Extracellular recordings in the colchicine-lesioned rat dentate gyrus following transplants of fetal dentate gyrus and CA1 hippocampal subfield tissue (original) (raw)
Related papers
Integration of hippocampal suspension grafts with host neocortex
Neuroscience, 1995
The possibility of histological and functional integration of nervous tissue heterotopically grafted into the adult host brain was investigated. Suspensions of embryonic (E17-18) rat hippocampus with dentate fascia were placed into acute cavities in the barrel field of young adult rats (n = 25). Golgi-Cox silver impregnation and Cresyl Violet stain were used for histological analysis 3~, months postgrafting. The surviving grafts were present in 80% of the grafted animals. Only three out of 20 surviving grafts were completely isolated from the surrounding host brain; other grafts had areas of direct confluence with the host neuropil. Extracellular recording of neuronal activity revealed normal spontaneous activity typical of the hippocampus in the majority of the grafts. Electrical stimulation of the posterior nucleus of the thalamus, homolateral motor neocortex, contralateral barrel field, and sensory stimulation of the host evoked responses in 50-60% of the grafted neurons. This did not differ significantly from the responsiveness of the similarly tested neurons of homotopic neocortical suspension grafts. The latencies of the responses in the hippocampal grafts were consistently longer (by about 10 ms) than in the neocortical ones. Comparison of the hippocampal suspension grafts with other types of hippocampal and neocortical grafts suggests that under certain conditions heterotopic tissue can be successfully integrated into the host brain. Development of the host-graft interconnections depends on topical proximity, the presence of denervated synaptic loci in both tissues, elimination of the intragraft neuronal targets and disruption of the intrinsic connections between them.
New Aspects of Graft-induced Central Plasticity and Neuroregeneration at T 10 in a Rat Model†
Journal of Neurology & Neurophysiology, 2017
Objective: Retest Brunelli's graft induced glutamate neurotransmitter switch at the neuromuscular junction in rat for the translation of new aspects of central plasticity concepts for human reconstructive surgery in spinal cord lesions. Methods: Randomized double blind controlled study in rat, which was limited to 30 animals (Charles River, 220 to 280 g). Ethical research approval was obtained from the Animal Research Committee of the University Hospital Schleswig Holstein, UK-SH, Lübeck, D, and legitimated by the Governmental Department of Agriculture, Natural Environments and Agriculture Kiel, D, in compliance with the European Commission Recommendation to retest and review of graft-induced glutamatergic regeneration and /or cholinergic co-transmission at the neuromuscular junction for reinnervation of the skeletal internal obliquus abdominal muscle fibres. Assessments were performed to demonstrate pharmacological neuromodulation after attaching the lateral corticospinal tract at T10 to the bisected skeletal motor nerve. Medication was administered for 14 days postoperatively-a) verum Cerebrolysin ® IP=12-b) shams NaCl 0.9% IP=11, and c) 7 controls (nil). 2nd Op at day 90 (16 surviving rats) for open proof of reinnervation and its type by a) CMAP, b)Vecuronium ® application. Fast Blue ® labeling were performed. 10 days later, on the 3rd Op N=15, euthanasia and organ fixation were performed. Extensive histology-morphology examinations were performed in Cluj. Results: Eight rats showed positive CMAPs. Reinnervation and neuromodulation were demonstrated by counting and comparison of the grafted muscle fibers diameter. Four CAMP-positive-rats received Vecuronium ® : 1 CERE and 1 NaCl each demonstrated a loss of amplitude respectively two an incomplete muscle blockage due to the coexistence of glutamatergic and cholinergic neurotransmission. Confirmation of the VGluT2 in axons was observed by immunofluorescence. FB+ neurons were observed in many Rexed laminae in grafted spinal cord, but not in the brain. Conclusion: The coexistence of graft-induced cholinergic and glutamatergic neurotransmission and a great capacity of lower motor neurons and other types of spinal neurons to regenerate were observed. Because of limited animals, pharmacological neuromodulation requires further investigation.
