It was suggested in 1986 that cue-induced drug craving in cocaine addicts progressively increases... more It was suggested in 1986 that cue-induced drug craving in cocaine addicts progressively increases over the first several weeks of abstinence and remains high for extended periods. During the past decade, investigators have identified an analogous incubation phenomenon in rodents, in which time-dependent increases in cue-induced drug seeking are observed after withdrawal from intravenous cocaine self-administration. Such an incubation of drug craving is not specific to cocaine, as similar findings have been observed after self-administration of heroin, nicotine, methamphetamine and alcohol in rats. In this review, we discuss recent results that have identified important brain regions involved in the incubation of drug craving, as well as evidence for the underlying cellular mechanisms. Understanding the neurobiology of the incubation of drug craving in rodents is likely to have significant implications for furthering understanding of brain mechanisms and circuits that underlie cravin...
Primate-specific genes and isoforms could provide insight into human brain diseases. Our bioinfor... more Primate-specific genes and isoforms could provide insight into human brain diseases. Our bioinformatic analysis revealed that there are possibly five isoforms of human GDNF gene with different pre- and pro-regions by inter- and intra-exon splicing. By using TaqMan primer probe sets, designed between exons, we verified the expression of all isoforms. Furthermore, a novel GDNFOS gene was found to be transcribed from the opposite strand of GDNF gene. GDNFOS gene has four exons that are spliced into different isoforms. GDNFOS1 and GDNFOS2 are long noncoding RNAs, and GDNFOS3 encodes a protein of 105 amino acids. To study human GDNF and GDNFOS regulation in neurodegenerative diseases, the protein and mRNA levels were measured by Western blot and RT-quantitative PCR, respectively, in postmortem middle temporal gyrus (MTG) of Alzheimer disease (AD) and Huntington disease (HD) patients in comparison with those of normal controls. In the MTG of AD patients, the mature GDNF peptide was down-r...
For stroke patients the recovery of cognitive and behavioral functions is often incomplete. Funct... more For stroke patients the recovery of cognitive and behavioral functions is often incomplete. Functional recovery is thought to be mediated largely by connectivity rearrangements in the peri-infarct region. A method for manipulating gene expression in this region would be useful for identifying new recovery-enhancing treatments. We have characterized a way of targeting adeno-associated virus (AAV) vectors to the peri-infarct region of cortical ischemic lesion in rats 2days after middle cerebral artery occlusion (MCAo). We used magnetic resonance imaging (MRI) to show that the altered properties of post-ischemic brain tissue facilitate the spreading of intrastriatally injected nanoparticles toward the infarct. We show that subcortical injection of green fluorescent protein-encoding dsAAV7-GFP resulted in transduction of cells in and around the white matter tract underlying the lesion, and in the cortex proximal to the lesion. A similar result was achieved with dsAAV7 vector encoding the cerebral dopamine neurotrophic factor (CDNF), a protein with therapeutic potential. Viral vector-mediated intracerebral gene delivery has been used before in rodent models of ischemic injury. However, the method of targeting gene expression to the peri-infarct region, after the initial phase of ischemic cell death, has not been described before. We demonstrate a straightforward and robust way to target AAV vector-mediated over-expression of genes to the peri-infarct region in a rat stroke model. This method will be useful for studying the action of specific proteins in peri-infarct region during the recovery process.
Stroke is a major complication of cardiovascular surgery, resulting in over 100,000 deaths and ov... more Stroke is a major complication of cardiovascular surgery, resulting in over 100,000 deaths and over a million postoperative encephalopathies annually in the US and Europe. While mitigating damage from stroke after it occurs has proven elusive, opportunities to reduce the incidence and/or severity of stroke prior to surgery in at-risk individuals remain largely unexplored. We tested the potential of short-term preoperative dietary restriction to provide neuroprotection in rat models of focal stroke. Rats were preconditioned with either three days of water-only fasting or six days of a protein free diet prior to induction of transient middle cerebral artery occlusion using two different methods, resulting in either a severe focal stroke to forebrain and midbrain, or a mild focal stroke localized to cortex only. Infarct volume, functional recovery and molecular markers of damage and protection were assessed up to two weeks after reperfusion. Preoperative fasting for 3 days reduced infa...
