Glaucoma is a chronic optic neuropathy characterized by progressive damage to the optic nerve, de... more Glaucoma is a chronic optic neuropathy characterized by progressive damage to the optic nerve, death of retinal ganglion cells and ultimately visual field loss. It is one of the leading causes of irreversible loss of vision worldwide. The most important trigger of glaucomatous damage is elevated eye pressure, and the current standard approach in glaucoma therapy is reduction of intraocular pressure (IOP). However, despite the use of effective medications or surgical treatment leading to lowering of IOP, progression of glaucomatous changes and loss of vision among patients with glaucoma is common. Therefore, it is critical to prevent vision loss through additional treatment. To implement such treatment(s), it is imperative to identify pathophysiological changes in glaucoma and develop therapeutic methods taking into account neuroprotection. Currently, there is no method of neuroprotection with long-term proven effectiveness in the treatment of glaucoma. Among the most promising molecules shown to protect the retina and optic nerve are neurotrophic factors. Thus, the current focus is on the development of safe and non-invasive methods for the long-term elevation of the intraocular level of neurotrophins through advanced gene therapy and topical eye treatment and on the search for selective agonists of neurotrophin receptors affording more efficient neuroprotection.
The article summarizes the most meaningful studies which have provided evidence that protein synt... more The article summarizes the most meaningful studies which have provided evidence that protein synthesis in neurons can occur not only in cell perikarya but also locally in dendrites. The presence of the complete machinery required to synthesize cytoplasmic and integral membrane proteins in dendrites, identification of binding proteins known to mediate mRNA trafficking in dendrites and the ability to trigger "on-site" translation make it possible for the synthesis of particular proteins to be regulated by synaptic signals. Until now over 100 different mRNAs coding the proteins involved in neurotransmission and modulation of synaptic activity have been identified in dendrites. Local protein synthesis is postulated to provide the basic mechanism of fast changes in the strength of neuronal connections and to be an important factor in the molecular background of synaptic plasticity, giving rise to enduring changes in synaptic function, which in turn play a role in local homeosta...
Bilateral transection of the lateral fimbria, which disrupts partially the septo-hippocampal proj... more Bilateral transection of the lateral fimbria, which disrupts partially the septo-hippocampal projections and results in partial hippocampal denervation, produced a significant increase in the ornithine decarboxylase (ODC) activity in the hippocampus. An increase occurred already 0.5 h after the operation and the activity remained intensified for at least 22 h after injury. The enzyme response was enhanced by a single dose of GM1 monosialoganglioside (30 mg/kg) administered directly after the operation. This enhancement, detected 2 h after the injury, persisted for at least 22 h after the operation. Lack of influence of GM1 ganglioside on ODC activity in the hippocampus of unlesioned animals allows us to ascribe the observed effect to the processes induced by the lesion. This study confirms the involvement of ODC in GM1 ganglioside neurotrophic effects produced in an injured brain.
The article presents the state of the art based on experimental studies in vivo and concerning th... more The article presents the state of the art based on experimental studies in vivo and concerning the mechanisms of stroke-induced neurodegeneration in the brain. Molecular bases of differences in brain regions affected indirectly and directly by cortical ischaemia are also discussed. Proteins which may play a key role in apoptosis, including the Bcl-2 protein family, are described in relation to their responses to the infarct. Finally, therapeutic perspectives connected with modulation of function of these proteins are outlined.
Partial deafferentation of the hippocampus due to trimethyltin (TMT) intoxication has been report... more Partial deafferentation of the hippocampus due to trimethyltin (TMT) intoxication has been reported to induce plastic rearrangements of neuronal elements but the factors that direct these responses are unknown. To assess the possible involvement of nerve growth factor (NGF) in the phenomenon we evaluated the presumable changes in the expression pattern of NGF immunoreactivity (NGF-IR) in rat hippocampus 21 days after administration of TMT (8 mg/kg, i.p.) when reactive changes are fully developed. Immunolabelling for TrkA known to mediate biological effects of NGF and for GFAP to identify astroglial cells as a one of presumed source of postinjury produced factors was carried out on adjacent sections to establish the relation between expression of these proteins. In control hippocampus NGF-IR and TrkA-IR were localized in neurons and/or neuropil. After exposure to TMT remarkable non-neuronal expression of both proteins was observed. The distribution pattern of NGF, TrkA and GFAP overl...
