bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calbindin‐D28K (CaBP28k)‐like Immunoreactivity in Ascending Projections
Authors: Menétrey D. , de Pommery J. , Thomasset M. , Baimbridge K. G. 
Published: April 2006

AbstractThis study concerns the involvement of calbindin‐D28K (CaBP28k)‐containing neurons in ascending spinal projections to the brainstem (nucleus of the solitary tract, lateral reticular nucleus area), pontine (parabrachial area) and mesencephalic (periaqueductal grey) structures. All these central structures are important in the processing of visceroception and visceronociception and all are targets for spinal efferents from similar areas. CaBP28k controls the excitability of cells by acting on intrinsic calcium metabolism. Results refer to the caudal spinal areas where the visceroceptive regions are concentrated. Experiments were performed through a double labelling approach that combined the retrograde transport of a protein ‐ gold complex to identify the projection cells and immunohistochemistry to identify the CaBP28k‐positive cells. The caudal spinal cord is rich in both CaBP28k‐containing and projection cells. Cells colocalizing the protein and the retrograde tracer were quite numerous, with a particularly high concentration in the superficial layers of the dorsal horn (laminae I and outer II) and the lateral spinal nucleus. The other spinal areas containing immunoreactive projection cells were the reticular part of the neck of the dorsal horn, the medial laminae VII and VIII, lamina X and the sacral parasympathetic nucleus. The superficial layers and the neck of the dorsal horn are targets for nociceptive, visceroceptive and thermal inputs; the sacral parasympathetic column and lamina X are involved in visceroceptive integration. A functional role for the lateral spinal nucleus has not yet been established. Quite similar results were obtained for each of the ascending pathways under study. The high incidence of CaBP28k in spinal pathways suggests that calbindin has a major role in controlling the excitability of spinal cells subserving the processing of visceroception and/or visceronociception information to supraspinal levels. The participation of CaBP28k‐immunoreactive cells in spinal ascending tract cells largely outnumbers those previously reported for various neuropeptides (Leah et al., Neuroscience, 24, 195–207, 1988)
Heterotopic Cortical Afferents to the Medial Prefrontal Cortex in the Rat. A Combined Retrograde and Anterograde Tracer Study
Authors: van Eden C. G. , Lamme V. A. F. , Uylings H. B. M. 
Published: April 2006

AbstractCortical afferent projections towards the medial prefrontal cortex (mPFC) were investigated with retrograde and anterograde tracer techniques. Heterotopical afferent projections to the medial prefrontal cortex arise in secondary, or higher order, sensory areas, motor areas and paralimbic cortices. On the basis of these projections three subfields can be discriminated within the mPFC. (1) The ventromedial part of mPFC, comprising the pre‐ and infralimbic areas, receives mainly projections from the perirhinal cortex. (2) The caudal two‐thirds of the dorsomedial PFC, comprising frontal area 2 and the dorsal anterior cingulate area, receives projections from the secondary visual areas, the posterior agranular insular area and the retrosplenial areas. (3) The rostral one‐third of the dorsomedial PFC is the main recipient of projections from the somatosensory and motor areas and the posterior agranular insular area. The laminar distribution of cells projecting to the mPFC varies considerably in the different cortical areas, just as the laminar distribution of termination of their fibres within the mPFC does. It is concluded that the corticocortical connections corroborate with subcortical connectivity in attributing to the mediodorsal projection cortex of the rat functions which are comparable to those of certain prefrontal, premotor and anterior cingulate areas in the monkey.
Two GTP‐binding Proteins Control Calcium‐dependent Exocytosis in Chromaffin Cells
Authors: Sontag Jean‐Marie , Aunis Dominique , Bader Marie‐France 
Published: April 2006

AbstractThe effect of guanosine triphosphate analogues on catecholamine secretion from permeabilized bovine chromaffin cells was examined. Guanosine 5′‐[γ‐thio]triphosphate was demonstrated to produce a dual effect on calcium‐evoked secretion, enhancing the release through a mechanism involving protein kinase C and inhibiting secretion by a protein kinase C‐independent pathway. We propose that two functionally distinct G‐proteins control the stimulus ‐ secretion coupling in chromaffin cells.
Triple Immunofluorescence Evidence for the Coexistence of Acetylcholine, Enkephalins and Calcitonin Gene‐related Peptide Within Efferent (Olivocochlear) Neurons of Rats and Guinea‐pigs
Authors: Safieddine Saaid , Eybalin Michel 
Published: April 2006

