bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of thyroid deficiency on the development of cholinergic, GABA, dopaminergic and glutamate neuron markers and DNA concentrations in the rat corpus striatum
Authors: Kalaria Rajesh N. , Prince Alan K.
Published: April 2003

The effects of propylthiouracil (PTU)‐induced thyroid deficiency on the postnatal development of synaptic markers for cholinergic, GABA, dopaminergic and glutamate neurons in the rat corpus striatum were investigated. Similar effects were also assessed on β‐alanine uptake by fine prisms and on DNA concentrations in striatal samples from 3‐ and 6‐week‐old rats. Thyroid deficiency (Tx) in rats markedly impaired the development of choline acetyltransferase activity and [3H]spiroperidol and [3H]‐glutamate binding capacities. In contrast, small but significant increases were evident in γ‐aminobutyric acid uptake and glutamate decarboxylase activity. β‐Alanine uptake, a possible glial marker, was increased by up to 50% in samples from the Tx rats compared to controls. Consistent with deficits in striatal weight and greater DNA concentrations in the striatum of the Tx rats those neuronal markers which showed impairments on a mg tissue basis manifest even greater impairments expressed per whole striatum. Present findings suggest differential effects on neuronal markers, with the greatest impairments in the presynaptic markers for cholinergic interneurons in striatum during neonatal thyroid deficiency. The differential sensitivity on neuronal markers of the relatively late onset of thyroid deficiency seems likely to reflect the timing of the morphological differentiation of cholinergic and the other neurons in striatum.
Oligodendrocyte production and myelin recovery in heterozygous jimpy mice: An autoradiographic study
Authors: Rosenfeld Jeffrey , Friedrich Victor L.
Published: April 2003

Jimpy is a genetic disorder of mouse resulting in hypomyelination. In this study oligodendrocyte proliferation was examined in heterozygous carriers of the jimpy gene. The incorporation of [3H]‐thymidine into DNA is increased in jimpy heterozygotes compared to controls. An autoradiographic analysis indicated that oligodendrocytes are the predominant neuroglial cell type being produced in the brain at the ages studied in both heterozygotes and control animals. In addition, the total number of labeled oligodendrocytes was increased in the heterozygote animals compared to controls. These results, taken together, indicate that the rate of oligodendrocyte production is greater in jimpy heterozygotes than in control animals.

We have previously shown that young jimpy heterozygotes have a reduced myelin content and older heterozygotes do not. The increased rate of oligodendrocyte production, demonstrated in this study, is most likely responsible for the increasing myelin content in the heterozygote.

Further study of the cellular interactions which trigger oligodendrocyte production and myelin recovery in the jimpy heterozygote may be relevant to remyelination in other disease states, including those affecting humans.
Developmental aspects of polyamine interconversion in rat brain
Authors: Bolkenius F.N. , Seiler N.
Published: April 2003

In the mammalian organism putrescine is formed by two reactions: (a) decarboxylation of ornithine and (b) degradation of spermidine via the so‐called interconversion pathway. The latter comprises N1‐acetylation of spermidine by a cytosolic acetyltransferase. and oxidative splitting of N1‐acetylspermidine to putrescine by polyamine oxidase (PAO). It has previously been shown that specific inhibition of PAO causes a time‐dependent accumulation of N1‐acetylspermidine in brain, which is a measure of spermidine turnover. Another consequence of PAO inhibition is the decrease of brain putrescine concentration, proportional to its normal formation from spermidine. This observation allowed us to demonstrate the increasing significance of polyamine interconversion with brain maturation. The results support our hypothesis that the mechanisms which regulate cellular polyamine concentrations change during normal brain maturation from a system in which l‐ornithine decarboxylase is dominating to a more sophisticated system in which both synthetic and catabolic processes become equally important regulatory factors.

In contrast with current views, the activity of S‐adenosylmethionine decarboxylase rather than that of ornithine decarboxylase limits the rate of polyamine biosynthesis during early brain development. In the mature brain the total amount of putrescine, which is formed both by decarboxylation of ornithine and by degradation of spermidine, limits the rate of spermidine formation. Changes of the regulatory system analogous to those described in this work are presumably not exclusive for brain, but rather characteristic for a variety of differentiating cells.
Neurogenesis in the rat primary olfactory cortex
Authors: Bayer Shirley A.
Published: April 2003