In view of neuroprotective effects of neurotrophins and neurotrophic factors on the damaged nervo... more In view of neuroprotective effects of neurotrophins and neurotrophic factors on the damaged nervous tissue clinical attempts have been made to use these proteins in the treatment of neurodegenerative diseases. However, the attempts were unsuccessful. We discuss the main causes of this failure and outline a new clinical prospect due to the growing understanding of the mechanisms underlying neurotrophin activity in the nervous system. A special emphasis has been laid on advances in the research aimed at optimization of pharmacodynamics of neurotrophins, and at development of new delivery systems that would not only supplement the nervous system with required neurotrophins locally, but also regulate their quantity and time span of their delivery. An alternative method of physical exercise allowing to upregulate neurotrophins and their receptors is also discussed.
INTRODUCTION AND METHODS: Locomotor training leads to improvement of stepping ability in animals ... more INTRODUCTION AND METHODS: Locomotor training leads to improvement of stepping ability in animals after spinal cord transection (1). Recent data point to neurotrophins as possible factors involved in this improvement. Motoneurones synthesising BDNF, NT-4 and NT-3 are a potent source of neurotrophins for the spinal network (2, 3). Physical exercise increases BDNF neurotrophin gene expression in the rat hippocampus (4). If exercise enhances BDNF expression also in the spinal cord, upregulation of its receptor Trk B may occur. To verify this hypothesis we tested whether exercise influences TrkB receptor system in the spinal cord. Six adult, male Wistar rats walked on the treadmill five days a week, 1,000 m daily with the speed of 20 to 25 cm/s. After 4 weeks of training animals were anaesthetised with pentobarbital sodium (80 mg/kg b.w.) and perfused with 0.01 M PBS followed by 2% paraformaldehyde and 0.2% parabenzoquinone in 0.1 M PB. Three non-trained animals were used as controls. Cr...
Locomotor exercise increases neurotrophin BDNF and its receptor TrkBFL expression in the lumbar s... more Locomotor exercise increases neurotrophin BDNF and its receptor TrkBFL expression in the lumbar spinal cord. Involvement of BDNF/TrkBFL in synaptic transmission raises the questions which intracellular compartments are involved in this upregulation and whether exercise leads to redistribution of these proteins related to the duration of exercise. We have investigated the influence of short-term (7 days) locomotor exercise (ST) on intracellular distribution of BDNF and TrkBFL in the rat lumbar spinal cord comparing it with the effects of long-term (28 days) exercise (LT) described earlier. Immunofluorescence (IF) of proteins was analyzed with confocal microscopy. ST exercise caused a redistribution of perikaryonal BDNF IF toward periphery resulting in an increase of dendritic signal. In contrast to an enhancement of perikaryonal BDNF staining following LT, no increase of BDNF IF in cell bodies was observed after ST. An increase of TrkBFL IF in oligodendrocytes was consistent with tha...
Septal cholinergic neurones depend on trophic support by nerve growth factor (NGF) which can resc... more Septal cholinergic neurones depend on trophic support by nerve growth factor (NGF) which can rescue them from injury-induced degeneration. Since NGF exerts its effects via p75NTR and TrkA receptors coexpressed in vast majority of these neurones and down-regulated without NGF treatment after injury, in this study we aimed to examine how does the lesion to the cholinergic tracts affect distribution of both types of receptor proteins in damaged fibres. Early changes (two and seven days) were examined immunocytochemically within the septum and supracallosal stria after unilateral lesion to the supracallosal area and cingulum transecting some septal cholinergic efferents. We found accumulation of p75NTR and TrkA immunoreactive material (so-called "pile-up") within axonal segments of distended appearance proximal to the transection at two days postlesion and its translocation towards cell bodies seven days postsurgery. We observed p75NTR pile-up to be more intense than TrkA, whi...
Beneficial effects of locomotor training on the functional recovery after complete transection of... more Beneficial effects of locomotor training on the functional recovery after complete transection of the spinal cord indicate that in chronic spinal animals spontaneous recovery processes are enhanced and shaped by the training. The mechanisms of that use-dependent improvement are still not fully understood. This review tackles three aspects of this issue: (1) neurochemical attributes of functional improvement showing that concentrations of excitatory and inhibitory amino acids in the lumbar spinal segments, which were changed after transection, normalize after the training, or even raise beyond normal. As it does not translate to functional equilibrium between excitatory and inhibitory neurotransmission and may lead to hyperexcitability, the postsynaptic mechanisms which might be responsible for the hyperexcitability are discussed, including (i) dysfunction of K(+)-Cl(-) cotransporter KCC2, which controls the strength and robustness of inhibition, and (ii) altered function of 5-HT2 re...
Acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) activity and muscarinic receptor... more Acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) activity and muscarinic receptor binding of homogenates from several brain structures were inhibited by beta-carbolines. The inhibition was of the noncompetitive type in the case of the enzyme and of the mixed type in the case of the receptor binding. This effect was most strongly manifested by pyridoindoles(harmane, norharmane), i.e., carbolines containing an aromatic C ring than by the corresponding piperidoindoles (tetrahydroharmane, tetrahydronorharmane), i.e., those with a reduced C ring. The activity of choline acetyltransferase (acetyl-CoA:choline O-acetyltransferase, EC 2.3.1.6) was not altered. These data are further evidence of the interactions between indoleamine derivatives and the cholinergic system. The results are discussed in terms of their possible biological significance.
The influence of bilateral electrolytic lesions of different parts of the septum on muscarinic re... more The influence of bilateral electrolytic lesions of different parts of the septum on muscarinic receptor binding in the hippocampus was studied within 14-21 days after operation. The effect of total septal lesion upon receptor binding was also investigated separately in the dorsal and ventral hippocampus and in five consecutive hippocampal parts along the septotemporal axis of the structure. The data indicate that: (i) differential response of muscarinic receptors, as revealed by a decrease, increase or lack of changes in the [3H]QNB binding depends on the site and extent of the lesion, (ii) lack of changes in muscarinic receptor binding can be spurious when the investigation is performed on the whole hippocampus, and masked by regional response differences, (iii) differential response of [3H]QNB binding sites in distinct parts of the hippocampus to total septal lesion may depend on the preexisting differences in the density of cholinergic innervation and of muscarinic receptors.
The effect of chronic GMl ganglioside administration (30 mg/kg, daily) for 6, 21, 42 and 90 days ... more The effect of chronic GMl ganglioside administration (30 mg/kg, daily) for 6, 21, 42 and 90 days on the activity of choline acetyltransferase was investigated in the hippocampus of rats with partial electrolytic lesions of the dorsal hippocampal afferents and in unoperated rats. No influence of GM1 administration on ChAT activity was noted in unoperated animals. The lesions caused denervation in the hippocampus, which occurred with varying intensity along its dorsoventral axis, as shown by the gradual pattern of decrease in ChAT activity. GM1 counteracted the decline in enzyme activity, however the intensity of this influence diminished with the time after surgery. A positive correlation between the GM1 effectiveness and the degree of denervation at early postsurgical stages (6, 21 days) was found, which may be ascribed to the appearance of neuronotrophic factors at this period, proportional to the severity of damage. We suggest that the decline of the GM1 effectiveness is due to a ...
The effect of long-term (4 weeks) moderate locomotor exercise on segmental distribution of glutam... more The effect of long-term (4 weeks) moderate locomotor exercise on segmental distribution of glutamate (Glu), aspartate, gamma-aminobutyric acid, glycine (Gly), serotonin and noradrenaline in the spinal cord of adult rats was investigated. In light of the data showing modulation of some neurotransmitters in the low-lumbar segments of the rat due to physical exercise, our aim was to establish how segmentally specific is this effect with respect to neuroactive amino acids and monoamines. Laboratory of Reinnervation Processes, Department of Neurophysiology, Nencki Institute of Experimental Biology, Warsaw, Poland. Amino acids and monoamines content was measured by means of HPLC in the whole tissue homogenate of the spinal cord in nonexercised and exercised rats. Glu and Gly homogenate concentration was the highest among all tested compounds. There was an intersegmental rostro-caudal gradient of concentration of neuroactive amino acids and monoamines, progressing caudally. Exercise modified this gradient exerting opposite effect on their concentration of amino acids and monoamines in the rostral and caudal lumbar segments. Locomotor exercise leads to neurochemical remodeling of the spinal cord, which is differently manifested in the rostral and caudal lumbar segments of the spinal cord.
Strategies to induce recovery from lesions of the spinal cord have not fully resulted in clinical... more Strategies to induce recovery from lesions of the spinal cord have not fully resulted in clinical applications. This is a consequence of a number of impediments that axons encounter when trying to regrow beyond the lesion site, and that intraspinal rearrangements are subjected to. In the present study we evaluated (1) the possibility to improve locomotor recovery after complete transection of the spinal cord by means of an adeno-associated (AAV) viral vector expressing the neurotrophin brain-derived neurotrophic factor (BDNF) in lumbar spinal neurons caudal to the lesion site and (2) how the spinal cord transection and BDNF treatment affected neurotransmission in the segments caudal to the lesion site. BDNF overexpression resulted in clear increases in expression levels of molecules involved in glutamatergic (VGluT2) and GABAergic (GABA, GAD65, GAD67) neurotransmission in parallel with a reduction of the potassium-chloride co-transporter (KCC2) which contributes to an inhibitory neurotransmission. BDNF treated animals showed significant improvements in assisted locomotor performance, and performed locomotor movements with body weight support and plantar foot placement on a moving treadmill. These positive effects of BDNF local overexpression were detectable as early as two weeks after spinal cord transection and viral vector application and lasted for at least 7 weeks. Gradually increasing frequencies of clonic movements at the end of the experiment attenuated the quality of treadmill walking. These data indicate that BDNF has the potential to enhance the functionality of isolated lumbar circuits, but also that BDNF levels have to be tightly controlled to prevent hyperexcitability.