AbstractThe efferent (olivocochlear) nerve supply to the cochlea is subdivided into a lateral and a medial innervation according to several criteria, e.g. locus of origin in the superior olivary complex and type of synaptic connections established in the organ of Corti. We have used a triple immunofluorescence colocalization approach to determine whether putative cholinergic neurons from the lateral innervation contain both metenkephalin and calcitonin gene‐related peptide (CGRP), and whether those from the medial innervation also contain CGRP. About 80% of the choline acetyltransferase (ChAT)‐like immunostained lateral efferent neurons within the lateral superior olive were CGRP‐ and metenkephalin‐like immunostained. In the organ of Corti, colocalization of the three antigens within the inner spiral bundle was also found. This bundle contains the lateral efferent synapses, with the dendrites of the primary auditory neurons innervating the sensory inner hair cells. Most of the medial efferent neurons in the ventral nucleus of the trapezoid body were only immunoreactive for ChAT. However, in the rostral part of the nucleus, a minority of ChAT‐like immunostained neurons were also CGRP‐like immunostained. None of the ChAT‐like immunostained medial efferent neurons presented metenkephalin‐like immunostaining. In agreement with these brainstem data, partial colocalization of the ChAT‐ and CGRP‐like immunostaining and a lack of metenkephalin immunoreactivity was noted below the sensory outer hair cells, which are the synaptic targets of medial efferent terminals in the organ of Corti. This distinction in the coexistence pattern of the two efferent innervations probably reflects distinct modes of action for acetylcholine in the cochlea. In one case, the effects of acetylcholine on the primary auditory neurons innervating the inner hair cells may require balanced modulation by metenkephalin and CGRP. In the other case, modulation of the effects of acetylcholine on the outer hair cells by neuropeptides would be less critical.
GABAB Receptors in the Parallel Fibre Pathway of Rat Cerebellum
Authors: Batchelor Andrew M. , Garthwaite John 
Published: April 2006

AbstractBinding studies indicate that the molecular layer of the cerebellum has a high concentration of γ‐aminobutyric acid type B (GABAB) receptors. In order to elucidate the function of these receptors we have recorded from Purkinje cells in biplanar slices of immature (14‐day‐old) and adult rat cerebellum using a low‐noise, non‐invasive, gap technique. The responses of Purkinje cells to parallel fibre stimulation in slices from both immature and adult rats contained a wave that could be inhibited by the GABAA antagonist, bicuculline. In slices from immature animals, application of 30–50 μM bicuculline revealed a slow (400 ms to peak) and very long‐lasting (up to 1 s) hyperpolarizing wave which was inhibited by GABAB antagonists. Activation of GABAB receptors on Purkinje cells with an exogenous agonist, baclofen, also generated a hyperpolarization. Baclofen additionally inhibited the synaptic potentials generated in Purkinje cells on stimulating parallel fibres, an effect which could be reversed by GABAB antagonists. The potency of baclofen in this respect was similar in adult and immature tissue but another excitatory pathway in the cerebellar cortex, the mossy fibre to granule cell synapse, proved to be much less sensitive. We conclude that, at least in the immature rat, there are GABAB receptors on Purkinje cell dendrites and that these receptors can be activated following parallel fibre stimulation; there are also GABAB receptors on presynaptic terminals within the molecular layer of immature and adult cerebellum that, when stimulated, inhibit transmitter release.
Neurophysiological Correlates of Colour Induction on White Surfaces
Authors: Kastner Sabine , Crook John M. , Pei Xing , Creutzfeldt Otto D. 
Published: April 2006

