Glial Cell Line-derived Neurotrophic Factor Immunoreactivity Research Articles

Structural and chemical changes in glial cells in the rat neocortex induced by constant occlusion of the middle cerebral artery

Stroke-induced changes in neuroglia determine the basic conditions for the survival and damage of neurons in the ischemic core. Here, we studied the immunolocalization of glial cell line-derived neurotrophic factor (GDNF), glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor molecule 1 (Iba-1), and S-100β in the rat parietal cortex after constant occlusion of the middle cerebral artery. These cytoplasmic proteins are specific for different glial cell types. They are used as indicators of activated microglia and astrocytes in immunocytochemical studies.The distribution pattern of all markers changed dramatically with time. GFAP- and S-100β-positive astrocytes were observed in the penumbra zone and marked its boundaries. In days 1–8 after surgery, in the ischemic core, the number of S-100β-immunoreactive astrocytes decreased, and individual pyramidal cells appeared. S-100β-expressing pyramidal cells were localized in cortical layers III and V. They were only found in the ischemic core. Their proportion to the total number of cells was 37.3 ± 3.9 %, 22.2 ± 1.2 %, 16.3 ± 2.3 %, and 5.4 ± 0.3 % on days 1, 3, 8, and 14 after surgery. On day 21, no S-100β-expressing pyramidal cells were observed. The spatial density of GFAP- and S-100β-positive astrocytes increased in the penumbra region adjacent to the ischemic core and decreased in the penumbral periphery. As a result, the width of the perifocal penumbra zone decreased substantially at later stages of the stroke. In the penumbra, on days 1–3 after ischemic injury, GDNF immunoreactivity was mainly localized in neurons, while later on (days 8–21) it was mainly constrained to astrocyte glia. In intact rats, GDNF-positive neurons were situated in cortical layers II/III and V/VI and made up 52 ± 4.5 % of the total neuron population. Their proportion to the total number of neurons was 29 ± 2.1 %, 13.8 ± 0.6 %, and 3.1 ± 0.2 % on days 1, 8, and 21 after surgery. The number of GDNF-positive astrocytes, on the opposite, increased with time after ischemic injury. Iba-1-reactive microglia was mainly localized to the ischemic core. Microglial cells appeared activated as evidenced by their increased size and decreased number of processes and branching density. The spatial density of microglia reached a peak ​​on day 8 after ischemic injury both in the ischemic core and penumbra. An increase in the number of Iba-1-reactive microglia in the ischemic core correlated with a decrease of the number of GFAP-positive astrocytes. The results are discussed in the context of participation of neuroglia in regulation of various neuroprotective and destructive processes.

GDNF and GFRα co-receptor family in the developing feline gut

Glial cell-line derived neurotrophic factor (GDNF) and the GFRα co-receptors play a role in the developing enteric nervous system. The co-receptors elicit their action by binding receptor tyrosine kinase RET.This immunohistochemical study reports the presence of GDNF and its specific co-receptor GFRα1 in the cat gastrointestinal apparatus during development, from stage 9 to 22. At stage 9 and 11, immunoreactivity (IR) to GDNF was observed in the cells of mesenchyme of the anterior gut. From stage 14 to 22, GDNF IR was detected in nervous plexuses; moreover, GDNF and GFRα1 IR appeared localized in gastrointestinal endocrine cells. The presence of GDNF in the enteric nervous system and in the endocrine cells suggests an involvement of this neurotrophic factor in the gastrointestinal development. Moreover, the presence of the co-receptor GFRα1 in endocrine cells and its absence in the enteric nervous system seems to indicate a different mode of transduction of GDNF signal. GFRα2 and GFRα3 co-receptors were not detected.