Metabotropic glutamate (mGlu) receptors, which are present on neurons and glial cells, have been ... more Metabotropic glutamate (mGlu) receptors, which are present on neurons and glial cells, have been shown to play a role in neuropathic pain. The present study sought to investigate how the glial inhibitors minocycline and pentoxifylline alter the effect that chronic constriction injury (CCI) has on the expression of mGlu receptors and on their associated ligands. RT-PCR analysis revealed that seven days after CCI, the mRNA levels of glial markers C1q and GFAP, as well as those of mGlu5 and mGlu3, but not mGlu7, were elevated in the lumbar spinal cord - ipsilateral to the injury. The protein levels of the microglial marker OX42, the astroglial marker GFAP, and mGlu5 receptor protein were increased, whereas the levels of mGlu2/3 and mGlu7 receptor proteins were reduced. Preemptive and repeated intraperitoneal (i.p.) administration (16 and 1h before nerve injury and then twice daily for seven days) of minocycline (30mg/kg) and pentoxifylline (20mg/kg) prevented the injury-induced changes in the levels of mGlu3 and mGlu5 receptor mRNAs and the injury-induced changes in the protein levels of all the receptors. Repeated administration of minocycline and pentoxifylline significantly attenuated CCI-induced allodynia (von Frey test) and hyperalgesia (cold plate test) measured on day seven after injury and potentiated the antiallodynic and antihyperalgesic effects of single i.p. and intrathecal (i.t.) injections of mGlu receptor ligands: MPEP, LY379268 or AMN082. We conclude that attenuation of injury-induced glial activation can reduce glutamatergic activity, thereby contributing to regulation of pain sensation.
A loss of target-derived neurotrophic factors is hypothesized to be one of the major determinants... more A loss of target-derived neurotrophic factors is hypothesized to be one of the major determinants of central nervous system neuronal degeneration. In order to obtain further insight into early neuronal responses to injury, lesion-induced alterations in the expression of high- and low-affinity nerve growth factor receptors, as well as growth-associated phosphoprotein-43 genes in nucleus basalis magnocellularis, thalamic and neocortical neurons were studied. For this purpose, unilateral cortical devascularization operations were conducted on adult rats. Animals received i.c.v. infusions of vehicle or nerve growth factor (12 micrograms/day) and were killed at one, three, seven and 15 days post-lesion. In situ hybridization studies using 35S-labelled oligonucleotide probes for p75NGFR, p140trk and growth-associated phosphoprotein-43 messenger RNAs reveals that these genes were differentially regulated following the lesion. In the nucleus basalis magnocellularis ipsilateral to the lesion, p140trk gene expression significantly decreased on days 3 and 7, while p75NGFR messenger RNA initially increased on day 3 and decreased on days 7 and 15 after lesion. GAP-43 messenger RNA levels were significantly increased in the nucleus basalis magnocellularis on post-lesion days 3 and 7. Moreover, in contrast to p75NGFR or 140trk, growth-associated phosphoprotein-43 messenger RNA levels were significantly increased in pyramidal neurons located in the remaining cortex adjacent to the cortical lesion at all time points. In the lateral and ventroposterior nuclei of the thalamus, growth-associated phosphoprotein-43 messenger RNA level was slightly increased on days 1 and 3 and was dramatically decreased, significantly below the levels in sham-operated controls, on post-lesion days 7 and 15. During nerve growth factor application, the level of p140trk messenger RNA in the lesioned nucleus basalis magnocellularis returned to values observed in the contralateral nucleus basalis magnocellularis while p75NGFR messenger RNA was increased above values noted in all animals not treated with nerve growth factor. Nerve growth factor treatment did not affect the expression of growth-associated phosphoprotein-43 messenger RNA in any of the areas studied. p140trk messenger RNA was not up-regulated during the time that nerve growth factor was applied, as observed for p75NGFR, but only eight days after interrupting nerve growth factor treatment. Three cell types, nucleus basalis magnocellularis, cortical pyramidal and thalamic neurons, were probably affected in different ways by the devascularization with respect to lesion extent. Consequently, the remaining number of synaptic contacts in each of these brain areas is most likely different which may lead to a differential regulation of growth-associated phosphoprotein-43 messenger RNA.(ABSTRACT TRUNCATED AT 400 WORDS)
Glaucoma is a chronic optic neuropathy characterized by progressive damage to the optic nerve, de... more Glaucoma is a chronic optic neuropathy characterized by progressive damage to the optic nerve, death of retinal ganglion cells and ultimately visual field loss. It is one of the leading causes of irreversible loss of vision worldwide. The most important trigger of glaucomatous damage is elevated eye pressure, and the current standard approach in glaucoma therapy is reduction of intraocular pressure (IOP). However, despite the use of effective medications or surgical treatment leading to lowering of IOP, progression of glaucomatous changes and loss of vision among patients with glaucoma is common. Therefore, it is critical to prevent vision loss through additional treatment. To implement such treatment(s), it is imperative to identify pathophysiological changes in glaucoma and develop therapeutic methods taking into account neuroprotection. Currently, there is no method of neuroprotection with long-term proven effectiveness in the treatment of glaucoma. Among the most promising molecules shown to protect the retina and optic nerve are neurotrophic factors. Thus, the current focus is on the development of safe and non-invasive methods for the long-term elevation of the intraocular level of neurotrophins through advanced gene therapy and topical eye treatment and on the search for selective agonists of neurotrophin receptors affording more efficient neuroprotection.