Neurogenesis in the rat primary olfactory cortex was examined with [3H]thymidine autoradiography. The experimental animals were the offspring of pregnant females given an injection of [3H]thymidine on two consecutive gestation days. Nine groups of embryos were exposed to [3H] thymidine on E13–E14, E14–E15, … E21–E22, respectively. On P60, the percentage of labeled cells and the proportion of cells originating during 24 hr periods were quantified at selected anatomical levels of the anterior and posterior piriform cortex, dorsal lateral peduncular cortex, and posterior two‐thirds of the ventral agranular insular cortex. Throughout most of the primary olfactory cortex, deep cells are generated earlier than superficial cells: the ‘dinside‐out’ pattern. Neurons in the anterior (prepiriform) cortex are located lateral to the caudal anterior olfactory nucleus and olfactory tubercle, and are generated mainly between E14 and E18 in a caudal (older) to rostral (younger) neurogenetic gradient. Neurons in the posterior (periamygdaloid) cortex are located lateral to the caudal olfactory tubercle and amygdala, and are generated mainly between E14 and E17 simultaneously along the rostrocaudal plane. Superficial cells in the piriform cortex have some additional neurogenetic gradients; ventromedial cells forming transition zones with either the olfactory tubercle or amygdala originate earlier than cells located dorsally and laterally. In the posterior piriform cortex, younger neurons are located at middle dorsoventral levels while older neurons lie above and below. Neurons in the dorsolateral peduncular cortex originate between E14 and E20 in a caudal to rostral gradient of neurogenesis; caudal parts also have a lateral to medial neurogenetic gradient. The most lateral part of the dorsolateral peduncular cortex is unique and does not have the typical ‘inside‐out’ cortical neurogenetic gradient. Neurons in the ventral agranular insular cortex (area 13) originate mainly between E15 and E17 in combined caudal to rostral and ventral to dorsal neurogenetic gradients. The neurogenetic gradients in the primary olfactory cortex, along with patterns of neurogenesis throughout the olfactory projection field are related to the termination patterns of afferents from the main olfactory bulb.
Current aspects of the development of the blood‐brain barrier
Authors: Joó Ferenc
Published: April 2003

Results of earlier studies clearly indicated that, during development, a number of enzymes are sequentially expressed in the brain endothelial cells correlating in time with the maturation of brain tissue. More recent data suggested that differentiation of endothelium in the intraparenchymal cerebral microvessels into one with blood‐brain barrier characteristics seems to be induced by astrocytes at a specific time of embryonic development. Details of the above‐mentioned and other important aspects of the development of the blood‐brain barrier will be discussed in the present mini review.
Axonal maturaion in development—I. Characterization of monoclonal antibodies reacting with axon‐specific neurofilament epitopes
Authors: Dahl D. , Gardner E. E. , Crosby C. J.
Published: April 2003

Monoclonal antibodies reacting with the high molecular weight neurofilament polypeptides (NF 150K and NF 200K) were obtained upon immunization with NF 150K and NF 200K isolated from bovine spinal cord by anion exchange chromatography. The five monoclonal antibodies obtained with NF 200K stained only axons. With three monoclonals the reactivity was abolished by digestion with phosphatase and by dilution of the supernatants in sodium potassium phosphate. The nine monoclonal antibodies obtained upon immunization with NF 150K stained both high molecular weight neurofilament polypeptides on immunoblots of bovine and rat spinal cord extracts with the exception of one monoclonal only reacting with the homologous antigen. The antibodies could be divided into two groups, axon‐specific and conventional. Conventional antibodies decorated neurofilaments regardless of their location, i.e. axons, perikarya and dendrites. With all these antibodies the immunostaining was not affected by phosphatase digestion of neurofilament protein nor by dilution of the supernatants in sodium potassium phosphate. Axon‐specific antibodies reacting with both NF 150K and NF 200K in rat spinal cord only stained the heterologous antigen (NF 200K) in rat optic nerve and sciatic nerve extracts. We suggest that some axon‐specific neurofilament antibodies recognize neurofilament modifications other than phosphorylation; or, alternatively that they react with phosphorylated epitopes not accessible to phosphate or to exogenous phosphatases. Furthermore, we suggest that some neurofilament modifications do not occur uniformly throughout the nervous system.
Chromaffin cell proliferation in the adult rat adrenal medulla
Authors: Tischler Arthur S. , Ruzicka Laurel A. , Donahue Stephen R. , DeLellis Ronald A.
Published: April 2003

Epinephrine and norepinephrine‐containing chromaffin cells proliferate in the adrenal glands of normal adult rats throughout life. Moreover, their rate of proliferation is markedly increased by short‐term administration of reserpine, one of many agents which in long‐term experiments are associated with the development of adrenal medullary tumors. Current data suggest that chromaffin cell proliferation in the adult rat adrenal is mediated by the interaction of neurogenic and hormonal signals. Reserpine is known to directly deplete catecholamine stores, and to reflexively increase the activity of the splanchnic nerve endings innervating the adrenal medulla to stimulate both secretion and synthesis of catecholamines and other secretory granule constituents. Its effect on chromaffin cell proliferation suggests that the same signals may regulate chromaffin cell number to meet physiological needs. The reserpine model might shed light on signal transduction mechanisms which normally promote or prevent proliferation of chromaffin cells and of other neuroendocrine cells during development or in adult life, and on ways in which such mechanisms are altered in the course of the development and progression of tumors. It also suggests the possibility that chromaffin cells might be propagated in vitro for use in basic biological studies or in transplants for the treatment of Parkinson's disease.
Capsaicin treatment to developing rats induces increase of noradrenaline levels in the iris without affecting the adrenergic terminal density
Authors: Luthman J. , Strömberg I. , Brodin E. , Jonsson G.
Published: April 2003

