bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of the mRNA of Seven Metabotropic Glutamate Receptors (mGluR1 to 7) in the Rat Retina. An In Situ Hybridization Study on Tissue Sections and Isolated Cells
Authors: Hartveit E. , Brandstätter J. H. , Enz R. , Wässle H. 
Published: April 2006

AbstractWe have studied the expression of mRNAs for seven metabotropic glutamate receptors (mGluR1–7) in the retina of the adult rat by in situ hybridization with tissue sections and isolated cells using [α35S]dATP‐labelled oligonucleotide probes. Hybridization revealed the expression of six of the metabotropic receptor mRNAs, mGluR1, 2 and 4–7, in the retina, while mGluR3 was not detected. Each of the expressed receptor mRNAs showed a distinct pattern of expression. In the outer nuclear layer, corresponding to photoreceptor somata, no labelling was detected. In the outer part of the inner nuclear layer, putative horizontal cells were labelled for mGluR5. More proximal in this layer, corresponding to the position of bipolar cell somata, there was strong labelling for mGluR6. A small number of bipolar cells were also labelled for mGluR5 and mGluR7. In situ hybridization with isolated cells showed that mGluR6 was expressed by rod bipolar cells. Subsets of amacrine cells, with cell bodies along the border between the inner nuclear layer and the inner plexiform layer, were positive for mGluR1, 2, 4 and 7, suggesting considerable heterogeneity of these receptors among amacrine cells. None of the seven metabotropic receptor mRNAs was expressed in isolated Müller glial cells. In the ganglion cell layer, virtually every ganglion cell and displaced amacrine cell was labelled for mGluR1 and mGluR4. Some cells in this layer (˜20% of the total), most likely both ganglion cells and displaced amacrine cells, were also labelled for mGluR2 and mGluR7. These findings suggest that metabotropic glutamate receptors are considerably more widespread among neurons in the retina than indicated by previous physiological and pharmacological investigations.
Immunocytochemical Localization of trkA Receptors in Chemically Identified Subgroups of Adult Rat Sensory Neurons
Authors: Averill S. , McMahon S. B. , Clary D. O. , Reichardt L. F. , Priestley J. V. 
Published: April 2006

AbstractImmunocytochemistry has been used to examine the location of trkA, the high‐affinity receptor for nerve growth factor, in adult rat dorsal root ganglia, trigeminal ganglia and spinal cord. TrkA immunoreactivity was observed in small and medium sized ganglion cells and in the dorsal horn of the spinal cord. In lumbar L4 and L5 ganglia trkA‐immunoreactive cells constitute 40% of dorsal root ganglion cells and range in size from 15 to 45 μm in diameter. Double labelling using markers for various dorsal root ganglion subpopulations revealed that virtually all (92%) trkA‐immunoreactive cells express calcitonin gene‐related peptide (CGRP) immunoreactivity. In contrast only 4 and 13% of trkA‐immunoreactive cells are labelled by the monoclonal antibody LA4 or the lectin Griffonia simplicifolia IB4, markers for small non‐peptide‐containing cells. Eighteen percent of trkA‐immunoreactive cells belong to the ‘large light’subpopulation, identified by their strong immunostaining by the neurofilament antibody RT97. TrkA immunoreactivity in the dorsal horn is heaviest in laminae I and II outer, has a similar distribution to CGRP, and is depleted by dorsal rhizotomy. Our results show that trkA‐expressing cells in dorsal root ganglia correspond almost exactly with the CGRP, peptide‐producing population. The receptor is present not only on cell bodies but also on central terminals. Non‐peptide‐containing small cells, which constitute 30% of dorsal root ganglion cells, are not trkA‐immunoreactive and therefore most probably are functionally independent of nerve growth factor.
Expression of GABA Receptor ρ1 and ρ2 Subunits in the Retina and Brain of the Rat
Authors: Enz Ralf , Brandstätter Johann Helmut , Hartveit Espen , Wässle Heinz , Bormann Joachim 
Published: April 2006

