Localisation of Formyl-Peptide Receptor 2 in the Rat Central Nervous System and Its Role in Axonal and Dendritic Outgrowth

Arachidonic acid and docosahexaenoic acid (DHA) released by the action of phospholipases A₂ (PLA₂) on membrane phospholipids may be metabolized by lipoxygenases to the anti-inflammatory mediators lipoxin A4 (LXA4) and resolvin D1 (RvD1), and these can bind to a common receptor, formyl-peptide receptor 2 (FPR2). The contribution of this receptor to axonal or dendritic outgrowth is unknown. The present study was carried out to elucidate the distribution of FPR2 in the rat CNS and its role in outgrowth of neuronal processes. FPR2 mRNA expression was greatest in the brainstem, followed by the spinal cord, thalamus/hypothalamus, cerebral neocortex, hippocampus, cerebellum and striatum. The brainstem and spinal cord also contained high levels of FPR2 protein. The cerebral neocortex was moderately immunolabelled for FPR2, with staining mostly present as puncta in the neuropil. Dentate granule neurons and their axons (mossy fibres) in the hippocampus were very densely labelled. The cerebellar cortex was lightly stained, but the deep cerebellar nuclei, inferior olivary nucleus, vestibular nuclei, spinal trigeminal nucleus and dorsal horn of the spinal cord were densely labelled. Electron microscopy of the prefrontal cortex showed FPR2 immunolabel mostly in immature axon terminals or ‘pre-terminals’, that did not form synapses with dendrites. Treatment of primary hippocampal neurons with the FPR2 inhibitors, PBP10 or WRW4, resulted in reduced lengths of axons and dendrites. The CNS distribution of FPR2 suggests important functions in learning and memory, balance and nociception. This might be due to an effect of FPR2 in mediating arachidonic acid/LXA4 or DHA/RvD1-induced axonal or dendritic outgrowth.

Distribution of Alox15 in the Rat Brain and Its Role in Prefrontal Cortical Resolvin D1 Formation and Spatial Working Memory

Docosahexaenoic acid (DHA) is enriched in membrane phospholipids of the central nervous system (CNS) and has a role in aging and neuropsychiatric disorders. DHA is metabolized by the enzyme Alox15 to 17S-hydroxy-DHA, which is then converted to 7S-hydroperoxy,17S-hydroxy-DHA by a 5-lipoxygenase, and thence via epoxy intermediates to the anti-inflammatory molecule, resolvin D1 (RvD1 or 7S,8R,17S-trihydroxy-docosa-Z,9E,11E,13Z,15E,19Z-hexaenoic acid). In this study, we investigated the distribution and function of Alox15 in the CNS. RT-PCR of the CNS showed that the prefrontal cortex exhibits the highest Alox15 mRNA expression level, followed by the parietal association cortex and secondary auditory cortex, olfactory bulb, motor and somatosensory cortices, and the hippocampus. Western blot analysis was consistent with RT-PCR data, in that the prefrontal cortex, cerebral cortex, hippocampus, and olfactory bulb had high Alox15 protein expression. Immunohistochemistry showed moderate staining in the olfactory bulb, cerebral cortex, septum, striatum, cerebellar cortex, cochlear nuclei, spinal trigeminal nucleus, and dorsal horn of the spinal cord. Immuno-electron microscopy showed localization of Alox15 in dendrites, in the prefrontal cortex. Liquid chromatography mass spectrometry analysis showed significant decrease in resolvin D1 levels in the prefrontal cortex after inhibition or antisense knockdown of Alox15. Alox15 inhibition or antisense knockdown in the prefrontal cortex also blocked long-term potentiation of the hippocampo-prefrontal cortex pathway and increased errors in alternation, in the T-maze test. They indicate that Alox15 processing of DHA contributes to production of resolvin D1 and LTP at hippocampo-prefrontal cortical synapses and associated spatial working memory performance. Together, results provide evidence for a key role of anti-inflammatory molecules generated by Alox15 and DHA, such as resolvin D1, in memory. They suggest that neuroinflammatory brain disorders and chronic neurodegeneration may 'drain' anti-inflammatory molecules that are necessary for normal neuronal signaling, and compromise cognition.

Expression of DHA-Metabolizing Enzyme Alox15 is Regulated by Selective Histone Acetylation in Neuroblastoma Cells

The omega-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA) is enriched in neural membranes of the CNS, and recent studies have shown a role of DHA metabolism by 15-lipoxygenase-1 (Alox15) in prefrontal cortex resolvin D1 formation, hippocampo-prefrontal cortical long-term-potentiation, spatial working memory, and anti-nociception/anxiety. In this study, we elucidated epigenetic regulation of Alox15 via histone modifications in neuron-like cells. Treatment of undifferentiated SH-SY5Y human neuroblastoma cells with the histone deacetylase (HDAC) inhibitors trichostatin A (TSA) and sodium butyrate significantly increased Alox15 mRNA expression. Moreover, Alox15 expression was markedly upregulated by Class I HDAC inhibitors, MS-275 and depsipeptide. Co-treatment of undifferentiated SH-SY5Y cells with the p300 histone acetyltransferase (HAT) inhibitor C646 and TSA or sodium butyrate showed that p300 HAT inhibition modulated TSA or sodium butyrate-induced Alox15 upregulation. Differentiation of SH-SY5Y cells with retinoic acid resulted in increased neurite outgrowth and Alox15 mRNA expression, while co-treatment with the p300 HAT inhibitor C646 and retinoic acid modulated the increases, indicating a role of p300 HAT in differentiation-associated Alox15 upregulation. Increasing Alox15 expression was found in primary murine cortical neurons during development from 3 to 10 days-in-vitro, reaching high levels of expression by 10 days-in-vitro—when Alox15 was not further upregulated by HDAC inhibition. Together, results indicate regulation of Alox15 mRNA expression in neuroblastoma cells by histone modifications, and increasing Alox15 expression in differentiating neurons. It is possible that one of the environmental influences on the immature brain that can affect cognition and memory, may take the form of epigenetic effects on Alox15 and metabolites of DHA.

Docosahexaenoic acid and L-Carnitine prevent ATP loss in SH-SY5Y neuroblastoma cells after exposure to silver nanoparticles

Silver nanoparticles (AgNPs) are among the most commonly used nanomaterials, but thus far, little is known about ways to mitigate against potential toxic effects of exposure. In this study, we examined the potential effects of AgNPs on mitochondrial function and cellular ATP levels, and whether these could be prevented by treatment with docosahexaenoic acid (DHA) and L-carnitine (LC). Acute exposure of AgNPs for 1 h to SH-SY5Y cells resulted in decreased mitochondrial membrane potential, and decreased ATP and ADP levels, indicating mitochondrial damage and reduced production of ATP. Incubation of cells with DHA partially reduced, while treatment with LC and DHA completely abolished the AgNP induced decreases in ATP and ADP levels. This could be due to a LC-facilitated entry of DHA to mitochondria, for repair of damaged phospholipids. It is postulated that DHA and LC may be useful for treatment of accidental environmental exposure to AgNPs.