The effects of administration of capsaicin to developing and adult Sprague‐Dawley rats on substance P‐containing primary afferent and peripheral adrenergic nerves were analysed by histochemical and neurochemical techniques. In control rats a relatively dense innervation with substance Pimmunoreactive fibers was seen in the iris, while 10 weeks after a single neonatal injection of capsaicin (50 mg/kg s.c.) a moderate loss of substance P‐immunoreactive nerve fibers was observed. The substance P level was decreased by 60%, while the noradrenaline level, 3H‐noradrenaline uptake in vitro and the noradrenaline nerve density were unaltered. Repeated injections of capsaicin (2 × 50 mg/kg, 3 × 20 mg/kg s.c.) for 5 weeks to developing rats led to a very marked decrease of the substance P level and an almost complete disappearance of substance P‐immunoreactive fibers in the iris, when analysed at 10 weeks of age. The noradrenaline level in the iris was significantly increased (+42%), while no significant changes in noradrenaline level were observed in heart auricula or superior cervical ganglion. The uptake in vitro of 3H‐noradrenaline in irides and heart auriculae, as well as the noradrenaline terminal density in the dilator plate and surrounding blood vessels in the iris, were unaffected by repeated capsaicin treatment to developing rats. Capsaicin administration to adult rats (50 mg/kg s.c.), leading to a profound decrease in substance P, did not affect the noradrenaline levels at 24 hr after the injections. The results indicate that an extensive sensory denervation with capsaicin during development can induce an increase of noradrenaline levels in sympathetic nerve terminals in a target area (rat iris) with a rich SP‐ergic sensory innervation, although the sympathetic terminal density is not influenced. Furthermore the increase in noradrenaline seems to require an extensive loss of SP‐immunoreactive fibers and not solely a reduction of SP levels.
Polyamines induce precocious development in rats. Possible interaction with growth factors
Authors: Gilad Gad M. , Dornay Menashe , Gilad Varda H.
Published: April 2003

The study reports the effects of daily subcutaneous injections of the biogenic polyamines putrescine, spermidine and spermine (10 mg/kg each) given for a short postnatal period, on growth and development of rats. Polyamine treatment, while only slightly enhancing normal body weight gain, prevented the weight loss caused by surgical injury of 5‐day‐old animals. The treatment resulted in earlier eyelid and ear opening and in earlier maturation of righting and gripping responses. Increased number of neurons in the superior cervical ganglion that is caused by polyamine treatment, could not be prevented by castration of newborn rats, thus excluding the testes as a site through which polyamines may exert their action. An apparent increase in immunohistochemically detectable nerve growth factor was evident in iris and submaxillary salivary gland of polyamine‐treated animals, but no change in epidermal growth factor immunohistochemistry was detected in the salivary gland. We conclude: (1) treatment of newborn rats with polyamines can accelerate somatic and neurobehavioral development; (2) further studies are required in order to verify and quantitate the effects of polyamines on growth factors, and (3) the results imply that exogenous polyamines may exert their growth‐promoting effects on a number of cell types when these cells experience periods of polyamine dependence.
Antioxidant enzymatic activities and resistance to oxidative stress in primary and subcultured rat astroglial cells
Authors: Vanella A. , Avola R. , Condorelli D. F. , Campisi A. , Costa A. , Stella A. M. Giuffrida , Perez‐Polo J. R.
Published: April 2003

The survival of neural tissues depends in part on the balance between the formation of free radicals due to oxidative metabolism and the transformation of the free radicals to non‐toxic compounds. Serial subculture of rat glial cells as described here resulted in a decrease of the specific activities of several antioxidant enzymes and a glial specific marker for astrocytes. Thus, there was an increased susceptibility to oxidative stress in cultures by the third passage. These subcultured glial cell cultures may represent a useful model for the study of free radical induced neural damage that may be relevant to CNS trauma and aging.
The interaction of substrate and taurine modulates the outgrowth from regenerating goldfish retinal explants
Authors: Lima L. , Matus P. , Drujan B.
Published: April 2003

Retinal growth from expiants attached to different substrates was evaluated in the absence and the presence of various concentrations of taurine. Fiber thickness was higher in poly‐l‐lysine, collagen and laminin than in the other substrates tested. Explants on wheatgerm, soybean, and red kidney bean lectins did not show emission of neuntes at 5 days in culture; growth on laminin was very poor at this period of time. By day 10 nerve growth index was possible to evaluate on soybean and laminin. Outgrowth from retinal explants on wheatgerm lectin was only observed in the presence of taurine. The percentage of growing explants on laminin was increased by the amino acid. Emission of neurites from explants on concanavalin A and lentil lectin was constant from 5 to 10 days in culture and was not accelerated or increased by taurine. Growth on poly‐l‐lysine and collagen was stimulated by the addition of taurine in a concentration‐dependent manner. The amino acid stimulates outgrowth from expiants attached to peanut lectin in a bell‐shaped concentration dependency similar to that observed on poly‐l‐lysine. The effect of taurine on retinal expiants is substrate‐dependent, as an indication of the interaction of soluble molecular components plus charge and structure of the extracellular matrix in order to modulate the outgrowth from regenerating tissue.
Nerve growth factor induces neurite outgrowth in a clone derived from an NGF‐insensitive human neuroblastoma cell line
Authors: Reynolds C. Patrick , Perez‐Polo J. Regino
Published: April 2003

Nerve growth factor (NGF) plays a trophic and tropic role in the development of vertebrate sympathetic and sensory ganglia; however, the precise nature of the NGF effect(s) is not understood. Study of NGF‐responsive human neuroblastoma cell lines allows characterization of NGF‐induced neunte outgrowth in cells not dependent on NGF for survival. The human neuroblastoma line SK‐N‐SH did not significantly extend neuntes in response to NGF, but did show an increase in cell number. By contrast, a clone of the line, SH‐IN, extended neuntes in response to NGF or dibutyryl cyclic AMP, and showed inhibition of cell proliferation. Thus, cells capable of morphological differentiation in response to NGF can be cloned from neuroblastoma cell lines in which the majority of the cells fail to extend neurites even in the presence of NGF.
Postnatal development of the excitatory amino acid system in visual cortex of the rat. Changes in uptake and levels of aspartate and glutamate
Authors: Erdö Sandor L. , Wolff Joachim R.
Published: April 2003