Subtle adjustments of the glucose-6-phosphate dehydrogenase (G6PD) mutation database and reference sequence

Glial cell-line derived neurotrophic factor (GDNF) and the GFRα co-receptors play a role in the developing enteric nervous system. The co-receptors elicit their action by binding receptor tyrosine kinase RET.This immunohistochemical study reports the presence of GDNF and its specific co-receptor GFRα1 in the cat gastrointestinal apparatus during development, from stage 9 to 22. At stage 9 and 11, immunoreactivity (IR) to GDNF was observed in the cells of mesenchyme of the anterior gut. From stage 14 to 22, GDNF IR was detected in nervous plexuses; moreover, GDNF and GFRα1 IR appeared localized in gastrointestinal endocrine cells. The presence of GDNF in the enteric nervous system and in the endocrine cells suggests an involvement of this neurotrophic factor in the gastrointestinal development. Moreover, the presence of the co-receptor GFRα1 in endocrine cells and its absence in the enteric nervous system seems to indicate a different mode of transduction of GDNF signal. GFRα2 and GFRα3 co-receptors were not detected.

Lipopolysaccharide-induced nigral inflammation leads to increased IL-1β tissue content and expression of astrocytic glial cell line-derived neurotrophic factor

Reactive gliosis and inflammatory change is a key component of nigral dopaminergic cell death in Parkinson's disease (PD). Astrocyte derived glial cell line-derived neurotrophic factor (GDNF) promotes the survival and growth of dopaminergic neurones and it protects against or reverses nigral degeneration induced by 6-OHDA and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in rodents and primates. But the effect of increased levels of pro-inflammatory cytokines on the release of GDNF is unknown. This study examined the relationship between release of tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) and the expression of GDNF in rats following nigral lipopolysaccharide (LPS) administration. Acute nigral administration of LPS led to marked elevation of IL-1β but insignificant TNF-α tissue content and to a prominent expression of GDNF immunoreactivity in astrocytes but not microglia. The results suggest that inflammation is not only involved in neuronal loss but could promote neuronal survival through increased release of GDNF following up-regulation of IL-1β.

Comparative Effects between Bone Marrow and Mesenchymal Stem Cell Transplantation in GDNF Expression and Motor Function Recovery in a Motorneuron Degenerative Mouse Model

Motorneuron degenerative diseases, such as amyotrophic lateral sclerosis (ALS), are characterized by the progressive and rapid loss of motor neurons in the brain and spinal cord, leading to paralysis and death. GDNF (glial cell line derived neurotrophic factor) has been previously shown to be capable of protecting motor-neurons in ALS animal models although its delivery to the spinal cord after systemic administration is blocked by the blood brain barrier. Thus, it is necessary to develop new neurotrophic approaches to protect these motor neurons from death. Bone marrow-derived stem cells have been shown to be capable of improving a large variety of neurodegenerative disorders through neurotrophic mediated mechanisms. Here we analyzed the effect of transplanting whole bone marrow or cultured mesenchymal stem cells into the spinal cord of a motor neuron degenerative mouse model. Motor functions were analyzed using various behavior tests for several weeks after transplantation. We observed that bone marrow, and to a lesser degree mesenchymal stem cell, treated mice improved significantly in the motor tests performed, coinciding with a higher GDNF immunoreactivity in the grafted spinal cord. In several cases, the treated spinal cords were extracted, the engrafted bone marrow cells isolated and cultured, and finally re-transplanted into the spleen of immunodeficient mice. Re-grafted cells were detected in the host spleen, bloodstream and bone marrow, demonstrating a phenotypic stability. Thus, bone marrow cells do not suffer significant phenotypic modifications and is an efficient procedure to ameliorate motor-neuron degeneration, making it a possible therapeutic approach.

Glial cell line-derived neurotrophic factor in Purkinje cells of adult zebrafish: An autocrine mode of action?

