Restorative Neurology and Neuroscience - Volume 5, issue 2

Authors: Knoops, Bernard | Ponsar, Cécile | Hubert, Isabelle | van den Bosch de Aguilar, Philippe

Article Type: Research Article

Abstract: The damaged septohippocampal pathway was utilized to study the axonal regeneration of injured neurons. Semipermeable tubes, 2-mm long, were placed in the axis of the transected septohippocampal pathway of adult rats. In a first series of experiments, empty tubes were implanted. Even six weeks after the operation, no regenerated axons were observed in the conduit. In a second series of experiments, in order to validate our approach, segments of pre-degenerated sciatic nerves were introduced into the tubes. Under these experimental conditions, acetylcholinesterase (AChE)-containing regenerated axonal processes were detected in the grafted sciatic nerves. Glial fibrillary acidic protein (GFAP)-immunodetection showed that …astroglial cells and astrocyte processes were able to progress on and into the peripheral grafts. At the electron microscopic level, axons were observed in close contact with Schwann cells which myelinated some of them. In some other cases, unmyelinated axons were also present at the surface of reactive astroglial cells filled by numerous intermediate filaments. These central glial cells had migrated among the sciatic nerve collagen fibers. No axon was detected without glial cell contact. In a third series of experiments, we implanted semipermeable tubes previously filled with a fibrin–fibronectin-containing matrix provided by peripheral regeneration chambers. One week after the implantation of the tubes containing this peripheral substrate, different cell types were observed migrating into the conduit and replacing the fibrin–fibronectin-containing matrix. Among these cells astrocytes were present as revealed by GFAP-immunocytochemistry and electron microscopic examinations. During the following weeks, axons were detected in contact with the reactive astroglial cells. AChE-histochemistry showed that axons were able to cross the two millimeter distance separating the septal part and the hippocampal part of the lesion site. GABA (γ-aminobutyric acid)-ergic fibers were also detected in the regenerated structure. These experiments show that cellular or acellular substrates provided by the PNS can promote the regeneration of CNS GABAergic and cholinergic neurons. Our observations suggest that astrocytes can take an important part, after their migration or after extending processes, in the axonal regeneration in the adult CNS of the rat, possibly in furnishing a cellular terrain for the progression of growth cones over a distance of two millimeters and in maintaining regenerated axons at least until the sixth week after the operation. Show more

Keywords: Septum, Hippocampus, Cholinergic neuron, GABAergic neuron, Axonal regeneration, Schwann cell, Astrocyte, Rat

DOI: 10.3233/RNN-1993-5201

Citation: Restorative Neurology and Neuroscience, vol. 5, no. 2, pp. 103-117, 1993

Authors: Sherwood, A.M. | Dimitrijevic, M.R. | Bacia, T. | McKay, W.B.

Article Type: Research Article

Abstract: The tonic stretch reflex elicited by vibration of a muscle or tendon provides a means of studying segmental reflex activity in humans with impaired volitional motor activity due to spinal cord injury (SCI). Vibration applied to the achilles or patellar tendon in a group of 51 SCI subjects elicited motor unit activity different from that found in 12 healthy subjects. Four distinct features of motor unit responses to vibration of a single tendon (achilles or patellar) could be seen in the SCI subjects: (i) a rapid onset, tonic response, frequently beginning with a single burst analogous to a tendon jerk, …in 72% of vibrated sites; (ii) repetitive, phasic bursts of activity or vibratory-induced clonus in 23% of the tonic responses; (iii) spread of activity to muscles distant from the vibration in 44% of the tonic responses; and vibratory-induced withdrawal reflexes (VWR) which occurred after vibration of 37% of the sites. Overall, 81% of stimulated sites responded to vibration in SCI subjects. In contrast, only 54% of vibrated sites responded in control subjects, always with a gradual onset tonic response, never accompanied by a VWR. The VWR in SCI subjects was typically of much larger amplitude than the tonic responses and involved a mean of 5 muscles (41% bilaterally). Features of these responses provide an insight into underlying neurocontrol mechanisms which may provide guidance in the selection of appropriate intervention or management strategies. Show more

Keywords: Spinal cord injury, Vibration, Vibratory reflex, Tonic vibratory reflex, Long loop reflexe, Motor control, Upper motor neuron

DOI: 10.3233/RNN-1993-5202

Citation: Restorative Neurology and Neuroscience, vol. 5, no. 2, pp. 119-129, 1993

