Glial cell-line derived neurotrophic factor is essential for electroconvulsive shock-induced neuroprotection in an animal model of Parkinson's disease

Noninvasive Neuromodulation in Parkinson's Disease: Insights from Animal Models

The mainstay treatments for Parkinson's Disease (PD) have been limited to pharmacotherapy and deep brain stimulation. While these interventions are helpful, a new wave of research is investigating noninvasive neuromodulation methods as potential treatments. Some promising avenues have included transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), electroconvulsive therapy (ECT), and focused ultrasound (FUS). While these methods are being tested in PD patients, investigations in animal models of PD have sought to elucidate their therapeutic mechanisms. In this rapid review, we assess the available animal literature on these noninvasive techniques and discuss the possible mechanisms mediating their therapeutic effects based on these findings.

Mild traumatic brain injury exacerbates Parkinson's disease induced hemeoxygenase-2 expression and brain pathology: Neuroprotective effects of co-administration of TiO2 nanowired mesenchymal stem cells and cerebrolysin

Mild traumatic brain injury (mTBI) is one of the leading predisposing factors in the development of Parkinson's disease (PD). Mild or moderate TBI induces rapid production of tau protein and alpha synuclein (ASNC) in the cerebrospinal fluid (CSF) and in several brain areas. Enhanced tau-phosphorylation and ASNC alters the molecular machinery of the brain leading to PD pathology. Recent evidences show upregulation of constitutive isoform of hemeoxygenase (HO-2) in PD patients that correlates well with the brain pathology. mTBI alone induces profound upregulation of HO-2 immunoreactivity. Thus, it would be interesting to explore whether mTBI exacerbates PD pathology in relation to tau, ASNC and HO-2 expression. In addition, whether neurotrophic factors and stem cells known to reduce brain pathology in TBI could induce neuroprotection in PD following mTBI. In this review role of mesenchymal stem cells (MSCs) and cerebrolysin (CBL), a well-balanced composition of several neurotrophic factors and active peptide fragments using nanowired delivery in PD following mTBI is discussed based on our own investigation. Our results show that mTBI induces concussion exacerbates PD pathology and nanowired delivery of MSCs and CBL induces superior neuroprotection. This could be due to reduction in tau, ASNC and HO-2 expression in PD following mTBI, not reported earlier. The functional significance of our findings in relation to clinical strategies is discussed.

Loss of TrkB Signaling Due to Status Epilepticus Induces a proBDNF-Dependent Cell Death

Neurotrophins (NTs) are secretory proteins that bind to target receptors and influence many cellular functions, such as cell survival and cell death in neurons. The mammalian NT brain-derived neurotrophic factor (matBDNF) is the C-terminal mature form released by cleavage from the proBDNF precursor. The binding of matBDNF to the tyrosine kinase receptor B (TrkB) activates different signaling cascades and leads to neuron survival and plasticity, while the interaction of proBDNF with the p75 NT receptor (p75NTR)/sortilin receptor complex has been highly involved in apoptosis. Many studies have demonstrated that prolonged seizures such as status epilepticus (SE) induce changes in the expression of NT, pro-NT, and their receptors. We have previously described that the blockage of both matBDNF and proBDNF signaling reduces neuronal death after SE in vivo (Unsain et al., 2008). We used an in vitro model as well as an in vivo model of SE to determine the specific role of TrkB and proBDNF signaling during neuronal cell death. We found that the matBDNF sequestering molecule TrkB-Fc induced an increase in neuronal death in both models of SE, and it also prevented a decrease in TrkB levels. Moreover, SE triggered the interaction between proBDNF and p75NTR, which was not altered by sequestering matBDNF. The intra-hippocampal administration of TrkB-Fc, combined with an antibody against proBDNF, prevented neuronal degeneration. In addition, we demonstrated that proBDNF binding to p75NTR exacerbates neuronal death when matBDNF signaling is impaired through TrkB. Our results indicated that both the mature and the precursor forms of BDNF may have opposite effects depending on the scenario in which they function and the signaling pathways they activate.

Glial Cell Line-Derived Neurotrophic Factor-Transfected Placenta-Derived Versus Bone Marrow-Derived Mesenchymal Cells for Treating Spinal Cord Injury

Background

Placenta-derived mesenchymal stem cells (PMSCs) were isolated from placenta and had differentiation and self-renewal potential. We transfected PMSCs with glial cell line-derived neurotrophic factor (GDNF) and compared their effect for repairing spinal cord injury (SCI) with that of GDNF-transfected bone marrow-derived mesenchymal stem cell (BMSC).