The article summarizes the most meaningful studies which have provided evidence that protein synt... more The article summarizes the most meaningful studies which have provided evidence that protein synthesis in neurons can occur not only in cell perikarya but also locally in dendrites. The presence of the complete machinery required to synthesize cytoplasmic and integral membrane proteins in dendrites, identification of binding proteins known to mediate mRNA trafficking in dendrites and the ability to trigger "on-site" translation make it possible for the synthesis of particular proteins to be regulated by synaptic signals. Until now over 100 different mRNAs coding the proteins involved in neurotransmission and modulation of synaptic activity have been identified in dendrites. Local protein synthesis is postulated to provide the basic mechanism of fast changes in the strength of neuronal connections and to be an important factor in the molecular background of synaptic plasticity, giving rise to enduring changes in synaptic function, which in turn play a role in local homeosta...
Bilateral transection of the lateral fimbria, which disrupts partially the septo-hippocampal proj... more Bilateral transection of the lateral fimbria, which disrupts partially the septo-hippocampal projections and results in partial hippocampal denervation, produced a significant increase in the ornithine decarboxylase (ODC) activity in the hippocampus. An increase occurred already 0.5 h after the operation and the activity remained intensified for at least 22 h after injury. The enzyme response was enhanced by a single dose of GM1 monosialoganglioside (30 mg/kg) administered directly after the operation. This enhancement, detected 2 h after the injury, persisted for at least 22 h after the operation. Lack of influence of GM1 ganglioside on ODC activity in the hippocampus of unlesioned animals allows us to ascribe the observed effect to the processes induced by the lesion. This study confirms the involvement of ODC in GM1 ganglioside neurotrophic effects produced in an injured brain.
The article presents the state of the art based on experimental studies in vivo and concerning th... more The article presents the state of the art based on experimental studies in vivo and concerning the mechanisms of stroke-induced neurodegeneration in the brain. Molecular bases of differences in brain regions affected indirectly and directly by cortical ischaemia are also discussed. Proteins which may play a key role in apoptosis, including the Bcl-2 protein family, are described in relation to their responses to the infarct. Finally, therapeutic perspectives connected with modulation of function of these proteins are outlined.
Partial deafferentation of the hippocampus due to trimethyltin (TMT) intoxication has been report... more Partial deafferentation of the hippocampus due to trimethyltin (TMT) intoxication has been reported to induce plastic rearrangements of neuronal elements but the factors that direct these responses are unknown. To assess the possible involvement of nerve growth factor (NGF) in the phenomenon we evaluated the presumable changes in the expression pattern of NGF immunoreactivity (NGF-IR) in rat hippocampus 21 days after administration of TMT (8 mg/kg, i.p.) when reactive changes are fully developed. Immunolabelling for TrkA known to mediate biological effects of NGF and for GFAP to identify astroglial cells as a one of presumed source of postinjury produced factors was carried out on adjacent sections to establish the relation between expression of these proteins. In control hippocampus NGF-IR and TrkA-IR were localized in neurons and/or neuropil. After exposure to TMT remarkable non-neuronal expression of both proteins was observed. The distribution pattern of NGF, TrkA and GFAP overl...
