bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prenatal treatment with 6‐hydroxydopa and DSP 4: Biochemical, endocrinological and behavioural effects
Authors: König Norbert , Serrano Jean‐Jacques , Jonsson Gösta , Malayal Francis , Szafarczyk Alain 
Published: April 2003

AbstractBiochemical, hormonal, and behavioural aspects of the effects of prenatal treatment (foetal days 18 and 19) with 6‐hydroxydopa (2 × 40 mg/kg) and DSP 4 (2 × 20 mg/kg) have been studied in the rat. The results of the catecholamine assays suggest that the 6‐hydroxydopa treatment produced a transient decrease of noradrenaline concentration in the cerebral cortex, and a long‐lasting decrease in the cerebellum, whereas DSP 4 produced a long‐lasting decrease in the cerebral cortex and a tendency towards increase in the cerebellum. Assays of adrenocorticotropic hormone and corticosterone indicated a general tendency towards increase in base line as well as in moderate stress situations. The results of behavioural tests indicated hyperactivity and/or hyperreactivity, but not restlessness, and partly supranormal sensorimotor performances.
The microtubular apparatus of cerebellar purkinje cell dendrites during postnatal development of the rat: The density and cold‐stability of microtubules increase with age and are sensitive to thyroid hormone deficiency
Authors: Faivre C. , Legrand Ch. , Rabié A. 
Published: April 2003

AbstractA quantitative ultrastructural study of microtubules in Purkinje cell dendrites of normal and hypothyroid developing rats was performed after fixation either at room or at low temperature (4°C). In normal animals, the density of microtubules and their fold‐stability increased with age, more especially during the period of intense dendritic growth. Thyroid deficiency delayed the appearance of microtubules and still more the acquisition of their fold‐stability. These effects might explain the defects in Purkinje cell dendritic growth and branching observed in hypothyroid animals.
Development of trochlear motor neurons, superior oblique muscle, and neuromuscular junctions following prevention of cell death by myasthenia gravis immunoglobulin
Authors: Sohal G.S. , Swift T.R. 
Published: April 2003

AbstractParalysis of embryo during the period of naturally occurring motor neuron death produces an increase in the number of surviving neurons while the progressive differentiation and maturation of target muscle is severely retarded. Application of immunoglobulin G from patients with acquired myasthenia gravis to duck embryos during the period of trochlear motor neuron death also prevents this neuron loss but without paralyzing the embryo. The present study was conducted to investigate whether or not the differentiation and maturation of motor neurons, target muscle, and neuromuscular junctions were retarded following prevention of cell loss with myasthenic immunoglobulin. Immunoglobulin concentrates from myasthenics and normal human volunteers were applied daily to the chorioallantoic membrane of duck embryos from day 10 onward. The development of the trochlear neurons and the superior oblique muscle was examined with light and electron microscopy on embryonic days 12, 16 and 20. The motor neurons at the light and electron microscopic level were cytologically indistinguishable between the myasthenic and normal immunoglobulin‐treated embryos. Myoblasts fused to form myotubes. which further differentiated into mature myofibers at the same time in both groups. Numerous neuromuscular junctions of normal ultrastructure and nerve fibers with myelin wrappings were observed in both cases. It is concluded that the increased neuron survival following myasthenic immunoglobulin treatment does not accompany retardation in differentiation and maturation of the target muscle which is contrary to the results obtained from studies utilizing neuromuscular blocking agents producing increased cell survival.
Morphological and biochemical maturation of rat astroglial cells grown in a chemically defined medium: Influence of an astroglial growth factor
Authors: Weibel M. , Pettmann B. , Labourdette G. , Miehe M. , Bock E. , Sensenbrenner M. 
Published: April 2003