The postnatal changes of aspartate (Asp) and glutamate (Glu) levels, as well as the development of the high‐affinity uptake of [3H]d‐Asp were examined in the visual cortex of rats, aged 2–360 days. Perinatal (day 2) levels of Asp were relatively lower than those of Glu, i.e. about 30 and 60% of the respective values for adults (day 180). Both Asp and Glu levels showed a rapid increase during the second and third postnatal weeks. Asp reached its maximal concentration (day 20) a few days earlier than Glu (day 25). Thereafter, both Asp and Glu levels slowly declined to the adult values which were reached by day 90 and remained unchanged up to day 360. The uptake of d‐Asp was low in newborns (5% of that in adult) and progressively increased with age up to about day 20, when adult values were attained. The increase of Asp and Glu levels showed a close correlation with the maturation of uptake capacity. Our findings indicate that the developmental increase of Asp and Glu levels is associated with the maturation of excitatory innervation in the visual cortex, but they do not support the concept of a transient Asp/Gluergic innervation of the immature visual cortex.
Activation of the glycine site associated with the NMDA receptor is required for induction of LTP in neonatal hippocampus
Authors: Oliver M. W. , Larson J. , Lynch G.
Published: April 2003

The role played by the glycine site associated with the NMDA receptor in inducing long‐term potentiation (LTP) in neonatal hippocampus was examined. An antagonist of the glycine site, 7‐chlorokynurenic acid (Cl‐Kyn), completely blocked both the short‐term and the long‐term potentiation associated with theta burst stimulation (TBS) linked to NMDA receptor activation in slices from hippocampus at postnatal days 10–16; this effect was reversed by the glycine agonist, d‐serine. Analysis of the TBS‐evoked responses showed: (1) a developmental alteration in the burst response morphology that may be related to maturation of GABA‐mediated inhibition; and (2) that, unlike 2‐amino‐5‐phosphonovalerate (APS), Cl‐Kyn did not reduce any portion of the burst response. These results suggest that stimulation of the glycine site coupled to the NMDA receptor complex is necessary to induce LTP in neonatal tissue and that two NMDA receptor types may be present in the hippocampus.
Proteoglycan synthesis by clonal skeletal muscle cells during in vitro myogenesis: Differences detected in the types and patterns from primary cultures
Authors: Miller Raymond R. , Rao Jasti S. , Burton Willis V. , Festoff Barry W.
Published: April 2003

Proteoglycan synthesis by two clonal murine skeletal muscle cell lines, G8‐1 and C2, was examined. Cultures of skeletal muscle cells at both the myoblast and myotube stages were radiolabeled using [35S]sulfate as a precursor. The proteoglycans of the cell layer and medium were separately extracted and isolated by ion exchange chromatography on DEAE‐Sephacel followed by gel filtration chromatography on Sepharose CL‐2B. The cell layer proteoglycans eluted from Sepharose CL‐20 as a single peak with a Kav of 0.66 and contained glycosaminoglycan chains with an average molecular weight of 20,000. The glycosaminoglycan chains were composed of nearly equal mixtures of chondroitin sulfate and heparan sulfate with the exception that C2 myoblast cultures contained larger amounts of heparan sulfate. Of interest, this line differentiates more rapidly in our laboratory than G8‐1. The medium proteoglycans also eluted from Sepharose CL‐2B as a single peak with a Kav of 0.66 but contained glycosaminoglycan chains with an average molecular weight of 32,000. Based upon enzymatic and chemical analysis, the medium glycosaminoglycan chains were composed of a mixture of chondroitin sulfate (71–80%) and heparin sulfate (19–22%). Following chondroitinase ABC digestion, the predominant disaccharide released from all glycosaminoglycan fractions was chondroitin‐4‐sulfate. When the extracted cell layer proteoglycans were chromatographed on Sepharose CL‐28 in the absence of detergent, a small but consistent proportion (14–18%) eluted in the void volume, suggesting the association of at least a portion of this proteoglycan with cellular lipid. These differences distinguish proteoglycan metabolism in fusing clonal lines from primary muscle cell cultures suggesting their utility in evaluating the contribution of these macromolecules in myogenesis.
Synapse formation on trochlear motor neurons in relation to naturally occurring cell death during development
Authors: Hirano S. , Kumaresan K. , Ali M.M. , Sohal G.S.
Published: April 2003

About half of the trochlear motor neurons die during the course of normal development. The present study was undertaken to determine whether the afferent synapses form before the onset of motor neuron death and also to determine whether the number of synapses differs between the healthy and degenerating trochlear motor neurons. Brains of duck embryos from days 10 to 20 were prepared for quantitative electron microscopical observations on synaptogenesis. Results indicate that synapses form on the trochlear motor neuron soma before cell death begins suggesting that afferent input is in a position to exert an influence on survival or death of motor neurons. There were no significant differences in the number of synapses between the healthy and dying neurons during the period of cell death. This observation suggests that the mechanism by which afferent synapses could be involved in neuron survival or death is not related to the number of synapses on the cell soma. The number of synapses on the cell process, synaptic transmission and/or molecules released at the synapses are likely candidates for the mechanism of action of afferent input.
Macrophage‐like cells originate from neuroepithelium in culture: Characterization and properties of the macrophage‐like cells
Authors: Hao C. , Richardson A. , Fedoroff S.
Published: April 2003