In view of neuroprotective effects of neurotrophins and neurotrophic factors on the damaged nervo... more In view of neuroprotective effects of neurotrophins and neurotrophic factors on the damaged nervous tissue clinical attempts have been made to use these proteins in the treatment of neurodegenerative diseases. However, the attempts were unsuccessful. We discuss the main causes of this failure and outline a new clinical prospect due to the growing understanding of the mechanisms underlying neurotrophin activity in the nervous system. A special emphasis has been laid on advances in the research aimed at optimization of pharmacodynamics of neurotrophins, and at development of new delivery systems that would not only supplement the nervous system with required neurotrophins locally, but also regulate their quantity and time span of their delivery. An alternative method of physical exercise allowing to upregulate neurotrophins and their receptors is also discussed.
INTRODUCTION AND METHODS: Locomotor training leads to improvement of stepping ability in animals ... more INTRODUCTION AND METHODS: Locomotor training leads to improvement of stepping ability in animals after spinal cord transection (1). Recent data point to neurotrophins as possible factors involved in this improvement. Motoneurones synthesising BDNF, NT-4 and NT-3 are a potent source of neurotrophins for the spinal network (2, 3). Physical exercise increases BDNF neurotrophin gene expression in the rat hippocampus (4). If exercise enhances BDNF expression also in the spinal cord, upregulation of its receptor Trk B may occur. To verify this hypothesis we tested whether exercise influences TrkB receptor system in the spinal cord. Six adult, male Wistar rats walked on the treadmill five days a week, 1,000 m daily with the speed of 20 to 25 cm/s. After 4 weeks of training animals were anaesthetised with pentobarbital sodium (80 mg/kg b.w.) and perfused with 0.01 M PBS followed by 2% paraformaldehyde and 0.2% parabenzoquinone in 0.1 M PB. Three non-trained animals were used as controls. Cr...
Locomotor exercise increases neurotrophin BDNF and its receptor TrkBFL expression in the lumbar s... more Locomotor exercise increases neurotrophin BDNF and its receptor TrkBFL expression in the lumbar spinal cord. Involvement of BDNF/TrkBFL in synaptic transmission raises the questions which intracellular compartments are involved in this upregulation and whether exercise leads to redistribution of these proteins related to the duration of exercise. We have investigated the influence of short-term (7 days) locomotor exercise (ST) on intracellular distribution of BDNF and TrkBFL in the rat lumbar spinal cord comparing it with the effects of long-term (28 days) exercise (LT) described earlier. Immunofluorescence (IF) of proteins was analyzed with confocal microscopy. ST exercise caused a redistribution of perikaryonal BDNF IF toward periphery resulting in an increase of dendritic signal. In contrast to an enhancement of perikaryonal BDNF staining following LT, no increase of BDNF IF in cell bodies was observed after ST. An increase of TrkBFL IF in oligodendrocytes was consistent with tha...
Septal cholinergic neurones depend on trophic support by nerve growth factor (NGF) which can resc... more Septal cholinergic neurones depend on trophic support by nerve growth factor (NGF) which can rescue them from injury-induced degeneration. Since NGF exerts its effects via p75NTR and TrkA receptors coexpressed in vast majority of these neurones and down-regulated without NGF treatment after injury, in this study we aimed to examine how does the lesion to the cholinergic tracts affect distribution of both types of receptor proteins in damaged fibres. Early changes (two and seven days) were examined immunocytochemically within the septum and supracallosal stria after unilateral lesion to the supracallosal area and cingulum transecting some septal cholinergic efferents. We found accumulation of p75NTR and TrkA immunoreactive material (so-called "pile-up") within axonal segments of distended appearance proximal to the transection at two days postlesion and its translocation towards cell bodies seven days postsurgery. We observed p75NTR pile-up to be more intense than TrkA, whi...
Beneficial effects of locomotor training on the functional recovery after complete transection of... more Beneficial effects of locomotor training on the functional recovery after complete transection of the spinal cord indicate that in chronic spinal animals spontaneous recovery processes are enhanced and shaped by the training. The mechanisms of that use-dependent improvement are still not fully understood. This review tackles three aspects of this issue: (1) neurochemical attributes of functional improvement showing that concentrations of excitatory and inhibitory amino acids in the lumbar spinal segments, which were changed after transection, normalize after the training, or even raise beyond normal. As it does not translate to functional equilibrium between excitatory and inhibitory neurotransmission and may lead to hyperexcitability, the postsynaptic mechanisms which might be responsible for the hyperexcitability are discussed, including (i) dysfunction of K(+)-Cl(-) cotransporter KCC2, which controls the strength and robustness of inhibition, and (ii) altered function of 5-HT2 re...
Acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) activity and muscarinic receptor... more Acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) activity and muscarinic receptor binding of homogenates from several brain structures were inhibited by beta-carbolines. The inhibition was of the noncompetitive type in the case of the enzyme and of the mixed type in the case of the receptor binding. This effect was most strongly manifested by pyridoindoles(harmane, norharmane), i.e., carbolines containing an aromatic C ring than by the corresponding piperidoindoles (tetrahydroharmane, tetrahydronorharmane), i.e., those with a reduced C ring. The activity of choline acetyltransferase (acetyl-CoA:choline O-acetyltransferase, EC 2.3.1.6) was not altered. These data are further evidence of the interactions between indoleamine derivatives and the cholinergic system. The results are discussed in terms of their possible biological significance.
The influence of bilateral electrolytic lesions of different parts of the septum on muscarinic re... more The influence of bilateral electrolytic lesions of different parts of the septum on muscarinic receptor binding in the hippocampus was studied within 14-21 days after operation. The effect of total septal lesion upon receptor binding was also investigated separately in the dorsal and ventral hippocampus and in five consecutive hippocampal parts along the septotemporal axis of the structure. The data indicate that: (i) differential response of muscarinic receptors, as revealed by a decrease, increase or lack of changes in the [3H]QNB binding depends on the site and extent of the lesion, (ii) lack of changes in muscarinic receptor binding can be spurious when the investigation is performed on the whole hippocampus, and masked by regional response differences, (iii) differential response of [3H]QNB binding sites in distinct parts of the hippocampus to total septal lesion may depend on the preexisting differences in the density of cholinergic innervation and of muscarinic receptors.
The effect of chronic GMl ganglioside administration (30 mg/kg, daily) for 6, 21, 42 and 90 days ... more The effect of chronic GMl ganglioside administration (30 mg/kg, daily) for 6, 21, 42 and 90 days on the activity of choline acetyltransferase was investigated in the hippocampus of rats with partial electrolytic lesions of the dorsal hippocampal afferents and in unoperated rats. No influence of GM1 administration on ChAT activity was noted in unoperated animals. The lesions caused denervation in the hippocampus, which occurred with varying intensity along its dorsoventral axis, as shown by the gradual pattern of decrease in ChAT activity. GM1 counteracted the decline in enzyme activity, however the intensity of this influence diminished with the time after surgery. A positive correlation between the GM1 effectiveness and the degree of denervation at early postsurgical stages (6, 21 days) was found, which may be ascribed to the appearance of neuronotrophic factors at this period, proportional to the severity of damage. We suggest that the decline of the GM1 effectiveness is due to a ...
The effect of long-term (4 weeks) moderate locomotor exercise on segmental distribution of glutam... more The effect of long-term (4 weeks) moderate locomotor exercise on segmental distribution of glutamate (Glu), aspartate, gamma-aminobutyric acid, glycine (Gly), serotonin and noradrenaline in the spinal cord of adult rats was investigated. In light of the data showing modulation of some neurotransmitters in the low-lumbar segments of the rat due to physical exercise, our aim was to establish how segmentally specific is this effect with respect to neuroactive amino acids and monoamines. Laboratory of Reinnervation Processes, Department of Neurophysiology, Nencki Institute of Experimental Biology, Warsaw, Poland. Amino acids and monoamines content was measured by means of HPLC in the whole tissue homogenate of the spinal cord in nonexercised and exercised rats. Glu and Gly homogenate concentration was the highest among all tested compounds. There was an intersegmental rostro-caudal gradient of concentration of neuroactive amino acids and monoamines, progressing caudally. Exercise modified this gradient exerting opposite effect on their concentration of amino acids and monoamines in the rostral and caudal lumbar segments. Locomotor exercise leads to neurochemical remodeling of the spinal cord, which is differently manifested in the rostral and caudal lumbar segments of the spinal cord.
Strategies to induce recovery from lesions of the spinal cord have not fully resulted in clinical... more Strategies to induce recovery from lesions of the spinal cord have not fully resulted in clinical applications. This is a consequence of a number of impediments that axons encounter when trying to regrow beyond the lesion site, and that intraspinal rearrangements are subjected to. In the present study we evaluated (1) the possibility to improve locomotor recovery after complete transection of the spinal cord by means of an adeno-associated (AAV) viral vector expressing the neurotrophin brain-derived neurotrophic factor (BDNF) in lumbar spinal neurons caudal to the lesion site and (2) how the spinal cord transection and BDNF treatment affected neurotransmission in the segments caudal to the lesion site. BDNF overexpression resulted in clear increases in expression levels of molecules involved in glutamatergic (VGluT2) and GABAergic (GABA, GAD65, GAD67) neurotransmission in parallel with a reduction of the potassium-chloride co-transporter (KCC2) which contributes to an inhibitory neurotransmission. BDNF treated animals showed significant improvements in assisted locomotor performance, and performed locomotor movements with body weight support and plantar foot placement on a moving treadmill. These positive effects of BDNF local overexpression were detectable as early as two weeks after spinal cord transection and viral vector application and lasted for at least 7 weeks. Gradually increasing frequencies of clonic movements at the end of the experiment attenuated the quality of treadmill walking. These data indicate that BDNF has the potential to enhance the functionality of isolated lumbar circuits, but also that BDNF levels have to be tightly controlled to prevent hyperexcitability.
