Restorative Neurology and Neuroscience - Volume 6, issue 3

Authors: Kerns, James M. | Pavkovic, Ivan M. | Fakhouri, Anton J. | Gray, George T.

Article Type: Research Article

Abstract: The effect of D.C. electrical fields on in vivo nerve regeneration following rat sciatic nerve transection was assessed by a toe-twitch tension method for motor recovery. Two groups for baseline comparisons received either a nerve transection and a neutral battery implant or a nerve crush and no implant. Two treatment groups each received a nerve transection and an implant delivering either cathodal (–10 μA) or anodal (+10 μA) current via electrodes positioned on either side of the transection site. The contralateral nerve was exposed but not given a lesion. The functional recovery was assessed at weekly intervals by comparing the …amplitude and area of the twitch tension curves on both sides, expressed as a ratio (index of motor recovery = IMR). By 28–35 days postoperative (dpo) the crushed/untreated group had mean IMR values not significantly different than the preoperative values. The transected/neutral group appeared to have the worst recovery throughout the study. Compared to these two groups, both the cathodal and anodal treatment groups with a transected nerve showed intermediate IMR values, but by 63 dpo the group differences were less. These results indicate that following a nerve transection lesion steady D.C. electrical fields may temporarily enhance the early functional recovery of motor nerve regeneration compared to conventional nerve repair alone. Show more

Keywords: Direct current, Electrical stimulation, Implantable stimulator, Nerve regeneration, Twitch tension

DOI: 10.3233/RNN-1994-6301

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 175-180, 1994

Authors: Kato, Sadafumi | Ide, Chizuka

Article Type: Research Article

Abstract: In order to examine whether the axonal sprouting at the node of Ranvier is a local event reactive to the lesion independent of influences from the cell body, the sciatic nerve of mouse (ddY strain) was freeze-injured at the mid-thigh and at the same time transected at the level 2 cm proximal to the frozen site. Within 5 h after freeze-transection, sprouts were formed at some nodes of Ranvier located within 0.5 mm proximal to the frozen site. These sprouts had almost the same ultrastructural features as those found in ordinary freeze-injury, showing a tendency to grow toward the overlying …Schwann cell basal lamina. However, the sprouts thus formed ceased to grow and became atrophic within 10 h after freeze-transection. This fact indicates that the axon has a property of sprouting at the node of Ranvier in the absence of the cell body. However, nutritional as well as constitutive substances from the cell body are needed to maintain the growth of the sprout. Show more

Keywords: Sprout, Node of Ranvier, Nodal axolemma, Freeze-transection, Cell body, Axonal transport, Atrophy

DOI: 10.3233/RNN-1994-6302

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 181-187, 1994

Authors: Walker, Janet L. | Resig, Philip | Guarnieri, Stuart | Sisken, Betty F. | Evans, Joyce M.

Article Type: Research Article

Abstract: Footprint analysis is a non-invasive method to quantitate functional recovery after crush injury in the rat sciatic nerve model. Traditional methods of producing the footprints for measurement are limited by inability to reliably produce clear prints when the injury is severe. We describe the use of video technique with image analysis to record and measure these prints. Video had fewer unmeasurable prints than ink. For the 1–5 and 2–4 toe spreads, there was good correlation of video measurements with ink method and better repeatability using video as compared with ink. However, the print length parameter determined by video had poorer …repeatability and poorly correlated with that measured by ink. Therefore, calculation of a Sciatic Function Index by video is not appropriate. Since the print length also varies with gait velocity, we believe that a ratio of injured:uninjured hindfoot 1–5 toe spreads as measured by video is a more reliable and repeatable measure of functional recovery in this model. Show more

Keywords: Nerve injury, Peripheral nerve, Axonotmesis, Nerve regeneration, Functional recovery

DOI: 10.3233/RNN-1994-6303

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 189-193, 1994

Authors: Abbadie, Catherine | Lombard, Marie-Christine | Morain, Françoise | Besson, Jean-Marie