Material/Methods

The PMSCs were isolated from Sprague-Dawley rat placenta; BMSCs were isolated from Sprague-Dawley rat thigh bone marrow. Primary cultured BMSCs and PMSCs were uniformly spindle-shaped. Flow cytometry indicated that both cell types were CD29- and CD90-positive and CD34- and CD45-negative, confirming that they were MSCs. The PMSCs and BMSCs were transfected with recombinant lentivirus containing the GDNF gene in vitro. PMSC and BMSC viability was increased after transfection, and GDNF expression was increased until 10 d after transfection. SCI was created in the rats (n=64) and was repaired using transfected PMSCs and BMSCs or untransfected PMSCs and BMSCs.

Results

The transfected PMSCs and BMSCs repaired the SCI. Flow cytometry, histology, immunohistochemical, kinesiology properties, and Basso-Beattie-Bresnahan locomotion score measurements determined no significant difference between transfected PMSCs and BMSCs at 7, 14, and 21 d post-transplantation (P>0.05); the injury healed better in transfected PMSCs and BMSCs than in untransfected PMSCs and BMSCs (P<0.05).

Conclusions

MSCs have similar biology characteristics and capacity for SCI repair to BMSCs and can be used as a new resource for treating SCI.

GDNF From Human Periodontal Ligament Cells Treated With Pro-Inflammatory Cytokines Promotes Neurocytic Differentiation of PC12 Cells

Glial cell line-derived neurotrophic factor (GDNF) is known to mediate multiple biological activities such as promotion of cell motility and proliferation, and morphogenesis. However, little is known about its effects on periodontal ligament (PDL) cells. Recently, we reported that GDNF expression is increased in wounded rat PDL tissue and human PDL cells (HPDLCs) treated with pro-inflammatory cytokines. Here, we investigated the associated expression of GDNF and the pro-inflammatory cytokine interleukin-1 beta (IL-1β) in wounded PDL tissue, and whether HPDLCs secrete GDNF which affects neurocytic differentiation. Rat PDL cells near the wounded area showed intense immunoreactions against an anti-GDNF antibody, where immunoreactivity was also increased against an anti-IL-1β antibody. Compared with untreated cells, HPDLCs treated with IL-1β or tumor necrosis factor-alpha showed an increase in the secretion of GDNF protein. Conditioned medium of IL-1β-treated HPDLCs (IL-1β-CM) increased neurite outgrowth of PC12 rat adrenal pheochromocytoma cells. The expression levels of two neural regeneration-associated genes, growth-associated protein-43 (Gap-43), and small proline-rich repeat protein 1A (Sprr1A), were also upregulated in IL-1β-CM-treated PC12 cells. These stimulatory effects of IL-1β-CM were significantly inhibited by a neutralizing antibody against GDNF. In addition, U0126, a MEK inhibitor, inhibited GDNF-induced neurite outgrowth of PC12 cells. These findings suggest that an increase of GDNF in wounded PDL tissue might play an important role in neural regeneration probably via the MEK/ERK signaling pathway. J. Cell. Biochem. 118: 699-708, 2017. © 2016 Wiley Periodicals, Inc.

GDNF-based therapies, GDNF-producing interneurons, and trophic support of the dopaminergic nigrostriatal pathway. Implications for Parkinson's disease

The glial cell line-derived neurotrophic factor (GDNF) is a well-established trophic agent for dopaminergic (DA) neurons in vitro and in vivo. GDNF is necessary for maintenance of neuronal morphological and neurochemical phenotype and protects DA neurons from toxic damage. Numerous studies on animal models of Parkinson’s disease (PD) have reported beneficial effects of GDNF on nigrostriatal DA neuron survival. However, translation of these observations to the clinical setting has been hampered so far by side effects associated with the chronic continuous intra-striatal infusion of recombinant GDNF. In addition, double blind and placebo-controlled clinical trials have not reported any clinically relevant effect of GDNF on PD patients. In the past few years, experiments with conditional Gdnf knockout mice have suggested that GDNF is necessary for maintenance of DA neurons in adulthood. In parallel, new methodologies for exogenous GDNF delivery have been developed. Recently, it has been shown that a small population of scattered, electrically interconnected, parvalbumin positive (PV+) GABAergic interneurons is responsible for most of the GDNF produced in the rodent striatum. In addition, cholinergic striatal interneurons appear to be also involved in the modulation of striatal GDNF. In this review, we summarize current knowledge on brain GDNF delivery, homeostasis, and its effects on nigrostriatal DA neurons. Special attention is paid to the therapeutic potential of endogenous GDNF stimulation in PD.