AbstractWe have investigated the distribution of GABA receptor ρ1 and ρ2 subunits in the rat central nervous system. Cloning of rat ρ1 and ρ2 cDNA fragments revealed similarities to the corresponding human sequences of 99% (ρ1) and 88% (ρ2) at the protein level. Whereas the human ρ2 subunit has no consensus sequence for phosphorylation by protein kinase C, the cytoplasmic loop of the rat sequence contains two such sites. Use of the polymerase chain reaction with reverse‐transcribed total RNA (RT‐PCR) from different brain tissues revealed that transcript for the ρ1 subunit was present in the retina only. The ρ2 mRNA was detected in all brain regions, with the highest level of expression in the retina.In situhybridization of retinal sections revealed that ρ1 and ρ2 transcripts are present in the inner nuclear layer. RT‐PCR andin situhybridization of isolated retinal cells showed that both ρ subunits are present in rod bipolar cells. Since these cells express bicuculline‐insensitive GABA receptors, our results further support the idea that ρ subunits are part of the GABACreceptor.
BDNF Protein Measured by a Novel Enzyme Immunoassay in Normal Brain and after Seizure: Partial Disagreement with mRNA Levels
Authors: Nawa Hiroyuki , Carnahan Josette , Gall Christine 
Published: April 2006

AbstractMessenger RNA for brain‐derived neurotrophic factor (BDNF) is distributed in many brain regions and regulated by excitatory neuronal activity. Despite numerous studies of BDNF mRNA, the distribution and regulation of BDNF protein are poorly understood because of the difficulty of its quantitative measurement. We have established a two‐site enzyme immunoassay that detects trace amounts of BDNF protein (>1 pg/assay) but not other neurotrophins or growth factors. The highest levels of BDNF in adult rat brain were found in the hippocampus, followed by the hypothalamus, neocortex, cerebellum, thalamus and striatum. This pattern is similar, but not identical, to the distribution of BDNF mRNA. A similar disparity between BDNF protein and mRNA levels was observed in their changes after hilus lesion‐induced limbic seizures. In limbic structures, BDNF concentrations remained elevated 4 days after seizure onset, whereas BDNF mRNA has been reported previously to return to basal levels within 46 h. The temporal and spatial differences between the dynamics of protein and mRNA levels suggest the importance of post‐translational and/or subcellular processes for BDNF production. The persistence of the increases in BDNF content was also reflected in its biological activity, e.g. peptidergic differentiation activity. After limbic seizures, neuropeptide Y content was most markedly and persistently elevated in the entorhinal/amygdaloid region, where the most sustained up‐regulation of BDNF protein was observed. These results suggest that the sustained increase of BDNF protein in these limbic structures is involved in prolonged post‐seizure phenomena, including peptidergic alterations.
Properties of K+ Conductances in Cat Retinal Ganglion Cells During the Period of Activity‐mediated Refinements in Retinofugal Pathways
Authors: Skaliora I. , Robinson D. W. , Scobey R. P. , Chalupa L. M. 
Published: April 2006

AbstractDuring ontogeny retinal ganglion cells manifest pronounced changes in excitable membrane properties. To further our understanding of the ionic conductances underlying such functional changes, the whole‐cell voltage‐clamp variation of the patch‐clamp technique was used to record potassium currents in 220 ganglion cells dissociated from cat retinas ranging in age from embryonic day 31 to postnatal day 10. Potassium currents were isolated by blocking voltage‐gated Na+ and Ca2+ currents with tetrodoxin (TTX) and CoCl2 respectively and were characterized by their pharmacology, kinetics and voltage‐dependence of activation and inactivation. In all cases, a combination of three currents accounted for the total outward calcium‐independent K+ current: (i) a steady linear conductance; (ii) a voltage‐gated transient current, lA, and (iii) a voltage‐gated sustained current, lk. Both voltage‐gated currents were affected by the application of 4‐aminopyridine and tetraethylammonia (TEA): lA showed a greater sensitivity to 4‐aminopyridine, while lk was more sensitive to TEA. Both voltagegated currents were present throughout the developmental period examined; however, the percentage of retinal ganglion cells (RGCs) expressing lA showed a marked decline from 82% at E31 to 45% at postnatal ages. During this developmental period there was an increase in the density of the two voltage‐gated and the linear conductance. Additionally, with maturation, significantly slower inactivation kinetics were observed for lK. These findings, and our previous results dealing with maturational changes in the TTX‐sensitive voltage‐gated Na current, are related to the generation of excitability in developing retinal ganglion cells. Furthermore, the presence of cells with and without transient K+ conductance throughout development suggests that the different spiking patterns observed in RGC classes may be partially due to differences in their membrane properties.
Calcium Deposit Formation and Glial Reaction in Rat Brain after Ibotenic Acid‐induced Basal Forebrain Lesion
Authors: Saura J. , Boatell M. L. , Bendahan G. , Mahy N. 
Published: April 2006