AbstractColoured light surrounding a white surface of about equal luminance makes the white surface appear illuminated with an unsaturated light of the complementary colour. In an attempt to discover the neurophysiological basis of such colour induction, we recorded from spectrally opponent cells of the parvocellular layers of the lateral geniculate nucleus (P‐LGN) of anaesthetized macaques. Only cells with wide‐band (W) spectral sensitivity in the short (S) or long wavelength (L) part of the spectrum (WS, WL) are excited by white spots of light centred on their receptive field. Cells with narrow‐band (N) spectral sensitivity (NS, NL) and light‐inhibited (L1) cells are inhibited by white light. Therefore, it is likely that the code for white is contained in a balanced excitation of the W cells. The effects of continuous illumination of remote surrounds with different wavelengths on the responses to achromatic light stimuli were investigated. Responses [on minus maintained discharge rate (MDR) or on‐minus‐off] were determined for white spots (1–3° diameter) flashed on the receptive field centre, presented either alone or in the presence of an annular surround of equal luminance (inner diameter 5°; outer diameter 20°). During red surround illumination the responses of WL cells to white spots tended to be reduced as were those of WS cells during blue surround illumination. Surround illumination with the opponent colour had more variable effects, neither WS nor WL cells showing a significant alteration of their mean response to white during surround illumination with opponent light. Response alterations were to a large extent due to changes in MDR, which increased in WS cells during blue surround illumination and in WL cells during red surround illumination. It is argued that the surround effects on centre responses are due to intraocular stray light rather than lateral connections in the retina. The surround effects also depended to some extent on the size of the test spot. L1 cells and the very rare parvocellular panchromatic on‐cells showed no chromatic response changes during coloured surround illumination. Inasmuch as the excitation of WS cells, either alone or in combination with NS cell activation, is involved in coding for green and blue, and that of WL cells, in combination with NL cell activation, is involved in coding for red and yellow in perception, the shift of excitation towards one or the other W cell group indicates relatively more red or green signals in the white response, consistent with and in the same direction as colour induction. In addition, the summed population response of WS and WL cells is decreased during surround illumination with any colour including white. This is related to brightness decrease during surround illumination in perception.
Neonatal Anti‐NGF Treatment Reduces the Aδ‐ and C‐Fibre Evoked Vasodilator Responses in Rat Skin: Evidence That Nociceptor Afferents Mediate Antidromic Vasodilatation
Authors: Lewin Gary R. , Lisney Stephen J. W. , Mendell Lorne M. 
Published: April 2006

AbstractElectrical stimulation of cutaneous nerve Aδ‐fibres can lead to increases in skin blood flow (Jänig and Lisney, J. Physiol. (Lond.), 415, 477–486, 1989). Here we have examined this phenomenon in adult rats treated neonatally with antisera to nerve growth factor between postnatal days 2 and 14. This treatment forces many Aδ nociceptor afferents to take on the phenotype of low‐threshold D‐hair afferents (Lewin et al., J. Neurosci., 12, 1896–1905, 1992). In animals treated this way we found a parallel decrease in the ability of Aδ‐fibres to increase skin blood flow. The increase in blood flow evoked by C‐fibre stimulation was also reduced, but no change was seen in the ability of C‐fibres to elicit neurogenic extravasation in skin. These data may be taken as evidence that in rats, amongst the cutaneous Aδ‐fibres, nociceptor but not D‐hair afferents are capable of producing blood flow changes in the skin.
Synaptic Contacts and the Transient Dendritic Spines of Developing Retinal Ganglion Cells
Authors: Wong R. O. L. , Yamawaki R. M. , Shatz C. J. 
Published: April 2006