Although initially thought to be important primarily in neural development, a number of trophic p... more Although initially thought to be important primarily in neural development, a number of trophic proteins have been found to have neuroprotective and neuroregenerative activity in the adult central system, particularly for midbrain dopamine neurons (MDN). Neurorestoration is potentially feasible for MDN since there is an initial loss of phenotype for these neurons in Parkinson's disease (PD) rather than neuronal death. There is a considerable recent literature on trophic properties of TGF-ß superfamily proteins for MDN's, including glial cell-derived neurotrophic factor (GDNF), neurturin, and bone morphogenetic proteins (BMPs). This paper will review studies with the factors listed above, as well as describe more recent studies with two newly described trophic proteins, MANF and CDNF. Data will be presented from various animal models of PD suggesting that these trophic proteins may eventually lead to PD therapeutics in man. In addition, some data on small molecules with neuroprotective properties (AP 4 A, retinoic acid and vitamin D 3 ) will also be described.
Ret is the common signaling receptor for glial cell line-derived neurotrophic factor (GDNF) and o... more Ret is the common signaling receptor for glial cell line-derived neurotrophic factor (GDNF) and other ligands of the GDNF family that have potent effects on brain dopaminergic neurons. The Met918Thr mutation leads to constitutive activity of Ret receptor tyrosine kinase, causing the cancer syndrome called multiple endocrine neoplasia type B (MEN2B). We used knock-in MEN2B mice with the Ret-MEN2B mutation to study the effects of constitutive Ret activity on the brain dopaminergic system and found robustly increased concentrations of dopamine (DA) and its metabolites in the striatum, cortex, and hypothalamus. The concentrations of brain serotonin were not affected and those of noradrenaline were slightly increased only in the lower brainstem. Tyrosine hydroxylase (TH) protein levels were increased in the striatum and substantia nigra/ventral tegmental area (SN/VTA), and TH mRNA levels were increased in SN/VTA of MEN2B mice, suggesting that constitutive Ret activity increases DA levels by increasing its synthesis. Also, the striatal DA transporter protein levels in the MEN2B mice were increased, which agrees with increased sensitivity of these mice to the stimulatory effects of cocaine. In the SN pars compacta of homozygous MEN2B mice, we found a 26% increase in the number of TH-positive cells, but no differences were found in the VTA. Thus, we show here that the constitutive Ret activity in mice is sufficient to increase the number of dopaminergic neurons and leads to profound elevation of brain DA concentration. These data clearly suggest that Ret activity per se can have a direct biological function that actively changes and shapes the brain dopaminergic system.
Glial cell line-derived neurotrophic factor (GDNF) regulates striatal dopaminergic neurons. To st... more Glial cell line-derived neurotrophic factor (GDNF) regulates striatal dopaminergic neurons. To study whether reduced endogenous GDNF affect morphine's effects on striatal dopamine transmission, we estimated extracellular concentrations of dopamine and its metabolites by microdialysis in vivo and tissue concentrations post mortem in mice lacking one GDNF allele (GDNF+/- mice). In the wild-type mice, acute morphine (5 and 10 mg/kg s.c.) increased accumbal dopamine output dose-dependently (maximally by 30 and 80%, respectively). In the GDNF+/- mice, 5 mg/kg of morphine enhanced the accumbal dopamine output maximally by 110%, and significantly more than morphine 10 mg/kg (maximally by 60%). Also, the response of extracellular accumbal DOPAC to acute morphine was significantly altered in the GDNF+/- mice. In mice of both genotypes, the responses to morphine in the caudate putamen were similar to but much less intense than those in the nucleus accumbens. Morphine at the doses 5, 10, and 30 mg/kg dose-dependently elevated the striatal tissue concentrations of DOPAC and HVA, but the effect of 30 mg/kg was significantly smaller in the GDNF+/- mice than in their wild-type littermates. The binding of [(3)H]DAMGO to striatal membrane homogenates was similar between the genotypes. However, morphine induced antinociception in the GDNF+/- mice at a smaller dose than in the controls. The finding that reduced GDNF level alters the effects of morphine on striatal dopamine and our previous findings of elevated extracellular striatal dopamine concentrations and FosB/DeltaFosB expression in the GDNF+/- mice show the importance of GDNF in the regulation of striatal dopaminergic system.