Cultures of astroglia from C3H/HeJ mice, which are resistant to bacterial cell wall polysaccharide (LPS), initiated from embryos of Theiler stage 14 (9 days of gestation) up to Theiler stage 25 (17 days of gestation) as well as newborn animals, when subjected to nutritional deprivation, i.e. non‐feeding of cultures, form large numbers of macrophage‐like cells. These cells express Mac‐1, Mac‐3, F4/80 and Fc antigens. The cells are negative for GFAP, positive for vimentin, express Ia antigen and take up DiL‐Ac‐LDL. They are positive to non‐specific esterase, secrete lysozyme and are phagocytic. Their morphology and ultrastructure closely resemble those of macrophages. Cultures initiated from neuroepithelium of Theiler stage 13 (8.5 days of gestation), before vascularization, when subjected to nutritional deprivation, also produce macrophage‐like cells. Using spleen colony assay and methyl cellulose cultures, we were unable to detect the presence of hemopoietic (macrophage) precursor cells in astroglia cultures. This supports the hypothesis that the macrophage‐like cells are of neuroectodermal origin and probably correspond to resident microglia of the CNS. Using nutritionally deprived astroglia cultures, a procedure was developed for isolation of macrophage‐like cells and production of highly enriched macrophage‐like (microglia) cultures.
Quantitative histochemical changes in enzymes involved in energy metabolism in the rat brain during postnatal development. II. Glucose‐6‐phosphate dehydrogenase and β‐hydroxybutyrate dehydrogenase
Authors: Bilger Anne , Nehlig Astrid
Published: April 2003

The postnatal maturation of glucose‐6‐phosphate and β‐hydroxybutyrate dehydrogenase activity was assessed by histochemistry in rats at eight postnatal stages, P0, P5, P10, P14, P17, P21, P35 and the adult stage. Enzyme activities were revealed on cryostat brain sections with nitroblue tetrazolium. Both enzyme activities were low and homogenous at birth, and increased to reach a peak in all areas studied, at P17 for β‐hydroxybutyrate dehydrogenase and at P21 for glucose‐6‐phosphate dehydrogenase. Then, glucose‐6‐phosphate dehydrogenase activity decreased regularly by 20–49% from P21 to adult stage, except in cerebellar white matter where activity did not change after P21. β‐hydroxybutyrate dehydrogenase activity decreased regularly from P17 to adult stage in globus pallidus, hippocampus, thalamus, brainstem, genu of corpus callosum and cerebellar white matter. In sensorimotor cortex, medial geniculate body, caudate nucleus, hypothalamus and inferior colliculus, β‐hydroxybutyrate dehydrogenase activity stayed stable between P17 and P35 and decreased thereafter to adult levels. Finally, in parietal, auditory and cerebellar cortices, β‐hydroxybutyrate dehydrogenase activity either stayed stable or slightly increased after P17. The present study shows that there is a quite good correlation between postnatal changes in cerebral glucose‐6‐phosphate and β‐hydroxybutyrate dehydrogenase activities and the importance of pentose phosphate pathway and ketone body utilization in the developing brain. Our results also reflect the regional heterogeneity of β‐hydroxybutyrate utilization in the adult rat brain, translating into a remaining high activity of β‐hydroxybutyrate dehydrogenase in cerebral cortex.
Screening of adrenal medullary neuropeptides for putative neurotrophic effects
Authors: Unsicker Klaus , Stögbauer Florian
Published: April 2003

Chromaffin granules, the secretory organelles of the neuron‐like adrenal medullary chromaffin cells, have previously been shown to store and liberate neurotrophic activities that support in vitro survival of several neuron populations including those innervating the adrenal medulla. Molecules resembling fibroblast growth factor and ciliary neurotrophic factor have been identified among these activities. Since chromaffin granules store a variety of neuropeptides and many neuropeptides can have pleiotropic effects on neuronal growth and maintenance we have tested 24 different neuropeptides for their capacities to promote survival of embryonic chick ciliary, dorsal root and sympathetic ganglionic neurons. Peptides tested included several derivatives of proenkephalin (Leu‐ and met‐enkephalin, fragments BAM 22, B, F and E), somatostatin, substance P, neuropeptide Y, neurotensin, VIP, bombesin, secretin, pancreastatin, dynorphin B, dynorphin 1–13, β‐endorphin, alpha‐, beta‐, and gamma‐MSH. Control cultures received saturating concentrations of ciliary neurotrophic or nerve growth factor (CNTF; NGF), or no trophic supplements. At 1 × 10−5 M leu‐ and met‐enkephalin as well as somatostatin supported sympathetic neurons to the same extent as NGF. At the same concentrations, leuenkephalin, the proenkephalin fragments BAM 22 and E, and somatostatin maintained about half of the dorsal root ganglionic neurons supported by NGF, but were not effective on ciliary neurons. VIP promoted the survival of approximately 50% of the ciliary and embryonic day 10 dorsal root ganglionic neurons as compared to saturating amounts of CNTF, but required the presence of non‐neuronal cells in the cultures to be effective. Neurotensin (1 × 10−5M) had a small effect on ciliary neurons. All other peptides had no effect on any neuron population tested. Our results suggest that neuropeptides that occur in the adrenal medulla may play a role for the maintenance of cholinergic, sensory, and sympathetic neurons innervating the adrenal medulla.
In vitro differentiation inhibits the migration of cultured neonatal rat cortical astrocytes transplanted to the neonatal rat cerebrum
Authors: Hatton James D. , Hoi Sang U.
Published: April 2003