Epigenetic Regulation of Cytosolic Phospholipase A2 in SH-SY5Y Human Neuroblastoma Cells

Group IVA cytosolic phospholipase A2 (cPLA2 or PLA2G4A) is a key enzyme that contributes to inflammation via the generation of arachidonic acid and eicosanoids. While much is known about regulation of cPLA2 by posttranslational modification such as phosphorylation, little is known about its epigenetic regulation. In this study, treatment with histone deacetylase (HDAC) inhibitors, trichostatin A (TSA), valproic acid, tubacin and the class I HDAC inhibitor, MS-275, were found to increase cPLA2α messenger RNA (mRNA) expression in SH-SY5Y human neuroblastoma cells. Co-treatment of the histone acetyltransferase (HAT) inhibitor, anacardic acid, modulated upregulation of cPLA2α induced by TSA. Specific involvement of class I HDACs and HAT in cPLA2α regulation was further shown, and a Tip60-specific HAT inhibitor, NU9056, modulated the upregulation of cPLA2α induced by MS-275. In addition, co-treatment of with histone methyltransferase (HMT) inhibitor, 5'-deoxy-5'-methylthioadenosine (MTA) suppressed TSA-induced cPLA2α upregulation. The above changes in cPLA2 mRNA expression were reflected at the protein level by Western blots and immunocytochemistry. Chromatin immunoprecipitation (ChIP) showed TSA increased binding of trimethylated H3K4 to the proximal promoter region of the cPLA2α gene. Cell injury after TSA treatment as indicated by lactate dehydrogenase (LDH) release was modulated by anacardic acid, and a role of cPLA2 in mediating TSA-induced injury shown, after co-incubation with the cPLA2 selective inhibitor, arachidonoyl trifluoromethyl ketone (AACOCF3). Together, results indicate epigenetic regulation of cPLA2 and the potential of such regulation for treatment of chronic inflammation.

Unilateral ureteric stone associated with gross hydronephrosis and kidney shrinkage: a cadaveric report

Ureteric stones are a common cause of obstruction of the urinary tract, usually presenting with characteristic signs and symptoms, such as acute ureteric colic and hematuria. Occasionally, stones may present with non-specific symptoms such as low back pain and remain unidentified, leading to stone growth, chronic ureteric obstruction and complications such as hydronephrosis and renal damage. Here, we report a large ureteric stone in a cadaver with complete obstruction at the left ureterovesical junction, resulting in severe dilatation of the left ureter and renal pelvis.

Effects of salinity on antibiotic production in sponge-derived Salinispora actinobacteria

AIMS

To investigate the effects of growth conditions related to marine habitat on antibiotic production in sponge-derived Salinispora actinobacteria.

METHODS AND RESULTS

Media with varying salt concentration were used to investigate the effects of salinity in relation to Salinispora growth and rifamycin production. The chemotypic profiles of the model strain Salinispora arenicola M413 was then assessed using metabolomic fingerprints from high-pressure liquid chromatography with diode array detection (HPLC-DAD) and multivariate data analysis, before extending this approach to two other strains of S. arenicola. Fingerprint data were generated from extracts of S. arenicola broth cultures grown in media of varying salt (NaCl) concentrations. These fingerprints were then compared using multivariate analysis methods such as principal components analysis (PCA) and orthogonal projection to latent structures discriminant analysis (OPLS-DA). From the analysis, a low-sodium growth condition (1% NaCl) was found to delay the onset of growth of the model S. arenicola M413 strain when compared to growth in media with either 3% artificial sea salt or 3% NaCl. However, low-sodium growth conditions also increased cell mass yield and contributed to at least a significant twofold increase in rifamycin yield when compared to growth in 3% artificial sea salt and 3% NaCl.

CONCLUSIONS

The integration of HPLC-DAD and multivariate analysis proved to be an effective method of assessing chemotypic variations in Salinispora grown in different salt conditions, with clear differences between strain-related chemotypes apparent due to varying salt concentrations.

SIGNIFICANCE AND IMPACT OF THE STUDY

The observed variation in S. arenicola chemotypic profiles further suggests diversity in secondary metabolites in this actinomycete in response to changes in the salinity of its environment.

Brain 3-Mercaptopyruvate Sulfurtransferase (3MST): Cellular Localization and Downregulation after Acute Stroke

3-Mercaptopyruvate sulfurtransferase (3MST) is an important enzyme for the synthesis of hydrogen sulfide (H2S) in the brain. We present here data that indicate an exclusively localization of 3MST in astrocytes. Regional distribution of 3MST activities is even and unremarkable. Following permanent middle cerebral artery occlusion (pMCAO), 3MST was down-regulated in both the cortex and striatum, but not in the corpus collosum. It appears that the down-regulation of astrocytic 3MST persisted in the presence of astrocytic proliferation due to gliosis. Our observations indicate that 3MST is probably not responsible for the increased production of H2S following pMCAO. Therefore, cystathionine β-synthase (CBS), the alternative H2S producing enzyme in the CNS, remains as a more likely potential therapeutic target than 3MST in the treatment of acute stroke through inhibition of H2S production.

Upregulation of Dpysl2 and Spna2 gene expression in the rat brain after ischemic stroke

Ischemia activates the synthesis of potentially damaging and protective proteins in the central nervous system. Dihydropyrimidinase-like 2 (Dpysl2), a protein involved in neuronal differentiation and axonal guidance, and alpha-spectrin 2 (Spna2), a protein involved in maintaining neuronal membrane integrity, were found altered in various nervous system diseases. Modifications of Dpysl2 and Spna2 proteins have been reported in focal ischemic stroke, but their significance is not yet established. Therefore, this study was aimed to investigate the temporal expression of Dpysl2 and Spna2 genes in normal and stroke rat brain and to characterize stroke brains for cell areas, apoptosis, and microglia cells. The middle cerebral artery of rat brain was occluded and the brain tissue was sectioned for in situ hybridization of Dpysl2 and Spna2 genes, TUNEL, and OX-42 immunofluorescence staining. Dpysl2 and Spna2 mRNA expression was quantified by real-time RT-PCR. Characterization of stroke brain for apoptosis and microglia cells showed apoptotic cells and activated microglia, mainly in the infarct core of ipsilateral cortex and striatum of stroke brain. Significant upregulation of Dpysl2 and Spna2 mRNA expression in the penumbra region after stroke was observed predominantly in injured swollen cells in the cortex and striatum. Upregulation of Dpysl2 and Spna2 expression in hypertrophic cells in the penumbra regions of cortex and striatum of stroke brain indicates an early neuronal defense mechanism involving active neuronal repair, regeneration and development, as these genes are known to be involved in neurite outgrowth and plasticity.

Effect of maternal age, birth weight and infant sex on total nucleated cell (TNC) count and volume of umbilical cord blood (UCB) collected

This study evaluates the effect of maternal age, birth weight and infant sex on two main UCB parameters for use and long-term cryopreservation: TNC and volume. Data from 1000 UCB units were collected and analyzed in this study. The results indicate that TNC is correlated to infant birth weight and sex but not maternal age at delivery. Volume is only correlated to birth weight but not maternal age and infant sex.

Heat shock proteins and neurodegenerative disorders

Heat shock proteins (HSPs) are evolutionarily conserved molecules and play important roles in fundamental cellular processes. They serve as molecular chaperones and hence provide a protective function in ensuring cell survival and repair of cellular damage after a stressful stimulus. This paper summarizes the current knowledge about the different roles of HSPs in aging and disease, focusing on the neurodegenerative disorders of Alzheimer's marks disease, Parkinson's disease, Huntington's marks disease, and prion disease.

Combinatorial-approached neuroprotection using pan-caspase inhibitor and poly (ADP-ribose) polymerase (PARP) inhibitor following experimental stroke in rats; is there additional benefit?

Energy requiring apoptosis and presumably unregulated necrosis are considered conceptually and morphologically distinct forms of cell death which have been initially identified as two exclusive pathways. However, several apoptotic characteristics have been observed in the necrotic core lesion in ischemia which led to the controversial theory that cell death advances via a number of hybrid pathways among a continuum between the two processes. ATP availability has been shown to influence the decision between apoptosis and necrosis. The aims of our study are 1) to determine if combined inhibitors administration of pan-caspase inhibitor Carbobenzoxy-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk) and non-selective poly (ADP-ribose) polymerase (PARP) inhibitor 3-aminobenzamide (3-AB) can further reduce infarct volume compared to single modality of either inhibitor following ischemic insult, 2) to ascertain the pharmacological intervention up to 24 hour post-middle cerebral artery occlusion (MCAo), and 3) to correlate intracellular ATP level with infarct volume. Single modality treatment was optimised at 3 mg/kg z-VAD-fmk and 30 mg/kg 3-AB with infarct volume measured at 24.13%+/-3.89% and 26.98%+/-2.22% respectively, while untreated control group was determined at 45.97%+/-1.86%. Combined inhibitors treatment rendered further reduction in infarct volume, measuring 7.228%+/-1.988%, 21.02%+/-1.06%, 24.40%+/-2.12% at 30 min, 6 h, 24 h post-ischemia respectively. In conclusion, the combined inhibitors administration of both z-VAD-fmk and 3-AB show further increased in infarct volume reduction with our ischemic model up to the 24 hour post-MCAo. However, in our in vivo study, no correlation between intracellular ATP level and infarct size was established.