AbstractThe mechanisms underlying amino acid neurotoxicity may involve a rise in the intracellular concentration of calcium. Some neurons appear to die as a consequence of increased intracellular calcium levels induced by excitatory amino acids. One month after injection of ibotenic acid in the rat basal forebrain, the induced formation of calcium deposits and concomitant glial reaction were studied. Alizarine Red‐positive calcium deposits were observed after ibotenic acid injection in the ventral part of the globus pallidus, but not in the medial septum. These deposits were present in the globus pallidus, ventral pallidum, substantia innominata, zona incerta, lateral hypothalamic area, entopeduncular nucleus, medial amygdaloid nucleus and several thalamic nuclei. Three types of round shaped deposit were identified morphologically. Differential astroglial and microglial reactions, studied autoradiographically with the monoamine oxidase‐B marker [3H]Ro 19‐6327 and the peripheral benzodiazepine receptor marker [3H]Ro5‐4864 respectively, were observed after both lesions. Our data suggest that excitotoxic lesions in the globus pallidus and medial septum lead with time to different neurodegenerative consequences and glial reactions. This differential sensitivity is discussed on the basis of the presence of different glutamate receptor subtypes and calcium‐binding proteins.
The Rate of Wallerian Degeneration in Cultured Neurons from Wild Type and C57BL/WldS Mice Depends on Time in Culture and may be Extended in the Presence of Elevated K+ Levels
Authors: Buckmaster E. A. , Perry V. H. , Brown M. C. 
Published: April 2006

AbstractWallerian degeneration of severed axons is delayed in C57BL/Wlds mice. We have examined this further in cultured sympathetic, sensory and CNS neurons using superior cervical ganglion (SCG), dorsal root ganglion (DRG) and cerebellar granule neurons respectively from neonatal mice. We found that the time taken for the neurites to degenerate depends upon the length of time in culture before cutting, reaching a maximum by ‐7 days when C57BL/WldS neurites survive for >6 days after axotomy. The onset of degeneration could also be extended in SCG and DRG neurites from wild type C57BL/6J mice. After 7 days in culture these neurites normally degenerate within ‐12–16 h of axotomy, but in the presence of raised K+ (50 mM) degeneration often did not begin until a further 2 days had lapsed. Under similar conditions degeneration of neurites from C57BL/WldS mice was also found to be further delayed, extending survival from ‐5–6 days to >7 days. The L‐type Ca2+ channel blockers nifedipine (5 μM) and verapamil (10 μM) both blocked the effect of raised [K+], although not completely. Thapsigargin, which raises cytoplasmic [Ca2+], and the cAMP analogue 8‐(4‐chlorophenylthio)cAMP were also able to delay degeneration, but only when added 24 h prior to axotomy. These results show that it is possible to influence the course of Wallerian degeneration and that increases in levels of cytoplasmic Ca2+ can protect neurites from its onset.
Persistence of Neuromuscular Junctions after Axotomy in Mice with Slow Wallerian Degeneration (C57BL/Wlds)
Authors: Ribchester R. R. , Tsao J. W. , Barry J. A. , Asgari‐Jirhandeh N. , Perry V. H. , Brown M. C. 
Published: April 2006

AbstractThe present study was undertaken to examine the fate of neuromuscular junctions in C57BL/Wlds mice (formerly known as OLA mice) after nerve injury. When a peripheral nerve is injured, the distal axons normally degenerate within 1‐3 days. For motor axons, an early event is deterioration of motor nerve terminals at neuromuscular junctions. Previously, the vulnerability of motor terminals has been attributed either to a ‘signal’originating at the site of nerve injury and transported rapidly to the terminals or to their continual requirement for essential maintenance factors synthesized in the motor neuron cell body and supplied to the terminals by fast axonal transport. Mice of the Wlds strain have normal axoplasmic transport but show an abnormally slow rate of axon and myelin degeneration. Structure and function are retained in the axons of distal nerve stumps for several days or even weeks after nerve injury in these mice. The results of the present study show that Wlds neuromuscular junctions are also preserved and continue to release neurotransmitter and recycle synaptic vesicle membrane for at least 3 days and in some cases up to 2 weeks after nerve injury. Varying the site of the nerve lesion delayed degeneration by ‐1‐2 days per centimetre of distal nerve remaining. These findings suggest that the mechanisms of nerve terminal degeneration after injury are more complex than can be accounted for simply by the failure of motor neuron cell bodies to supply their terminals with essential maintenance factors. Rather, the data support the view that nerve section normally activates cellular components or processes already present, but latent, in motor nerve endings, and that in Wlds mice either the trigger or the cellular response is abnormal.
Neuroanatomy of Cardiac Activity‐regulating Circuitry: A Transneuronal Retrograde Viral Labelling Study in the Rat
Authors: Ter Horst Gert J. , Hautvast Raymond W. M. , De Jongste Mike J. L. , Korf Jakob 
Published: April 2006