Neonatal rat astrocytes transplanted into the rat cerebrum migrate extensively. However, few of the molecular signals determining this migration have been defined. In the present study, in vitro modifications were designed to examine whether differentiation prior to transplantation would affect the magnitude or pattern of astrocyte migration in the neonatal host brain. Here, cortical astrocytes were collected from the brains of rats 1–3 days postpartum and purified by culturing them in DME medium supplemented with 10% calf serum. After 14–21 days, astrocytes were labelled with fluorescein‐tagged latex microspheres for 16 hr; the label was then removed and replaced with either fresh medium or fresh serum‐free medium plus 1 mM dbcAMP. After 48 hr, cells were harvested and then transplanted into the right frontal cerebrum of neonatal rats at 3 days postpartum by injection with a hand‐held Hamilton syringe. Animals were sacrificed at 3, 6, 9, 15, 21 and 28 days after inoculation and their brains examined with fluorescence microscopy. Astrocytes not exposed to dbcAMP prior to implantation migrated along the corpus callosum, internal capsule, glial limitans, ventricular linings and the hippocampal structure. They also appeared to migrate in a radial fashion toward the periphery from the ventricular lining. Astrocytes treated with dbcAMP prior to transplantation did not appear to migrate into the neonatal parenchyma, remaining confined to the injection site for at least 6 days. Migration then appeared to commence at a normal rate after 9 days. Thus, neonatal cortical migrate outward in a pattern similar to that defined by the radial glia. Astrocytes differentiated by dbcAMP treatment, however, do not appear to migrate to any large degree in the neonatal brain until the treatment effect diminishes, suggesting that differentiation may represent an end‐point to glial migration in the neonatal host brain.
Postnatal development of functional dopamine, opioid and tachykinin receptors that regulate acetylcholine release from rat neostriatal slices. Effect of 6‐hydroxydopamine lesion
Authors: Pérez‐Navarro Esther , Alberch Jordi , Marsal Jordi
Published: April 2003

In the present work we have studied the postnatal development of functional dopamine, opioid and tachykinin receptors, which regulate cholinergic activity in the neostriatum. The release of endogenous acetylcholine from rat striatal slices was measured using a chemiluminescent method. We have observed that the inhibition mediated by dopamine through D2 receptors was not detectable until postnatal day 10, whereas the inhibition mediated by opioid receptors was detectable at postnatal day 15 for δ‐receptors ([D‐Pen2, D‐Pen5]‐enkephalin) and at postnatal day 21 for μ‐receptors ([D‐Ala2, Gly(ol)5]‐enkephalin). Excitatory effect mediated by tachykinins through NK1 ([Sar9, Met(O2)11]‐Substance P), NK2 ([Nle10]‐Neurokinin A4–10), or NK3 (senktide) receptors was already detectable at postnatal day 5.

In order to examine the influence of dopamine in the development of tachykinin and opioid systems in the neostriatum, we induced dopamine deficiency by intraventricular injection of 6‐hydroxydopamine at postnatal day 3. We observed an increase in senktide‐evoked acetylcholine release at postnatal day 30. The effect produced by [Sar9, Met(O211]‐Substance P and [Nle10]‐Neurokinin A4–10 was not modified. Furthermore, at postnatal day 35, we could observed that the two opioid receptor agonists have no effect.

Our results show that dopamine, tachykinins and opioids are already able to mediate the modulation of acetylcholine release in early stages of development with a different pattern of postnatal development. Furthermore, the integrity of a dopaminergic system plays an important role in the functional development of the neostriatal cholinergic neurons which are differentially modulated by opioids or tachykinins.
The role of neuronal activity in upregulating GFAP mRNA levels after electrolytic lesions of the entorhinal cortex
Authors: Kelley Melinda S. , Steward Oswald
Published: April 2003

This study evaluates whether the rapid transient increases in glial fibrillary acidic protein (GFAP) mRNA in the hippocampus after electrolytic lesions of the entorhinal cortex (EC) are triggered by lesion‐induced changes in hippocampal neuronal activity (either the decreases that result from loss of afferent drive or transient increases that occur during lesion production). To evaluate the role of activity, we carried out four experiments: (1) tetrodotoxin (TTX) was injected into the EC to mimic the decreases in afferent drive that occur after lesion; (2) TTX was injected into the EC or hippocampus before producing electrolytic lesions to block any abnormal activity induced during lesion production; (3) the EC was destroyed by aspiration, thus creating a lesion comparable in size to the electrolytic lesion, without passing direct current; (4) seizures were elicited by stimulating the EC of anesthetized rats, to examine whether electrographic seizures alone can induce the same type of increases in GFAP mRNA as lesions. Our results demonstrated that: (1) TTX injections into the EC did not induce the same increases in GFAP mRNA levels that occurred after EC lesions; (2) animals that received TTX injections into the EC prior to lesions exhibited increases in hippocampal GFAP mRNA that were nearly as great as following EC lesions alone; (3) aspiration lesions of the EC resulted in increases in GFAP mRNA that were comparable to those observed after electrolytic lesions (4) seizure‐inducing stimulation of the EC resulted in 2‐fold increases in GFAP mRNA in the hippocampus 24 hr after stimulation rather than the 5–13‐fold increases observed after lesions. These results suggest that lesion‐induced changes in hippocampal neuronal activity are not solely responsible for inducing the rapid transient increases in GFAP mRNA levels in the hippocampus ipsilateral to EC lesions.
Reactive astroglia‐neuron relationships in the human cerebellar cortex: A quantitative, morphological and immunocytochemical study in Creutzfeldt‐Jakob disease
Authors: Lafarga M. , Berciano M.T. , Saurez I. , Andres M.A. , Berciano J.
Published: April 2003