Alterations in spatial learning and memory after forced exercise

Exercise has been shown to influence learning and memory. Most studies were performed with a voluntary running paradigm (e.g. running wheel) in mice. However, such effects of exercise on learning and memory are less well demonstrated using a forced running paradigm (e.g. treadmill). The present study was designed to examine the effects of 12 weeks of forced treadmill running on learning and memory performance in rats. We have previously shown that forced running resulted in qualitative and quantitative changes in the cholinergic neurons of the horizontal diagonal band of Broca (HDB) in the septum. This study was conducted in order to determine whether or not these changes occur simultaneously with enhanced learning and memory. The one-day version of the Morris water maze (MWM) test [Frick, K.M., Stillner, E.T., Berger-Sweeney, J., 2000. Mice are not little rats: species differences in a one-day water maze task. NeuroReport 11, 3461-3465] was used to test spatial learning and memory after the exercise period. Our data showed that runners displayed better spatial learning and memory when compared to nonrunners. This was evidently shown by a reduction in the time required for spatial acquisition (p<0.05) and superior probe trial performance (p<0.05). A shorter distance swam by the runners also suggested improved learning over the nonrunners (p<0.05). In an attempt to revalidate our earlier quantitative results, we used design-based stereology (DBS) to estimate the number of cholinergic neuronal profile population in the medial septum and diagonal band (MSDB). We confirmed that forced running increased the cholinergic neuronal profile subpopulation in the HDB (Coefficient of Error<0.2). Taken together, these results indicate that forced exercise could influence learning and memory with a concomitant increase in the number of cholinergic neurons in the HDB.

Factors contributing to neuronal degeneration in retinas of experimental glaucomatous rats

After our studies on ganglion cell degeneration in the glaucomatous retina, the current work further confirmed the reduction of amacrine cells in the retina after the onset of glaucoma. Present study also tried to understand the possible mechanisms underlying neuronal degeneration in the glaucomatous retina. Changes of expressions in immediate early genes (IEGs), glutamate receptors (GluRs), calcium-binding proteins (CaBPs), 8-hydroxy-deoxyguanosine (8-OH-dG) and nitric oxide synthase (NOS), as well as apoptotic-related factors including caspase 3, bax, and bcl-2 were examined. IEGs such as c-fos and c-jun were induced in the retina of the glaucomatous rat as early as 2 hr after the onset of glaucoma and lasted up to 2 weeks. Expressions of GluRs and CaBPs (i.e., parvalbumin and calbindin D-28k) were observed to be increased in the retinal ganglion cell layer (GCL) and inner nuclear layer (INL) at 3 days and 1 week after the onset of glaucoma. The increase occurred well before and during the phase where significant neuronal death was observed in the GCL and INL of the glaucomatous retinae. Induction of 8-OH-dG was present in both the GCL and INL of the glaucomatous retina at 3 days after the onset of glaucoma before significant neuronal death was observed. Furthermore, confocal microscopy study showed the complete colocalization of immunohistochemical expression of caspase 3 with glial fibrillary acidic protein (GFAP), but not with neuronal nuclei (NeuN). It indicates that astrocytes and Müller cells are involved in the pathological processes of neuronal death. The relationship between the linked factors and neuronal degeneration is also discussed.

Beacon immunoreactivity in the rat hypothalamus

Beacon (BC) is a peptide of 73 amino acids, whose gene expression was first reported in the hypothalamus of Psammomys obesus (or Israeli sand rat). To appreciate better the functional role of BC in normal rats and sand rats, the distribution of BC immunoreactivity (irBC) and its subcellular localization were studied in the brain of Sprague-Dawley rats. In the hypothalamus, intense staining was present in neurons of the supraoptic (SO), paraventricular (PVH), and accessory neurosecretory nuclei and in cell processes of median eminence. Double labeling of the hypothalamic sections with mouse monoclonal oxytocin (OT) antibody and rabbit polyclonal BC antiserum revealed that nearly all OT-immunoreactive cells from SO, PVH, and accessory neurosecretory nuclei were irBC. Double labeling of the sections with guinea pig vasopressin (VP) antiserum and BC antiserum showed that a population of VP-immunoreactive neurons was irBC. By immunoelectron microscopy, immunoreactive product was associated with mitochondrial membranes or appeared as electron-dense bodies in many PVH and SO neurons. Most of the neurosecretory granules were unstained for BC. Taken together, our results indicate the presence of beacon in the OT-containing neurons and a population of VP-containing neurons, mostly associated with mitochondrial membrane. Insofar as the amino acids sequence of beacon is identical to that of ubiquitin-like 5, it is possible that the distribution of BC immunoreactivity noted in our study is that of ubiquitin-like 5 peptide in the rat hypothalamus.

Improved neuronal transgene expression from an AAV-2 vector with a hybrid CMV enhancer/PDGF-beta promoter

BACKGROUND

Adeno-associated virus type 2 (AAV-2) vectors are highly promising tools for gene therapy of neurological disorders. After accommodating a cellular promoter, AAV-2 vectors are able to drive sustained expression of transgene in the brain. This study aimed to develop AAV-2 vectors that also facilitate a high level of neuronal expression by enhancing the strength of a neuron-specific promoter, the human platelet-derived growth factor beta-chain (PDGF) promoter.

METHODS AND RESULTS

A hybrid promoter approach was adopted to fuse the enhancer of human cytomegalovirus immediately early (CMV) promoter to the PDGF promoter. In cultured cortex neurons, AAV-2 vectors containing the hybrid promoter augmented transgene expression up to 20-fold over that mediated by titer-matched AAV-2 vectors with the PDGF promoter alone and 4-fold over the CMV enhancer/promoter. Injection of AAV-2 vectors with the hybrid promoter into the rat striatum resulted in neuron-specific transgene expression, the level of which was about 10-fold higher than those provided by the two control AAV-2 expression cassettes at 4 weeks post-injection and maintained for at least 12 weeks. Gene expression in the substantia nigra through possible retrograde transport of the AAV-2 vectors injected into the striatum was not obvious. After direct injection of AAV-2 vectors into the substantia nigra, transgene expression driven by the hybrid promoter was observed specifically in dopaminergic neurons and its level was about 3 and 17 times higher than that provided by the PDGF promoter alone and the CMV enhancer/promoter, respectively.

CONCLUSIONS

Enhanced transgene capacity plus neuron-specificity of the AAV-2 vectors developed in this study might prove valuable for gene therapy of Parkinson's disease.

Distinct roles of oxidative stress and antioxidants in the nucleus dorsalis and red nucleus following spinal cord hemisection

Oxidative stress plays an important role in the pathogenesis of neurodegeneration after the acute central nervous system injury. We reported previously that increased nitric oxide (NO) production following spinal cord hemisection tends to lead to neurodegeneration in neurons of the nucleus dorsalis (ND) that normally lacks expression of neuronal NO synthase (nNOS) in opposition to those in the red nucleus (RN) that constitutively expresses nNOS. We wondered whether oxidative stress could be a mechanism underlying this NO involved neurodegeneration. In the present study, we examined oxidative damage evaluated by the presence of 4-hydroxynonenal (HNE) and iron accumulation and expression of putative antioxidant enzymes heme oxygenase-1 (HO-1) and superoxide dismutase (SOD) in neurons of the ND and RN after spinal cord hemisection. We found that HNE expression was induced in neurons of the ipsilateral ND from 1 to 14 days following spinal cord hemisection. Concomitantly, iron staining was seen from 7 to 14 days after lesion. HO-1, however, was only transiently induced in ipsilateral ND neurons between 3 and 7 days after lesion. In contrast to the ND neurons, HNE was undetectable and iron level was unaltered in the RN neurons after spinal cord hemisection. HO-1, SOD-Cu/Zn and SOD-Mn were constitutively expressed in RN neurons, and lesion to the spinal cord did not change their expression. These results suggest that oxidative stress is involved in the degeneration of the lesioned ND neurons; whereas constitutive antioxidant enzymes may protect the RN neurons from oxidative damage.