Article Type: Research Article

Abstract: The aim of this study was to gauge the possible sprouting of primary afferent fibers following dorsal rhizotomies using Fos-like immunoreactivity (Fos-LI) in order to label neurons activated by formalin injection into the rat forepaw. To assess the functional consequences of possible sprouting of fine diameter primary afferents, we monitored the behavioral responses and to visualize fine afferent fiber sprouting, we examined calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) in the superficial laminae of the dorsal horn. Two types of dorsal rhizotomies and two delays post-rhizotomy were used: one dorsal root, C7 (C7 cut) or three consecutive dorsal roots, C6, C7 and …C8 (C6, C7, C8 cut), were sectioned on the right side three months or 7 days before the day when formalin was injected in the extremity of the ipsilateral forelimb. Control animals had no rhizotomy but received the formalin injection. In control animals, following the formalin injection the greatest number of Fos-LI neurons was encountered in the superficial laminae and in the neck of the dorsal horn of segments C5–T1. In the C7 cut group, the number of Fos-LI neurons was slightly decreased in all segments 7 days after the lesion whereas it was slightly increased 3 months after the lesion as compared to 7 days. In C6, C7 C8 cut group, the number of Fos-LI significantly decreased (90% of the control values) 7 days after the lesion, but after three months, it significantly increased in segments C7 and C8 as compared to 7 days. In parallel in this latter group, a marked depletion of CGRP-LI fibers was observed in the medial part of the superficial laminae at 7 days whereas a clear increase in CGRP-LI occured in the same region at 3 months. Behavioral observations showed a slight decrease in the licking time induced by the formalin injection in the C7 cut group both at 7 days and 3 months after the lesion as compared to the control group. The significant decrease of this behavior observed in C6, C7, C8 cut group at 7 days was not changed after 3 months. The increase in the number of Fos-LI neurons after 3 months in the C6, C7, C8 cut group is discussed in terms of collateral sprouting of thin primary afferent fibers and/or central compensatory mechanisms in response to peripheral deafferentation. Our data favor the first hypothesis, and in addition, support the use of the Fos-LI technique to assess the functional post-synaptic changes at the dorsal horn level. Show more

Keywords: Collateral sprouting, Immediate early gene, Immunohistochemistry, Deafferentation, Nociceptive behavior, Spinal cord

DOI: 10.3233/RNN-1994-6304

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 195-207, 1994

Authors: Clowry, G.J. | Sieradzan, K. | Vrbová, G.

Article Type: Research Article

Abstract: Solid grafts of E12 embryonic spinal ventral horn were transplanted into motoneuron-depleted adult lumbar spinal cord in the rat. A muscle was implanted parallel to the vertebral column with its nerve inserted into the lumbar cord at the site of transplantation so as to provide a target for innervation by the grafted neurons. Previous retrograde labelling studies have shown that modest numbers of grafted motoneuron-like cells participate in the muscle's reinnervation and these are often found outside the graft within the host spinal cord. However, Nissl stained sections show that larger numbers of neurons survive within tissue recognisable as being …of graft origin. In this study we have examined the expression of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) by neurons within the graft. These enzymes are involved in cholinergic neurotransmission and are characteristic of motoneurons. Thirty-four to seventy days following transplantation the grafts contained numerous neurons with acetylcholinesterase (AChE) activity. Different patterns of AChE staining were observed which probably reflected the degree of differentiation and maturation within the graft. AChE positive neurons were found in isolation or in groups resembling developing motor pools. Most of the AChE-positive neurons appeared immature with scant cytoplasm. However, neurons could be found which appeared relatively mature with a regularly shaped nucleus, prominent nucleolus and Nissl bodies. The grafts contained few AChE-positive axons and no dense plexuses of varicose fibres around the neurons such as are found around motoneurons in the mature ventral horn. Comparisons between the size of AChE-positive neurons in the graft and the size of AChE-positive neurons in the developing ventral horn found that the size of grafted neurons to be intermediate between the sizes of spinal motoneurons at E19 and P0. Far fewer grafted neurons were found to be immunoreactive for choline acetyltransferase (ChAT) than histochemically reactive for AChE. This was consistent with our findings in the spinal cord during normal development where we found that fixation and staining procedures which labelled adult motoneurons failed to reliably demonstrate ChAT immunoreactivety in normal motoneurons prenatally, although AChE histochemical reactivity could be demonstrated as early as E16. We conclude that the grafts contain numbers of immature motoneurons which fail to proceed beyond a certain stage of development, perhaps because of a failure to form appropriate efferent and afferent connections. Show more

Keywords: Acetylcholinesterase, Choline acetyltransferase, Developmental neurobiology, Histochemistry, Immunocytochemistry, Motoneuron, Neural grafting

DOI: 10.3233/RNN-1994-6305

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 209-219, 1994

Authors: Harvey, A.R. | Chen, M. | Plant, G.W. | Dyson, S.E.

