ABSTRACT
The receptor tyrosine kinase RET is part of a functional receptor for glial cell derived neurotrophic factor (GDNF) and neurturin (NTN) which are potent neurotrophic factors for motoneurons. Here, we have studied RET-like immunoreactivity of motoneurons in post-mortem spinal cords of patients with amyotrophic lateral sclerosis (ALS) and in controls. We report that the intensity of RET-like immunostaining of motoneurons in ALS is decreased significantly to 81% of control values. Despite this change, the proportion of all large (>40 micron diameter) motoneurons showing RET-like immunoreactivity in ALS remains high (82-85%) and is not significantly different to controls. The persistence of RET-like immunoreactivity in the majority of large motoneurons in ALS could be important in the design of clinical trials of GDNF and NTN.
Subject(s)
Amyotrophic Lateral Sclerosis/metabolism , Drosophila Proteins , Motor Neurons/metabolism , Proto-Oncogene Proteins/metabolism , Receptor Protein-Tyrosine Kinases/metabolism , Spinal Cord/metabolism , Aged , Aged, 80 and over , Glial Cell Line-Derived Neurotrophic Factor Receptors , Humans , Immunohistochemistry , Middle Aged , Proto-Oncogene Proteins c-ret , Reference Values , Spinal Cord/pathology , Tissue DistributionABSTRACT
Three months after facial nerve transection, total numbers of motoneurons in the facial nucleus of six month (adult) Fischer 344 and Wistar rats were reduced to 83% and 75% of contralateral values, respectively (P < 0.05). This procedure in 22-26 month (ageing) Fischer 344 rats and Wistar rats resulted in a reduction of motoneuron numbers to 77% and 60% of the respective contralateral values (P < 0.05). Compared to adults, contralateral facial nuclei of aging Fischer 344 rats contained 10% fewer motoneurons (non-significant), while ageing Wistar rats had 22% fewer (P < 0.05). No significant changes were found in the proportion of surviving motoneurons expressing calcitonin gene-related peptide, galanin, receptor tyrosine kinase-C or the alpha subunit of the ciliary neurotrophic factor receptor. We conclude that ageing reduces facial motoneuron number and increases their vulnerability to axotomy in Wistar rats, but not in Fischer 344 rats. In neither strain, however, does the proportion of surviving motoneurons expressing the above neuropeptides or neurotrophic factor receptors change. This information may be relevant to those hypotheses of age-related neuronal degenerations which assume that decreased neurotrophic support renders ageing neurons more vulnerable to injury.
Subject(s)
Aging/metabolism , Axotomy , Motor Neurons/physiology , Neuropeptides/metabolism , Receptors, Nerve Growth Factor/metabolism , Animals , Brain Stem/pathology , Brain Stem/physiology , Cell Survival/physiology , Facial Nerve/physiology , Male , Rats , Rats, Inbred F344 , Rats, WistarABSTRACT
Neurotrophin-like immunoreactivity was studied in post-mortem motor cerebral cortex from patients with Amyotrophic Lateral Sclerosis (ALS) and controls. Neurotrophin-4/5 immunoreactivity was seen in small-(12-25 microm), medium-(26-39 microm), and large-(> 40 microm), neurones, neurotrophin-3 was seen in medium and small neurones, while brain-derived neurotrophic factor was restricted to small neurones. No difference in number or intensity of immunostained neurones was found between ALS and controls.
Subject(s)
Amyotrophic Lateral Sclerosis/metabolism , Motor Cortex/chemistry , Nerve Growth Factors/analysis , Aged , Aged, 80 and over , Brain-Derived Neurotrophic Factor/analysis , Humans , Immunohistochemistry , Middle Aged , Neuroprotective Agents/analysis , Neurotrophin 3ABSTRACT
We have demonstrated neurotrophin-3 (NT-3)-like immunoreactivity and tyrosine kinase C (Trk C) receptor expression in motoneurones in postmortem amyotrophic lateral sclerosis (ALS) and control human spinal cord sections. We report that NT-3-like immunoreactivity in motoneurones is decreased in ALS when compared to control tissue. Trk C is expressed in low abundance in both control and ALS motoneurones. These findings are of importance in developing therapeutic strategies for ALS.