Gene Transfer to Dorsal Root Ganglia by Intrathecal Injection: Effects on Regeneration of Peripheral Nerves

Gene delivery to sensory neurons of the dorsal root ganglion (DRG) offers the prospect of developing new clinical interventions against peripheral nerve diseases and disorders. Here we show that genes can be transferred to rat DRG through lumbar intrathecal injection of delivery vectors into the cerebrospinal fluid. Genes could be transferred to DRG using polyethylenimine (PEI)/DNA complexes, Lipofectamine 2000/DNA complexes, adeno-associated virus vectors, or baculovirus vectors. We also show that nerve growth factor cDNA, delivered through lumbar intrathecal injection of PEI complexes, was able to improve regeneration of transected rat sciatic nerves. These data demonstrate the viability of using an intrathecal gene delivery approach for treating peripheral neuropathies.

Role of GABA in electro-acupuncture therapy on cerebral ischemia induced by occlusion of the middle cerebral artery in rats

This study investigated the possible involvement of gamma-aminobutyric acid (GABA) in the therapeutic effect of cerebral ischemia by electro-acupuncture (EA) using the rat model with middle cerebral artery occlusion (MCAO). By immunohistochemistry, the changes of GABA expression level in the primary infarct area and its penumbral regions were examined. The changes in infarct area and survival neuron percentages were also assessed using haematoxylin and eosin stained sections after picrotoxin (PTX) injection, a GABA receptor's antagonist. Our results showed that EA markedly decreased the ischemic damaged areas in the cerebral cortex and hippocampus. Concomitant to this was an up-regulation of GABA immunoexpression in MCAO rats with EA treatment (P < 0.05). Furthermore, injection of PTX in rats subjected to MCAO or MCAO followed by EA treatment increased the infarct area and decreased survival cell percentage significantly when compared with those without PTX injection. In the light of these findings, it is suggested that EA on specific and established acupoints that are commonly used in clinical management of cerebral ischemia may have elicited an up-regulated expression of GABA that would have a neuroprotective effect.

Cytokine changes in the horizontal diagonal band of Broca in the septum after running and stroke: a correlation to glial activation

The relationship between running, glial cell activation and pro-inflammatory cytokines was studied in the context of neuroprotection against ischemic stroke induced by middle cerebral artery occlusion (MCAO). This was investigated in four groups of rats, namely, (1) nonrunner, (2) runner after 12 weeks of treadmill running, (3) nonrunner with MCAO and (4) runner with MCAO. The horizontal diagonal band of Broca (HDB) in the septum was scrutinized for qualitative cum quantitative changes in the microglia and astrocytes. Reverse transcription-polymerase chain reaction and immunoblot work were carried out in the forebrain homogenate to determine, respectively, the gene and protein expression of several pro-inflammatory cytokines. Our results indicated that the runner exhibited less immunoreactivity and reduced numbers of glial cells within the HDB compared with the nonrunner. Interestingly, the mRNA and protein levels of tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6 and interferon-gamma, were significantly downregulated in the runner. Our data also suggest albeit with some inconsistency that the runner/MCAO rats had benefited from running. These observations suggest that running can result in changes to the microenvironment, in which the microglia and astrocytes exist in a state of quiescence concomitant with a reduced expression of pro-inflammatory cytokines, that may lead to beneficial effects seen in ischemic stroke induced by MCAO.

Expression of glutamate receptors and calcium-binding proteins in the retina of streptozotocin-induced diabetic rats

This study was aimed to investigate the expression of glutamate receptors and calcium-binding proteins in 1- and 4-month/s (mo) streptozotocin (STZ)-induced diabetic rats. Upregulation of glutamate receptors' [N-methyl-D-aspartate receptor (NMDAR)1 and GluR2/3] immunoreactivities was observed in the ganglion, amacrine and bipolar cells as well as in the inner and outer plexiform layers (IPL and OPL) in 1 mo diabetes and was further enhanced at 4 mo. Immunoreactivity of calcium-binding proteins (calbindin and parvalbumin) was also concomitantly increased. The present results suggest that upregulation of glutamate receptors and calcium-binding proteins may reflect changes of the glutamate and calcium metabolism in the diabetic retina. It is speculated that the above changes in the IPL and OPL may be linked to alteration of synaptic transmission in the diabetic retina.

Factors associated with psychosis among patients with severe acute respiratory syndrome: a case-control study

We observed that a number of patients with severe acute respiratory syndrome (SARS) developed affective psychosis during the acute phase of their illness. We reviewed all SARS-related psychiatric consultations in Hong Kong and investigated the risk factors for psychosis among patients with SARS in a matched case-control study. Patients with SARS-related psychosis received higher total doses of steroids and had higher rates of family history of psychiatric illness. The findings of the present study suggest that steroid toxicity, personal vulnerability, and, probably, psychosocial stressors jointly contributed to the development of psychosis in patients with SARS.

THE EFFECT OF CHRONIC BLADDER OUTLET OBSTRUCTION ON NEURONAL NITRIC OXIDE SYNTHASE EXPRESSION IN THE INTRAMURAL GANGLIA OF THE GUINEA PIG BLADDER

PURPOSE

We examined the effect of chronic partial outlet obstruction on expression of neuronal nitric oxide synthase (nNOS) in the intramural ganglion cells of the guinea pig bladder.

MATERIALS AND METHODS

Partial urethral ligation was done in young male guinea pigs. The animals were sacrificed 2, 4, 6, 8 and 12 weeks after partial outlet obstruction and nNOS immunohistochemistry was done in the intramural neurons of the bladder. This was compared to controls (normal and sham operated). In addition, the mRNA expression of nNOS in bladders of 4-week sham operated and operated animals was also investigated using real-time quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Two weeks after urethral obstruction a decrease in the number of nNOS positive intramural neurons was detected. This decrease was most drastic at 4 weeks. Cell counting showed a 60.6% decrease in the number of nNOS positive neurons compared to controls. Some neurons appeared to undergo degenerative changes, such as irregular outline, vacuolation and lysis. At 6 weeks the number of nNOS positive neurons increased from the nadir level at 4 weeks and the increase was sustained until 12 weeks, when the number of nNOS positive neurons was almost at the level of controls. Quantitative reverse transcriptase-polymerase chain reaction also showed 42.4% down-regulation of nNOS expression 4 weeks after obstruction comparing with sham operation.

CONCLUSIONS

Partial urethral ligation resulted in an initial decrease in nNOS positive neurons, which have been due to actual neuronal loss and/or enzyme down-regulation. This may be attributable to regional hypoxia as a result of decreased blood flow consequent to high intravesical pressure created by partial ligation. The decrease in nNOS expression followed by a compensatory increase in nNOS positive neurons also suggests an attempt or mechanism to up-regulate nitric oxide bioactivity following increased bladder outlet resistance.

Axoglial interaction via the notch receptor in oligodendrocyte differentiation

INTRODUCTION

Increasing evidence has revealed that the Notch signalling pathway is one of the pivotal systems that mediate oligodendrocyte development. The Notch receptor is a type I transmembrane molecule that represents a novel cellular signalling paradigm, namely, regulated intramembrane proteolysis (RIP).

METHOD

The typical Notch ligands, such as Delta, Serrate/Jagged and Lag2 (DSL), promote the formation of oligodendocyte precursor cells (OPCs) and maintain them in an uncommitted stage, thus retarding oligodendrocyte appearance in the central nervous system (CNS).

