bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal development of γ‐GT activity in rat brain microvessels corresponds to capillary growth and differentiation
Authors: Santoso A. W. Budi , Bär Th. 
Published: April 2003

AbstractIt has been demonstrated histochemically that endothelial cells of the cerebral capillaries show a high activity in γ‐glutamyl transpeptidase (γ‐GT), an enzyme which takes part in the transfer of large neutral amino acids across the blood‐brain barrier. Reports of the disappearance of enzyme activity in endothelial cells (EC) grown in culture12 suggest that the presence of astroglial cells (AG) is required for the expression of γ‐GT in these cells. The present study deals with the developmental changes in γ‐GT activity in capillaries of rat cerebral cortex during ontogenesis (i.e. on days 2, 7, 11, 14, 21 and 60 after birth).γ‐GT activity is determined by measuring the enzyme kinetics of the histochemical reaction on isolated brain capillaries using a flying spot microscope densitometer. Enzyme activity is expressed as an increase in relative optical density (at 500 nm) in arbitrary units/min/μm2 during the 2 min immediately after initiating incubation and corresponds to the γ‐GT active area (in μm2) of the capillary segment. During early postnatal development, a biphasic change of γ‐GT activity in capillaries of rat cerebral cortex is observed. The first phase (i.e. the postnatal period between the 2nd and 12th day) is characterized by a significant decrease in γ‐GT activity, which coincides with the onset of the rapid mitotic proliferation of cortical endothelial cells. During the second phase (i.e. the postnatal period between the 12th and 21st day), a fast increase in the γ‐GT activity can be measured. Then enzyme activity reaches the adult level between the 21st and 60th postnatal day.With regard to changes in capillary length density and in astroglial proliferation the results correspond to the differentiation and maturation of the blood‐brain barrier and confirm evidence stressing the important role of astroglial cells for the expression of γ‐GT activity.
The role of neuron death in the development of the gender difference in the number of neurons in the rat superior cervical ganglion
Authors: Wright L. L. , Smolen A. J. 
Published: April 2003

AbstractAdult male rats have more neurons in their superior cervical ganglia than do adult females. This difference arises over the first two postnatal weeks and is apparently related to perinatal levels of circulating testosterone.Exposure of neonatal rats to testosterone or estradiol during the first postnatal weeks results in an increase in the number of neurons in the superior cervical ganglion seen at 15, 30 or 60 days postnatally. The present studies were undertaken to determine whether this observed increase in neurons is due to an increase in neuronal proliferation or to a decrease in neuronal death. Results of autoradiographic studies show no evidence of enhanced neuronal proliferation following postnatal exposure to estradiol, but do show an increased survival of a prenatally labeled population of cells.Counts of degenerating cells in the superior cervical ganglion show that during the peak period of normal neuronal degeneration, on postnatal day 5, 17‐β‐estradiol or testosterone propionate treated animals have significantly fewer degenerating superior cervical ganglion cells than do vehicle‐injected littermate controls. In addition, vehicle‐injected females have more degenerating cells on day 5 than do vehicle‐injected males. Taken together these results provide strong evidence that the increase in superior cervical ganglion neurons seen after neonatal exposure to estradiol results from a reduction in developmental neuron death.
Intraocular herpes simplex virus injection in neonatal rats induces sympathetic nerve cell destruction: Effect of nerve growth factor
Authors: Aloe Luigi 
Published: April 2003

AbstractThe effect of herpes simplex virus (HSV) injection on the sympathetic nerve system of newborn rats was studied at structural, ultrastructural and immunohistochemical levels. It was found that HSV injected into the anterior eye chamber is retrogradely transported and reaches the nerve cell bodies of the ipsilateral superior cervical ganglion (SCG) after 18–24 hr, causing complete cell destruction within 3–4 days. In subsequent days, nerve cells of the contralateral SCG, spinal sensory ganglia, chromaffin cells and brain cells also become infected and are eventually killed by the virus. Pretreatment with nerve growth factor (NGF) produces an initial protection from viral cell destruction, but does not block the final, lethal effect of the virus. These investigations demonstrate that sympathetic nerve cell destruction can be induced in newborn rodents by HSV and that NGF treatment renders the cells, for a time‐limited period, more resistant to the virus.
Effects of gonadal steroids on nerve growth factor receptors in sympathetic and sensory ganglia of neonatal rats
Authors: Wright L. L. , Marchetti D. , Perez‐Polo J. R. 
Published: April 2003