Metabotropic glutamate (mGlu) receptors, which are present on neurons and glial cells, have been ... more Metabotropic glutamate (mGlu) receptors, which are present on neurons and glial cells, have been shown to play a role in neuropathic pain. The present study sought to investigate how the glial inhibitors minocycline and pentoxifylline alter the effect that chronic constriction injury (CCI) has on the expression of mGlu receptors and on their associated ligands. RT-PCR analysis revealed that seven days after CCI, the mRNA levels of glial markers C1q and GFAP, as well as those of mGlu5 and mGlu3, but not mGlu7, were elevated in the lumbar spinal cord - ipsilateral to the injury. The protein levels of the microglial marker OX42, the astroglial marker GFAP, and mGlu5 receptor protein were increased, whereas the levels of mGlu2/3 and mGlu7 receptor proteins were reduced. Preemptive and repeated intraperitoneal (i.p.) administration (16 and 1h before nerve injury and then twice daily for seven days) of minocycline (30mg/kg) and pentoxifylline (20mg/kg) prevented the injury-induced changes in the levels of mGlu3 and mGlu5 receptor mRNAs and the injury-induced changes in the protein levels of all the receptors. Repeated administration of minocycline and pentoxifylline significantly attenuated CCI-induced allodynia (von Frey test) and hyperalgesia (cold plate test) measured on day seven after injury and potentiated the antiallodynic and antihyperalgesic effects of single i.p. and intrathecal (i.t.) injections of mGlu receptor ligands: MPEP, LY379268 or AMN082. We conclude that attenuation of injury-induced glial activation can reduce glutamatergic activity, thereby contributing to regulation of pain sensation.
A loss of target-derived neurotrophic factors is hypothesized to be one of the major determinants... more A loss of target-derived neurotrophic factors is hypothesized to be one of the major determinants of central nervous system neuronal degeneration. In order to obtain further insight into early neuronal responses to injury, lesion-induced alterations in the expression of high- and low-affinity nerve growth factor receptors, as well as growth-associated phosphoprotein-43 genes in nucleus basalis magnocellularis, thalamic and neocortical neurons were studied. For this purpose, unilateral cortical devascularization operations were conducted on adult rats. Animals received i.c.v. infusions of vehicle or nerve growth factor (12 micrograms/day) and were killed at one, three, seven and 15 days post-lesion. In situ hybridization studies using 35S-labelled oligonucleotide probes for p75NGFR, p140trk and growth-associated phosphoprotein-43 messenger RNAs reveals that these genes were differentially regulated following the lesion. In the nucleus basalis magnocellularis ipsilateral to the lesion, p140trk gene expression significantly decreased on days 3 and 7, while p75NGFR messenger RNA initially increased on day 3 and decreased on days 7 and 15 after lesion. GAP-43 messenger RNA levels were significantly increased in the nucleus basalis magnocellularis on post-lesion days 3 and 7. Moreover, in contrast to p75NGFR or 140trk, growth-associated phosphoprotein-43 messenger RNA levels were significantly increased in pyramidal neurons located in the remaining cortex adjacent to the cortical lesion at all time points. In the lateral and ventroposterior nuclei of the thalamus, growth-associated phosphoprotein-43 messenger RNA level was slightly increased on days 1 and 3 and was dramatically decreased, significantly below the levels in sham-operated controls, on post-lesion days 7 and 15. During nerve growth factor application, the level of p140trk messenger RNA in the lesioned nucleus basalis magnocellularis returned to values observed in the contralateral nucleus basalis magnocellularis while p75NGFR messenger RNA was increased above values noted in all animals not treated with nerve growth factor. Nerve growth factor treatment did not affect the expression of growth-associated phosphoprotein-43 messenger RNA in any of the areas studied. p140trk messenger RNA was not up-regulated during the time that nerve growth factor was applied, as observed for p75NGFR, but only eight days after interrupting nerve growth factor treatment. Three cell types, nucleus basalis magnocellularis, cortical pyramidal and thalamic neurons, were probably affected in different ways by the devascularization with respect to lesion extent. Consequently, the remaining number of synaptic contacts in each of these brain areas is most likely different which may lead to a differential regulation of growth-associated phosphoprotein-43 messenger RNA.(ABSTRACT TRUNCATED AT 400 WORDS)
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