Immunocytochemistry of B-50 (GAP-43) in the spinal cord and in dorsal root ganglia of the adult cat

Summary The distribution of the neural-specific growth associated protein B-50 (GAP-43), which persists in the mature spinal cord and dorsal root ganglia, has been studied by light and electron microscopic immunohistochemistry in the cat. Throughout the spinal cord, B-50 immunoreactivity was seen confined to the neuropil, whereas neuronal cell bodies were unreactive. The most conspicuous immunostaining was observed in the dorsal horn, where it gradually decreased from superficial laminae (I–II) toward more ventral laminae (III–V), and in the central portion of the intermediate gray (mainly lamina X). In these regions, the labelling was localized within unmyelinated, small diameter nerve fibres and axon terminals. In the rest of the intermediate zone (laminae VI–VIII), B-50 immunoreactivity was virtually absent. The intermediolateral nucleus in the thoracic and cranial lumbar cord showed a circumscribed intense B-50 immunoreactivity brought about by the labelling of many axon terminals on preganglionic sympathetic neurons. In motor nuclei of the ventral horn (lamina IX), low levels of B-50 immunoreactivity were present in a few axon terminals on dendritic and somal profiles of motoneurons. In dorsal root ganglia, B-50 immunoreactivity was mainly localized in the cell bodies of small and medium-sized sensory neurons. The selective distribution of persisting B-50 immunoreactivity in the mature cat throughout sensory, motor, and autonomie areas of the spinal cord and in dorsal root ganglia suggests that B-50-positive systems retain in adult life the capacity for structural and functional plasticity.     

Presumed capillary telangiectasia of the pons: MRI and follow-up

Capillary telangiectasia is a vascular abnormality primarily of the brainstem. The clinical relevance is unclear as is the association with clearly pathologic findings such as cavernous haemangioma. We report on four cases with capillary telangiectasia proven by follow-up und describe the imaging characteristics. T2 abnormality was only observed in half of the patients as was the presence of a discernable collecting vein. Whereas two cases were incidental findings in neurologically normal persons and one had symptoms clearly attributable to lacunar stroke, one patient may have had symptoms due to the vascular abnormality in the pons. Received: 26 January 1999; Revised: 24 August 1999; Accepted: 23 September 1999     

Changes in regional energy metabolism after closed head injury in the rat

We examined in the present investigation regional ATP, glucose, and lactate content in the cortical and subcortical structures, in a rat model of closed head injury (CHI). In serial tissue sections bioluminescence imaging of ATP, glucose, and lactate was performed at 4 h, 12 h and 24 h (n=4/5 per time point with) after the induction of CHI or sham surgery. Bioluminescence images were analyzed by computer-assisted densitometry, at the lesion site, in remote cortical areas, and in the subcortical structures (thalamus and caudate nucleus). ATP content was significantly decreased at the lesion site after 4 h and in the remote cortex at 12 h post-injury. At 12 h, the ATP content reached baseline levels on the ipsilateral side and at 24 h also at remote lateral parietal sites. In the contralateral cortex, ATP increased transiently above the baseline at 12 h. No significant changes in ATP were found in the thalamus and caudate nucleus. Cortical glucose and lactate contents could not be discerned over time. Following CHI there is an acute and progressive, yet transient, ischemic cortical profile, which is not reflected in subcortical areas.     

Bilaterale Hypoglossusparese als isolierte neurologische Symptomatik nach Schädel-Hirn-Trauma

We report a 72-year-old patient who developed an isolated bilateral hypoglossal nerve paralysis following head trauma with complete recovery after three months. Since the CT scan did not show any fractures of the posterior skull base, we discuss a traction nerve injury as a possible mechanism.     

Astrocytes re-express nestin in deafferented target territories of the adult rat hippocampus.

Up-regulation of the intermediate filament protein, nestin, is a sensitive indicator for the extent of astrocytic activation in regions of CNS close to the point of injury. However, it remains unclear whether activated astrocytes in distant, deafferented CNS territories are also capable of nestin re-expression. Here, we demonstrate that traumatic injury to the dentate gyrus is followed by the rapid but transient expression of nestin in astrocytes located in the stratum lucidum of field CA3. Up-regulation of nestin was first detected at 1 day, was still visible at 14 days, and returned to close to control levels by 28 days post-injury. The present investigation clearly demonstrates the sensitivity of nestin expression as a indicator of astroglial activation in hippocampal target territories undergoing deafferentation-related changes.     

Cytochemistry of 5'-nucleotidase in the superior cervical ganglion of the rat: effects of pre- and postganglionic axotomy

5'-Nucleotidase, a prominent nucleoside-producing ectoenzyme of glial plasma membranes, was studied by enzyme cytochemistry in the superior cervical ganglion of the rat under normal conditions and after pre- and postganglionic axotomy. In normal ganglia 5'-nucleotidase was restricted to capillary endothelial cells, localized both on the luminal surface and in pinocytotic vesicles. Following preganglionic axotomy, the number of enzyme-positive endothelial vesicles increased, whereas no 5'-nucleotidase was found on reactive Schwann cells during phagocytosis of degenerating preganglionic axon terminals. After postganglionic axotomy an even stronger increase in enzyme-containing endothelial vesicles occurred. In addition, 5'-nucleotidase activity became detectable on the plasma membrane of Schwann cells and proliferating satellite cells, which participate in the detachment of synapses from axotomized neurons. Fibroblasts in the endoneuronal connective tissue of regenerating ganglia also exhibited 5'-nucleotidase on their surface. The results obtained suggest that 5'-nucleotidase may be related to specific metabolic requirements of Schwann and satellite cells during regeneration and that these requirements differ from those of reactive Schwann cells after denervation of the ganglion. Postoperative changes in 5'-nucleotidase activity on endothelial cells and fibroblasts of the ganglion indicate an involvement of these cells in metabolic response elicited by pre- or postganglionic axotomy.     

B-50 (GAP-43) in the spinal cord caudal to hemisection: Indication for lack of intraspinal sprouting in dorsal root axons

Sprouting of dorsal root axons has been suggested to occur in the mature cat spinal cord caudal to a hemisection at a low thoracic level sparing the dorsal columns. The lesion interrupts supraspinal descending projections, while leaving ascending collaterals of dorsal root axons intact. This hypothesis was re-evaluated by comparing the light and electron microscopic immunoreactivity of B-50 (GAP-43) on both sides of the postulated target regions for sprouting, the intermediate gray and the dorsal horn. The neural-specific phosphoprotein B-50 is involved in regenerative and developmental axonal outgrowth and synaptic plasticity. The light microscopic distribution pattern and density of B-50 immunostaining, measured by quantitative densitometry, were bilaterally symmetrical in all segments below the hemisection 3.5, 8, 14, 21, and 56 days postoperatively, as they were in the intact animal. Ultrastructurally, growth cone-like profiles were not detectable during putative periods of sprouting in regions of interest. After removal of degenerated axon terminals, vacated postsynaptic places appeared to be covered by astrocytic processes. These results indicate that, under the present experimental conditions, sprouting of primary afferents in adult cats is unlikely to be involved in functional plasticity after removal of descending pathways. © 1993 Wiley-Liss, Inc.