RESULTS

In contrast, our recent studies have revealed that F3/contactin, a GPI-linked neural adhesion molecule, interacts with Notch and speeds up the generation and maturation of oligodendrocytes.

CONCLUSIONS

Considering the distinct, albeit somewhat overlapping expression patterns of F3 and DSL in the CNS, the Notch receptor appears to function ligand-dependently during oligodendrocyte development. This multipotentiality may well designate the Notch receptor as one of the therapeutic targets that one can manoeuvre to treat demyelinating diseases, such as multiple sclerosis, that is characterised by chronic myelin degeneration.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in a Chinese family: clinical, radiological and skin biopsy features

We describe the clinical, radiological, genetic and skin biopsy findings of the first Chinese family with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Of the 43-member family tree extending over three generations, eight had typical clinical features of CADASIL with recurrent ischemic stroke. In the three surviving affected family members, brain MRI showed extensive leukoaraiosis. Genotyping revealed heterozygous C to T mutation at nucleotide 406 in exon 3. Unusual clinical features were cerebellar infarction as a presenting complaint and a late age of onset with mild symptoms at age 69. A novel finding is the suggestion of a direct correlation between clinical disease severity and the quantity of ultrastructural pathognomonic granular osmophilic material (GOM) seen on skin biopsy.

Altered gene expression with abnormal patterning of the telencephalon in embryos of diabetic Albino Swiss mice

AIMS/HYPOTHESIS

Several studies have shown that maternal diabetes increases the risk of congenital malformations in various organ systems including the neural tube. The present study analysed molecular and morphological changes in the forebrain of embryos from diabetic Albino Swiss mice.

METHODS

Maternal diabetes-induced morphological changes in the forebrain were examined histologically. Cell proliferation index was assayed by BrdU labelling. In situ hybridisation and quantitative real-time PCR were used to analyse the expression of genes coding for sonic hedgehog ( Shh), Nkx2.1, brain factor-1 ( BF-1) and bone morphogenetic protein-4 ( Bmp4) that control forebrain patterning.

RESULTS

There were no distinguishable abnormalities in the forebrain of embryos from diabetic pregnancies on embryonic day 0.5. At embryonic day 11.5, embryos of diabetic pregnancies displayed a fusion and thickening of the ventral telencephalic neuroepithelium and a partial absence of the dorsal telencephalon, indicating a severe patterning defect in the dorsoventral axis of the telencephalon. The cell proliferation index was also higher in the ventral telencephalon of these embryos. Molecular analyses indicated that expression of Shh, Nkx2.1 and BF-1 was increased and their expression domains expanded dorsally in the ventral telencephalon in embryos of diabetic mice at embryonic day 11.5. The expression of Bmp4 was reduced in the dorsal forebrain of these embryos. At embryonic day 8.5, only Shh expression was increased.

CONCLUSIONS/INTERPRETATION

Altered expression of various genes involved in dorsoventral patterning of the forebrain is associated with forebrain malformations in embryos of diabetic mice.

Nogo-A at CNS paranodes is a ligand of Caspr: possible regulation of K(+) channel localization

We report Nogo-A as an oligodendroglial component congregating and interacting with the Caspr-F3 complex at paranodes. However, its receptor Nogo-66 receptor (NgR) does not segregate to specific axonal domains. CHO cells cotransfected with Caspr and F3, but not with F3 alone, bound specifically to substrates coated with Nogo-66 peptide and GST-Nogo-66. Binding persisted even after phosphatidylinositol- specific phospholipase C (PI-PLC) removal of GPI-linked F3 from the cell surface, suggesting a direct interaction between Nogo-66 and Caspr. Both Nogo-A and Caspr co-immunoprecipitated with Kv1.1 and Kv1.2, and the developmental expression pattern of both paralleled compared with Kv1.1, implicating a transient interaction between Nogo-A-Caspr and K(+) channels at early stages of myelination. In pathological models that display paranodal junctional defects (EAE rats, and Shiverer and CGT(-/-) mice), distances between the paired labeling of K(+) channels were shortened significantly and their localization shifted toward paranodes, while paranodal Nogo-A congregation was markedly reduced. Our results demonstrate that Nogo-A interacts in trans with axonal Caspr at CNS paranodes, an interaction that may have a role in modulating axon-glial junction architecture and possibly K(+)-channel localization during development.

F3/contactin acts as a functional ligand for Notch during oligodendrocyte maturation

Axon-derived molecules are temporally and spatially required as positive or negative signals to coordinate oligodendrocyte differentiation. Increasing evidence suggests that, in addition to the inhibitory Jagged1/Notch1 signaling cascade, other pathways act via Notch to mediate oligodendrocyte differentiation. The GPI-linked neural cell recognition molecule F3/contactin is clustered during development at the paranodal region, a vital site for axoglial interaction. Here, we show that F3/contactin acts as a functional ligand of Notch. This trans-extracellular interaction triggers gamma-secretase-dependent nuclear translocation of the Notch intracellular domain. F3/Notch signaling promotes oligodendrocyte precursor cell differentiation and upregulates the myelin-related protein MAG in OLN-93 cells. This can be blocked by dominant negative Notch1, Notch2, and two Deltex1 mutants lacking the RING-H2 finger motif, but not by dominant-negative RBP-J or Hes1 antisense oligonucleotides. Expression of constitutively active Notch1 or Notch2 does not upregulate MAG. Thus, F3/contactin specifically initiates a Notch/Deltex1 signaling pathway that promotes oligodendrocyte maturation and myelination.

Inducible nitric oxide synthase and bcl-2 expression in nasopharyngeal cancer: correlation with outcome of patients after radiotherapy

PURPOSE

The expression of inducible nitric oxide synthase (iNOS) and bcl-2 proteins was evaluated and the prognostic significance determined in nasopharyngeal cancer (NPC) patients treated by radiotherapy.

METHODS AND MATERIALS

Tissue sections from 55 patients with NPC were assessed for iNOS and bcl-2 protein expression by immunohistochemistry, immunoelectron microscopy, and in situ hybridization before treatment. The markers were correlated with apoptosis (detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay) and clinicopathologic parameters.

RESULTS

All NPC sections exhibited positive iNOS and bcl-2 immunoreactivity, with a mean percentage of 6.24% +/- 0.58% and 17.09% +/- 2.48%, respectively. A significant positive correlation was observed between iNOS expression and the apoptotic index (p < 0.0001, Pearson's r = 0.8518), and bcl-2 expression correlated inversely with apoptosis (p = 0.0001; Pearson's r = -0.6170). A significant inverse correlation was found between iNOS and bcl-2 immunoreactivity (p < 0.0001, Pearson's r = -0.7144). Bcl-2 but not iNOS expression was associated with the stage of the tumor according to the criteria of the American Joint Committee on Cancer (1997) (p < 0.0001). Patients who had recurrence of the tumor and metastasis after radiotherapy had a lower expression of iNOS (p = 0.014 and p = 0.035, respectively), although overall survival was not significantly different statistically. Higher bcl-2 expression was also associated with local tumor recurrence (p = 0.005) but not with metastasis or overall survival.

CONCLUSION

It appears that iNOS and bcl-2 expression may be potentially useful biomarkers for predicting the outcome of radiotherapy in NPC patients.