AbstractThe numbers of neurons in the rat superior cervical sympathetic ganglion (SCG) differ in males and females, with the males having 30% more SCG neurons than females at 60 days of age. This sex difference arises during the early postnatal period, when testosterone administration increases the numbers of neurons and alters the nerve growth factor (NGF) content of the rat SCG. In contrast, there is no gender difference in number of neurons in the L1 dorsal root ganglion.In both males and females, the amount of NGF bound per ganglion increased between postnatal days 5 and 15 (P5 and P15) in both dorsal root ganglia (DRGs) and the SCG. There is also a gender difference in NGF binding: SCGs and DRGs of female rats at both P5 and P15 bind more NGF per ganglion than do those of males. This effect was more marked in DRGs than in the SCG. Treatment of neonatal females with testosterone reduced NGF binding in both SCGs and DRGs to levels comparable to males at P5, and in DRGs at P15. In contrast, treatment of males with testosterone from birth resulted in a 2–3 fold increase of NGF binding in both SCGs and DRGs as compared to controls at P15. At P15, testosterone treatment of females increased NGF binding in the SCG. Males and females had opposing responses to neonatal exposure to estradiol. Treatment with estradiol from birth increased NGF binding in SCGs and DRGs of females, but had no effect on NGF binding of SCGs, and reduced NGF binding in DRGs of males.These data suggest that there are more NGF receptors in sensory and sympathetic ganglia in developing females as compared to males, and that neonatal exposure to gonadal steroids affects the expression of NGF receptors.
Cytoarchitecture in cultured rat neocortex explants
Authors: de Jong B. M. , Ruijter J. M. , Romijn H. J. 
Published: April 2003

AbstractNeocortex explants obtained from 6‐day‐old rat pups and cultured in a serum‐free medium from 5 hr to 13 days in vitro (DIV) show preservation of cytoarchitectural characteristics. Major changes in the size of the explants and their layers occur during the first 2 DIV. A radial arrangement of neurons within layer 2‐3‐4, which becomes apparent between 2 and 10 DIV, suggests an advance in maturation in culture. In contrast to the situation in vivo, a distinct layer 4 cannot be consistently identified. During the first 2 DIV, a transposition of cells into the pial direction can be seen. Individual degenerated cells are spotted especially in layer 5. The presence of these cells amidst healthy neurons suggests that their death has a functional cause. Neurons at the ventricular border of layer 6 become relatively large in comparison with other neurons. Within the cultured tissue there is a marked increase in GFA reactivity compared to the situation in vivo. The described results clearly indicate that in these cultured expiants, both similarities and differences are of interest for studies on the formation of neuronal circuitry within the cerebral cortex.
Histochemical localization of Ca2+, Mg2+‐ATPase of the rat cerebellar cortex during postnatal development
Authors: Yoshioka Takafumi , Tanaka Osamu 
Published: April 2003

AbstractIn order to investigate the membrane activities underlying development of neural cells, a histochemical localization of Ca2+‐ATPase, Mg2+‐ATPase and alkaline phosphatase (AlPase) activities in the rat cerebellar cortex during postnatal development was carried out. In the developing cerebellar cortex, ATPase activity was mainly associated with the plasma membranes of Purkinje and granular cells. This activity appeared in the immature Purkinje cells at birth and was proportionally increased throughout postnatal development. It was observed that the ATPase activity of migratory granular cells during a critical period from 3 and 15 postnatal days was increased in a funicular pattern in the developing cerebellar cortex. Conversely, peak AlPase activity in the developing cerebellar cortex was localized in the proliferative external granular cells until 7 postnatal days. Apparently, these phosphatase activities were not present in Bergmann glial fibers during the course of granular cell migration. The present findings were taken to indicate that neuronal cells in the cerebellar cortex have acquired a membrane‐bound ATPase which can participate in Ca2+ transport or ATP metabolism during the course of early postnatal development.
Neuronal localization of the nerve growth factor precursor‐like immunoreactivity in the rat brain
Authors: Senut Marie‐Claude , Lamour Yvon , Lee James , Brachet Philippe , Dicou Eleni 
Published: April 2003