Glial cell line-derived neurotrophic factor (GDNF) has a neuroprotective role in Purkinje cells of cerebellum, promoting the survival and the differentiation of these cells. Its signalling is mediated by a receptorial complex GFRalpha1/RET. In the brain of adult zebrafish (Danio rerio) we previously investigated GDNF expression and localization, but no data exist regarding GFRalpha1 and RET presence. Thus, the present study was designed to clarify the morphological relation between GDNF and its receptorial complex GFRalpha1/RET immunoreactivity in the cerebellum of adult zebrafish. The expression of gdnf, GFRalpha1 and ret genes was demonstrated in adult zebrafish cerebellum by a standard RT-PCR. The distribution of GDNF and its receptorial complex GFRalpha1/RET was examined by single and double immunocytochemical stainings. In the valvula and corpus cerebelli GDNF, GFRalpha1 and RET immunoreactivity was seen co-localized in Purkinje cells, identified morphologically and by using an antiserum against a specific marker for these cells, aldolase C enzyme. In the vestibulolateralis lobe, Purkinje neurons were lacking in both the eminentiae granulares and medial caudal lobe. These results demonstrated the expression of the GDNF receptorial complex in adult zebrafish cerebellum and suggest an autocrine mode of action of GDNF in Purkinje cells.

Immunoreactivity to glial cell line-derived neurotrophic factor and its receptors in the trout pancreas: a further endocrine-exocrine relationship?

Glial cell line-derived neurotrophic factor (GDNF) is a growth factor promoting the survival of several neuronal populations in the central, peripheral and autonomous nervous system. Outside the nervous system, GDNF functions as a morphogen in kidney development and regulates spermatogonial differentiation. GDNF exerts its roles by binding to glial cell line-derived neurotrophic factor receptor (GFR) a1, which forms a heterotetramic complex with rearranged during transfection (RET) proto-oncogene product, a tyrosine kinase receptor. In this study we report the presence of GDNF-, RET- and GFRa1-like immunoreactivity in the pancreas of juvenile trout. GDNF immunoreactivity was observed in the islet cells, while GFRa1- and RET- immunoreactivity was observed in the exocrine portion. These findings suggest a paracrine role of GDNF towards exocrine cells showing GDNF receptors GFRa1 and RET. The relationship could reflect physiological interactions, as previously indicated in mammalian pancreas, and/or a trophic role by endocrine cells on exocrine parenchyma, which shows a conspicuous increase during animal growth.

Cellular localization of GDNF and its GFRalpha1/RET receptor complex in the developing pancreas of cat

Glial cell line-derived neurotrophic factor (GDNF) acts through RET receptor tyrosine kinase and its co-receptor GFRalpha1. In an effort to better understand the possible biological contribution of the GDNF and GFRalpha1/RET complex in pancreatic development, in this study we report the cellular localization of these proteins in the pancreas of domestic cat embryos and fetuses by immunocytochemical methods. In early embryos, GDNF, GFRalpha and RET immunoreactivity (IR) was localized in closely intermingled cells. GDNF and RET immunoreactive cells displayed chromogranin (an endocrine marker) and PGP 9.5 (a neuronal marker) IR, respectively. GFRalpha IR was present in both a few GDNF/chromogranin and RET/PGP 9.5 immunoreactive cells. In elderly fetuses, GDNF and GFRalpha IR were co-localized in glucagon cells and RET IR was detected in few neurons and never co-localized with GFRalpha or GDNF IR. In early embryos, the presence of GDNF IR in chromogranin immunoreactive cells and GFRalpha1/RET complex IR in PGP9.5 immunoreactive cells seems to suggest a paracrine action of GDNF contained in endocrine cell precursors on neuronal cell precursors expressing its receptor complex. The presence in different cell populations of RET and its co-receptor GFRalpha1 IR could be due to independent signaling of GRFalpha1. Thus, the co-presence of GDNF and GFRalpha1 in chromogranin and glucagon cells could lead to the hypothesis that GDNF can act in an autocrinal manner. In fetuses, RET IR was detected only in intrapancreatic ganglia. Because of the lack of GFRalpha1 IR in pancreatic innervation, RET receptor could be activated by other GFR alphas and ligands of GDNF family. In conclusion, these findings suggest that in differently aged embryos and fetuses the GDNF signal is differently mediated by RET and GFRalpha1.