Neurotrophic and neuroprotective efficacy of intranasal GDNF in a rat model of Parkinson's disease

Glial cell line-derived neurotrophic factor (GDNF) exerts neurotrophic and neuroprotective effects on substantia nigra (SN) dopamine neurons and has great therapeutic potential for Parkinson's disease (PD). Hindering this potential is the fact that GDNF cannot cross the blood-brain barrier. The aim of this study was to assess the effects of GDNF administered by the intranasal route in normal rats, and in the unilateral 6-hydroxydopamine (6-OHDA) model of PD. In the first study, rats received single intranasal doses of 50-μg GDNF in phosphate-buffered saline (PBS) or cationic liposomes, but no 6-OHDA. In the second study, rats were nasally administered 10, 50 or 150 μg of GDNF in PBS or cationic liposomes 1h before injection of 6-OHDA. All groups were sacrificed 3-4 weeks later. Both intranasal GDNF treatments induced a neurotrophic effect in the SN insofar as the number of tyrosine hydroxylase (TH)-positive neurons was significantly higher than in controls given intranasal PBS liposomes. Dopamine cell counts were also higher in the intact SN of 6-OHDA-lesioned rats compared to controls given PBS liposomes. Most importantly, intranasal GDNF provided significant neuroprotective efficacy indicated by greater TH immunostaining density in the lesioned versus intact SN of rats given single 50-μg doses of GDNF in PBS, or 150-μg doses of liposomal GDNF, compared to lesioned rats given PBS liposomes. Three 50-μg doses given at daily intervals (1 day before, 1h before, and 1 day after 6-OHDA) provided even greater protection than single 150-μg doses. Multiple doses at short intervals may therefore provide greater neuroprotection than single bolus doses. These results demonstrate both a neurotrophic effect of intranasal GDNF in the intact SN as well as neuroprotective efficacy in the unilateral 6-OHDA model, supporting pursuit of this approach as a potential treatment for PD.

Intracerebral administration of ultrasound-induced dissolution of lipid-coated GDNF microbubbles provides neuroprotection in a rat model of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by loss of dopaminergic neurons in the substantia nigra. Neurotrophic factors, such as glial cell derived neurotrophic factor (GDNF), have been shown to provide a neuroprotective effect in PD rats. We have previously reported that ultrasound-induced lipid-coated GDNF microspheres, which release GDNF in a sustained manner after low frequency ultrasound stimulation, can reduce hypoxic-ischemic injury in neonatal rats. In the present study, we investigated whether lipid-coated GDNF microspheres can provide a neuroprotective effect in a rat model of PD. After a rat model of PD was produced by 6-hydroxydompamine (6-OHDA) injections, lipid-coated GDNF microspheres (1.5mg/kg) were injected into the striatum of PD rats. We found that GDNF levels were increased in the striatum of PD rats after lipid-coated GDNF microspheres administration following low frequency ultrasound stimulation (20kHz, 5min per day, daily for 4 weeks). Moreover, GDNF microspheres reduced apomorphine-induced rotations, and increased striatal dopamine and nigral tyrosine hydroxylase (TH) levels in PD rats. Additionally, GDNF microspheres reduced caspase-3, tumor necrosis factor-alpha, matrix metalloproteinase 9 (MMP-9) and OX-6 levels induced by 6-OHDA injections in PD rats. These data indicated that lipid-coated GDNF microspheres can provide a neuroprotective effect in PD rats.

Are there really "epileptogenic" mechanisms or only corruptions of "normal" plasticity?

Plasticity in the nervous system, whether for establishing connections and networks during development, repairing networks after injury, or modifying connections based on experience, relies primarily on highly coordinated patterns of neural activity. Rhythmic, synchronized bursting of neuronal ensembles is a fundamental component of the activity-dependent plasticity responsible for the wiring and rewiring of neural circuits in the CNS. It is therefore not surprising that the architecture of the CNS supports the generation of highly synchronized bursts of neuronal activity in non-pathological conditions, even though the activity resembles the ictal and interictal events that are the hallmark symptoms of epilepsy. To prevent such natural epileptiform events from becoming pathological, multiple layers of homeostatic control operate on cellular and network levels. Many data on plastic changes that occur in different brain structures during the processes by which the epileptogenic aggregate is constituted have been accumulated but their role in counteracting or promoting such processes is still controversial. In this chapter we will review experimental and clinical evidence on the role of neural plasticity in the development of epilepsy. We will address questions such as: is epilepsy a progressive disorder? What do we know about mechanism(s) accounting for progression? Have we reliable biomarkers of epilepsy-related plastic processes? Do seizure-associated plastic changes protect against injury and aid in recovery? As a necessary premise we will consider the value of seizure-like activity in the context of normal neural development.