bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proliferation of rat astrocytes, but not of oligodendrocytes, is stimulated in vitro by protease inhibitors
Authors: Perraud F. , Besnard F. , Labourdette G. , Sensenbrenner M. 
Published: April 2003

AbstractVarious natural protease inhibitors stimulate the proliferation of rat astrocytes grown in primary culture in the absence of serum. They are inactive on the proliferation of oligodendrocytes. The mean level of stimulation of the astrocyte proliferation elicited by the protease inhibitors is higher when the cells are in the growth phase, at low cell density than when they are quiescent, at high cell density. Among the protease inhibitors tested three serum proteins, α1‐antitrypsin, α2‐macroglobulin and antithrombin III were the most active. The present results, taken together with our previous finding that thrombin and some other proteases also stimulate the proliferation of astroglial cells but not of oligoden‐droglial cells, suggest that proteases and protease inhibitors participate, through still unclear mechanisms, in the control of the proliferation of astrocytes, but not in that of oligodendrocytes, during brain ontogenesis.
Responses of cholinergic markers to a pre‐ or a postsynaptic pharmacological blockage in the developing chick embryo spinal cord
Authors: Thiriet G. , Kempf E. , Ebel A. 
Published: April 2003

AbstractThe response of cholinergic markers to pre‐ or postsynaptic blockage was followed during development of the chick embryo spinal cord, to understand better the maturation sequence of the developing cholinergic synapse. It has been shown that the developing neurotransmitter system is able to react to pre‐ or postsynaptic disturbances by compensatory mechanisms, as early as 7.5 days of incubation. From 12.5 days of incubation the synaptic reactivity to such blockage changes in complexity as well as in nature. At this developmental stage muscarinic receptors show capacity for intrinsic regulation, similar to that of the adult nervous system. These results together with our previous studies clearly demonstrate that 12.5–15.5 days of embryonic life appears to be a crucial period in ontogenesis of the cholinergic neurotransmission in the chick embryo spinal cord.
A critical period of the development of β‐adrenergic receptor binding in the visual system of rat during visual deprivation
Authors: Aurich Marina , Bigl Volker 
Published: April 2003

AbstractThe density of [3H]dihydroalprenolol binding to β‐adrenergic receptors in the visual structures (visual cortex, superior colliculus and lateral geniculate nucleus) of rats raised under a normal 12 hr light‐dark cycle was compared to those of rats visually deprived at different postnatal ages. Unilateral eyelid suture from postnatal days 10 or 16 to 3 months resulted in an increased [3H]dihydroalprenolol bilateral binding in the lateral geniculate nucleus compared to control animals. Monocular deprivation from postnatal days 25, 40, 60 and 90 had no effect on the density of [3H]dihydroalprenolol binding. After re‐opening of the eyelid, which was sutured on postnatal day 10, at postnatal day 25 no changes in β‐adrenergic receptor binding in the lateral geniculate nucleus of the adult animal could be detected. After re‐opening of the sutured eyelid on day 90, followed by examination of the adrenoceptor density 4 weeks later, the [3H]dihydroalprenolol binding in both lateral geniculate nuclei remained elevated as was also found in corresponding regions of monocular deprived animals.Binocular visual deprivation from postnatal day 10 until the age of 3 months had no effect on [3H]dihydroalprenolol binding in the visual centres in comparison to corresponding control animals.The data suggest that there exists a critical period for the ontogenetic development of β‐adrenergic receptors binding in the visual system of rats during which permanent alterations of receptor binding can be induced by monocular but not binocular visual deprivation.
Immunocytochemical study of the postnatal development of 5‐HT‐containing neurons and fibers in the cerebroid ganglia of Cryptomphalus aspersa
Authors: Flores Vladimir , Brusco Alicia , Saavedra Jorge Pecci 
Published: April 2003