Distribution and immunohistochemical localization of GDNF protein in selected neural and non-neural tissues of rats during development and changes in unilateral 6-hydroxydopamine lesions

The tissue distribution of glial cell line-derived neurotrophic factor (GDNF) during development and changes in GDNF levels by unilateral 6-hydroxydopamine lesions were investigated in rats using a newly established enzyme immunoassay system and by immunohistochemistry. The detection limit of the assay was 0.3 pg/0.2 ml and the system recognized glycosylated mature GDNF. Concentrations of GDNF were relatively high in the kidney and testis during the embryonic and neonatal periods, respectively, and decreased with age. In the striatum, hippocampus and brain stem, GDNF reached a maximal level at around postnatal day 14. However, brain levels were generally lower than those in non-neural tissues. In the CNS, GDNF immunoreactivity was observed in striatal neurons, pyramidal neurons in the hippocampus and the Vth layer of the cortex, large neurons in the diagonal band and brain stem, and spinal motor neurons. It was also evident in several non-neural, tissue-specific cells, such as cells in the renal collecting ducts and distal tubules, and testicular Sertoli cells. Destruction of nigral dopaminergic neurons by 6-hydroxydopamine enhanced the levels of striatal GDNF protein, with apparent involvement of astrocytes. These results suggest that GDNF is normally synthesized in neurons, but may also be produced by astroglial cells in damaged brains.

Reduced Neuronal Innervation in the Distal End of the Proximal Esophageal Atretic Segment in Cases of Esophageal Atresia with Distal Tracheoesophageal Fistula

Esophageal dysmotility is a common occurence after surgical repair of proximal esophageal atresia (EA) and distal tracheoesophageal fistula (TEF). The etiology of this motility disorder, however, remains controversial. Esophageal dysmotility also is present in isolated TEF or EA before surgery, suggesting a congenital cause. However, there is no information available in the literature with regard to the intramural nervous system of the human esophagus in EA-TEF. We examined the distal end of proximal esophageal atretic segment of neonates undergoing EA-TEF repair for intrinsic neuronal innervation. Using specific antibodies, we studied neuronal markers of specimens from nine cases of EA-TEF and 9 cases of normal esophagus by immunohistochemistry using neurofilament (NF), synaptophysin (SY), S100, and glial cell line-derived neurotrophic factor (GDNF). In the atretic segment, specimens staining with hematoxylin and eosin showed that there were marked hypoganglionosis and immature ganglion cells in the myenteric plexus. GDNF immunoreactivity in the atretic esophagus were markedly reduced in both the muscular layer and myenteric plexus. SY and NF-immunorective nerve fibers were distributed throughout the myenteric plexus of the normal esophagus, but the scarcity of these immunoreactive nerve fibers in the atretic esophagus was apparent. In contrast, the density of immunorective nerve fibers for S100 in the myenteric plexus and muscular layer was increased in the distal end of the atretic esophagus. We concluded that the distribution of ganglion cells and some nerve fibers in the distal end of the atretic esophageal segment is deficient. Inadequate and abnormal neuronal innervation of the esophagus could be related to the esophageal dysmotility seen in EA. Because GDNF is a survival factor for central and peripheral neurons, defective expression of GDNF could have an important role in the defective and/or abnormal neuronal innervation of atretic esophageal segment.

Ischemia-related changes of glial-derived neurotrophic factor and phosphatidylinositol 3-kinase in the hippocampus: Their possible correlation in astrocytes

In the present study, we observed the changes of endogenous expression of glial-cell-line-derived neurotrophic factor (GDNF) and phosphatidylinositol 3-kinase (PI-3 kinase) in the gerbil hippocampus after transient forebrain ischemia and investigated the correlation between GDNF and PI-3 kinase in the ischemic hippocampus. In the sham-operated group, GDNF and PI-3 kinase immunoreactivity was not found in any cells in the hippocampal CA1 region. GDNF, not PI-3 kinase, immunoreactivity was expressed in non-pyramidal cells in the CA1 region at 6 h after ischemic insult. At 12–24 h after ischemia, GDNF and PI-3 kinase immunoreactivity in the CA1 region was similar to that of the sham-operated group. From 2 days after ischemic insult, GDNF- and PI-3-kinase-immunoreactive astrocytes were detected in the CA1 region, and GDNF and PI-3 kinase immunoreactivity in astrocytes was highest in the CA1 region 4 days after ischemic insult. Moreover, at this time point, GDNF and PI-3 kinase were co-localized in some astrocytes. Western blotting showed that ischemia-related changes of GDNF and PI-3 kinase protein levels were similar to the immunohistochemical changes after ischemia. These results suggest that GDNF and PI-3 kinase may be related to delayed neuronal death and that GDNF and PI-3 kinase may be involved in activation of astrocytes.