AbstractAstroglial cells from cerebral hemispheres of newborn rats were cultured for 5 days in Waymouth's MD 705/1 medium containing 10% fetal calf serum. Thereafter, cells were grown in a chemically defined medium consisting of basal Waymouth's medium supplemented with insulin (5 μg/ml) and fatty acid free bovine serum albumin (0.5 mg/ml). The cells underwent morphological and biochemical development over a period of 28 days. The changes in the amount of glial fibrillary acidic protein indicated a development of gliofilaments. The level of S100 protein increased during the entire culture period, while glutamine synthetase activity remained low and relatively constant. The addition of an astroglial growth factor, partially purified from bovine brain soluble extract, stimulated the morphological maturation of the astroglial cells. The cells extended cytoplasmic processes and resembled mature astrocytes. At the ultrastructural level an increase in free ribosomes was observed and the intermediate filaments became organized into large bundles. The amount of glial fibrillary acidic protein was not significantly increased, but the level of S100 protein and the glutamine synthetase activity were greatly enhanced. Our results indicate that astroglial cells undergo limited maturation in the chemically defined medium and that this process is positively affected by the astroglial growth factor.
Gangliosides induce microfilament‐dependent changes in membrane surface activity of Neuro‐2a neuroblastoma cells
Authors: Spero David A. , Roisen Fred J. 
Published: April 2003

AbstractExogenous mixtures of bovine brain gangliosides (BBG) initiated a rapid series of sequential changes in surface activity in Neuro‐2a neuroblastoma cells. These changes were characterized by the formation of microvilli, ridge‐like projections and ruffled membranes within l min of BBG exposure. A maximum number of microvilli was reached after 10 min exposure and disappeared by 30 min. Ruffled membranes were most prominent within 5 min, but were still present after 60 min. These surface changes were accompanied by the formation of a thick subcortical meshwork of microfilaments which formed the cores of the microvilli and ruffled membranes. The simultaneous treatment of cells with BBG and an agent known to disrupt microfilaments (cytochalasin D) inhibited the formation of both microvilli and ruffles. In contrast, the simultaneous application of BBG and agents affecting microtubule polymerization (Colcemid and taxol) did not inhibit the formation of these surface structures. Treatment of Neuro‐2a cells with cyclic AMP (cAMP) analogs (dibutyryl cAMP and 8‐bromo cAMP) induced a similar series of surface changes which were inhibited by cytochalasin D. Furthermore, these surface changes may be specific to cAMP since neither cGMP analogs (dibutyryl cGMP and 8‐bromo cGMP) nor 5′AMP induced surface changes. We propose that the initial membrane response to exogenous gangliosides is mediated by a microfilament‐dependent mechanism. The basic similarities in surface responses elicited by BBG and cAMP analogs suggest that the effects of gangliosides on surface activity may be induced in part by a cAMP‐dependent mechanism.
New formation of sensory cells in the tuberous organ (Electroreceptor) of Brienomyrus niger (Mormyridae) induced by transection of afferent nerve
Authors: Denizot J.P. , Libouban S. 
Published: April 2003

AbstractThe tuberous organs—cutaneous electroreceptors of the mormyrid fish Brienomyrus niger—were examined, with the light and electron microscope, after sectioning of the afferent nerve of the lateral line. Transection of the afferent nerve leads to the concomitant complete degeneration of all sensory cells, and to a differentiation of new sensory cells from accessory cells, which constitute the platform. Ultrastructural examination of the newly formed sensory cells shows that within a few days these gain the characteristics of normal sensory cells. The rapidly growing cytoplasm is enclosed in a folded membrane; the foldings develop typical dense microvilli. At the same time, in spite of lack of innervation, synaptic bars surrounded by vesicles differentiate in the cytoplasm; these are opposed to the basal cell membrane which is attached to the accessory cell platform. The newly formed sensory cells never reach the size of normally developed sensory cells. Their existence is transitory, for they degenerate, together with the sensory cells, one month after de‐afferentiation.
Membrane acetylcholinesterase in murine muscular dystrophy In vivo and in cultured myotubes
Authors: Poiana G. , Scarsella G. , Biagioni S. , Senni M.I. , Cossu G. 
Published: April 2003