AbstractIn this work we have studied the organization of the serotonergic system in new‐hatched snails and the developmental changes that occur postnatally. The serotonergic system of the newhatched snail is not completely developed. Tracts previously described in the adult were already present at hatching; however immunoreactivity of these tracts was somewhat less intense than that in adults, but, their location was practically the same.At hatch the pro‐ and postcerebral serotonergic plexi were poorly developed, while the mesocerebral one was nearly absent. The procerebral plexus occupied only the caudal half of the procerebral neuropile. Growth cone profiles were found in all plexi.The paired giant dorsal serotonergic neurons were the only stained neurons constantly found at hatching; they were symmetrically located. The paired medium‐sized neurons were not found in all brains examined. Sometimes only one of them was present at hatching; it was located either in the right or in the left ganglion.The small neurons were absent in most cases. They gradually appeared during the first three postnatal months. Following hatching the procerebral plexus had undergone an intense growth. By the third postnatal month it innervated completely the procerebral neuropile. At hatching the area innervated by the procerebral plexus was 4500 μm2, by the third month this area was about 58,000 μm2 and in the adult was 80,000 μm2.The postnatal development of the procerebral serotonergic plexus proceeds through two different modalities of neuritic growth: expansive growth is mediated by centrifugal elongation of terminal branches while the increase in fiber density within the plexus results from lateral sprouting. This growth probably depends on dynamic interactions with afferent fibers proceeding from the tentacular sensory organs.
Development of membrane interactions between brain endothelial cells and astrocytes in vitro
Authors: Tao‐Cheng Jung‐Hwa , Brightman Milton W. 
Published: April 2003

AbstractTo ascertain whether there is a mutual influence on the structure of their cell membranes, brain endothelial cells and their closest neighbor, astrocytes, were grown alone or together in vitro and freeze‐fractured. When cultured separately, the brain endothelial cells had a low frequency of short, fragmented tight junctions. Many gap junctions, which are absent from mature brain capillaries in vivo, intercalated among the tight junctional strands, or were separate from them. The separately cultured astrocytes had low concentrations of randomly distributed assemblies (1–30/μm2) in their membranes. When the two cell types were co‐cultured, the endothelial tight junctions were greatly enhanced in frequency, length, width and complexity, and the gap junctional area enclosed by the tight junctional strands were markedly reduced. Thus, the in vitro endothelial junctional complex resembled their in vivo counterpart, the tight junctions of brain capillaries, when co‐cultured with astrocytes. Reciprocally, brain endothelial cells induced the astrocytic membrane assemblies to increase in concentrations by 5̃ fold, and sometimes to form aggregates with very high concentrations (400/μm2) which approached the concentration of the perivascular astrocytic membranes in vivo. Substituting astrocytes with fibroblasts or smooth muscle cells in co‐cultures did not enhance the tight junctions in the brain endothelium. On the other hand, substituting brain endothelium with endothelium from pulmonary artery or aorta in cocultures did not increase the concentration or induce aggregation of the assemblies in the astrocytes. Thus, the two close neighbors in vivo, brain endothelium and astrocytes, interact specifically in vitro to induce development of membrane specializations which resemble those at the site of the blood‐brain barrier.
Maturational changes in neonatal rat motor system with early postnatal administration of nicotine
Authors: Frischer Ruth E. , King Jean A. , Rose Kenneth J. , Strand Fleur L. 
Published: April 2003

AbstractExperiments were designed to assess the effects of chronic maximum ‘smoking dose’ nicotine administration on neonatal motor behavior and neuromuscular structural maturation. Thus, Sprague‐Dawley rat neonates received daily subcutaneous injections of nicotine (0.05 mg/kg/day) from postnatal days 1 to 14. Motor behavior (ambulations, stop and go movements) was not affected, but a marked increase in grasping duration resulted, indicating increased neuromuscular maturation. Concomitantly, neuromuscular morphological and dynamic contractile changes were observed in the in situ extensor digitorum longus (EDL) muscle. The EDL muscle showed accelerated morphological dimensions of the endplate at postnatal day 7 and a more rapid twitch at 2 weeks of age. The results suggest that this maximum ‘smoking dose’ of nicotine induces time‐dependent maturational changes in the neuromuscular model.
Transferrin: An early marker of oligodendrocytes in culture
Authors: de los Monteros Araceli Espinosa , Chiapelli Francesco , Fisher R. S. , de Vellis J. 
Published: April 2003