Rationale-Methamphetamine is a commonly abused drug and dopaminergic neurotoxin. Repeated adminis... more Rationale-Methamphetamine is a commonly abused drug and dopaminergic neurotoxin. Repeated administration of high doses of methamphetamine induces programmed cell death, suppression of dopamine release, and reduction in locomotor activity. Previous studies have shown that pretreatment with Peroxisome Proliferator-Activated Receptor gamma (PPARγ) agonist reduced Methamphetamine -induced neurodegeneration.
Migration of new neuroprogenitor cells (NPCs) from the subventricular zone (SVZ) plays an importa... more Migration of new neuroprogenitor cells (NPCs) from the subventricular zone (SVZ) plays an important role in neurorepair after injury. Previous studies have shown that brain derived neurotrophic factor (BDNF) enhances the migration of NPCs from SVZ explants in neonatal mice in vitro. The purpose of this study was to identify the role of BDNF in SVZ cells using AAV-BDNF in an animal model of stroke. BDNF protein production after AAV-BDNF infection was verified in primary neuronal culture. AAV-BDNF or AAV-RFP was injected into the left SVZ region of adult rats at 14 days prior to right middle cerebral artery occlusion (MCAo). SVZ tissues were collected from the brain and placed in Metrigel cultures 1 day after MCAo. Treatment with AAV-BDNF significantly increased the migration of SVZ cells in the stroke brain in vitro. In another set of animals, AAV-GFP was co-injected with AAV-BDNF or AAV-RFP to label cells in left SVZ prior to right MCAo. Local administration of AAV-BDNF significantly enhanced recovery of locomotor function and migration of GFP-positive cells from the SVZ toward the lesioned hemisphere in stroke rats. Our data suggest that focal administration of AAV-BDNF to the SVZ increases behavioral recovery post stroke, possibly through the enhancement of migration of cells from SVZ in stroke animals. Regional manipulation of BDNF expression through AAV may be a novel approach for neurorepair in stroke brains.
Following the onset of an ischemic brain injury, the excitatory neurotransmitter glutamate is rel... more Following the onset of an ischemic brain injury, the excitatory neurotransmitter glutamate is released. The excitotoxic effects of glutamate are a major contributor to the pathogenesis of a stroke. The aim of this study was to examine if overexpression of a glutamate transporter (GLT-1) reduces ischemic brain injury in a rat model of stroke. We generated an adeno-associated viral (AAV) vector expressing the rat GLT-1 cDNA (AAV-GLT1). Functional expression of AAV-GLT1 was confirmed by increased glutamate clearance rate in non-stroke rat brain as measured by in vivo amperometry. AAV-GLT1 was injected into future cortical region of infarction 3 weeks prior to 60 min middle cerebral artery occlusion (MCAo). Tissue damage was assessed at one and two days after MCAo using TUNEL and TTC staining, respectively. Behavioral testing was performed at 2, 8 and 14 days post-stroke. Animals receiving AAV-GLT1, compared to AAV-GFP, showed significant decreases in the duration and magnitude of extracellular glutamate, measured by microdialysis, during the 60 minute MCAo. A significant reduction in brain infarction and DNA fragmentation was observed in the region of AAV-GLT1 injection. Animals that received AAV-GLT1 showed significant improvement in behavioral recovery following stroke compared to the AAV-GFP group. We demonstrate that focal overexpression of the glutamate transporter, GLT-1, significantly reduces ischemia-induced glutamate overflow, decreases cell death and improves behavioral recovery. These data further support the role of glutamate in the pathogenesis of ischemic damage in brain and demonstrate that targeted gene delivery to decrease the ischemia-induced glutamate overflow reduces the cellular and behavioral deficits caused by stroke.
Although initially thought to be important primarily in neural development, a number of trophic p... more Although initially thought to be important primarily in neural development, a number of trophic proteins have been found to have neuroprotective and neuroregenerative activity in the adult central nervous system, particularly for midbrain dopamine neurons (MDN). Neurorestoration is potentially feasible for MDN since there is an initial loss of phenotype for these neurons in Parkinson's disease (PD) rather than neuronal death. There is a considerable recent literature on trophic properties of TGF-β superfamily proteins for MDN's, including glial cell-derived neurotrophic factor (GDNF), neurturin, and bone morphogenetic proteins (BMPs). This paper will review studies with the factors listed above, as well as describe more recent studies with two newly described trophic proteins, MANF and CDNF. Data will be presented from various animal models of PD suggesting that these trophic proteins may eventually lead to PD therapeutics in man. In addition, some data on small molecules with neuroprotective properties (AP(4)A, retinoic acid and vitamin D(3)) will also be described.
