bluuebunny/crossref_metadata_2025 huggingface dataset:
A critical period of the development of β‐adrenergic receptor binding in the visual system of rat during visual deprivation
Authors: Aurich Marina , Bigl Volker
Published: April 2003

The density of [3H]dihydroalprenolol binding to β‐adrenergic receptors in the visual structures (visual cortex, superior colliculus and lateral geniculate nucleus) of rats raised under a normal 12 hr light‐dark cycle was compared to those of rats visually deprived at different postnatal ages. Unilateral eyelid suture from postnatal days 10 or 16 to 3 months resulted in an increased [3H]dihydroalprenolol bilateral binding in the lateral geniculate nucleus compared to control animals. Monocular deprivation from postnatal days 25, 40, 60 and 90 had no effect on the density of [3H]dihydroalprenolol binding. After re‐opening of the eyelid, which was sutured on postnatal day 10, at postnatal day 25 no changes in β‐adrenergic receptor binding in the lateral geniculate nucleus of the adult animal could be detected. After re‐opening of the sutured eyelid on day 90, followed by examination of the adrenoceptor density 4 weeks later, the [3H]dihydroalprenolol binding in both lateral geniculate nuclei remained elevated as was also found in corresponding regions of monocular deprived animals.

Binocular visual deprivation from postnatal day 10 until the age of 3 months had no effect on [3H]dihydroalprenolol binding in the visual centres in comparison to corresponding control animals.

The data suggest that there exists a critical period for the ontogenetic development of β‐adrenergic receptors binding in the visual system of rats during which permanent alterations of receptor binding can be induced by monocular but not binocular visual deprivation.
Immunocytochemical study of the postnatal development of 5‐HT‐containing neurons and fibers in the cerebroid ganglia of Cryptomphalus aspersa
Authors: Flores Vladimir , Brusco Alicia , Saavedra Jorge Pecci
Published: April 2003

In this work we have studied the organization of the serotonergic system in new‐hatched snails and the developmental changes that occur postnatally. The serotonergic system of the newhatched snail is not completely developed. Tracts previously described in the adult were already present at hatching; however immunoreactivity of these tracts was somewhat less intense than that in adults, but, their location was practically the same.

At hatch the pro‐ and postcerebral serotonergic plexi were poorly developed, while the mesocerebral one was nearly absent. The procerebral plexus occupied only the caudal half of the procerebral neuropile. Growth cone profiles were found in all plexi.

The paired giant dorsal serotonergic neurons were the only stained neurons constantly found at hatching; they were symmetrically located. The paired medium‐sized neurons were not found in all brains examined. Sometimes only one of them was present at hatching; it was located either in the right or in the left ganglion.

The small neurons were absent in most cases. They gradually appeared during the first three postnatal months. Following hatching the procerebral plexus had undergone an intense growth. By the third postnatal month it innervated completely the procerebral neuropile. At hatching the area innervated by the procerebral plexus was 4500 μm2, by the third month this area was about 58,000 μm2 and in the adult was 80,000 μm2.

The postnatal development of the procerebral serotonergic plexus proceeds through two different modalities of neuritic growth: expansive growth is mediated by centrifugal elongation of terminal branches while the increase in fiber density within the plexus results from lateral sprouting. This growth probably depends on dynamic interactions with afferent fibers proceeding from the tentacular sensory organs.
Development of membrane interactions between brain endothelial cells and astrocytes in vitro
Authors: Tao‐Cheng Jung‐Hwa , Brightman Milton W.
Published: April 2003

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

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

In this study, the developmental pattern of transferrin expression, the iron transporting glycoprotein, was investigated morphologically and immunocytochemically in mixed glial cultures as well as pure cultures of mature oligodendrocytes, both derived from newborn rat brain.