AbstractMurine muscular dystrophy is characterized by a reduction of the 10S molecular form of acetylcholinesterase (AChE); this reduction occurs in both strains of dystrophic mice and at the time of the phenotypic appearance of the disease.In the present study we have analyzed the biochemical features, the cellular distribution and the developmental appearance of the AChE alteration. Sequential extractions with low salt, detergent and high salt revealed that this alteration affects only membrane‐bound forms (those requiring Triton X‐100 for solubilization), while both the low salt soluble and the high salt soluble forms appeared almost identical in normal and dystrophic muscles. Specific activity, sensitivity to different ions, pH dependence and Km were found to be identical in the enzymes from normal and dystrophic muscles, suggesting that the catalytic site of the 10S form is probably not altered.Further analysis, by non‐denaturing gel electrophoresis, of the detergent soluble forms separated by sedimentation, revealed a single band for the 4S, a doublet for the 6S and three bands for the 10S peaks, indicating the existence of charge heterogeneity in AChE molecular forms. The corresponding molecular forms from dystrophic muscles behaved identically upon electrophoresis: the residual activity in the detergent soluble 10S form could still be separated into three bands, comigrating with their normal counterparts. Neuraminidase treatment resulted in a reduction of migration of both the 6S and 10S derived bands, but not of the 4S species, showing that sialic acid is added only to polymeric forms. Interestingly, the reduction of the 10S form appears to be linked to a developmental stage not reached in cell cultures, as cultured myotubes from muscles of dystrophic mice contained normal amounts of membrane‐bound AChE forms. The molecular mechanism underlying the reduction of the tetrameric membrane bound AChE form in dystrophic muscle and the possible functional consequences are discussed.
Distribution of pipecolic acid and proline in the developing rat brain and peripheral organs
Authors: Nishio Hiroaki , Yamada Yutaka , Giacobini Ezio , Segawa Tomio 
Published: April 2003

AbstractThe regional distribution of pipecolic acid and proline was studied in the adult and newborn rat brain. The brain concentration of pipecolic acid in the 1 and 3‐day‐old rat was 6–10 times higher than in the adult. The brain concentration of proline was found to be about 3 times higher in the brain of a newborn rat than in the adult, then it gradually decreased during the period of lactation. In plasma as well as in peripheral tissues, such as heart, kidney and liver, the highest concentration of pipecolic acid was observed at 1 day and in the adult. Secretion of pipecolic acid into the urine was highest at early stages of development. In the gastrointestinal tract, pipecolic acid was found to be most abundant in the adult, whereas low levels were found during the period of lactation. The developmental and regional changes in concentration of proline were quite different from those of pipecolic acid. Our results suggest that the contribution of dietary pipecolic acid in building up levels of pipecolic acid in rat brain is small.
Perinatal dietary exposure to soy lecithin: Altered sensitivity to central cholinergic stimulation
Authors: Bell Joanne M. , Whitmore William L. , Barnes Gloria , Seidler Frederic J. , Slotkin Theodore A. 
Published: April 2003

AbstractThe effects of perinatal exposure to soy lecithin preparation (SLP) on the development of cholinergic responses in the rat brain were examined by assessing the ability of intracisternally administered carbachol to stimulate 33Pi incorporation into phospholipids in vivo, an effect of carbachol mediated by muscarinic cholinergic receptors. Maternal intake of SLP produced a suppression of the cholinergic response in the offspring, an effect which was specific in that basal (unstimulated) incorporation rates were not reduced (in fact, they eventually became elevated), nor was the response to another neurotransmitter (dopamine) compromised. The effect occurred early in the preweanling stage, a period in which SLP exposure also enhances development of cholinergic nerve terminals. These results suggest that SLP exposure has a major effect on cholinergic synaptic development and reactivity, followed by secondary changes in other neurotransmitter pathways and by more generalized effects on basal membrane phospholipid turnover.
Increase in neuronotrophic activity during the period of smooth muscle innervation
Authors: Rush R. A. , Abrahamson I. K. , Murdoch S. Y. , Renton F. J. , Wilson P. A. 
Published: April 2003

AbstractThe expansor secundariorum is a unique smooth muscle of the avian wing that receives a dense sympathetic innervation and contains high concentrations of survival factors for sympathetic neurons. In the present study it has been possible to simultaneously examine the appearance of the neuronotrophic activity and the arrival of nerve fibres during the period of innervation. The results show that catecholamine containing nerve fibres can first be detected within the muscle on the fourteenth day of incubation (stage 40) followed by a rapid increase in the density of fibres during the next few days until the adult pattern is reached shortly before hatch. Biochemical estimation of the innervation process by measurement of dopamine β‐hydroxylase activity was supported by the histochemical findings. Estimation of neuronotrophic activity revealed that muscle from stage 40 embryos contains only low levels of activity which increases rapidly as innervation proceeds and further, that this increase in neuronotrophic activity was directly correlated with the dopamine β‐hydroxylase activities. Possible mechanisms regulating this dramatic increase in the specific activity of trophic factors are discussed.
The biphasic effect of phospholipase A2 inhibitors on axon elongation
Authors: Suburo Angela , de Job Claudia Cei 
Published: April 2003