The identification of genes linked to neurodegenerative diseases such as Alzheimer's disease (AD)... more The identification of genes linked to neurodegenerative diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD) and Parkinson's disease (PD) has led to the development of animal models for studying mechanism and evaluating potential therapies. None of the transgenic models developed based on disease-associated genes have been able to fully recapitulate the behavioral and pathological features of the corresponding disease. However, there has been enormous progress made in identifying potential therapeutic targets and understanding some of the common mechanisms of neurodegeneration. In this review, we will discuss transgenic animal models for AD, ALS, HD and PD that are based on human genetic studies. All of the diseases discussed have active or complete clinical trials for experimental treatments that benefited from transgenic models of the disease.
Background: Glial cell line-derived neurotrophic factor (GDNF) has been effective therapy in labo... more Background: Glial cell line-derived neurotrophic factor (GDNF) has been effective therapy in laboratory animal models of Parkinson disease. Results: A human GDNFOS (GDNF opposite strand) gene was discovered and potentially encodes a 105-amino acid peptide. Conclusion: GDNF sense and GDNFOS antisense genes are differentially regulated in human tissues. Significance: GDNF and GDNFOS isoforms may have roles in human neurodegenerative diseases.
Mesencephalic astrocyte-derived neurotrophic factor (MANF), also known as Arginine-rich, Mutated ... more Mesencephalic astrocyte-derived neurotrophic factor (MANF), also known as Arginine-rich, Mutated in Early Stage of Tumors (ARMET), is a secreted protein which reduces endoplasmic reticulum (ER) stress. Previous studies have shown that MANF mRNA expression and protein levels are increased in the cerebral cortex after brain ischemia, a condition which induces ER stress. The function of MANF during brain ischemia is still not known. The purpose of this study was to examine the protective effect of MANF after ischemic brain injury. Recombinant human MANF was administrated locally to the cerebral cortex before a 60-min middle cerebral artery occlusion (MCAo) in adult rats. Triphenyltetrazolium chloride (TTC) staining indicated that pretreatment with MANF significantly reduced the volume of infarction at two days after MCAo. MANF also attenuated TUNEL labeling, a marker of cell necrosis/apoptosis, in the ischemic cortex. Animals receiving MANF pretreatment demonstrated a decrease in body asymmetry and neurological score as well as an increase in locomotor activity after MCAo. Taken together, these data suggest that MANF has neuroprotective effects against cerebral ischemia, possibly through the inhibition of cell necrosis/apoptosis in cerebral cortex.
Glial cell line-derived neurotrophic factor (GDNF) has been shown to be involved in the maintenan... more Glial cell line-derived neurotrophic factor (GDNF) has been shown to be involved in the maintenance of striatal dopaminergic neurons. Neurotrophic factors are crucial for the plasticity of central nervous system and may be involved in long-term responses to drug exposure. To study the effects of reduced GDNF on dopaminergic behaviour related to addiction, we compared the effects of morphine on locomotor activity, conditioned place preference (CPP) and extracellular accumbal dopamine in heterozygous GDNF knockout mice (GDNF1/2) with those in their wild-type (Wt) littermates. When morphine 30 mg/kg was administered daily for 4 days, tolerance developed towards its locomotor stimulatory action only in the GDNF1/2 mice. A morphine 5 mg/kg challenge dose stimulated locomotor activity only in the GDNF1/2 mice withdrawn for 96 h from repeated morphine treatment, whereas clear and similar sensitization of the locomotor response was seen after a 10 mg/kg challenge dose in mice of both genotypes. Morphine-induced CPP developed initially similarly in Wt and GDNF1/2 mice, but it lasted longer in the Wt mice. The small challenge dose of morphine increased accumbal dopamine output slightly more in the GDNF1/2 mice than in the Wt mice, but doubling the challenge dose caused a dose-dependent response only in the Wt mice. In addition, repeated morphine treatment counteracted the increase in the accumbal extracellular dopamine concentration we previously found in drug-naive GDNF1/2 mice. Thus, reduced endogenous GDNF level alters the dopaminergic behavioural effects to repeatedly administered morphine, emphasizing the involvement of GDNF in the neuroplastic changes related to long-term effects of drugs of abuse.