AbstractThe anatomy of cardiac activity‐regulating circuitry was studied with retrograde transneuronal viral labelling after pseudorabies virus injections into different parts of the rat heart. Transection of the spinal cord at Th1 was used to reveal selectively the parasympathetic neuronal networks. Virus‐labelled sympathetic preganglionic cells were found in the Th1‐Th7 thoracic intermediolateral cell groups, with some additional infections at Th8‐Thll after inoculations of the ventricular myocardium. After ventricular injections the thoracic spinal labelling pattern was bilateral and after right atrial infection it was contralateral. Approximately 20% of the parasympathetic preganglionic cells were located in the dorsal motor vagus nucleus; the rest occupied positions in the peri‐ambiguus area ventrolateral to the nucleus ambiguus. Here and in the ventrolateral reticular formation myocardiotopy was found. Supraspinal transneuronal infections were bilateral, showed no apparent side dominance and were found in the nucleus of the solitary tract, the area postrema, the raphe nuclei, the A5 group, the parabrachial region, the periaqueductal grey, the hypothalamus, the amygdala and the cortex, in particular the anterior cingulate, the frontal, prelimbic, infralimbic and insular cortices. Spinal transections at Th1 reduced the number of labelled cells, gave a right side labelling dominance and affected the infection patterns in the ventrolateral reticular area, the raphe nuclei, the periaqueductal grey matter, the perifornical and retrochiasmatic area and the rostra1 parts of the insular cortex. The latter structures are linked selectively to the sympathetic innervation of the heart. The anatomical and functional aspects of these findings are discussed in relation to the autonomic control of heart activity.
Dopamine Agonists Increase Nitric Oxide Production in the Paraventricular Nucleus of the Hypothalamus: Correlation with Penile Erection and Yawning
Authors: Melis Maria Rosaria , Succu Salvatora , Argiolas Antonio 
Published: April 2006

AbstractA low dose of apomorphine (80 μg/kg s.c.), a mixed D1/D2 agonist that induces penile erection and yawning, increased the concentration of NO2−from 1.12 ± 0.45 μM to 3.8 ± 0.75 μM and NO3−from 5.53 ± 0.82 to 11.25 ± 2.30 μM in the dialysate collected from the paraventricular nucleus of the hypothalamus of male rats byin vivomicrodialysis. The NO2−concentration was also increased by LY 171555 (50 μg/kg s.c.), a D2 agonist that induces penile erection and yawning, but not by SKF 38393 (5 mg/kg s.c.), a D1 agonist with no effect on these responses. Conversely, apomorphine's effect on NO2−was prevented by haloperidol (0.5 mg/kg i.p.), a mixed D1/D2 antagonist and L‐sulpiride (25 mg/kg i.p.), a D2 antagonist, but not by the D1 agonist SCH 23390 (50 μg/kg s.c.), although all three compounds prevented penile erection and yawning. The apomorphine effect on NO2−, penile erection and yawning was also prevented by the nitric oxide synthase inhibitorNG‐nitro‐L‐arginine methyl ester (200 μg l.c.v.). The nitric oxide scavenger haemoglobin (200 μg l.c.v.) also prevented the NO2−increase, but was ineffective against penile erection and yawning. In contrast, the oxytocin antagonist d(CH2)5Tyr(Me)‐Orn8‐vasotocin (1 μg i.c.v.) and the guanylate cyclase inhibitor methylene blue (300 μg l.c.v.) had no effect on the NO2−increase, but did prevent the behavioural responses. We infer from this that dopamine agonists induce penile erection and yawning by acting on D2 receptors that increase nitric oxide synthase activity in the cell bodies of paraventricular oxytocinergic neurons projecting to extra‐hypothalamic brain areas.
Kindled Seizure‐induced c‐fos and Prodynorphin mRNA Expressions are Unrelated in the Rat Brain
Authors: Simonato M. , Bregola G. , Donatini A. , Bianchi C. , Beani L. , Ferri S. , Romualdi P. 
Published: April 2006