Neural grafting to ischemic lesions of the adult rat hippocampus
Experimental Brain Research, 1989
The purpose of this study was to examine the structural and connective integration of developing hippocampal neurons grafted to ischemic lesions of the adult rat hippocampus. The 4-vessel occlusion model was used to cause transient cerebral ischemia which damages CA1 pyramidal cells in the dorsal hippocampus, but spares nonpyramidal neurons and afferents in the area. One week later, cell suspensions were made from the CA1 region of fetal (E18-20) rats and injected stereotaxically into the lesion. The recipient brains were examined 6 weeks to 6 months later for survival, morphology, and intrinsic and extrinsic connections of the grafts. The methods used included cell stains, histochemical staining for acetylcholinesterease (ACHE), immunocytochemical staining for neuropeptides (cholelecystokinin (CCK), somatostatin (SS), enkephalin (Enk) and an astrocytic marker, glial fibrillary acidic protein (GFAP), as well as tracing by retrograde axonal transport of fluorochromes and light and electron microscopy of anterograde axonal degeneration. The grafts survived well (80%) and were often quite large. They were well integrated in the lesioned host brain area, contained both pyramidal cells and neuropeptidergic neurons and displayed a near normal GFAP immunoreactivity for astrocytes. The latter contrasted the dense gliosis of the host ischemic lesion. Judged by the AChE staining the grafts were innervated by cholinergic host septohippocampal fibers. Ingrowth of host hippocampal commissural fibers was demonstrated by Fink-Heimer staining for degenerating nerve terminals following acute lesions of the hippocampal commissures. At the ultrastructural level degenerating, electron dense terminals of host commissural origin were found even deep inside the graft neuropil in synaptic contact with mainly dendritic spines. A transplant efferent connection to Offprint requests to: N. T0nder (address see above) the host brain was demonstrated by retrograde fluorochrome tracing and consisted of a homotypic projection to more posterior levels of the ipsilateral host CA1 and subiculum. Minor abnormal, efferent projections to the host dentate molecular layer were shown in Timm staining. We conclude that fetal CA1 neurons grafted to one week old ischemic lesions of the dorsal CA1 in adult rats become structurally well incorporated and can establish nerve connections with the host brain.
Effects of Conditioning Lesions on Transplant Survival, Connectivity, and Function
Annals of the New York Academy of Sciences, 1987
Are there mechanisms intrinsic to the brain that can be drawn upon to promote functional repair after central nervous system (CNS) injury? Brain transplants provide a powerful approach for investigating this question. The successful grafting of neurons into damaged brain depends not only on the type of neurons transplanted but on the ability of the host brain to support and integrate these cells. In cell culture, for example, neurons will grow only if provided the proper medium and substrate. Similarly, the mature brain must provide the proper environment and be sufficiently adaptable to incorporate fetal neurons into its circuits. One of the first clues to the nature of intrinsic mechanisms came from the observation that introducing a delay between the time of injury and transplantation could significantly enhance the survival and integration of grafted neurons. This effect is correlated with the production and accumulation of trophic factors in the brain in response to injury. Thus, transplanted neurons may depend upon the establishment of proper "conditions" to enhance survival, integration, and behavioral function.
Experimental Neurology, 1983
Autologous sciatic nerve was grafted into rat brain by (i) passing an 8-mm segment of nerve tied to a straight surgical needle through two craniotomy holes ("throughand-through" model); (ii) inserting a small tube of polyethylene containing the 8mm nerve piece ("nerv~within-tube" model). Longitudinally oriented neurofilament-positive fibers were consistently observed within the graft. Compared with the through-and-through model, axonal sprouting in the nerve-within-tube model followed a slow-motion pattern so that a growing front of regenerating axons could be easily identified and more easily related to the cellular events occurring in Wallerian degeneration. In the through-and-through model, regenerated axons at the brainnerve interface followed a disorgamxed, tortuous course so that direct continuity between brain and graft was difficult to demonstrate. The reverse was true in the nerve-within-tube model, i.e., axons penetrated directly into the graft. The ditference in orientation of axonal growth at the brain-graft interface appeared to be related to the glial reaction. In the through-and-through model, reactive astrocytes formed a mesh of mndomly oriented fibers in the damaged brain tissue facing the graft (anisomorphic gliosis). Conversely, longitudinally oriented fibers extended directly from the brain to the graft in the nerve-within-tube model, where brain damage was substantially reduced (isomorphic gliosis). A different type of glial fibrillary acidic (GFA) protein-positive fibrous structures was identified in the graft. Compared with Abbreviations: GFA-glial fibrillary acidic, polys-polymorphonuclear leucocytes, NFneurohlament.