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

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

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

In the adrenal medulla of adult rat, physiological levels of glucocorticoid hormones are required to maintain the catalytic activity of the epinephrine‐synthesizing enzyme, phenylethanolamine N‐methyltransferase (PNMT). The present study was undertaken to determine whether glucocorticoid regulation of PNMT occurs at the level of mRNA coding for PNMT. Adult male Sprague‐Dawley rats were hypophysectomized (HPX) and killed after 2 weeks; pellets of corticosterone were implanted for 1, 3 or 7 days prior to killing. Determinations were made of plasma corticosterone levels, adrenal PNMT activity and PNMT mRNA levels by Northern gel analysis. HPX resulted in a decrease in plasma corticosterone to undetectable levels and decreases in PNMT activity and PNMT mRNA levels to 1 and 18% of the levels observed in sham rats, respectively. Corticosterone replacement produced high prolonged plasma levels of corticosterone which were 10 times those of sham rats, and significantly increased levels of PNMT activity and mRNA. However, corticosterone replacement failed to restore PNMT activity and mRNA levels fully.

These results suggest that the maintenance of PNMT mRNA levels is dependent on maintaining corticosterone levels and supports the hypothesis that PNMT gene expression in the adrenal medulla is directly regulated by glucocorticoids produced by the adrenal cortex. However, the results also suggest that in the chronically HPX rat, factors in addition to naturally produced glucocorticoids are required for full restoration of PNMT mRNA levels.
Cell number, tissue thickness and protein content as measures for development and variability in cultured neocortex explants
Authors: De Jong B. M. , Ruijter J. M.
Published: April 2003

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

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

We have found that cholinergic neurons in spinal cord‐dorsal root ganglion cultures derived from E12–E13 mouse embryos are sensitive, as measured by changes in choline acetyltransferase activity, to factors secreted by non‐neuronal cells derived from the same tissue at an identical developmental stage. Conditioned medium was produced by incubating non‐neuronal cultures for 4 days in defined medium. The cholinotrophic activity present in the conditioned medium had a molecular weight of greater than 50,000 as determined by ultrafiltration and bound wheat germ lectin and heparin sepharose. Total RNA isolated from the non‐neuronal cells, used to produce the conditioned medium, was translated in frog oocytes. Conditioned medium from the injected oocytes was also found to contain cholinotrophic activity. In contrast, the conditioned medium from water‐injected oocytes was inactive.

The interaction between the cholinotrophic activity in conditioned medium from frog oocytes and known second messengers was also examined. Dibutyryl cyclic AMP produced a concentrationdependent increase in choline acetyltransferase activity. If a maximal effective dose of dibutyryl cyclic AMP was added in conjunction with a maximal effective dose of conditioned medium from oocytes injected with total RNA a nearly additive response was noted. In contrast, the phorbol ester, phorbol 12‐myristate 13‐acetate, produced a biphasic change in the level of choline acetyltransferase activity; with lower doses stimulating and higher doses inhibiting the enzyme activity. When conditioned medium from oocytes injected with non‐neuronal cell RNA was added in conjunction with the phorbol ester a decrease in the physiological response was noted.
Developing rat cerebellum—I. Effects of abnormal thyroid states and undernutrition on sulfated glycosaminoglycans
Authors: Normand G. , Clos J. , Vitiello F. , Gombos G.
Published: April 2003

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

Post‐translational modifications of chromatin‐bound proteins play an important role in the regulation of eukaryotic gene expression. Processes such as acetylation, methylation, phosphorylation and ADP‐ribosylation may alter the interaction of these proteins with DNA and consequently affect chromatin conformation and the binding of enzymes and other molecules involved in the regulation of gene expression.

In the present study the process of ADP‐ribosylation of chromosomal proteins (histone and nonhistone proteins) in some rat brain regions during postnatal development was investigated; also the effect of epidermal growth factor (EGF) on this process in fetal brain slices was studied.

It has been found that the process of ADP‐ribosylation of total histones extracted from rat cerebral cortex and cerebellum at 1, 10 and 30 days of age, increases from 1 to 10 days of age (i.e. the period of maximal cell proliferation) and decreases thereafter, while the process of ADP‐ribosylation of nonhistone proteins (NHPs) sharply decreases during the same developmental period.