AbstractThe distribution of the nerve growth factor precursor(proNGF)‐like immunoreactivity was examined in the adult rat brain with affinity‐purified antisera directed against synthetic peptides that reproduce sequences of the precursor protein. Immunoreactivity was localized in defined areas of the neocortex. hippocampal formation, thalamus/hypothalamus, striatum, olfactory bulb, pons and spinal cord, which are regions previously reported to contain NGF mRNA. Interestingly, immunoreactivity was also observed in the septum and diagonal band of Broca known to contain very low NGF mRNA levels. Using immunohistochemical methods combined with the retrograde transport of a protein gold complex we demonstrate that proNGF‐like immunoreactivity is localized within neuronal cell bodies, in the cortex, hippocampus and septum. These results suggest that the immunological approach may not only identify NGF‐synthesizing cells, but also cells which may accumulate proNGF or some cleavage products by an uptake mechanism.
Pre‐ and post‐synaptic cholinergic dysfunction in aged rodent brain regions: New findings and an interpretative review
Authors: Sherman Kathleen A. , Friedman Eitan 
Published: April 2003

AbstractAge‐related impairment of dynamic aspects of central cholinergic neurotransmission has been indicated by many studies of aged rodents, but the regional distribution of cholinergic deficits and the relative contribution of presynaptic hypofunction and reduced acetylcholine release, loss of synaptic integrity or loss of muscarinic receptors remains unclear. This study therefore compared choline acetyltransferase activity (as a structural marker) and sodium‐dependent high affinity choline uptake (which reflects both ongoing cholinergic neuronal activity and structural integrity) in the hippocampus, cortex and striatum of male C57BL mice at 3–4, 10–12 or 28–32 months of age. To evaluate the relationship of changes in muscarinic receptors to presynaptic alterations, binding of the antagonist 3H‐quinuclidinyl benzilate was compared in membranes prepared from each of these brain regions. High affinity choline uptake was significantly reduced in all three brain regions by 28–32 months of age. This trend was already evident by 10–12 months of age, especially in hippocampus and cortex. By contrast, choline acetyltransferase activity was unchanged in striatum and actually increased in hippocampus and cortex of aged mice. Muscarinic binding was reduced significantly only in striatum and this effect was significant by 10–12 months of age. This decrease in antagonist binding was accompanied by a small but significant reduction in the relative proportion of high affinity agonist sites as defined by carbachol displacement.The impairment of high affinity choline uptake in the absence of a parallel reduction of choline acetyltransferase activity suggests a decline of ongoing cholinergic activity rather than loss of terminal integrity as the basis of presynaptic deficits in aging. This functional decline may be exacerbated by reduction of muscarinic receptors in striatum. Despite considerable literature support for the hypothesis that cholinergic mechanisms are impaired with age, several controversies leave important issues unresolved. Therefore, the present results are discussed in the context of a critical review with emphasis on dynamic properties of presynaptic function which require analysis in experimental animal models. The impact of normal aging on brain cholinergic systems is distinguished from the neurodegenerative changes in Alzheimer disease in that presynaptic function is compromised with a relative preservation of the integrity of innervation. Nonetheless, in addition to a role in the behavioral changes associated with normal aging, age‐related cholinergic hypoactivity may contribute to the vulnerability of brain cholinergic neurons to degenerative insult and alter the efficacy of drug therapies for this age‐dependent disease.
Persistent protein damage despite reduced oxygen radical formation in the aging rat brain
Authors: LeBel Carl P. , Bondy Stephen C. 
Published: April 2003