It was suggested in 1986 that cue-induced drug craving in cocaine addicts progressively increases... more It was suggested in 1986 that cue-induced drug craving in cocaine addicts progressively increases over the first several weeks of abstinence and remains high for extended periods. During the past decade, investigators have identified an analogous incubation phenomenon in rodents, in which time-dependent increases in cue-induced drug seeking are observed after withdrawal from intravenous cocaine self-administration. Such an incubation of drug craving is not specific to cocaine, as similar findings have been observed after self-administration of heroin, nicotine, methamphetamine and alcohol in rats. In this review, we discuss recent results that have identified important brain regions involved in the incubation of drug craving, as well as evidence for the underlying cellular mechanisms. Understanding the neurobiology of the incubation of drug craving in rodents is likely to have significant implications for furthering understanding of brain mechanisms and circuits that underlie cravin...
Primate-specific genes and isoforms could provide insight into human brain diseases. Our bioinfor... more Primate-specific genes and isoforms could provide insight into human brain diseases. Our bioinformatic analysis revealed that there are possibly five isoforms of human GDNF gene with different pre- and pro-regions by inter- and intra-exon splicing. By using TaqMan primer probe sets, designed between exons, we verified the expression of all isoforms. Furthermore, a novel GDNFOS gene was found to be transcribed from the opposite strand of GDNF gene. GDNFOS gene has four exons that are spliced into different isoforms. GDNFOS1 and GDNFOS2 are long noncoding RNAs, and GDNFOS3 encodes a protein of 105 amino acids. To study human GDNF and GDNFOS regulation in neurodegenerative diseases, the protein and mRNA levels were measured by Western blot and RT-quantitative PCR, respectively, in postmortem middle temporal gyrus (MTG) of Alzheimer disease (AD) and Huntington disease (HD) patients in comparison with those of normal controls. In the MTG of AD patients, the mature GDNF peptide was down-r...
For stroke patients the recovery of cognitive and behavioral functions is often incomplete. Funct... more For stroke patients the recovery of cognitive and behavioral functions is often incomplete. Functional recovery is thought to be mediated largely by connectivity rearrangements in the peri-infarct region. A method for manipulating gene expression in this region would be useful for identifying new recovery-enhancing treatments. We have characterized a way of targeting adeno-associated virus (AAV) vectors to the peri-infarct region of cortical ischemic lesion in rats 2days after middle cerebral artery occlusion (MCAo). We used magnetic resonance imaging (MRI) to show that the altered properties of post-ischemic brain tissue facilitate the spreading of intrastriatally injected nanoparticles toward the infarct. We show that subcortical injection of green fluorescent protein-encoding dsAAV7-GFP resulted in transduction of cells in and around the white matter tract underlying the lesion, and in the cortex proximal to the lesion. A similar result was achieved with dsAAV7 vector encoding the cerebral dopamine neurotrophic factor (CDNF), a protein with therapeutic potential. Viral vector-mediated intracerebral gene delivery has been used before in rodent models of ischemic injury. However, the method of targeting gene expression to the peri-infarct region, after the initial phase of ischemic cell death, has not been described before. We demonstrate a straightforward and robust way to target AAV vector-mediated over-expression of genes to the peri-infarct region in a rat stroke model. This method will be useful for studying the action of specific proteins in peri-infarct region during the recovery process.
Stroke is a major complication of cardiovascular surgery, resulting in over 100,000 deaths and ov... more Stroke is a major complication of cardiovascular surgery, resulting in over 100,000 deaths and over a million postoperative encephalopathies annually in the US and Europe. While mitigating damage from stroke after it occurs has proven elusive, opportunities to reduce the incidence and/or severity of stroke prior to surgery in at-risk individuals remain largely unexplored. We tested the potential of short-term preoperative dietary restriction to provide neuroprotection in rat models of focal stroke. Rats were preconditioned with either three days of water-only fasting or six days of a protein free diet prior to induction of transient middle cerebral artery occlusion using two different methods, resulting in either a severe focal stroke to forebrain and midbrain, or a mild focal stroke localized to cortex only. Infarct volume, functional recovery and molecular markers of damage and protection were assessed up to two weeks after reperfusion. Preoperative fasting for 3 days reduced infa...