AbstractIn this study, the developmental pattern of transferrin expression, the iron transporting glycoprotein, was investigated morphologically and immunocytochemically in mixed glial cultures as well as pure cultures of mature oligodendrocytes, both derived from newborn rat brain.Double immunofluorescent labeling of pure oligodendrocyte cultures revealed that transferrin colocalizes with the oligodendroglial marker, myelin basic protein. During early development in mixed glial cultures, the presence of transferrin was detected at 3 days in vitro in small round process‐bearing cells lying on top of astrocytes. These cells were galactocerebroside negative. However, at 7 days these process‐bearing cells began to express galactocerebrosides and transferrin co‐localized with the oligodendroglial marker. Transferrin did not co‐localize with any neuronal or astroglial markers at any time. These results indicate that transferrin is an oligodendrocyte‐specific marker which is expressed earlier than galactocerebroside.
Neuron transplantation reverses phenobarbital‐induced behavioral birth defects in mice
Authors: Yanai Joseph , Pick Chaim G. 
Published: April 2003

AbstractMice were exposed to phenobarbital prenatally on gestation days 9–18 (B mice), and were tested at adulthood for behavioral changes. B mice showed deficits in the eight‐arm maze, a behavior related to the septohippocampal pathways. Consequently, transplantation of septal (mostly cholinergic) and locus coeruleus (mostly noradrenergic) neurons was applied to reverse the behavioral deficits. Most (75%) of the controls but none of the B mice reached a specific criterion in the eight‐arm maze. However, transplantation of fetal septal tissue into the hippocampus of B mice enabled 55% of them to reach criterion. Transplantation of locus coeruleus tissue did not improve the performance of B mice. The viability of the transplants was confirmed in cytochemical studies. The results suggest that transplantation of neurons can be applied to reverse phenobarbital‐induced behavioral birth defects.
Gestational exposure to phencyclidine (PCP) in rats decreases PCP binding sites in term fetal brain
Authors: Ali S. F. , Ahmad G. , Slikker W. , Bondy S. C. 
Published: April 2003

AbstractPregnant Sprague‐Dawley rats were treated with 5 mg/kg body weight of phencyclidine (PCP) injected at 1 ml/kg subcutaneously on three consecutive days at four different stages of gestation. Within 10–30 min after treatment, dams showed some lack of motor coordination and became lethargic. On gestational day 21, all rats were killed by decapitation and brains were dissected and stored from mother and fetus for neurochemical analysis. PCP, dopamine and muscarinic cholinergic receptor binding was measured in membranes prepared from maternal and fetal whole brain. Neurotransmitter concentrations were also measured in the fetal brain homogenates. There was a significant decrease in PCP binding sites in fetal but not maternal brains after maternal PCP injection at gestational days 12–14, 15–17 and 18–20, but not at 9–11 days. Dopamine and muscarinic cholinergic receptor binding was not significantly altered in fetal or maternal brain when compared with vehicle control animals. The whole brain dopamine, 3,4‐dihydroxyphenylacetic acid, serotonin, and 5‐hydroxyindoleacetic acid concentrations did not show significant change in any group studied. These data indicate that gestational exposure to PCP decreases high affinity binding of PCP in term fetal brain at doses which do not alter maternal PCP receptor binding.
Regulation of phenylethanolamine N‐methyltransferase (PNMT) mRNA in the rat adrenal medulla by corticosterone
Authors: Jiang W. , Uht R. , Bohn M. C. 
Published: April 2003