Repeated intrathecal administration of plasmid DNA complexed with polyethylene glycol-grafted polyethylenimine led to prolonged transgene expression in the spinal cord

Gene delivery into the spinal cord provides a potential approach to the treatment of spinal cord traumatic injury, amyotrophic lateral sclerosis, and spinal muscular atrophy. These disorders progress over long periods of time, necessitating a stable expression of functional genes at therapeutic levels for months or years. We investigated in this study the feasibility of achieving prolonged transgene expression in the rat spinal cord through repeated intrathecal administration of plasmid DNA complexed with 25 kDa polyethylenimine (PEI) into the lumbar subarachnoid space. With a single injection, DNA/PEI complexes could provide transgene expression in the spinal cord 40-fold higher than naked plasmid DNA. The transgene expression at the initial level persisted for about 5 days, with a low-level expression being detectable for at least 8 weeks. When repeated dosing was tested, a 70% attenuation of gene expression was observed following reinjection at a 2-week interval. This attenuation was associated with apoptotic cell death and detected even using complexes containing a noncoding DNA that did not mediate any gene expression. When each component of the complexes, PEI polymer or naked DNA alone, were tested in the first dosing, no reduction was found. Using polyethylene glycol (PEG)-grafted PEI for DNA complexes, no attenuation of gene expression was detected after repeated intrathecal injections, even in those rats receiving three doses, administered 2 weeks apart. Lumbar puncture is a routine and relatively nontraumatic clinical procedure. Repeated administration of DNA complexed with PEG-grafted PEI through this less invasive route may prolong the time span of transgene expression when needed, providing a viable strategy for the gene therapy of spinal cord disorders.

Neuroprotection associated with running: is it a result of increased endogenous neurotrophic factors?

The possible neuroprotective effect of physical exercise was investigated in rats after middle cerebral artery occlusion (MCAO), a focal stroke model. It was found that physical exercise in the form of a 12-week treadmill running programme reduced the volume of infarction caused by MCAO. At the molecular level, reverse transcription polymerase chain reaction revealed that the runner had increased gene expression for nerve growth factor (NGF) over the nonrunner with or without MCAO. Expression of the NGF receptors, p75, was increased only in the absence of MCAO. In addition, runners showed a significantly higher number of cholinergic neurons, which constitutively expressed p75, in the horizontal diagonal band of Broca. The present findings suggest that neuroprotection after physical exercise may be a result of an increase in an endogenous neurotrophic factor nerve growth factor and the proliferation of its receptive cholinergic neurons.

Airway obstruction in children with congenital heart disease: assessment by flexible bronchoscopy

We assessed the spectrum of airway disorders in children with congenital cardiac anomalies, and reviewed our experience in using flexible bronchoscopy for assessment of airway problems in this patient group. The clinical records, flexible bronchoscopic findings, and cardiac imaging results of pediatric cardiac patients who presented with either clinical or radiological signs of airway obstruction between 1992-1999 were reviewed. Flexible bronchoscopic assessment was performed with the patients under sedation and topical anesthesia, using one of two bronchoscopes, i.e., an Olympus BFN20 or Olympus BF3C20. Of a total of 52 patients, 33 had acyanotic cardiovascular lesions, the commonest being left-to-right shunts (61%), while 19 had cyanotic heart lesions, with right ventricular outflow obstruction being the commonest (63%). Twenty-seven patients had undergone either surgical or transcatheter interventions. The median age at bronchoscopic assessment was 6 months (range, 4 days to 6 years). None of the patients developed significant procedural complications. A definitive diagnosis was made in 48 (92%) patients, 8 of whom had abnormalities involving only the upper airways, 35 only the lower airways, and 5 both. Abnormalities of the upper airway included laryngomalacia (n = 6), subglottic stenosis (n = 3), pharyngeal collapse (n = 2), and 1 each of choanal stenosis and supraglottitis. Extrinsic compression was the commonest lower airway abnormality that was found in 27/40 patients (67%), with a predilection for the left main bronchus (18/27, 67%). The structures that caused extrinsic compression included dilated pulmonary arteries with or without left atrial dilation (n = 20), an anomalous aortic or pulmonary arterial course (n = 3), a dilated aorta (n = 1), and a shunt (n = 1), but were not obvious in 2 patients. Intrinsic lower airway abnormalities included bronchomalacia (n = 4), tracheal stenosis (n = 4), and one each of variant bronchial bifurcation and a pouch arising from the tracheal wall. Intraluminal mucus plugging of the lower airways occurred in the remaining 3 patients. Children with congenital heart disease are at risk of airway obstruction both before and after surgery. Flexible bronchoscopy, being safe and effective in diagnosing airway disorders in this patient group, should be considered as the first line of investigation.

An electron microscopic study of neuronal degeneration and glial cell reaction in the retina of glaucomatous rats

The present investigation was focused on the ultrastructural changes in the neurons and glial cells in the retina of rats with experimentally-induced glaucoma. An experimental glaucoma model was created by limbal-derived vein cauterization. Animals were sacrificed at 1, 3 weeks and 3 months post-operation. Retinae were dissected and processed for electron microscopy. Neuronal degeneration was observed in all the different layers of the retina at both 1 and 3 weeks post-operation. Some degenerating neurons were found in the ganglion cell layer (GCL), inner nuclear layer (INL) and outer nuclear layer (ONL). And the dying neurons presented apoptotic-like more than necrotic neurons. Many degenerating axons and axon terminals were observed between neurons in the GCL, inner plexiform layer (IPL), INL, and outer plexiform layer (OPL). Activated astrocytes and microglial cells were present in close association with degenerating neurons and axons. The Müller cells in the INL also presented longer and darker processes with more microfilaments than in normal cells. Degenerating neuronal debris, degenerating axonal profiles and electron-dense bodies were often found in the cytoplasm of macrophages. The results suggest that both microglial cells and astrocytes are activated in the process of neuronal degeneration in the retina of experimentally-induced glaucomatous rats. It is hypothesized that they may play a protective role in removing degenerating neuronal elements in the retina after the onset of glaucoma.

C-fos and c-jun expressions in nitric oxide synthase immunoreactive neurons in the lateral geniculate nucleus of experimental glaucomatous rats

The present study was initiated to investigate the expressions of c-fos and c-jun in nitric oxide synthase immunoreactive neurons and their possible roles in the lateral geniculate nucleus (LGN) of glaucomatous rats. An experimental one-eye glaucoma model was created by cauterisation of the limbal-derived veins. Animals were killed by cardiac perfusion, and brains containing the LGN were removed and processed for c-fos, c-jun and neuronal nitric oxide synthase (nNOS) immunohistochemistry. No c-fos or c-jun immunoreactivity was observed in the LGN of control rats. In the glaucomatous rats, expression of c-fos and c-jun was induced bilaterally in the ventral LGN (vLGN) as early as 2 h postoperation. The number of c-fos-immunopositive cells increased at 1 and 2 days postoperation in both the lateral and medial subdivisions of the vLGN (vLGN-l and vLGN-m). Thereafter, the expression decreased and was totally absent at 1 and 2 weeks. No c-fos was induced in the dorsal LGN (dLGN). C-jun-immunopositive cells were mainly localised in the intergeniculate leaflet and vLGN. Few neurons were observed in the dLGN. The number of c-jun-immunopositive cells decreased at 1 and 2 weeks postoperation. Some of the c-fos- and c-jun-immunopositive cells were also nNOS immunopositive. The present results reveal that glaucoma activates the expressions of immediate early genes (IEGs) in some cells of the LGN. It is postulated that they may play important roles in the pathologic processes of glaucoma. The relationship between these IEGs and nitric oxide was also discussed.

Positive and negative modulation by AMPA- and kainate-receptors of striatal kainate injection-induced neuronal loss in rat forebrain

We investigated the roles of ionotropic glutamate receptor subtypes in mediating striatal kainate injection-induced neuronal loss in rat forebrain, using subtype-specific antagonists and histochemical staining. Our study demonstrates that kainate injected unilaterally into the striatum induces a massive neuronal loss in the rat ipsilateral forebrain through activation of kainate receptors and, to a limited extent, a consequent involvement of M-methyl-D-aspartate (NMDA) receptors, whereas activation of alpha-amino-3-hydroxy-5-methylisoxazol-4-propionate (AMPA) receptors shows a neuroprotective effect. These and previous results suggest that three subtypes of ionotropic glutamate receptors play differential roles in mediating excitatory amino acid (EAA)-induced neurodegeneration.

[The role of neuroimmunoregulation mobilized by enhancing immunologic function via hou hai acupoint antigen injection]

OBJECTIVE

To study the mechanism of neuroimmunoregulation which is triggered by enhancing immunologic function via Hou Hai acupoint antigen injection.