AbstractThe relation between cerebral oxygen radicals and the aging process was investigated in crude synaptosomal (P2) fractions from rats. The rate of formation of oxygen radicals was measured using the probe 2′,7′‐dichlorofluorescein diacetate (DCFH‐DA), which is de‐esterified and subsequently oxidized by oxygen radicals to a fluorescent product 2′,7′‐dichlorofluorescein (DCF). There was a significant agedependent decrease in the formation rate of oxygen radicals, observed by decreased formation of DCF. No difference in oxygen radical formation was apparent between age groups following an in vitro challenge with an ascorbate/FeSO4 mixture. This age‐dependent decrease in cerebral oxygen radical generation coincided with age‐dependent increases in Superoxide dismutase. No age‐related alterations in lipid order in either the hydrophilic or lipophilic membrane regions were observed using fluorescence polarization analysis. Age‐dependent losses in cerebral P2 tryptophan fluorescence (a measure of protein degradation), and increased liberation of [14C]protein fragments into the acid‐soluble fraction (a measure of overall proteolytic activity) were observed. Results suggest that aging does not proceed as a result of elevated rates of generation of oxygen radicals, a finding that does not support the proposed free radical theory of aging. The observed age‐dependent decrease in the formation of oxygen radicals does not effect membrane lipid order. These findings implicate modifications in proteins and activated protein catabolic pathways as major contributing factors in the normal physiological process of senescence.
Effect of chronic exposure to high magnesium on neuron survival in long‐term neocortical explants of neonatal rats in vitro
Authors: Baker R.E. , Ruijter J.M. , Bingmann D. 
Published: April 2003

AbstractIn order to assess the effect of elevated magnesium, neuronal morphology and physiology was studied in chronically cultured organotypic neonatal rat occipital neocortex. Explants grown in 10 mM magnesium were found to experience an approximate 30% cell loss (as shown by cell count and DNA‐protein analysis), while 12.5 and 15 mM magnesium showed ca. 47 and 60% cell losses, respectively. Intracellular recording from 10 mM magnesium explants revealed that measurable postsynaptic potentials and action potentials could occur, apparently depending on the type of cell examined. All postsynaptic activities ceased in 12.5 mM magnesium cultures, though action potentials could be elicited by current stimulation. The effects of known depolarizing agents, viz. potassium and N‐methyl‐D‐aspartate, on 12.5 mM magnesium‐grown explants were also examined. Explants grown in the presence of 12.5 mM magnesium plus 10 mM potassium showed a dramatic increase in the loss of neurons. The simultaneous addition of 6,7‐dinitro‐quinoxaline‐2,3‐dione showed this to be due to an increase in non‐N‐methyl‐D‐aspartate mediated cell death in response to glutamate release brought about by the depolarizing effects of the potassium. The addition of 10 μM N‐methyl‐D‐aspartate to 12.5 mM magnesium‐grown cultures, on the other hand, improved cell survival to control levels. The mechanism of this reciprocal neuroprotective effect of N‐methyl‐D‐aspartate against magnesium has yet to be elucidated. We conclude that these findings are consistent with regard to the opposing actions of N‐methyl‐D‐aspartate and magnesium on calcium influx and various metabolic processes within the explants.
Distribution of taurine‐like immunoreactivity in cerebellum of kittens from taurine‐supplemented and taurine‐deficient mothers
Authors: Lu Peimin , Schuller‐Levis Georgia , Sturman John A. 
Published: April 2003

AbstractUsing an antibody prepared against taurine conjugated to bovine serum albumin with glutaraldehyde, the distribution of taurine in cerebellum of newborn and 8‐week‐old kittens from mothers fed 0, 0.02, 0.05, or 1% dietary taurine has been determined. In general, taurine‐like immunoreactivity was greater in kittens from mothers fed the greatest amounts of taurine, as was the total cerebellar taurine concentration. The most notable feature in newborn kitten cerebellum was a dense band of staining in the inner molecular layer adjacent to the Purkinje cell layer, which corresponds to the short Purkinje cell dendrites. In cerebellum of 8‐week‐old kittens, taurine‐like immunoreactivity was present in Purkinje cells and their dendrites, most granule cells, and a few interneurons in the molecular layer of the 0.02, 0.05, and 1% groups. The cerebellum of the 0% group was distinctive in that virtually no neurons were reactive, appearing as ‘ghosts’ against the background, and both white matter and the granule cell layer contained large numbers of reactive astrocytes. The presence of such large numbers of reactive astrocytes and the immunoglobulin within the brain suggests an impairment of the blood‐brain barrier in such taurine‐deficient kittens.
Different in vitro response to rIL‐1β of newborn and adult rat astroglia
Authors: Colasanti M. , Ramacci Maria T. , Foresta Piero , Lauro Giuliana M. 
Published: April 2003