AbstractThe dendrites of ganglion cells in the mammalian retina become extensively remodelled during synapse formation in the inner plexiform layer. In particular, after birth in the cat, many short spiny protrusions are lost from the dendrites of ganglion cells during the time when ribbon, presumably bipolar, synapses appear in the inner plexiform layer and when conventional, presumed amacrine, synapses increase significantly in number. It has therefore been postulated that these transient spines may be the initial or preferred substrates for competitive interactions between amacrine or bipolar cell terminals that subsequently result in the formation of appropriate synapses onto the ganglion cells. If so, the majority of synapses made onto developing ganglion cells should be found on these dendritic spines. To test this hypothesis, we determined the synaptic connectivity of identified ganglion cells in the postnatal cat retina during the period of peak spine loss and synapse formation. The dendritic trees of ganglion cells were intracellularly filled with Lucifer yellow that was subsequently photo‐oxidized into an electron‐dense product suitable for electron microscopy. In serial reconstructions of the dendrites of a postnatal day 11 (P11) alpha ganglion cell and a P14 beta ganglion cell, conventional and ribbon synapses were found predominantly on dendritic shafts. Only three out of a total of 341 dendritic spines from the two cells received direct presynaptic input, all of which were conventional synapses. Thus, our observations suggest that the transient dendritic spines are not the preferred postsynaptic sites as previously suspected. However, it is possible that these structures play a different role in synaptogenesis, such as mediating interactions between retinal neurons that may lead to cell‐cell recognition, a necessary step prior to synapse formation at the appropriate target sites (Cooper and Smith, Soc. Neurosci. Abstr., 14, 893, 1988).
7‐Chlorokynurenate Ameliorates Neuronal Injury Mediated by HIV Envelope Protein gp120 in Rodent Retinal Cultures
Authors: Lipton Stuart A. 
Published: April 2006

AbstractPrior studies with in vitro model systems have suggested that at least part of the neurological manifestations of AIDS may stem from neuronal injury involving the HIV‐1 coat protein gp120. This form of neuronal damage is most probably mediated indirectly by a complex set of cellular interactions among macrophages, astrocytes, and neurons, resulting in a final common pathway of overstimulation of N‐methyl‐d‐aspartate (NMDA) receptors. We studied the neuroprotective effect from gp120‐induced neuronal injury of an antagonist of the glycine site of the NMDA receptor, 7‐chlorokynurenate. In identified rat retinal ganglion cells in culture, we found that 50 μM 7‐chlorokynurenate significantly abrogated the injury engendered by 20 pM gp120. Addition of 300 μM exogenous glycine prevented this protective effect of 50 μM 7‐chlorokynurenate. These data suggest that glycine site antagonists of the NMDA receptor may have therapeutic potential for ameliorating neuronal damage associated with gp120.
Effect of Nucleus Basalis Magnocellularis Ablation on Local Brain Glucose Utilization in the Rat: Functional Brain Reorganization
Authors: Soncrant Timothy T. , Holloway Harold W. , Horwitz Barry , Rapoport Stanley I. , Lamour Yvon A. 
Published: April 2006

AbstractAfter unilateral destruction of the nucleus basalis magnocellularis (NBM) in 3‐month‐old rats, which reduces cholinergic inputs to the ipsilateral frontoparietal neocortex, regional cerebral metabolic rates for glucose (rCMRglc) of denervated cortex are initially reduced, but nearly normalize by 2 weeks. To examine functional reorganization of the brain after unilateral destruction of the NBM, a correlation analysis of rCMRglc was performed on two groups of 16 young rats 2 weeks after stereotaxic ablation of the right NBM with ibotenate or sham surgery. rCMRglc was measured in 117 brain regions of awake rats with the [14C]deoxyglucose method. For each region pair, a partial correlation coefficient was calculated for rCMRglc across animals. Most correlations between cholinergic nuclei of both left and right forebrain (medial septum and diagonal band) and right (66/72, mean increase 0.44) but not left (39/72) frontoparietal cortical regions were larger (P < 0.001) in lesioned rats, as were those between most frontoparietal region pairs (516/630, P < 0.001). These results suggest that, after unilateral NBM ablation, (1) functional interactions are established between the remaining cholinergic forebrain and the deafferented cortex, (2) the neocortex becomes more integrated, and (3) functional reorganization involves both cortical hemispheres. These changes do not correspond to those reported to occur in Alzheimer's disease.
Reduction of Potassium Conductances Mediated by Metabotropic Glutamate Receptors in Rat CA3 Pyramidal Cells Does Not Require Protein Kinase C or Protein Kinase A
Authors: Gerber U. , Sim J. A. , Gähwiler B. H. 
Published: April 2006

