bicuculline. In spite of its inhibitory action, in a minority of cells GABA was still depolarizing and excitatory as it was able to bring principal cells to fire, suggesting that a certain degree of immaturity is still present in cultured slices. This was in line with the transient bicuculline-induced block of GDPs and with the isoguvacine-induced increase of GDP frequency. [source] Stem/progenitor cell proliferation factors FGF-2, IGF-1, and VEGF exhibit early decline during the course of aging in the hippocampus: Role of astrocytesGLIA, Issue 3 2005Ashok K. Shetty Abstract Dentate neurogenesis, important for learning and memory, declines dramatically by middle age. Although studies have shown that this age-related decrease can be reversed to some extent by exogenous applications of mitogenic factors, it is unclear whether one or more of these factors exhibits decline by middle age. We hypothesize that multiple stem/progenitor cell proliferation factors exhibit early decline during the course of aging in the hippocampus, and some of these declines are linked to age-related alterations in hippocampal astrocytes. We measured the concentrations of fibroblast growth factor-2 (FGF-2), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF) in the hippocampus of young, middle-aged, and aged F344 rats, using enzyme-linked immunosorbent assay (ELISA). In addition, we quantified the total number of FGF-2 immunopositive (FGF-2+) and glial fibrillary acidic protein immunopositive (GFAP+) cells in the dentate gyrus and the entire hippocampus. Our results provide new evidence that the concentrations of FGF-2, IGF-1, and VEGF decline considerably by middle age but remain steady between middle age and old age. Further, decreased concentrations of FGF-2 during aging are associated with decreased numbers of FGF-2+ astrocytes. Quantification of GFAP+ cells, and GFAP and FGF-2 dual immunostaining analyses, reveal that aging does not decrease the total number of astrocytes but fractions of astrocytes that express FGF-2 decline considerably by middle age. Thus, dramatically decreased dentate neurogenesis by middle age is likely linked to reduced concentrations of FGF-2, IGF-1, and VEGF in the hippocampus, as each of these factors can individually influence the proliferation of stem/progenitor cells in the dentate gyrus. Additionally, the results demonstrate that decreased FGF-2 concentration during aging is a consequence of age-related impairment in FGF-2 synthesis by astrocytes. © 2005 Wiley-Liss, Inc. [source] Redefining the boundaries of the hippocampal CA2 subfield in the mouse using gene expression and 3-dimensional reconstructionTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2005Edward S. Lein Abstract The morphology of neurons in the main divisions of the hippocampal complex allow the easy identification of granule cells in the dentate gyrus and pyramidal cells in the CA1 and CA3 regions of Ammon's horn. However, neurons in the CA2 subfield have been much more difficult to reliably identify. We have recently identified a set of genes whose expression is restricted to either the dentate gyrus, CA1, CA2, or CA3. Here we show that these genes have an essentially nonoverlapping distribution throughout the entire septotemporal extent of the hippocampus. 3-Dimensional reconstruction of serial sections processed for in situ hybridization of mannosidase 1, alpha (CA1), bcl-2-related ovarian killer protein (CA3), and Purkinje cell protein 4 (dentate gyrus + CA2) was used to define the boundaries of each subregion throughout the entire hippocampus. The boundaries observed for these three genes are recapitulated across a much larger set of genes similarly enriched in specific hippocampal subregions. The extent of CA2 defined on the basis of gene expression is somewhat larger than that previously described on the basis of structural anatomical criteria, particularly at the rostral pole of the hippocampus. These results indicate that, at least at the molecular level, there are robust, consistent genetic boundaries between hippocampal subregions CA1, CA2, CA3, and the dentate gyrus, allowing a redefinition of their boundaries in order to facilitate functional studies of different neuronal subtypes in the hippocampus. J. Comp. Neurol. 485:1,10, 2005. © 2005 Wiley-Liss, Inc. [source] A comparative analysis of constitutive and cell-specific promoters in the adult mouse hippocampus using lentivirus vector-mediated gene transferTHE JOURNAL OF GENE MEDICINE, Issue 11 2008Hitoshi Kuroda Abstract Background Viral vectors provide powerful tools for transgene delivery to the mammalian brain to assess the effects of therapeutic proteins, antisense RNAs or small interfering RNAs. A key advantage of such approaches is that specific brain regions implicated in a particular disease can be independently targeted. Methods To optimize transgene expression in sub-regions of the mouse hippocampus and with a view towards devising gene therapy strategies for Alzheimer's disease, we designed lentivirus-based reporter vectors bearing various promoters, including constitutive and cell-specific promoters. Furthermore, we devised methods allowing a side-by-side comparison of transgene expression levels in neural cells both in vitro and in vivo. Results Following stereotaxic injection into the adult mouse hippocampus, titer-adjusted lentiviral vectors bearing constitutive promoters resulted in robust and sub-region-specific transgene expression. Our results show that the human CMV-IE promoter resulted in efficient transgene expression in the entire hippocampus whereas transgene expression mediated by the hybrid hEF1,/HTLV promoter was limited mainly in the dentate gyrus and the CA2/3 region. Finally, the neuron-specific human synapsin I promoter was particularly effective in the dentate gyrus. Conclusions These findings indicate that subregion-specific transgene expression in the hippocampus can be achieved following lentivirus vector-mediated gene transfer. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||