AbstractWe have analyzed changes in axon elongation rate in vitro induced by three different phospholipase A2 inhibitors, namely, bromophenacyl bromide (BPB), quinacrine and Sr2+. Spinal ganglia were obtained from 19.5‐day‐old rat fetuses and explanted onto polyornithine substrata. Axon length was measured at 1, 2 and 3 days in vitro (d.i.v.). We have previously shown that BPB added at 5 hr in vitro (h.i.v.) modifies the structure of growth cones and inhibits or promotes axon elongation according to its concentration. Now, we have observed that 0.5 × 10−6 M BPB also stimulates axon elongation when added at 1 d.i.v. Culture media with different Ca2+ concentrations were used to test Sr2+ added at 1 d.i.v. In 2.3 mM Ca2+ only an inhibitory effect was observed with 8 mM Sr2+. On the other hand, in 0.3 mM Ca2+, axon growth was stimulated by 0.6–1.2 mM Sr2+ but inhibited by 6 mM Sr2+. Quinacrine, added at 5 h.i.v. was inhibitory at 10−5 M and showed no effects at 10−6 M. However, after washing quinacrine, normal elongation rate was recovered by those previously treated with 10−5 M and axon growth was enhanced in those treated with 10−6 M. Since three different phospholipase A2 inhibitors, tested in different situations, produce a similar biphasic effect on axon elongation rate, we postulate that this enzymatic activity is involved in the motility of axon growth cones.
Thyroidal induction of tubulin in brain development — identification of the target cell
Authors: Chatterjee D. , Sarkar P.K. 
Published: April 2003

AbstractExposure of organ cultures of newborn rat brains to tri‐iodothyronine (T3) followed by cell fractionation as well as direct exposure of prefractionated neuronal (N) and glial (G) cells to the hormone results in an almost selective induction of tubulin in the glial cells. This is established from two independent assays of tubulin, viz. colchicine binding and vinblastin precipitation. In the newborn rat brain, the tubulin content of the G cells is almost 3‐fold higher than that of the N cells. Treatment with T3 elicits 40–50% stimulation of tubulin in the G cells within 2 hr without any significant increase in the N cells. Brains from 8‐ or 50‐day‐old rats are irresponsive to induction to tubulin by T3. The rate of incorporation of [3H]leucine into total protein is very similar in both N and G cells of newborn rat brain but that into tubulin of G cells is about 3‐fold higher than that of N cells. T3 promotes this incorporation by over 30% in the G cells with only a marginal 5% increase in the N cells. The overall results suggest that the glial cells represent the target cells for the T3‐induced synthesis of tubulin, the major structural protein of the developing brain.
Innervation is required to stabilize and amplify creatine kinase activity in regenerated extensor digitorum longus muscles of rats
Authors: Rossi Anna Maria , Savarese Nicola , Cotrufo Roberto 
Published: April 2003

AbstractNeural control of creatine kinase (CK, adenosine 5′‐triphosphate creatine phosphotransferase: EC 2.7.3.2) was investigated by measuring enzymatic activity and isoenzymatic representation of CK in extensor digitorum longus (EDL) muscles of adult rats during and after regeneration. Experimental models were ischemized EDLs, reversibly or permanently denervated. Results showed that, during regeneration, CK in muscle fibers was likewise modified in both reversibly and permanently denervated EDLs. After regeneration a clear dichotomy was observed between the regenerated EDLs which were innervated and recovering CK activity, and those in which innervation was prevented and were rapidly losing activity. Further to investigate the neural influence on CK turnover, merely denervated agematched EDLs were analysed and found to lose CK activity rapidly. The major conclusions are that during regeneration muscle CK is autonomously expressed, but following regeneration neural influence becomes an absolute requirement for stabilization and amplification of CK.
Thrombin is a potent mitogen for rat astroblasts but not for oligodendroblasts and neuroblasts in primary culture
Authors: Perraud Frédéric , Besnard François , Sensenbrenner Monique , Labourdette Gérard 
Published: April 2003