In order to investigate the role of neuron‐glia interactions in the response of astroglial to a non‐invasive cerebellar cortex injury, we have used two cases of the ataxic form of Creutzfeldt‐Jakob disease (CJD) with distinct neuronal loss and diffuse astrogliosis. The quantitative study showed no changes in cell density of either Purkinje or Bergmann glial cells in CJ‐1, whereas in the more affected CJ‐2 a loss of Purkinje cells and an increase of Bergmann glial cells was found. The granular layer in both CJD cases showed a similar loss of granule cells (about 60%) in parallel with the significant increase in GFAP+ reactive astrocytes. GFAP immunostaining revealed greater reactivity of Bergmann glia in CJ‐2 than in CJ‐1, as indicated by the thicker glial processes and the higher optical density. Granular layer reactive astrocytes were regularly spaced. In both CJD cases there was strict preservation of the spatial arrangement of all astroglial subtypes—Fañanas cells, Bergmann glia and granular layer astrocytes. Reactive Fañanas and Bergmann glial cells and microglia/macrophages expressed vimentin, while only a few vimentin+ reactive astrocytes were detected in the granular layer. Karyometric analysis showed that the increase in nuclear volume in reactive astrloglia was directly related with the level of glial hypertrophy. The number of nucleoli per nuclear section was constant in astroglial cells of human controls and CJD, suggesting an absence of polyploidy in reactive astroglia. Ultrastructural analysis revealed junctional complexes formed by the association of macula adherens and gap junctions. In the molecular layer numerous vacant dendritic spines were ensheathed by lamellar processes of reactive Bergmann glia. Our results suggest that quantitative (neuron/astroglia ratio) and qualitative changes in the interaction of neurons with their region‐specific astroglial partners play a central role in the astroglial response pattern to the pathogenic agent of CJD.
Endogenous stimulation of lipid peroxidation in brain increases proteolytic‐inactivation of mitochondrial monoamine oxidases
Authors: Medvedev Alexei E. , Gorkin Vladimir Z.
Published: April 2003

Stimulation of lipid peroxidation in vivo (in experimental epilepsy and closed cranio‐cerebral injury, as models for endogenous stimulation of lipid peroxidation) affects catalytic activity, substrate specificity of mitochondrial monoamine oxidases and increases their susceptibility to trypsinolysis. It is suggested that increased susceptibility to trypsinolysis reflects an appearance of new hydrophilic site(s) in monoamine oxidase molecules which may be responsible for an involvement of the modified enzymes in the deamination of other important nitrogenous compounds (such as γ‐aminobutyric acid) with subsequent impairment of a ratio between inhibition and excitation processes in the brain.
Development of human lateral geniculate nucleus: An electron microscopic study
Authors: Khan Aijaz Ahmed , Wadhwa Shashi , Bijlani Veena
Published: April 2003

A qualitative and quantitative ultrastructural study has been carried out on lateral geniculate nuclei (LGN) of 21 human fetuses ranging in gestational age from 13–14 to 34–35 weeks. At the early age period of 13–15 weeks, LGN is characterized by immature cells with indented nuclei possessing multiple nucleoli and by a sparse neuropil. During the subsequent age periods studied progressive maturational changes lead to neurons having round nuclei with a single nucleolus and well‐developed cytoplasmic organelles as well as to an elaborate neuropil. Synaptic contacts which are seen for the first time at the age of 13–14 weeks are of retinogeniculate type. They show features of immature synapses and are located mainly on the juxtasomatic parts of dendrites. With increasing gestational age, the synapses increase in size, maturity, types and complexity; an acquisition of complex synaptic arrangement (triad) occurs by 20–21 weeks. Excitatory synapses appear earlier than do the inhibitory ones. Formation of retinogeniculate contacts precedes that of the corticogeniculate type.