AbstractLevels of mRNA for c‐fos and prodynorphin were studied by in situ hybridization in adjacent coronal sections taken from kindled rats 30–60 min after the last seizure. Within this time frame, expression of both genes was induced in multiple brain areas. Anatomical colocalization of the induced gene expressions was found in the hippocampus. Induction of c‐fos in the dentate gyrus was bilateral and symmetrical in a subgroup of rats, ipsilateral in another subgroup and absent in a third subgroup. However, no relative increase was observed in the ipsilateral compared with the contralateral prodynorphin expression in the dentate gyrus when c‐fos expression was induced ipsilaterally only. These observations suggest that, at variance with other experimental situations, Fos is not involved in the mechanisms of kindled seizure‐induced activation of prodynorphin transcription in the rat forebrain.
Cyclic Nucleotide‐gated Channels in Identified Human Olfactory Receptor Neurons
Authors: Thüraüf N. , Gjuric M. , Kobal G. , Hatt H. 
Published: April 2006

AbstractPatch‐clamp recordings revealed the presence of a non‐desensitizing cyclic nucleotide‐gated channel on human olfactory receptor neurons and a fast‐desensitizing non‐specific cation channel activated by nucleotides on human supporting cells. Cyclic nucleotide‐gated channels on olfactory receptor neurons showed selective channel activation by cAMP (K1/2= 5 μM) and cGMP (K1/2= 2 μM), a unitary conductance of ∼20 pS, a reversal potential of single‐channel currents close to 0 mV, a linear current‐voltage relationship over the range of −80 to 80 mV and a strong extracellular but a weaker intracellular blocking effect of Ca2+. The channel activity outlasted the cyclic nucleotide pulses for hundreds of milliseconds when higher agonist concentrations (>50 μM cAMP) were applied. The duration of the response was longer than in cyclic nucleotide‐gated channels from other species studied so far. The plateau duration and the decay remained constant for pulses with a length of 50−150 ms, whereas pulses shorter than 50 ms successively reduced the time required by shortening the plateau phase. A larger difference for the K1/2 values of cAMP (K1/2= 22 μM) and cGMP (K1/2= 2.5 μM) were found for a small group (n = 3) of cyclic nucleotide‐gated channels, pointing to the selective expression of the a‐subunit in a small subgroup of olfactory receptor neurons.
Interaction between Low Voltage‐activated Currents in Reticular Thalamic Neurons in a Rat Model of Absence Epilepsy
Authors: Meis Susanne , Biella Gerardo , Pape Hans‐Christian 
Published: April 2006

AbstractA transient potassium (K+) outward current (IA) contributes to the distinctive patterns of low‐threshold spike firing observed in various classes of thalamic neurons through a functional interaction with a calcium (Ca2+)‐mediated inward current (IT). The present study was undertaken to investigate the properties of transient K+ currents and their interaction with IT in neurons of the reticular thalamic nucleus, and to compare these properties in reticular thalamic nucleus neurons from a rat model of absence epilepsy, designated the Genetic Absence Epilepsy Rat from Strasbourg (GAERS), with those from a Non‐epileptic Control strain (NEC). This comparative approach appeared to be particularly important in view of the recent finding of a selective increase in IT in reticular thalamic nucleus neurons from GAERS. Neurons were acutely isolated from the reticular thalamic nucleus through enzymatic procedures, and identified by morphological and immunocytochemical criteria. Ionic currents were analysed using whole‐cell patch‐clamp techniques. Transient K+ currents in reticular thalamic nucleus neurons with properties indicative of IA activated at ∼−55 mV (with half‐activation at −27 and −33 mV in NEC and GAERS respectively), declined rapidly with a voltage‐dependent time constant (τ= 4 ms at +45 mV), were 50% steady‐state‐inactivated at −81 and −86 mV in the two strains of rats respectively, and rapidly recovered from inactivation with a monoexponential time course (τ= 31 and 37 ms respectively). No significant differences in IA properties or densities were found between reticular thalamic nucleus neurons from GAERS and NEC rats. Analysis of the interaction between IA and IT indicated a shift in the balance between the two opposing membrane conductances towards the generation of a low‐voltage‐activated inward current in reticular thalamic nucleus neurons from GAERS compared with NEC, and a lack of IA to functionally compensate for this shift, which in turn may contribute to pathological forms of low‐threshold spike firing characterizing spike‐and‐wave discharges.