AbstractMetabotropic glutamate receptors, unlike ionotropic receptors, exert their actions on ion channels via G‐proteins coupled to second messenger systems. In the hippocampus stimulation of metabotropic receptors can lead to decreased potassium channel conductance, decreased accommodation of cell firing and inhibition of the slow calcium‐dependent afterhyperpolarizing current (IAHP). Using the single‐electrode voltage‐clamp technique in hippocampal slice cultures of the rat, the role of protein kinases in mediating these metabotropic glutamate responses was investigated. In the presence of staurosporin, protein kinase C activation by phorbol esters and protein kinase A activation by 8‐bromo‐cyclic adenosine monophosphate were blocked. Under these conditions, the inhibition of IAHB by 1‐aminc‐cyclopentyl‐trans‐dicarboxylate (ACPD), a metabotropic agonist, was unchanged, whilst the inward current elicited by ACPD was enhanced. These results demonstrate that, in the hippocampus, metabotropic glutamate responses persist during inhibition of protein kinase A and C activation. Furthermore, these responses are insensitive to pertussis toxin, confirming previous observations.
Tonotopic Order in the Adult and Developing Auditory System of the Rat as Shown by c‐fos Immunocytochemistry
Authors: Friauf Eckhard 
Published: April 2006

AbstractImmediate éarly genes such as the proto‐oncogene c‐fos can be expressed in neurons following synaptic excitation by sensory stimulation. C‐fos immunocytochemistry has subsequently been shown to be a very sensitive marking technique for neuronal activity. Here, antibodies against the c‐fos protein product Fos were used to map the tonotopic organization in the auditory system of adult and developing rats. After stimulating adult rats with pure‐tone pulses, bands of Fos‐immunoreactive neurons revealed the frequency representation in seven brainstem nuclei: all three subdivisions of the cochlear nucleus, the lateral superior olive, the medial nucleus of the trapezoid body, the ventral nucleus of the trapezoid body, the rostral periolivary nucleus, the dorsal nucleus of the lateral lemniscus and the inferior colliculus. With the exception of the dorsal cochlear nucleus and the inferior colliculus, tonotopicity has not been previously demonstrated in the brainstem nuclei of the rat. During development two striking results were obtained. First, beginning at postnatal day 14 (i.e. ∼2 days after physiological hearing begins in rats), not only low but also high frequencies were able to induce strong Fos immunoreactivity, indicating that gradual recruitment of formerly unresponsive high‐frequency sites does not occur in the rat. Second, a gradual age‐related shift of the position of isofrequency bands was not seen in any of the nuclei, suggesting that changes in frequency‐place code do not occur after 2 weeks postnatally. These results indicate that the rat's auditory brainstem nuclei achieve their adult‐like tonotopic organization early on, implying a somewhat different developmental time course than is found in other mammalian species.
Temporal Patterns in Spontaneous and Odour‐evoked Mitral Cell Discharges Recorded in Anaesthetized Freely Breathing Animals
Authors: Chaput M. A. , Buonviso N. , Berthommier F. 
Published: April 2006

AbstractThis study investigates in detail how mitral cell activity is distributed during the respiratory cycle in freely breathing animals and how this temporal pattern changes under odour stimulation. Results were obtained from 1408 sequences composed of a 30‐s period of spontaneous activity followed by a 10‐s period of stimulation. Spontaneously, a majority of the patterns did not show any clear relationship with respiration and were categorized as unsynchronized. Stimulations evoked a high proportion of synchronized patterns. About 40% displayed a single period of firing rate increase superimposed on no background activity or on sustained background activity, and were categorized as simple excitatory synchronized patterns. Thirty‐six per cent showed a single inhibitory trough, and were categorized as simple suppressive synchronized patterns, whereas the remaining 24% showed a succession of peaks and troughs, and were categorized as complex synchronized patterns. Under pure air delivery, the position in time of the firing peak in simple excitatory synchronized patterns was found to be generally phase‐locked on late inhalation and early exhalation. During stimulation, its position did not change in patterns which originated from spontaneous patterns having the same type whereas it was shifted towards earlier portions of the cycle in patterns originating from another type. Lastly, the possibilities of transition between spontaneous and odour‐evoked patterns seemed to follow general rules. Whereas any type of spontaneous patterns may transform into any other type under stimulation, a majority of synchronized odour response patterns originated from unsynchronized spontaneous patterns. This may reflect some potential of cells having a non‐modulated spontaneous activity to be more responsive to peripheral inputs.