The synaptic density and total synapse number show a progressive increase with increasing gestational age. The age period of 15–20 weeks of gestation is marked by presence of organelles suggestive of a high rate of metabolic activity, significant increase in synaptogenesis, presence of transient contacts on soma and large number of free postsynaptic membrane densities (PSD). The period thereby represents a critical period in the development of synapses in LGN. The numerical values obtained by the age of 34–35 weeks are still low as compared to the values reported for other areas of brain.
Changes in expression of the low affinity receptor for neurotrophins, p75NGFR, in the regenerating olfactory system
Authors: Turner Christopher P. , Perez‐Polo J.Regino
Published: April 2003

We have disrupted the integrity of the rat olfactory neuroepithelium using intranasally applied TX‐100, a procedure known to reversibly eliminate the sensory neuron input from the neuroepithelium to the olfactory bulb [Margolis et al. (1974) Denervation in the primary olfactory pathway of mice: biochemical and morphological effects. Brain Res.81, 469–483]. One week after TX‐100 exposure, we observed a disruption of the pseudo‐stratified organization of the neuroepithelium which was accompanied by a 60% reduction in neuroepithelial width, compared to saline‐treated controls. Full recovery of the neuroepithelium was not observed until 16 weeks post‐lesion. During this post‐lesion period, we monitored the expression of the low affinity receptor for neurotrophins, p75NGFR, in the olfactory bulb of saline‐ and TX‐100‐treated animals, using the monoclonal antibody, MAb192. In saline‐treated animals, p75NGFR‐immunoreactivity (p75NGFR‐ir) was localized to individual glomeruli in the olfactory bulb, with little or undetectable p75NGFR‐ir in the olfactory nerve layer. We have previously reported that pre‐lesioned levels of p75NGFR‐ir in the glomerular layer were dramatically reduced while an induction of p75NGFR‐ir was observed in the olfactory nerve layer, one and two weeks after intranasal exposure to TX‐100 [Turner & Perez‐Polo (1992) Regulation of the low affinity receptor for nerve growth factor, p75NGFR, in the olfactory system of neonatal and adult rat. Int. J. Devl Neurosci.10, 343–359]. In this paper, we demonstrate that this previously reported reduction in glomerular p75NGFR‐ir took 16 weeks to fully recover and was, thus, coincident with the post‐lesion recovery of the neuroepithelium. In the olfactory nerve layer, the return of p75NGFR‐ir to pre‐lesioned levels took only four weeks. No changes in neuroepithelial width and integrity or alterations in p75NGFR‐ir in the olfactory bulb were observed in saline‐treated animals. Thus, the TX‐100‐induced removal of the peripheral input to the olfactory bulb resulted in a reversible change in expression of p75NGFR‐ir in the bulb. We believe that these changes are a reflection of the regenerative capacity of the olfactory system.
Neuroprotective effect ofN‐methyl‐d‐aspartate non‐competitive antagonists (arylcyclohexylamine derivatives) on human cultured spinal cord cells
Authors: Levallois C. , Calvet M.C. , Petite D. , Kamenka J.M.
Published: April 2003

The non‐competitive N‐methyl‐d‐aspartate antagonist cis‐Pip/Me 1‐[1‐(2‐thienyl)‐2‐methyl‐cyclohexyl] piperidine (GK11) either in racemic(±) or (−) enantiomeric form has been investigated on survival of human fetal spinal cord cells in culture. The treated cultured cells were processed for immunocytochemical detection of GABA at different time intervals ranging from 3 to 27 weeks. The number of GABA‐stained cells was found to be greater in the treated cultures than in the control ones. The qualitative and quantitative morphological features of both control and treated cells were analysed by computer‐assisted methods which allowed us to individualize three different populations: (1) all control and treated small neuritic field neurons, (2) young control and old treated large neuritic field neurons and (3) old control neurons with large neuritic fields.
Subcellular location and differential antibody specificity of arginase in tissue culture and whole animals
Authors: Spector Elaine B. , Jenkinson Christopher P. , Grigor Murray R. , Kern Rita M. , Cederbaum Stephen D.
Published: April 2003

Studies in man and other mammals have demonstrated the existence of two forms of arginase, a cytoplasmic form located primarily in liver and a mitochondrial form expressed in lesser amounts in a larger number of organs, but especially kidney. They appear to be encoded in different gene loci. Using a colloidal silica gradient separation technique, we have now located arginase in H4 cells, a rat hepatoma‐derived line, to the cytoplasm and the arginase in human embryonic kidney‐derived line, to the mitochondrion. Antibody prepared against A1 precipitates all the arginase from liver, 50% from kidney and none of the activity from human embryonic kidney (HEK) cells. An antibody prepared against partially purified All, by contrast, precipitates >90% of arginase activity from HEK cells, half from kidney and virtually none from H4 cells or rat liver.
Isoprenoid biosynthesis via the methylerythritol phosphate pathway: the (E)‐4‐hydroxy‐3‐methylbut‐2‐enyl diphosphate reductase (LytB/IspH) from Escherichia coli is a [4Fe–4S] protein
Authors: Wolff Murielle , Seemann Myriam , Tse Sum Bui Bernadette , Frapart Yves , Tritsch Denis , Estrabot Ana Garcia , Rodrı́guez-Concepción Manuel , Boronat Albert , Marquet Andrée , Rohmer Michel
Published: April 2003

The last enzyme (LytB) of the methylerythritol phosphate pathway for isoprenoid biosynthesis catalyzes the reduction of (E)‐4‐hydroxy‐3‐methylbut‐2‐enyl diphosphate into isopentenyl diphosphate and dimethylallyl diphosphate. This enzyme possesses a dioxygen‐sensitive [4Fe–4S] cluster. This prosthetic group was characterized in the Escherichia coli enzyme by UV/visible and electron paramagnetic resonance spectroscopy after reconstitution of the purified protein. Enzymatic activity required the presence of a reducing system such as flavodoxin/flavodoxin reductase/reduced nicotinamide adenine dinucleotide phosphate or the photoreduced deazaflavin radical.