Article Type: Research Article

Abstract: The efficacy of Schwann cell-filled polycarbonate tubes as a bridging substrate for regrowing axons following lesions of the rat optic tract or cerebral cortex has been assessed after short (11–31 days) or long (82–119 days) survival times. Tubes were impregnated with Iaminin and poly-L-lysine, soaked in basic FGF and filled with Schwann cells. They were implanted into optic tract lesions in 34 rats aged 15–21 days and into cortical lesion cavities in 3 adult rats. Gelfoam soaked in basic FGF and Schwann cell conditioned medium was placed over the tubes. In one group of rats, axon regrowth into implants was …assessed using neurofilament antibody RT97; antibodies to proteolipid protein, Po , Iaminin, the low-affinity nerve growth factor receptor (NGFr), S-100 and EDI were also used to study myelination and the cellular content of the tubes. In a second group of rats, anterograde tracing techniques were used to specifically identify host retinal axons within the implanted polymers. After long survival times, the relationships between regrown axons and cells inside the tubes were also examined ultrastructurally. In all implants examined immunohistochemically at short survival times, large numbers of RT97+ axons were found throughout the tubes, usually in association with Iaminin+ , NGFr+ Schwann cells. At longer survival times, viable Schwann cells were still present, but tubes contained fewer axons and less cellular material. This material often formed a cord (200–250 μm thick) which extended the length of the implant. In the second group of rats, labelled retinal axons were found in 11 of the 16 implants that were attached to the dLGN. Axons regrew up to 1 mm but did not reach the distal (tectal) end of the implants. Interestingly, there was no evidence of myelinogenesis by either implanted Schwann cells or by host-derived oligodendroglia which had migrated into the tubes. Oligodendroglia were usually encircled by processes, many of which originated from Schwann cells, suggesting that the grafted cells may have been involved in isolating the central glia. The data show that Schwann cell-filled polycarbonate tubes provided a favourable milieu for axonal regeneration in the short term; however over time there was a decrease in the cellular and fibre content of the tubes. After intracranial implantation, an additional supporting matrix inside the polycarbonate tubes may aid in providing an environment conducive to the long term maintenance of regenerated retinal and other axons. Show more

Keywords: Schwann cell, Regeneration, Retinal axon, Polymer, Myelin

DOI: 10.3233/RNN-1994-6306

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 221-237, 1994

Authors: Tønder, Niels | Aznar, Susana | Johansen, Flemming Fryd

Article Type: Research Article

Abstract: Fascia dentata tissue blocks from newborn rats were grafted into one-week-old, ibotenic acid-induced lesions of the fascia dentata, or the normal fascia dentata of adult rats. After at least 2 months survival the recipient rats were subjected to 10 min of forebrain ischemia (4-vessel occlusion), and examined 2 or 4 days later for neuronal degeneration in the host hippocampi and the transplants, by silver staining and immunohistochemistry. Transplants survived well in both normal and lesioned host brains, with easily recognizable subfields and layers and presence of normal types of principal and non-principal neurons. As expected, argyrophilic, degenerating neurons were present …in the pyramidal cell layer of CAl and CA3c of the non-grafted contralateral host hippocampus and in the contralateral dentate hilus (CA4). In the hilus the degeneration corresponded to the loss of somatostatin-immunoreactive neurons, while parvalbumin-immunoreactive neurons were spared. In the dentate transplants degenerating neurons were observed in the granule cell layer, the hilus and the adjacent CA3 pyramidal cell layer. There was no obvious loss of either somatostatin- or parvalbumin-immunoreactive neurons. The degeneration varied considerably between transplants, from a few to large groups of silver stained neurons, but this difference did not display any obvious relation to grafting into normal or lesioned hosts, the exact location of the grafts or the general organization and distribution of intrinsic or extrinsic host afferents in the grafts. The results demonstrate that both ischemia-susceptible and -resistant types of neurons grafted to normal and lesioned adult rat brains are susceptible to transient forebrain ischemia after transplantation. In spite of an extensive reorganization of transplant nerve connections, the physiologicalbiochemical mechanisms necessary for the induction of ischemic cell death were accordingly present in the transplants. Show more

Keywords: Hippocampus, Grafting, Ibotenic acid, Functional integration, Degeneration, Somatostatin, Parvalbumin

DOI: 10.3233/RNN-1994-6307

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 239-249, 1994

Authors: Pyapali, Gowri K. | Dong, Wei-Qiang | Deupree, David L. | Bradley, Jennifer | Turner, Dennis A.

Article Type: Short Communication

Abstract: Effects of fetal hippocampal transplants were evaluated following a prolonged intraventricular excitotoxic lesion (1.0 mg of N-methyl-D-aspartate over two weeks infusion) in F344 rats. The septum and ipsilateral hippocampus (CA1 and dentate regions) showed extensive cell loss, decreased acquisition of spatial memory was observed and a decrease in AChE positive fiber innervation to the hippocampus was noted following the lesion. Fetal hippocampal transplants into the posterior lateral ventricle resulted in moderate graft survival and physiological analysis of graft–host interconnection in vitro demonstrated evoked field potentials. However, the transplants did not lead to significant improvement in behavior, possibly due to poor …synaptic integration of the intraventricular transplants into the host hippocampus. The prolonged intraventricular NMDA lesion may be helpful to understand a mixed lesion model of both septal areas and hippocampus and also as a background lesion in which to assess the connectivity and development of various types of neural grafts. Show more

Keywords: Fetal transplant, Hippocampus, N-methyl-D-aspartate, Water maze, Physiological recording, Experimental Alzheimer's model

DOI: 10.3233/RNN-1994-6308

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 251-256, 1994

Authors: Finger, Stanley

Article Type: Book Review

DOI: 10.3233/RNN-1994-6309

Citation: Restorative Neurology and Neuroscience, vol. 6, no. 3, pp. 257-258, 1994