Although initially thought to be important primarily in neural development, a number of trophic p... more Although initially thought to be important primarily in neural development, a number of trophic proteins have been found to have neuroprotective and neuroregenerative activity in the adult central system, particularly for midbrain dopamine neurons (MDN). Neurorestoration is potentially feasible for MDN since there is an initial loss of phenotype for these neurons in Parkinson's disease (PD) rather than neuronal death. There is a considerable recent literature on trophic properties of TGF-ß superfamily proteins for MDN's, including glial cell-derived neurotrophic factor (GDNF), neurturin, and bone morphogenetic proteins (BMPs). This paper will review studies with the factors listed above, as well as describe more recent studies with two newly described trophic proteins, MANF and CDNF. Data will be presented from various animal models of PD suggesting that these trophic proteins may eventually lead to PD therapeutics in man. In addition, some data on small molecules with neuroprotective properties (AP 4 A, retinoic acid and vitamin D 3 ) will also be described.
Ret is the common signaling receptor for glial cell line-derived neurotrophic factor (GDNF) and o... more Ret is the common signaling receptor for glial cell line-derived neurotrophic factor (GDNF) and other ligands of the GDNF family that have potent effects on brain dopaminergic neurons. The Met918Thr mutation leads to constitutive activity of Ret receptor tyrosine kinase, causing the cancer syndrome called multiple endocrine neoplasia type B (MEN2B). We used knock-in MEN2B mice with the Ret-MEN2B mutation to study the effects of constitutive Ret activity on the brain dopaminergic system and found robustly increased concentrations of dopamine (DA) and its metabolites in the striatum, cortex, and hypothalamus. The concentrations of brain serotonin were not affected and those of noradrenaline were slightly increased only in the lower brainstem. Tyrosine hydroxylase (TH) protein levels were increased in the striatum and substantia nigra/ventral tegmental area (SN/VTA), and TH mRNA levels were increased in SN/VTA of MEN2B mice, suggesting that constitutive Ret activity increases DA levels by increasing its synthesis. Also, the striatal DA transporter protein levels in the MEN2B mice were increased, which agrees with increased sensitivity of these mice to the stimulatory effects of cocaine. In the SN pars compacta of homozygous MEN2B mice, we found a 26% increase in the number of TH-positive cells, but no differences were found in the VTA. Thus, we show here that the constitutive Ret activity in mice is sufficient to increase the number of dopaminergic neurons and leads to profound elevation of brain DA concentration. These data clearly suggest that Ret activity per se can have a direct biological function that actively changes and shapes the brain dopaminergic system.
Glial cell line-derived neurotrophic factor (GDNF) regulates striatal dopaminergic neurons. To st... more Glial cell line-derived neurotrophic factor (GDNF) regulates striatal dopaminergic neurons. To study whether reduced endogenous GDNF affect morphine's effects on striatal dopamine transmission, we estimated extracellular concentrations of dopamine and its metabolites by microdialysis in vivo and tissue concentrations post mortem in mice lacking one GDNF allele (GDNF+/- mice). In the wild-type mice, acute morphine (5 and 10 mg/kg s.c.) increased accumbal dopamine output dose-dependently (maximally by 30 and 80%, respectively). In the GDNF+/- mice, 5 mg/kg of morphine enhanced the accumbal dopamine output maximally by 110%, and significantly more than morphine 10 mg/kg (maximally by 60%). Also, the response of extracellular accumbal DOPAC to acute morphine was significantly altered in the GDNF+/- mice. In mice of both genotypes, the responses to morphine in the caudate putamen were similar to but much less intense than those in the nucleus accumbens. Morphine at the doses 5, 10, and 30 mg/kg dose-dependently elevated the striatal tissue concentrations of DOPAC and HVA, but the effect of 30 mg/kg was significantly smaller in the GDNF+/- mice than in their wild-type littermates. The binding of [(3)H]DAMGO to striatal membrane homogenates was similar between the genotypes. However, morphine induced antinociception in the GDNF+/- mice at a smaller dose than in the controls. The finding that reduced GDNF level alters the effects of morphine on striatal dopamine and our previous findings of elevated extracellular striatal dopamine concentrations and FosB/DeltaFosB expression in the GDNF+/- mice show the importance of GDNF in the regulation of striatal dopaminergic system.