Glial cell line-derived neurotrophic factor contributes to delayed inflammatory hyperalgesia in adjuvant rat pain model

Neurotrophic factors, such as nerve growth factor and brain-derived neurotrophic factor, are members of the structurally related neurotrophin family that play important roles in pain modulation. Although there are also indications for the involvement of glial cell line-derived neurotrophic factor (GDNF), it is unclear whether and how GDNF is involved in inflammatory pain. In the present study, we studied the expression pattern of GDNF in dorsal root ganglia (DRG) and spinal cord, using confocal microscopy. We demonstrate that GDNF is well associated with nonpeptidergic pain pathway and that GDNF could possibly be anterogradely transported from DRG neurons to superficial spinal cord dorsal horn. We also studied the dynamic changes of GDNF expression in rats during chronic inflammation using injection of complete Freund’s adjuvant as a model of chronic pain. We found that GDNF was down-regulated in both dorsal root ganglia and spinal cords 2 weeks after arthritis induction. To assess the impact of this down-regulation on pain transmission, we used a function-blocking antibody against GDNF delivered intrathecally in the same chronic-pain animal models. Injection of this antibody to GDNF produced no immediate effect, but decreased the delayed, bilateral hyperalgesia induced from a unilateral injection of complete Freund’s adjuvant. The effect of this antibody coincided with the down-regulation of GDNF immunoreactivity in response to inflammation, suggesting that GDNF supports biochemical changes that contribute to hyperalgesia.

Neurturin enhances the survival of axotomized retinal ganglion cells in vivo: combined effects with glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor

In the present study we localized glial cell line-derived neurotrophic factor (GDNF), and the high affinity receptor for GDNF (GFRα-1) in the rat retina. We also examined the effects of neurturin on the survival of axotomized retinal ganglion cells (RGCs) and compared neurturin-mediated RGC rescue to GDNF and brain-derived neurotrophic factor (BDNF) neuroprotection. We administered combined injections of neurturin with BDNF or GDNF in order to determine if these factors rescue RGCs by different mechanisms. GDNF immunoreactivity was localized to RGCs, photoreceptors, and retinal pigment epithelial cells. GFRα-1 immunoreactivity was localized to RGCs, Müller cells, and photoreceptors. RGC densities in control retinas decreased from the original value of 2481±121 (RGCs/mm 2±S.D.) to 347±100 at 14 days post-axotomy. Neurturin treatment significantly increased RGC survival after axotomy (745±94) similar to GDNF (868±110). BDNF treatment resulted in higher RGC survival (1109±156) than either neurturin or GDNF. Combined administration of neurturin with BDNF had additive effects on the survival of axotomized RGCs (1962±282), similar to combined administration of GDNF and BDNF (1825±269). Combined administration of neurturin and GDNF (1265±178) had an enhanced effect on RGC survival. These results suggest that neurturin, GDNF, and BDNF act independently to rescue injured RGCs. Our results also suggest that RGCs and retinal Müller cells may be responsive to GDNF because they both express GFRα-1. The present findings have implications for the rescue of injured retinal ganglion cells, as well as other CNS neurons that are responsive to neurturin, GDNF, and BDNF, including midbrain dopaminergic neurons and motor neurons.