Authors: Sakai, Kyoji | Yoshimoto, Yusuke | Date, Isao

Article Type: Research Article

Abstract: We examined the effect of a short-course treatment with a new immunosuppressive agent FK506 (FK) on the survivability of neural xenografts. Pieces of ventral mesencephalic tissues from rat embryos were transplanted into the right lateral ventricle of adult mice. The mice were either assigned to a 4-day FK (10 mg/kg/day) immunosuppressive scheme or were given no immunosuppression. The 4-day course treatment with FK was started on postoperative day 0, 2, 4, 6 or 8. The incidence of graft rejection 28 days after transplantation was 82%, 55%, 55%, 100% and 100% when FK was given on days 0–3, 2–5, 4–7, 6–9 …and 8–11, respectively. As a separate group, we examined the cellular infiltration in neural xenografts of the non-immunosuppressed recipients at two different time points (3 days and 7 days) after transplantation. The infiltration of T-lymphocytes was not detected 3 days after transplantation, but had occurred by 7 days after transplantation. We speculate that FK is more effective in preventing the rejection of neural xenografts when it is given just before the initiation of the T-lymphocytic infiltration. Show more

Keywords: Neural transplantation, Xenograft, FK506, Short-course treatment, Graft survival

DOI: 10.3233/RNN-1993-5203

Citation: Restorative Neurology and Neuroscience, vol. 5, no. 2, pp. 131-139, 1993

Authors: Fantie, Bryan | Kolb, Bryan

Article Type: Research Article

Abstract: The spatial learning of rats with medial prefrontal lesions was compared to that of animals with cortical transplants of frontal tissue from donors of embryonic age 17, 19, 21, or 23 days. The age of the donor tissue significantly affected the extent that the transplanted tissue developed as the E17 and E19 grafts were markedly larger than those from E21 or E23 animals. Nonetheless, transplants were viable at all ages. Rats with E19 grafts, but not rats with grafts at other ages, showed significant reduction of the expected deficit on the Morris water task. In contrast, only rats with E21 …grafts showed enhanced performance on a T-maze alternation task. The contrasting effects of the grafts of different aged tissue suggests that there may be some specific contributions of cortical grafts of different ages that leads to partial restoration of function. Show more

Keywords: Frontal cortex, Cortical graft, Neural transplantation, Development, Neocortex

DOI: 10.3233/RNN-1993-5204

Citation: Restorative Neurology and Neuroscience, vol. 5, no. 2, pp. 141-149, 1993

Authors: Tona, Alessandro | Perides, George

Article Type: Short Communication

Abstract: Silicone regeneration chambers prefilled with sodium hyaluronate (HA) gels of different molecular weight (MW) and at different concentrations were used to tubulize the transected rat sciatic nerve. After two weeks, the tissue cables bridging the severed nerve ends within the silicone tubes were examined. Low MW HA gels had no significant effect while high MW HA gels reduced the diameter of the growing bridges.

Keywords: Hyaluronate, Peripheral nerve regeneration, Rat sciatic nerve

DOI: 10.3233/RNN-1993-5205

Citation: Restorative Neurology and Neuroscience, vol. 5, no. 2, pp. 151-154, 1993

Authors: Copray, Jef C.V.M. | Vincent, Arnaud J.P.E. | van Roon, Willeke | Tomasini, Ron | Staal, Michiel J.

Article Type: Research Article

Abstract: In order to establish the number, the viability and the developmental potential of GABAergic neurons present in dopaminergic ventral mesencephalic (VM) grafts from embryonic rat, we have studied the survival and development of these neurons in culture. The GABAergic fraction demonstrated a highly disproportionate survival in culture in relation to other VM neurons resulting in a drastic change in the neuronal composition of the dissociated VM grafts. The occurrence of a similar gradual dominance of GABAergic neurons at the site of intracerebral implantation, may affect the development of grafted dopaminergic VM neurons and their interaction with host striatal cells.

Keywords: Substantia nigra, GABA, Transplantation, Cell culture, Dopamine, Brain graft, Parkinson's disease

DOI: 10.3233/RNN-1993-5206

Citation: Restorative Neurology and Neuroscience, vol. 5, no. 2, pp. 155-160, 1993

Article Type: Research Article

DOI: 10.3233/RNN-1993-5207

Citation: Restorative Neurology and Neuroscience, vol. 5, no. 2, pp. 161-172, 1993