METHODS

Immunohistochemical method, immunofluorometric method and RT-PCR were used to examine the different distribution of cytokine immunopositive cells in the brain and expression of cytokines in the spleen of the human IgG sensitized rats received acupoint, subcutaneous and normal rats antigen injections.

RESULTS

In the areas of lateral hypothalamic nucleus (LH) and amygdaloid nuclear complex (AA), the distribution of cytokines immunopositive cells with acupoint injection group was significantly increased more than that in the subcutaneous injection group. But the expression of cytokines immunopositive cells both by the acupoint injection and the subcutaneous injection groups reached their peak value in similar time. Double-labelling results showed that the cytokine immunopositive cells were neurons. In the spleens, the expressions of cytokines, IL-2 and IFN, were significantly increased by acupoint injection more than subcutaneous injection.

CONCLUSIONS

The time course of neuroimmunoregulation is similar in the immunized rats via both acupoint injection and subcutaneous injection of antigens. But the activity of neuroimmunoregulation is not the same in acupoint and subcutaneous injection groups. Neurons of the LH and AA are the main source of the neuroimmunomodulators. The effect of enhancing immunologic function via Hou Hai acupoint injection is may be more efficient to mobilize the activity of neuroimmunoregulation of immune-associated brain region than modulation of the immune system.

Microglial reaction in focal cerebral ischaemia induced by intra-carotid homologous clot injection

This study examined the microglial reaction in a simulated thrombo-embolus ischaemia in rats given an intracarotid injection of a suspension of homologous blood clot. All rats including the controls receiving vehicle injection were perfused at 5 hours, and 1, 3 and 7 days post-operation. The brains were removed and processed for immunohistochemistry using a panel of monoclonal antibodies: OX-42, OX-18 and OX-6 for labeling of microglia. In rats given saline injection OX-42 immunoreactive microglial cells were observed to be distributed quite evenly throughout the whole brain. When injection of clot suspension was given, microglial cells responded vigorously, particularly in the ipsilateral hippocampus. Microglial reaction was also detected in the ipsilateral cerebral cortex, caudate as well as septal nuclei. The majority of the detected reactive microglial cells were hypertrophied showing thick or stout processes. Some rod-like and amoeboid microglia were also observed. Rarely did the reactive microglia express OX-6 immunoreactivity. All microglial cells were unreactive for OX-18. The actual mechanisms leading to the microglial activation as well as functions of reactive microglia in focal cerebral ischaemia remain speculative. In the absence of direct evidence, it could only be suggested that they may act as sensor cells for detection of subtle alterations in the microenvironment, probably in response to focal ischaemia and/or leakage of serum-derived factors induced by thrombo-embolus stroke.

Distinct subcellular localization and mRNA expression of neuronal nitric oxide synthase in the nucleus dorsalis and red nucleus and their correlation with inducible transcription factors after spinal cord hemisection

We previously reported on the differential expression of neuronal nitric oxide synthase (nNOS) in neurons of the nucleus dorsalis (ND) and red nucleus (RN), as well as differential roles of nitric oxide (NO) in these two distinct groups' neurons characterized with different nNOS phenotypes after lower thoracic spinal cord hemisection. To further understand the enzyme, nNOS expression was studied at the subcellular and mRNA levels by using electron microscopic immunohistochemistry (EM-IHC) and in situ hybridization respectively. Possible transcriptional regulation by c-Jun or CREB in the differential nNOS expression in both ND and RN neurons was also studied. nNOS mRNA was not found in the normal ND neurons, but was shown in the normal RN neurons. After spinal cord hemisection, nNOS mRNA was induced in the ipsilateral ND, while upregulated on both sides of the RN, which preceded protein induction or upregulation. By EM-IHC, nNOS immunoreaction products were predominantly bound to the membrane of the mitochondria, rough endoplasmic reticulum (rER), Golgi apparatus, and nuclear envelope in the RN neurons of normal rats as well as rats subjected to spinal cord hemisection. In contrast, nNOS-immunoreactive deposits in the experimental ND neurons were found to be mainly granular, being dispersed throughout the cytoplasmic matrix. It is speculated that the differential subcellular localizationof nNOS indicates that axotomy may trigger different nNOS transcripts and lead to different nNOS isoform expression in the normally non-nNOS- and normally nNOS-containing neurons. c-Jun was induced in the ipsilateral ND neuronsand upregulated only in the contralateral RN neurons. Activation of CREB by phosphorylation was occasionally detectable in the ND neurons, but not in the RN neurons. Double-labeling data showed a large proportion of c-Jun and nNOS colocalization in neurons of the ipsilateral ND and contralateral RN after spinal cord hemisection. However, dissociation of nNOS expression kinetics with c-Jun was observed in the ipsilateral RN. The results implied that nNOS expression might not be under the direct transcriptional regulation by c-Jun, although it seemed to be closely related to the c-Jun expression.

Nitric oxide, microglial activities and neuronal cell death in the lateral geniculate nucleus of glaucomatous rats

The present study was initiated to investigate neuronal degeneration, microglial reactivity and possible roles of NO in the lateral geniculate nucleus (LGN) of glaucomatous rats. An experimental one-eye glaucoma model was created by cauterization of the limbal-derived veins. Neuronal cell viability was studied by immunostaining with antibody against neuronal nuclei. Changes of expressions of nitric oxide synthase I (NOS I), NOS II, ED 1, OX6 and OX42 in the LGN were studied by immunohistochemistry. NADPH-d histochemistry was also employed. In the experimental glaucomatous rats, the number of NeuN labelled neurons was significantly decreased in both the ipsi- and contra-lateral sides of the ventral LGN (vLGN) but not the dorsal LGN (dLGN) at 1 month post-operation and beyond. Expressions of NOS I and NADPH-d were notably increased from 1 week post-operation in the ipsilateral vLGN. In the contralateral side of the vLGN, however, this change was only observed from 1 month post-operation. No NOS II immunoreaction was observed in LGN of both the normal control and glaucomatous rats. Increased microglial reactivity as indicated by OX-42 immunoreactivity was first observed in both sides of the LGN at 1 week post-operation, and this was most significant especially at 1 and 2 months post-operation. The present results suggest that NO and microglial cells may play some important roles in the pathologic processes of neuronal degeneration in the LGN of glaucomatous rats.

Bilateral accessory renal arteries associated with some anomalies of the ovarian arteries: a case study

Accessory renal arteries are found frequently--more often on the left side and occurring in as high as 30-35% of cases in some series. These arteries usually enter the upper or lower poles of the kidney. The main clinical significance of such arteries entering the lower pole is that they may obstruct the ureter and lead to hydronephrosis. We report the presence of accessory renal arteries found during routine dissection in an elderly female cadaver. The uniqueness in the variations noted in our cadaver included (1) a dual relationship of the ureters to the accessory renal arteries and (2) both the right and left ovarian arteries originating from their respective accessory arteries. Anomalous renal vessels arise as a result of the complicated development of the kidneys. Similarly, the aberrant origins of both the ovarian arteries observed here could be explained on an embryological basis.

An immunohistochemical study of neuronal and glial cell reactions in retinae of rats with experimental glaucoma

Glaucoma is a common disease seen in the eye clinic, but its associated pathological processes, especially the role of glial cells in glaucomatous retinae, are still under debate. The aim of the present work was to study the responses of astrocytes, Müller cells and microglia in retinae of rats with experimental glaucoma. Glaucoma was induced in adult male Wistar rats by cauterizing limbal-derived veins and the changes in glial fibrillary acidic protein (GFAP), OX42, OX18, OX6 and EDI expression were studied by immunohistochemical staining. Neuronal cell viability was studied by immunostaining with the neuronal nuclei (NeuN) antibody. In the experimental glaucomatous eyes, a significant drop in the number of NeuN-positive neurons was observed from 7 days postoperation and beyond in both the ganglion cell layer and inner nuclear layer. The expression of GFAP and OX42 was increased during the first 2 months after operation and reduced in rats at 3 and 4 months. OX6 and OX18 immunoreactivity was induced in some microglia of both glaucomatous and sham-operated control eyes. Possible mechanisms of the reaction of astrocytes, Müller cells and microglia in neuronal degeneration following glaucoma are discussed.