Neuroscience, 1986
Fetal noradrenergic neurons from the brain stem locus coeruleus region can be successfully grafted as a dissociated cell suspension provided that the dissociation is done in the absence of any trypsin digestion step. The survival, fiber outgrowth and biochemical function of locus coeruleus neurons, taken from 13-to 15-day-old rat embryos, have been studied after injection into the dorsal hippocampal formation and the thoracolumbar spinal cord in adult rats. All rats were treated with an i.v. injection of 6hydroxydopamine prior to grafting to remove the intrinsic locus coeruleus projections to these areas, and they were taken for fluorescence histochemical or biochemical analyses 2-7 months after transplantation. Up to 330 surviving noradrenaline neurons were found at each implantation site (injected with 2-3 ~1 of cell suspension) which represents an estimated survival rate of about 40%. In the most successful cases the entire dorsal hippocampal formation, and an approximately 4 cm long segment of the thoracolumbar spinal cord, was supplied with a new noradrenaline-containing terminal network, which reached normal densities in the regions closest to the grafts. In the hippocampal formation, in particular, the ingrowing axons re-established a laminar innervation pattern which resembled that of the normal locus coeruleus afferents. In the hippocampus, two 2-~1 injections of locus coeruleus cell suspension restored the total hippocampal noradrenaline content to an average of 55%, and the noradrenaline synthesis rate (as assessed by the rate of DOPA accumulation after synthesis inhibition) was found to be close to normal in the graft-reinnervated specimens. In the spinal cord, two 3-~1 injections restored the noradrenaline level in the thoracolumbar cord (a 4.5 cm long segment) to an average of 22% of normal, with the highest individual levels being close to normal. Determinations of the noradrenaline metabolite 3,4-dihydroxy-phenylethyleneglycol indicated that the rate of noradrenaline metabolism in the graftreinnervated spinal cord was close to that of the normal intact spinal cord. The results demonstrate the potential of the suspension grafting technique for extensive noradrenergic reinnervation of the hippocampal formation or large portions of the spinal cord. Fetal locus coeruleus neurons implanted in this way can re-establish fairly normal terminal innervation patterns and reinstate noradrenaline turnover and metabolism in a previously denervated central target. Recent studies during the last few years have shown that grafts of fetal monoaminergic neurons can at least to some degree substitute anatomically and functionally for damaged pathways in the adult rat CNS (see Ref. 3 for review). Similar to other types of central neurons, the noradrenergic neurons of the pontine locus coeruleus region survive grafting to the mature CNS provided that they are taken from fetal donors. The studies conducted so far have been confined to grafts of solid pieces of tissue into surgically prepared transplantation cavities provided
Cell Transplantation, 1995
techniques were employed to examine the distribution of cholinergic, catecholaminergic and serotonergic fibers within the transplants, and radiochemical enzyme assays and high performance liquid chromatography were used to determine the content of neurotransmitter markers for these same fiber systems. To examine functional integration of the transplanted neurons in terms of activation of molecular signaling systems, the graft recipient animals were exposed to a novel open field environment. This behavioral testing paradigm is known to induce c-fos mRNA and Fos protein within several areas of the normal brain, including the sensorimotor cortex. Subsequent detection of the induction of this particular immediate early gene (transcription as well as translation) in the grafts would accordingly indicate genomic activation and therefore functional integration at the level of molecular signaling systems. Our results showed that these global fiber systems are distributed evenly throughout the extent of three mo old neocortical grafts and that the content of transmitter-related markers for these systems do not differ significantly from control cortex. Open field exposure of the grafted animals resulted in c-jos mRNA and Fos protein expression of cells distributed throughout the transplants. We conclude that the "global" fiber system innervation of neocortical transplants placed into newborn rats is similar to the innervation of normal cortex and that grafted neurons respond to host brain activation at the level of molecular signaling systems. 0
Experimental Brain Research, 1995
The host response to immunologically incompatible intrastriatal neural grafts was studied using immunohistochemical techniques. Dissociated ventral mesencephalic tissue from embryonic donors of either syngeneic, allogeneic or xenogeneic (mouse) origin was stereotaxically implanted into adult rats. The brains were analysed 4 days, 2 weeks or 6 weeks after grafting with antibodies against the following antigenic structures: major histocompatibility complex (MHC) class I antigens; MHC class II antigens; complement receptor (CR) 3 (marker for microglia and macrophages); helper T-lymphocyte antigen-cluster of differentiation (CD) 4; cytotoxic T-lymphocyte antigen-CD8; tyrosine hydroxylase (TH) (marker for transplanted dopaminergic neurons). The number of surviving TH-positive cells was not different at the various time points in either the syngeneic or allogeneic groups, whereas the xenogeneic cells were all rejected by 6 weeks.