Adenovirus-mediated glial cell line–derived neurotrophic factor gene delivery reduces motor neuron injury after transient spinal cord ischemia in rabbits

Objective: Glial cell line–derived neurotrophic factor (GDNF) has protective effects on various injuries involving the central and peripheral nervous systems in vitro and vivo. However, the possible protective effect of GDNF on spinal cord ischemia and the exact mechanism involved in the ameliorative effect of GDNF on ischemic spinal cord injuries are not fully understood. Therefore, we investigated the possible protective effect of the adenovirus-mediated GDNF gene delivery on transient spinal cord ischemia in rabbits. Methods: The adenoviral vector (lacZ gene as a control or GDNF gene contained) was injected directly into the lumbar spinal cord via a needle inserted into the dorsal spine 2 days before the animal was subjected to 15 minutes of spinal cord ischemia induced by infrarenal aortic occlusion. In situ terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL staining) was performed, and temporal profiles of the GDNF and caspase-3 (caspase-3 is the marker of apoptotic change) immunoreactivity were investigated. Results: In the control rabbit, the majority of motor neurons showed selective cell death at 7 days of reperfusion. Immunocytochemistry showed that in situ TUNEL staining was selectively detected at 2 days of reperfusion in motor neuron nuclei. GDNF and caspase-3 were selectively induced in the motor neuron cells at 8 hours of reperfusion. In the GDNF-treated group, a large population of motor neuron cells was still surviving at 7 days after having been subjected to 15 minutes of ischemia. Unlike the control group, the GDNF-treated group expressed GDNF persistently. Induction of TUNEL staining and immunoreactivity for caspase-3 were greatly reduced by the GDNF treatment. Conclusion: These results suggest that the reduction in motor neuron death by GDNF was greatly associated with a reduction in DNA fragmentation and apoptotic signals of the caspase-3 cascade; they further suggest a great potential for gene therapy for paraplegic patients in the future. (J Thorac Cardiovasc Surg 2000;120:1148-57)

Up-regulation of glial cell line-derived neurotrophic factor (GDNF) following traumatic spinal cord injury.

We investigated the temporal and spatial expression patterns of the GDNF gene after subjecting rats to an acute contusion injury of the spinal cord using the weight drop technique. Reverse transcriptase-polymerase chain reaction (RT-PCR) revealed that GDNF transcription in the spinal cord began to increase within 30 min after injury and peaked within 3 h. Immunohistochemical analysis showed GDNF immunoreactivity to be present mainly in microglia and macrophages 1 day after injury, but not in neurons or astrocytes. This immediate upregulation of GDNF gene expression may be a component of an inflammatory process and probably exerts a protective effect on neurons following spinal cord injury (SCI).

Reactive Astrocytes of the Quinolinic Acid-Lesioned Rat Striatum Express GFRα1 as Well as GDNF in Vivo

Mechanical injury of the rodent striatum has recently been shown to cause a local increase in expression of mRNAs for glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor in the inflammatory cells, i.e., macrophages and activated microglia, respectively (3). An earlier study demonstrated an increase in GDNF mRNA levels in the adult rat striatum after administration of subseizure doses of N-methyl-d,l-aspartate and kainic acid (20) and identified astrocytes as the likely source of GDNF mRNA in the injected striatum. Our own recent work suggests that quinolinic acid (QA) induces moderate immunoreactivity to GDNF in a population of cells resembling reactive astrocytes within 1 week following intrastriatal injection (9). Therefore, the present follow-up experiment was performed with the aims: (I) to look at GDNF expression in the QA-injected striatum at 28 days, (II) to look for possible immunohistochemical expression of GFRα1 in the QA-injected striatum at the same observation time, and (III) to use confocal microscopy of double-immunofluorescence labeling of glial-cell-specific markers to identify the cell types expressing GDNF and GFRα1 in the striatum at 28 days following a QA injection. Our data indicate that GDNF immunoreactivity is high in the QA-injected striatum at 28 days and that the vast majority of cells displaying high labeling for GDNF also express glial fibrillary acidic protein and have a phenotype of reactive astrocytes. Interestingly, the same cells that express GDNF also display strong cytoplasmic immunolabeling to GFRα1.

GDNF and RET-gene expression in anterior pituitary-cell types.