Neuronal and microglial response in the retina of streptozotocin-induced diabetic rats

This study reports Müller cell and neuronal changes and microglial reaction in streptozotocin-induced diabetic rats. Glial fibrillary acidic protein (GFAP) immunoreactivity was largely confined to astrocytes in the nerve fiber layer (NFL) and ganglion cell layer (GCL) in control rats. In diabetic rats especially those killed after 12 months, GFAP immunostaining could be traced along the entire length of Müller cell processes, extending from the inner to the outer limiting membrane. With the antibody neuronal nuclei, immunopositive cells were located in the GCL and the inner part of the inner nuclear layer (INL) in both diabetic and age-matched control rats. In diabetic rats, labelled cells were reduced in both layers being more marked in the INL. In age-matched control rats, OX42-immunoreactive microglial cells were distributed mainly in the NFL and GCL; some cells were localized in the inner plexiform layer, but rarely in the outer plexiform layer (OPL). Beginning 1 month after diabetes, the microglial cells appeared hypertrophic. Furthermore, microglial number as estimated from cell counts in different layers of the retina was significantly increased, with the occurrence of some cells in the OPL at 4 months. At 14 and 16 months, reactive microglial cells were detected in the outer nuclear layer and photoreceptor layer. Present results suggest that microglial reaction in induced diabetes was elicited by neuronal cell loss in both GCL and INL as well as by some pathologic changes affecting the photoreceptors.

Expression of immunoregulatory cytokines in neurons of the lateral hypothalamic area and amygdaloid nuclear complex of rats immunized against human IgG

Present results showed that interleukin-1 (IL-1), IL-6 and transforming growth factor-beta (TGF-beta) were constitutively expressed in the supraoptic and paraventricular nuclei of the rat hypothalamus. Immunoreactive cells were also detected, but to a lesser extent, in other parts of hypothalamus as well as in the cerebral cortex. In rats immunized with IgG, there was moderate increase in immunoreactivities of the cytokines. A notable feature, however, was the induction of the cytokine expression in the lateral hypothalamic area and the amygdaloid nuclear complex, suggesting that the neurons in these two areas are involved in possible immune regulation.

Neuroprotective and neurodestructive functions of nitric oxide after spinal cord hemisection

Nitric oxide (NO) may subserve different functions in different central neurons subjected to axotomy. The difference may depend on whether the neurons basally express neuronal nitric oxide synthase (nNOS), a biosynthetic enzyme of NO. This is supported by our previous finding that suggests the differential role of NO in neurons of nucleus dorsalis (ND) and red nucleus (RN) which have different basal expression of nNOS. This study aimed to establish firmly the functions of NO, as revealed by nNOS immunoreactivity and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry, by the administration of endogenous NO donor, l-arginine (l-arg), and NOS inhibitor, l-N(G)-nitroarginine methyl ester (l-NAME). To relate the role of NO to glutamate receptors (GluR), the distributions of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and N-methyl-d-aspartate receptor (NMDAR) in the two nuclei were revealed by immunohistochemical techniques. nNOS immunoreactivity was void in ND neurons, but expressed weakly in the RN normally. It was induced in ipsilateral ND neurons and upregulated on both sides of RN after spinal cord hemisection. Neuronal loss in the ipsilateral ND was augmented by l-arg, but reduced by l-NAME. In the contralateral RN, l-arg attenuated neuronal loss. NMDAR1 was present in most neurons in ND. After axotomy, some NMDAR1 immunoreactive neurons of the ipsilateral ND were induced to express NOS, whereas RN neurons showed strong staining for NMDAR1 and all the AMPA subunits. Most of the NOS-positive neurons in the RN were coexistent with GluR2 in normal rats and those subjected to axotomy. The present data demonstrated that NO exerted neurodestructive function in the non-NOS-containing ND neurons characterized by NMDAR as the predominant glutamate receptor. NO might be beneficial to the NOS-containing RN neurons. This could be attributed to the presence of GluR2. Possible diverse synthesizing pathways of NO in two different central nuclei were suggested from the observation that NOS was colocalized with NADPH-d in ND neurons, but not in RN neurons.

Neuropeptide release by efficient recruitment of diffusing cytoplasmic secretory vesicles

Neuropeptides are slowly released from a limited pool of secretory vesicles. Despite decades of research, the composition of this pool has remained unknown. Endocrine cell studies support the hypothesis that a population of docked vesicles supports the first minutes of hormone release. However, it has been proposed that mobile cytoplasmic vesicles dominate the releasable neuropeptide pool. Here, to determine the cellular basis of the releasable pool, single green fluorescent protein-labeled secretory vesicles were visualized in neuronal growth cones with the use of an inducible construct or total internal reflection fluorescence microscopy. We report that vesicle movement follows the diffusion equation. Furthermore, rapidly moving secretory vesicles are used more efficiently than stationary vesicles near the plasma membrane to support stimulated release. Thus, randomly moving cytoplasmic vesicles participate in the first minutes of neuropeptide release. Importantly, the preferential recruitment of diffusing cytoplasmic secretory vesicles contributes to the characteristic slow kinetics and limited extent of sustained neuropeptide release.

Different distributions of nitric oxide synthase-containing neurons in the mouse and rat hypothalamus

The distribution of nitric oxide synthase-containing neurons was studied in the rat and mouse hypothalamus by immunohistochemistry and NADPH-diaphorase histochemistry. Immunostaining and NADPH-diaphorase staining of hypothalamic neurons were comparable in all hypothalamic nuclei of either species except in the arcuate nucleus that stained positive for nitric oxide synthase immunoreactivity but negative for NADPH-diaphorase reactivity. The presence of nitric oxide synthase-immunopositive neurons in the arcuate nucleus was confirmed by nitric oxide synthase immunofluorescence viewed under the confocal microscope at 1 microm thickness. Cross-species comparison showed that, in general, the number and intensity of nitric oxide synthase-containing neurons were much higher in the rat than in the mouse hypothalamus. Differences in the distribution of nitric oxide synthase-containing neurons between these two rodents were found in most hypothalamic nuclei. In particular, two dense clusters of nitric oxide synthase-containing neurons were found in the paraventricular and supraoptic nuclei of the rat hypothalamus in contrast to their scarcity in the same nuclei of the mouse hypothalamus.

Emperipolesis of lymphoid cells in vagal efferent neurons following an intraneural injection of ricin into the vagus nerve in rats

Injection of a minute amount of the toxic lectin, Ricinus communis agglutinin-60 (RCA-60) into the vagus nerve resulted in a selective destruction of the vagal efferent neurons in the ipsilateral dorsal motor nucleus (DMN). This has elicited a massive influx of mononuclear leucocytes, notably macrophages and T-lymphocytes, as detected with ED-1 and OX-19 antibodies, respectively. A small number of B-lymphocytes as identified by OX-33 antibody, were also observed in the neuropil of DMN. The influx of mononuclear leucocytes into the neuropil of DMN was by way of diapedesis, peaking in frequency at 4-6 days after the RCA administration. The infiltrated lymphocytes were closely associated with or penetrated the soma of the vagal neurons, some bearing intact axo-somatic synaptic contacts. The entrapped lymphocytes in neurons underwent degeneration and subsequently disintegrated. Macrophages and plasma cells in the neuropil did not appear to penetrate the neuronal soma. It is concluded that emperipolesis of lymphocytes, presumably cytotoxic T-cells, in RCA-poisoned neurons may represent a form of effector-target cell contact leading to cytotoxicity. In doing so, however, the invading lymphocytes were destroyed by the contents of RCA picked up by the neurons. The absence of macrophages and plasma cells in the RCA-poisoned neurons suggests the cellular specificity of emperipolesis.