AbstractAstroblasts from brain of newborn rat can survive and even proliferate to some extent in a chemically defined medium containing no other growth factor than insulin, providing they are grown first in the presence of fetal calf serum for at least 4 days (Weibel et al., 1984, Int. J. devl Neurosci, 2, 355–366). We found that thrombin is a potent mitogen for these cells, in vitro. The mitogenic activity of thrombin for astroblasts can be compared to that of the astroglial growth factor 2 (AGF2), also known as basic fibroblast growth factor (bFGF), which was, up to now, the most active factor on astroblasts. However, in contrast to the bFGF, thrombin does not modify significantly the morphology of the cells and their synthesis of glutamine synthetase, an astroglial marker in rat brain. Some other proteases are also able to stimulate the proliferation of astroblasts, but to a lesser extent than thrombin. Thrombin does not stimulate the proliferation of oligodendroblasts from newborn rat and of neuroblasts from 13‐day‐old rat embryo. These results suggest that in the central nervous system thrombin might play a role in the induction of astrocyte proliferation after brain injury.
Detachment of cultured neurons from substratum by astrocytic membrane‐associated activity. Implications for CNS regeneration?
Authors: Gilad Gad M. , Gilad Varda H. 
Published: April 2003

AbstractIn primary cultures of dissociated cells from 6‐day‐old rat cerebellum, astrocytes proliferated and grew under the initially formed network of neurons. The growing astrocytes invaded the culture growth surface, while the neurons detached from the substratum and died. By 8 days after plating a confluent layer of astrocytes has taken over the entire growth surface area and neurons have disappeared. Membrane fractions prepared from astrocytes of 8‐day‐old cultures, have led to detachment of growing neurons. After 2 days in the presence of membrane fractions, about 70% of the neurons disappeared and many of the remaining ones had detached or retracted processes. The results indicate that the well‐known phenomenon of disappearance of neurons from mixed primary CNS cultures, is probably caused by a membrane‐associated activity of the proliferating astrocytes which can disturb neuron‐substratum attachments. Our in vitro study implies that astrocytes may have a membrane‐associated activity which is expressed under certain conditions and can disturb the contacts of growing or regenerating axons with their growth substrata.
Sex steroids promote neurite growth in mesencephalic tyrosine hydroxylase immunoreactive neurons in vitro
Authors: Reisert Ingrid , Han Victor , Lieth Erich , Toran‐Allerand Dominique , Pilgrim Christoph , Lauder Jean 
Published: April 2003

AbstractThe influence of steroid hormones on the differentiation of catecholaminergic and serotonergic (5‐HT) neurons was studied in dissociated cell cultures from embryonic day 14 (E14) rat diencephalon, mesencephalon and metencephalon treated for 6 days with 17β‐estradiol (E), testosterone (T), 5α‐dihydrotestosterone (DHT), progesterone (P), dexamethasone (DEX), or E + T. The effects of these hormones on morphologic differentation were determined by morphometric measurements of total length of neurites of immunocytochemically identified neurons in culture, which were stained with antisera against tyrosine hydroxylase (TH) or 5‐HT. A significant increase in neurite length was observed in cultures of TH‐immunoreactive (TH‐IR) neurons from the mesencephalon treated with E, T, E + T, but not with P, DHT or DEX. Based on labeling with [3H]dopamine (DA) uptake and competition with specific inhibitors, these mesencephalic TH‐IR cells appear to represent DA neurons of the A8–A10 groups (which includes the substantia nigra). No statistically significant effects of these steroids were observed on TH‐IR neurons from the diencephalon (assumed to be precursors of the tuberoinfundibular and incertohypothalamic dopaminergic groups). The 5‐HT neurons of the raphe nuclei (metencephalon) showed no statistically significant response to steroids. We conclude that during the early fetal period, sex steroids can affect the morphologic differentiation of mesencephalic DA neurons in vitro, indicating that these hormones are capable of selectively influencing the development of a specific population of monoamine neurons during this critical period.