Rationale-Methamphetamine is a commonly abused drug and dopaminergic neurotoxin. Repeated adminis... more Rationale-Methamphetamine is a commonly abused drug and dopaminergic neurotoxin. Repeated administration of high doses of methamphetamine induces programmed cell death, suppression of dopamine release, and reduction in locomotor activity. Previous studies have shown that pretreatment with Peroxisome Proliferator-Activated Receptor gamma (PPARγ) agonist reduced Methamphetamine -induced neurodegeneration.
Migration of new neuroprogenitor cells (NPCs) from the subventricular zone (SVZ) plays an importa... more Migration of new neuroprogenitor cells (NPCs) from the subventricular zone (SVZ) plays an important role in neurorepair after injury. Previous studies have shown that brain derived neurotrophic factor (BDNF) enhances the migration of NPCs from SVZ explants in neonatal mice in vitro. The purpose of this study was to identify the role of BDNF in SVZ cells using AAV-BDNF in an animal model of stroke. BDNF protein production after AAV-BDNF infection was verified in primary neuronal culture. AAV-BDNF or AAV-RFP was injected into the left SVZ region of adult rats at 14 days prior to right middle cerebral artery occlusion (MCAo). SVZ tissues were collected from the brain and placed in Metrigel cultures 1 day after MCAo. Treatment with AAV-BDNF significantly increased the migration of SVZ cells in the stroke brain in vitro. In another set of animals, AAV-GFP was co-injected with AAV-BDNF or AAV-RFP to label cells in left SVZ prior to right MCAo. Local administration of AAV-BDNF significantly enhanced recovery of locomotor function and migration of GFP-positive cells from the SVZ toward the lesioned hemisphere in stroke rats. Our data suggest that focal administration of AAV-BDNF to the SVZ increases behavioral recovery post stroke, possibly through the enhancement of migration of cells from SVZ in stroke animals. Regional manipulation of BDNF expression through AAV may be a novel approach for neurorepair in stroke brains.
Following the onset of an ischemic brain injury, the excitatory neurotransmitter glutamate is rel... more Following the onset of an ischemic brain injury, the excitatory neurotransmitter glutamate is released. The excitotoxic effects of glutamate are a major contributor to the pathogenesis of a stroke. The aim of this study was to examine if overexpression of a glutamate transporter (GLT-1) reduces ischemic brain injury in a rat model of stroke. We generated an adeno-associated viral (AAV) vector expressing the rat GLT-1 cDNA (AAV-GLT1). Functional expression of AAV-GLT1 was confirmed by increased glutamate clearance rate in non-stroke rat brain as measured by in vivo amperometry. AAV-GLT1 was injected into future cortical region of infarction 3 weeks prior to 60 min middle cerebral artery occlusion (MCAo). Tissue damage was assessed at one and two days after MCAo using TUNEL and TTC staining, respectively. Behavioral testing was performed at 2, 8 and 14 days post-stroke. Animals receiving AAV-GLT1, compared to AAV-GFP, showed significant decreases in the duration and magnitude of extracellular glutamate, measured by microdialysis, during the 60 minute MCAo. A significant reduction in brain infarction and DNA fragmentation was observed in the region of AAV-GLT1 injection. Animals that received AAV-GLT1 showed significant improvement in behavioral recovery following stroke compared to the AAV-GFP group. We demonstrate that focal overexpression of the glutamate transporter, GLT-1, significantly reduces ischemia-induced glutamate overflow, decreases cell death and improves behavioral recovery. These data further support the role of glutamate in the pathogenesis of ischemic damage in brain and demonstrate that targeted gene delivery to decrease the ischemia-induced glutamate overflow reduces the cellular and behavioral deficits caused by stroke.
Although initially thought to be important primarily in neural development, a number of trophic p... more Although initially thought to be important primarily in neural development, a number of trophic proteins have been found to have neuroprotective and neuroregenerative activity in the adult central nervous system, particularly for midbrain dopamine neurons (MDN). Neurorestoration is potentially feasible for MDN since there is an initial loss of phenotype for these neurons in Parkinson's disease (PD) rather than neuronal death. There is a considerable recent literature on trophic properties of TGF-β superfamily proteins for MDN's, including glial cell-derived neurotrophic factor (GDNF), neurturin, and bone morphogenetic proteins (BMPs). This paper will review studies with the factors listed above, as well as describe more recent studies with two newly described trophic proteins, MANF and CDNF. Data will be presented from various animal models of PD suggesting that these trophic proteins may eventually lead to PD therapeutics in man. In addition, some data on small molecules with neuroprotective properties (AP(4)A, retinoic acid and vitamin D(3)) will also be described.