Glial cell line-derived neurotrophic factor (GDNF) is expressed in many neuronal and non-neuronal tissues during development as well as in adult animals. GDNF signaling is mediated through a two-component system consisting of the so called GDNF receptor-alfa (GFRalpha1) which binds to GDNF. Thereafter this complex binds to and activates the tyrosine kinase receptor RET. In this work, for the first time, we have characterized the expression of both GDNF and RET in the anterior pituitary. First of all, RT-PCR analysis, Western blot and immunohistochemistry of the whole anterior pituitary showed that GDNF, GFRalpha1 and RET are expressed in this gland. Following double-immunofluorescence of consecutive sections we found GDNF immunoreactivity in most cell types, and it was most abundant in corticotrophs (55%), LH (59%) and FSH-producing cells (81%). In contrast, while the majority of somatotrophs (87%) were stained for RET, no positive immunostaining could be detected in other cell types. Taken together, this data indicate that gonadotrophs and corticotrophs are the main source of GDNF synthesized in the anterior pituitary and that the somatotrophs appears to be their target cell. This study provides direct morphological evidences that GDNF may well be acting in a paracrine-like fashion in the regulation of somatotroph cell growth and/or cell function.

Regulation of glial cell line-derived neurotrophic factor expression by electroacupuncture after transient focal cerebral ischemia.

The present study was designed to investigate whether electroacupuncture (EA) is able to regulate glial cell line-derived neurotrophic factor (GDNF) expression following transient middle cerebral artery occlusion (MCAO) using reverse transcriptase polymerase chain reaction and immunohistochemistry in rats. The results indicate that after 2 h MCAO, GDNF mRNA and immunoreactivity profoundly increased in peri-infarct cerebral cortex, with peaks at 2 h after reperfusion, then declined dramatically at 12 and 24 h after reperfusion. Although EA given immediatelly after MCAO couldn't elevate the peaks of GDNF expression, it obviously raised the GDNF mRNA and immunoreactivity levels at 12 h after reperfusion, delayed the declining trends of GDNF mRNA and immunoreactivity levels. These results suggest that EA could upregulate GDNF expression after ischemic insult, elongating the duration of upregulated GDNF expression. This may be one of the mechanisms of EA anti-ischemic injury by augmenting endogenous protective mechanism.

Expression of RET proto-oncogene and GDNF deficit in Hirschsprung's disease

Purpose: The aim of this study was to investigate GDNF (glial cell line-derived neurotrophic factor) protein expression and RNA expression level of the RET proto-oncogene in human aganglionic (AG) bowel in Hirschsprung's disease (HD) and to further understand the pathophysiology of HD. Methods: To evaluate the possible implication of the RET gene and GDNF for the development of HD, mRNA expression level of the RET gene was examined by using the reverse transcription-polymerase chain reaction (RT-PCR) technique and protein expression level of the GDNF using an immunohistochemical technique in the bowel specimens of 15 HD patients. Results: A significantly less intense signal for RET mRNA was found in the AG bowel compared with the ganglionic bowel. In different age groups of patients, the intensities of RET level had similar results. In the same patients, there was strong GDNF immunoreactivity in the myenteric plexuse in ganglionic bowel. In the myenteron in AG bowel, the number of GDNF immunoreactive neuron cells was reduced significantly compared with normal ganglionic bowel. Conclusions: From these preliminary data we conclude that the decreased RET expression in the AG bowel may suggest maldevelopment of neural crest-derived cells in HD. The reduced level of GDNF in AG bowel may suggest a GDNF expression deficit interrupting the faithful signaling via RET, and both are implicated in the pathogenesis of HD.

Time course of transient expression of GDNF protein in rat granule cells of the bilateral dentate gyri after unilateral intrahippocampal kainic acid injection

We examined the time course of expression of glial cell line-derived neurotrophic factor (GDNF) protein in the granule cells of the dentate gyrus following unilateral intrahippocampal injection of kainic acid (KA). Recurrent behavioral seizures were observed approximately 1 h after KA injection, which lasted for 4–6 h. GDNF immunoreactivity began to increase bilaterally in the granule cells within 3 h after KA injection, continued to increase until post-injection day (PID) 4, and returned to the control level by PID 7. The results suggest that the increase of GDNF protein in the granule cells may be ascribable to seizures induced by the KA injection. The increase of GDNF protein might promote survival of the granule cells after the intrahippocampal KA injection.