Subject(s)
Amyotrophic Lateral Sclerosis/metabolism , Motor Neurons/chemistry , Nerve Growth Factors/immunology , Receptor Protein-Tyrosine Kinases/genetics , Receptors, Nerve Growth Factor/genetics , Spinal Cord/cytology , Aged , Aged, 80 and over , Female , Gene Expression/physiology , Humans , Immunohistochemistry , In Situ Hybridization , Male , Middle Aged , Motor Neurons/physiology , Nerve Growth Factors/analysis , Neurotrophin 3 , RNA, Messenger/analysis , Receptor, trkCABSTRACT
Expression by rat motoneurons of mRNAs for the alpha subunit of the ciliary neurotrophic factor receptor (CNTFR alpha), receptor tyrosine kinase-C (trkC), calcitonin gene-related peptide (CGRP) and galanin was studied by in situ hybridisation, 6d after rat facial nerve transection on postnatal day 1. Similar numbers of motoneurons in both injured and non-injured nuclei hybridised with all probes, despite a reduction in total numbers of motoneurons ipsilaterally. When ciliary neurotrophic factor (CNTF) was applied to the proximal nerve, twice as many motoneurons in the injured nucleus hybridised with the CNTFR alpha probe ipsilaterally compared to the non-injured nucleus, while motoneuronal loss was not evident. These results indicate that survival of motoneurons after neonatal axotomy and CNTF treatment is associated with increased CNTF receptor alpha expression.
Subject(s)
Axons/physiology , Facial Nerve/cytology , Motor Neurons/chemistry , Nerve Tissue Proteins/pharmacology , Receptors, Nerve Growth Factor/genetics , Animals , Ciliary Neurotrophic Factor , Denervation , Galanin/genetics , In Situ Hybridization , Motor Neurons/enzymology , Motor Neurons/ultrastructure , Nerve Growth Factors/pharmacology , RNA, Messenger/analysis , Rats , Rats, Wistar , Receptor Protein-Tyrosine Kinases/genetics , Receptor, Ciliary Neurotrophic Factor , Receptor, trkC , Receptors, Nerve Growth Factor/chemistryABSTRACT
The ultrastructural effects of CNTF or BSA on the retrograde response of adult rat spinal motoneurones were quantified at 7 days. Axotomy with or without CNTF or BSA generally resulted in fragmentation of the rough endoplasmic reticulum (RER). One third of CNTF-treated motoneurones had RER with a more ordered lamella arrangement than controls. Decreased area of the Golgi apparatus was seen after CNTF and BSA treatment. Other features of the retrograde response were unaffected.
Subject(s)
Axons/physiology , Microglia/ultrastructure , Motor Neurons/ultrastructure , Nerve Tissue Proteins/pharmacology , Animals , Axonal Transport , Axons/drug effects , Ciliary Neurotrophic Factor , Female , Microglia/cytology , Microglia/drug effects , Motor Neurons/cytology , Motor Neurons/drug effects , Rats , Rats, Wistar , Serum Albumin, Bovine/pharmacology , Spinal Cord/cytologyABSTRACT
Ciliary neurotrophic factor (CNTF) is known to rescue motor neurones in animal models of injury and neurodegeneration and we have recently described regional changes of CNTF protein levels in spinal cord from patients with sporadic motor neurone disease of the amyotrophic lateral sclerosis (ALS) type. However, information is lacking about the CNTF receptor in this condition. We have therefore studied mRNA levels for the alpha subunit of the CNTF receptor (CNTFR alpha) and for CNTF itself in postmortem spinal cord and cerebral cortex in patients with sporadic ALS and matched controls. We report that in the spinal cord of ALS patients there is a marked increase in the hybridisation signal for CNTFR alpha subunit mRNA overlying motor neurones. In contrast, very little mRNA for CNTFR alpha subunit was found in the motor cortex and no differences were seen between ALS and controls. We were unable to detect any hybridisation signal for CNTF mRNA. Our findings provide evidence for regional differences in CNTF receptor expression in upper- and lower-motor neurones in ALS.