The addition of EGF to fetal brain slices causes a significant increase of ADP‐ribosylation of total histones (particularly of the histone H1 fraction) and also of NHPs and microsomal proteins. This result is in agreement with the effect of EGF as a mitogen factor, previously shown in astroglial cell cultures.
Epidermal growth factor treatment during early postnatal development: Glutamine synthetase and glutamate decarboxylase activities in mouse brain
Authors: Condorelli Daniele , Nicoletti Vincenzo , Carpano Patrizia , Insirello Lucia , Avola Roberto , Giuffrida‐Stella Anna Maria
Published: April 2003

Results of experiments in cell cultures suggested that epidermal growth factor might influence an early stage of astroglial or neuronal cell differentiation. In order to evaluate this hypothesis the effects of subcutaneous and intracerebral treatment with epidermal growth factor on glutamine synthetase, an astroglial marker enzyme, and glutamate decarboxylase activity, a marker enzyme of GABAergic neurons, were investigated during postnatal development of mouse brain. Epidermal growth factor, at the dose used, induced the well‐known effects of the in vivo treatment, such as a decrease in body weight and a precocious incisor eruption and eyelid opening. A decrease in forebrain and cerebellum wet weight was also observed. However, repeated epidermal growth factor treatment, during early postnatal life, failed to influence glutamine synthetase activity in forebrain or cerebellum, while a significant decrease was observed in the brain stem. No effect of epidermal growth factor on forebrain glutamate decar‐boxylase activity was observed. Although epidermal growth factor receptors have been detected in the newborn rodent brain, the role of this growth factor in brain development remains to be elucidated.
effects of NGF and dibutyryl cAMP on neuronal differentiation of embryonal carcinoma cells
Authors: Sharma Shanti , Hansen John T. , Notter Mary F. D.
Published: April 2003

The P19S18O1A1 embryonal carcinoma cell line is capable of neuronal differentiation and is therefore useful in studying neuronal development and the influence of growth modulators on neuronal differentiation. We report here on the effects of nerve growth factor (NGF) and dibutyryl cyclic adenosine monophosphate (db cAMP), individually and combined, on differentiation of P19S18O1A1 cells. NGF alone did not induce any significant neuron‐like changes in cultures exposed to NGF for as long as 12 days. Treatment with db cAMP resulted in changes in a significant population of the cells, including development of a neuron‐like morphology, seen at both the light and electron microscopic level, loss of stage‐specific embryonic antigen expression and the appearance of two neuronal markers, neurofilament protein and neuron‐specific enolase. These changes were similar to changes seen when embryonal carcinoma (EC) cells are treated with retinoic acid. NGF in combination with dibutyryl cyclic adenosine monophosphate brought about similar changes as dibutyryl cyclic adenosine monophosphate alone, and was therefore not synergistic for induction of neuronal properties. In retinoic acid‐treated cultures, the neuron‐like cells had ultrastructural features very similar to neurons in non‐tumorous, normal tissue, with typical organelles, such as one nucleolus, neurotubules and neurofilaments, while db cAMP‐treated EC cells showed similar findings at the electronmicroscopic level. The results suggest that db cAMP can induce the neuronal phenotype in EC cells alone without pre‐treatment with retinoic acid.
Development of neurotransmitter systems in the mouse embryo following acute ethanol exposure: A histological and immunocytochemical study
Authors: Schambra Uta B. , Lauder Jean M. , Petrusz Peter , Sulik Kathleen K.
Published: April 2003