The identification of genes linked to neurodegenerative diseases such as Alzheimer's disease (AD)... more The identification of genes linked to neurodegenerative diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD) and Parkinson's disease (PD) has led to the development of animal models for studying mechanism and evaluating potential therapies. None of the transgenic models developed based on disease-associated genes have been able to fully recapitulate the behavioral and pathological features of the corresponding disease. However, there has been enormous progress made in identifying potential therapeutic targets and understanding some of the common mechanisms of neurodegeneration. In this review, we will discuss transgenic animal models for AD, ALS, HD and PD that are based on human genetic studies. All of the diseases discussed have active or complete clinical trials for experimental treatments that benefited from transgenic models of the disease.
Background: Glial cell line-derived neurotrophic factor (GDNF) has been effective therapy in labo... more Background: Glial cell line-derived neurotrophic factor (GDNF) has been effective therapy in laboratory animal models of Parkinson disease. Results: A human GDNFOS (GDNF opposite strand) gene was discovered and potentially encodes a 105-amino acid peptide. Conclusion: GDNF sense and GDNFOS antisense genes are differentially regulated in human tissues. Significance: GDNF and GDNFOS isoforms may have roles in human neurodegenerative diseases.
Mesencephalic astrocyte-derived neurotrophic factor (MANF), also known as Arginine-rich, Mutated ... more Mesencephalic astrocyte-derived neurotrophic factor (MANF), also known as Arginine-rich, Mutated in Early Stage of Tumors (ARMET), is a secreted protein which reduces endoplasmic reticulum (ER) stress. Previous studies have shown that MANF mRNA expression and protein levels are increased in the cerebral cortex after brain ischemia, a condition which induces ER stress. The function of MANF during brain ischemia is still not known. The purpose of this study was to examine the protective effect of MANF after ischemic brain injury. Recombinant human MANF was administrated locally to the cerebral cortex before a 60-min middle cerebral artery occlusion (MCAo) in adult rats. Triphenyltetrazolium chloride (TTC) staining indicated that pretreatment with MANF significantly reduced the volume of infarction at two days after MCAo. MANF also attenuated TUNEL labeling, a marker of cell necrosis/apoptosis, in the ischemic cortex. Animals receiving MANF pretreatment demonstrated a decrease in body asymmetry and neurological score as well as an increase in locomotor activity after MCAo. Taken together, these data suggest that MANF has neuroprotective effects against cerebral ischemia, possibly through the inhibition of cell necrosis/apoptosis in cerebral cortex.
Glial cell line-derived neurotrophic factor (GDNF) has been shown to be involved in the maintenan... more Glial cell line-derived neurotrophic factor (GDNF) has been shown to be involved in the maintenance of striatal dopaminergic neurons. Neurotrophic factors are crucial for the plasticity of central nervous system and may be involved in long-term responses to drug exposure. To study the effects of reduced GDNF on dopaminergic behaviour related to addiction, we compared the effects of morphine on locomotor activity, conditioned place preference (CPP) and extracellular accumbal dopamine in heterozygous GDNF knockout mice (GDNF1/2) with those in their wild-type (Wt) littermates. When morphine 30 mg/kg was administered daily for 4 days, tolerance developed towards its locomotor stimulatory action only in the GDNF1/2 mice. A morphine 5 mg/kg challenge dose stimulated locomotor activity only in the GDNF1/2 mice withdrawn for 96 h from repeated morphine treatment, whereas clear and similar sensitization of the locomotor response was seen after a 10 mg/kg challenge dose in mice of both genotypes. Morphine-induced CPP developed initially similarly in Wt and GDNF1/2 mice, but it lasted longer in the Wt mice. The small challenge dose of morphine increased accumbal dopamine output slightly more in the GDNF1/2 mice than in the Wt mice, but doubling the challenge dose caused a dose-dependent response only in the Wt mice. In addition, repeated morphine treatment counteracted the increase in the accumbal extracellular dopamine concentration we previously found in drug-naive GDNF1/2 mice. Thus, reduced endogenous GDNF level alters the dopaminergic behavioural effects to repeatedly administered morphine, emphasizing the involvement of GDNF in the neuroplastic changes related to long-term effects of drugs of abuse.
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Papers by Mikko Airavaara