AbstractIn recent literature, lymphokines have been reported to be able to promote both proliferation and maturation of some glial populations. In this paper, we compare the effect of rIL‐1 on newborn and adult rat astroglial cells in vitro. In newborn, but not in adult astrocytes, 100 U/ml of rIL‐1β increase [3H]thymidine incorporation with a maximal response by 3 days as compared to the control untreated culture. In contrast, rIL‐1β induces an increase of GFAP immunoreactivity both in newborn and in adult astrocytes, as compared to the control untreated cells. These data indicate that, while both newborn and adult astroglial cells are capable of responding to rIL‐1β, only newborn astrocytes can respond to this lymphokine with proliferation. Thus, it appears likely that different factors, other than rIL‐1β, are needed by adult astrocytes to proliferate.
Effect of a simple visual pattern on the early postnatal development oF GABA Receptor sites in the chick optic lobe
Authors: de Plazas Sara Fiszer , Conterjnic Daniela , Flores Vladimir 
Published: April 2003

AbstractIt is known that manipulation of the visual environment results in changes in the developmental pattern of several neurotransmitter receptors and that the GABA receptor shows a high degree of plasticity in differential illumination experiments. In the present paper we investigated whether exposure to a visual pattern has a developmental effect on GABA receptor expression during early postnatal life. Two groups of newly hatched chicks were used: one was exposed to a simple and specific visual pattern and the other was deprived of any visual pattern. GABA receptors at each developmental stage were determined by binding experiments performed in a crude membrane fraction. Saturation studies were carried out in a fraction enriched in synaptic membranes. The developmental pattern of both high and low affinity GABA binding sites was affected by the visual pattern. This effect displays its maximal expression by the end of the first postnatal week. The modification in receptor expression was due to a change in the receptor density while the affinity was not affected.The change in receptor density induced by the presence of a visual pattern was highest at the end of the first postnatal week suggesting that at that time there is a brief period of higher plasticity for GABA receptor expression in the visual system than at other times. Our results also suggest that variations in GABA receptor density could be instrumental in adaptative changes in the visual system in response to variations in the environmental stimulation.
Developmental changes in B‐50 (GAP‐43) in primary cultures of cerebral cortex: Content and phosphorylation of B‐50
Authors: Ramakers G.J.A. , De Graan P.N.E. , Oestreicher A.B. , Boer G.J. , Corner M.A. , Gispen W.H. 
Published: April 2003

AbstractThe content and phosphorylation of the neuronal growth‐associated protein B‐50 (GAP‐43) were studied in cultured neocortex as a function of normal development and development in the presence of tetrodotoxin (TTX), a blocker of bioelectric activity (BEA). The observations were correlated with previous morphological findings on neurite outgrowth and B‐50 immunolocalization in the same cultures.In control cultures, the concentration of B‐50 reached a maximum at 7 days in vitro (DIV) and decreased thereafter, whereas the concentration of neuron specific enolase (NSE), which was used as a neuronal reference marker, rose till 28 DIV and leveled off towards 42 DIV. The degree of basal phosphorylation of B‐50 (relative to that of total protein) decreased after the first week in vitro. Stimulation of B‐50 phosphorylation by phorbol ester also decreased with age in vitro, indicating that changes in B‐50 phosphorylation were mainly due to changes in protein kinase C (PKC) activity.The chronic presence of TTX led to a reduced content of B‐50 and NSE after 14 DIV. The basal phosphorylation of B‐50 was neither affected by acute nor chronic TTX treatment. However, upon stimulation of PKC with phorbol esters, some alterations of B‐50 phosphorylation were revealed in cultures grown in TTX. These biochemical observations are in line with the absence of effects of TTX on neurite outgrowth during the first 2 weeks in culture, and later effects of TTX on neuronal survival.The developmental changes in B‐50 concentration and phosphorylation largely correlate with previous morphological observations on axonal outgrowth and growth cone shape in the same cultures. We suggest that B‐50 phosphorylation plays an important role in transducing extracellular signals into directed neurite outgrowth.