AbstractIn the adrenal medulla of adult rat, physiological levels of glucocorticoid hormones are required to maintain the catalytic activity of the epinephrine‐synthesizing enzyme, phenylethanolamine N‐methyltransferase (PNMT). The present study was undertaken to determine whether glucocorticoid regulation of PNMT occurs at the level of mRNA coding for PNMT. Adult male Sprague‐Dawley rats were hypophysectomized (HPX) and killed after 2 weeks; pellets of corticosterone were implanted for 1, 3 or 7 days prior to killing. Determinations were made of plasma corticosterone levels, adrenal PNMT activity and PNMT mRNA levels by Northern gel analysis. HPX resulted in a decrease in plasma corticosterone to undetectable levels and decreases in PNMT activity and PNMT mRNA levels to 1 and 18% of the levels observed in sham rats, respectively. Corticosterone replacement produced high prolonged plasma levels of corticosterone which were 10 times those of sham rats, and significantly increased levels of PNMT activity and mRNA. However, corticosterone replacement failed to restore PNMT activity and mRNA levels fully.These results suggest that the maintenance of PNMT mRNA levels is dependent on maintaining corticosterone levels and supports the hypothesis that PNMT gene expression in the adrenal medulla is directly regulated by glucocorticoids produced by the adrenal cortex. However, the results also suggest that in the chronically HPX rat, factors in addition to naturally produced glucocorticoids are required for full restoration of PNMT mRNA levels.
Cell number, tissue thickness and protein content as measures for development and variability in cultured neocortex explants
Authors: De Jong B. M. , Ruijter J. M. 
Published: April 2003

AbstractThe development of neuronal number, explant thickness and amount of protein was studied in several series of rat neocortex expiants, cultured up to 21 days in vitro (DIV). In contrast to the dimensions of the explant, which rapidly stabilized, the amount of protein showed a prolonged increase with age in vitro. The number of neurons initially tended to decrease until a constant level was reached from 14 to 21 DIV. These findings are in good agreement with previously described cytoarchitectural characteristics. The present data also provided an opportunity to calculate the variance for various parameters within and between culture series obtained from different rats. Especially for the amount of protein, the variance between culture series appeared to be larger than within culture series. This difference was present already at the onset of culturing and persisted during development in vitro. Implications of these findings for experimental design are discussed.
Spatial distribution of glutamate, taurine and GABA in teleosts and mammals retina: In vivo and in vitro study
Authors: Lima L. , Matus P. , Drujan B. 
Published: April 2003

AbstractTeleost and amphibian retina grows throughout life at the circumferential margin distal to the center. Retinas of two teleosts, goldfish and Eugerres plumieri; and two mammals, rat and rabbit were dissected into concentric regions; center and periphery, or center, intermediate and periphery. The concentration of glutamic acid, taurine, and gamma‐aminobutyric acid was determined in these areas. A non‐significant difference was found between the center and periphery of retinas dissected into two regions. By dissecting the teleost retina in three concentric regions a progressive increase of gammaaminobutyric acid and taurine for center to periphery was observed, which was statistically significant for taurine. Rat and rabbit retina did not present this difference. The concentration of these amino acids was also determined in two concentric regions of goldfish retina 24 hr after crush of the optic nerve. Taurine content significantly increased in the center of the regenerating retina, but not in the periphery. Outgrowth was measured in expiants prepared from central and peripheral retina in the presence of exogenous taurine. The amino acid produced an increase of the nerve growth index of central expiants, but inhibited the growth from peripheral expiants. This report presents a correlation between taurine concentration in a region of the retina that could be considered as embryonic tissue, suggesting that this amino acid plays a role in the formation of new cells. Moreover, the results from post‐crush and cultured retina, with respect to taurine concentration or regenerating effect, suggest a saturation of the taurineenriched zone.
Modulation of neuronal choline acetyltransferase activity by factors derived from cultures of non‐neuronal cells from the CNS
Authors: Alderson Ralph F. , Sutton Fedora , Butler Eugene T. 
Published: April 2003

AbstractWe have found that cholinergic neurons in spinal cord‐dorsal root ganglion cultures derived from E12–E13 mouse embryos are sensitive, as measured by changes in choline acetyltransferase activity, to factors secreted by non‐neuronal cells derived from the same tissue at an identical developmental stage. Conditioned medium was produced by incubating non‐neuronal cultures for 4 days in defined medium. The cholinotrophic activity present in the conditioned medium had a molecular weight of greater than 50,000 as determined by ultrafiltration and bound wheat germ lectin and heparin sepharose. Total RNA isolated from the non‐neuronal cells, used to produce the conditioned medium, was translated in frog oocytes. Conditioned medium from the injected oocytes was also found to contain cholinotrophic activity. In contrast, the conditioned medium from water‐injected oocytes was inactive.The interaction between the cholinotrophic activity in conditioned medium from frog oocytes and known second messengers was also examined. Dibutyryl cyclic AMP produced a concentrationdependent increase in choline acetyltransferase activity. If a maximal effective dose of dibutyryl cyclic AMP was added in conjunction with a maximal effective dose of conditioned medium from oocytes injected with total RNA a nearly additive response was noted. In contrast, the phorbol ester, phorbol 12‐myristate 13‐acetate, produced a biphasic change in the level of choline acetyltransferase activity; with lower doses stimulating and higher doses inhibiting the enzyme activity. When conditioned medium from oocytes injected with non‐neuronal cell RNA was added in conjunction with the phorbol ester a decrease in the physiological response was noted.
Developing rat cerebellum—I. Effects of abnormal thyroid states and undernutrition on sulfated glycosaminoglycans
Authors: Normand G. , Clos J. , Vitiello F. , Gombos G. 
Published: April 2003

AbstractSulfated glycosaminoglycans deposition during rat postnatal cerebellar developmental is affected by altered thyroid states and undernutrition. These ontogenetic alterations seem not to be specific but to be one aspect of the general acceleration, slowing down and reduction of the cerebellar development occurring in thyroid‐deficient, hyperthyroid and undernourished rats, respectively.
ADP‐ribosylation of proteins in brain regions of rats during postnatal development
Authors: Spina‐Purrello V. , Avola R. , Condorelli D. F. , Nicoletti V. G. , Insirello L. , Reale S. , Costa A. , Ragusa N. , Stella A. M. Giuffrida 
Published: April 2003

AbstractPost‐translational modifications of chromatin‐bound proteins play an important role in the regulation of eukaryotic gene expression. Processes such as acetylation, methylation, phosphorylation and ADP‐ribosylation may alter the interaction of these proteins with DNA and consequently affect chromatin conformation and the binding of enzymes and other molecules involved in the regulation of gene expression.In the present study the process of ADP‐ribosylation of chromosomal proteins (histone and nonhistone proteins) in some rat brain regions during postnatal development was investigated; also the effect of epidermal growth factor (EGF) on this process in fetal brain slices was studied.It has been found that the process of ADP‐ribosylation of total histones extracted from rat cerebral cortex and cerebellum at 1, 10 and 30 days of age, increases from 1 to 10 days of age (i.e. the period of maximal cell proliferation) and decreases thereafter, while the process of ADP‐ribosylation of nonhistone proteins (NHPs) sharply decreases during the same developmental period.The addition of EGF to fetal brain slices causes a significant increase of ADP‐ribosylation of total histones (particularly of the histone H1 fraction) and also of NHPs and microsomal proteins. This result is in agreement with the effect of EGF as a mitogen factor, previously shown in astroglial cell cultures.
Epidermal growth factor treatment during early postnatal development: Glutamine synthetase and glutamate decarboxylase activities in mouse brain
Authors: Condorelli Daniele , Nicoletti Vincenzo , Carpano Patrizia , Insirello Lucia , Avola Roberto , Giuffrida‐Stella Anna Maria 
Published: April 2003

AbstractResults of experiments in cell cultures suggested that epidermal growth factor might influence an early stage of astroglial or neuronal cell differentiation. In order to evaluate this hypothesis the effects of subcutaneous and intracerebral treatment with epidermal growth factor on glutamine synthetase, an astroglial marker enzyme, and glutamate decarboxylase activity, a marker enzyme of GABAergic neurons, were investigated during postnatal development of mouse brain. Epidermal growth factor, at the dose used, induced the well‐known effects of the in vivo treatment, such as a decrease in body weight and a precocious incisor eruption and eyelid opening. A decrease in forebrain and cerebellum wet weight was also observed. However, repeated epidermal growth factor treatment, during early postnatal life, failed to influence glutamine synthetase activity in forebrain or cerebellum, while a significant decrease was observed in the brain stem. No effect of epidermal growth factor on forebrain glutamate decar‐boxylase activity was observed. Although epidermal growth factor receptors have been detected in the newborn rodent brain, the role of this growth factor in brain development remains to be elucidated.