Acute maternal ethanol administration to C57B1/6J mice on gestational day 7 (GD7) results in facial and brain abnormalities similar to those reported in human fetal alcohol syndrome (FAS). Using this model, we assessed the damage to brain structures using histological methods and changes in developing neurotransmitter systems with immunocytochemistry. Cholinergic neurons in the forebrain were stained with a monoclonal antibody to choline acetyltransferase (ChAT). Catecholaminergic neurons in the midbrain and serotoninergic neurons in the hindbrain were stained with polyclonal antisera to tyrosine hydroxylase (TH) and serotonin (5‐HT), respectively. Forebrain deficiencies, including loss of midline structures (olfactory bulbs, midline septation, medial septal area) and deficits in lateral and dorsal regions (neostriatum and cerebral cortex) were found in both GD14 embryos and GD18 fetuses. In severely affected offspring, complete loss of the septal region resulted in conjoined lateral ventricles and a reduction in the thickness of the ventricular zone surrounding the single ventricle, as well as a severe loss of ChAT neurons which would normally be located in this territory. However, no consistent changes were seen in the distribution or size of TH or 5‐HT neuronal cell groups in the midbrain and hindbrain. These differences in effects on specific neurotransmitter systems reflect the fact that the forebrain is most severely affected by early ethanol administration, whereas the hindbrain is relatively spared. Such differential effects could produce an imbalance in developing neurotransmitter systems in the embryonic and fetal brain, which could explain some of the functional deficits observed in children with FAS.
The effects of potassium‐induced depolarization, glutamate receptor antagonists and N‐methyl‐d‐aspartate on neuronal survival in cultured neocortex explants
Authors: Ruijter J. M. , Baker R. E.
Published: April 2003

The effects of elevating the potassium concentration of the growth medium of neocortical explants was studied. Under control conditions, 10 mM potassium resulted in ca 20% decrease in the number of surviving neurons. The same potassium concentration, however, was clearly neurotrophic in tetrodotoxin‐grown cultures: tetrodotoxin‐induced neuronal death was significantly reduced. Both effects could be mimicked by the addition of 10 μM N‐methyl‐d‐aspartate (NMDA); lower concentrations were without effect; higher concentrations were neurotoxic under both control and tetrodotoxin conditions. The neurotoxic, as well as the neurotrophic effects of 10 mM potassium appear to be mediated through depolarization‐induced glutamate release since they could be influenced by the application of glutamate receptor antagonists. The addition of the NMDA receptor antagonist d‐2‐amino‐7‐phosphonoheptanoate (APH) blocked the trophic effect of 10 mM potassium in tetrodotoxin‐grown cultures, resulting in low survival. On the other hand, the addition of the non‐NMDA antagonist 6,7‐dinitroquinoxaline‐2,3‐dione (DNQX) resulted in neuronal survival similar to control cultures, indicating that it blocked the toxic effects of glutamate, leaving the trophic effects on the NMDA receptor untouched. Under control (non‐TTX) conditions, neither DNQX nor APH showed significant effects on 10 mM potassium‐induced cell death, indicating that stimulation of the non‐NMDA, as well as the NMDA receptors is neurotoxic. This differential effect of NMDA receptor stimulation on neuronal survival is discussed with respect to the maturational and/or functional state of the neurons in the culture.
Kainic acid lesioning alters development of the outer plexiform layer in neonatal rabbit retina
Authors: Messersmith Elizabeth K. , Redburn Dianna A.
Published: April 2003

The first synaptic relay in the primary visual pathway occurs between terminals of photoreceptors and second‐order neurons within the outer plexiform layer of the retina. During development, one of these types of second‐order neurons, the type A horizontal cell, differentiates and assumes mature characteristics several days before any other cells ramifying in that synaptic layer. In neonates, horizontal cells appear to be GABAergic during the first 5 days of postnatal life and in addition they also are responsive to kainic acid. We have previously suggested that they may play a pioneering role in the postnatal development of the outer plexiform layer, perhaps providing structural guidance or trophic substances such as GABA, for synaptic development. To test this hypothesis, we first demonstrated that a single intraocular injection of kainic acid within 24 hr of birth results in a permanent and selective loss of type A horizontal cells in the outer retina. Retinas from animals maintained for 5 days postinjection were harvested for analysis of postnatal development of the outer plexiform layer in the absence of horizontal cells. One of the major findings was that kainic acid treatment caused a reversal of the normal complement of photoreceptor cell types, resulting in an abnormally high rod/cone ratio. The distribution of cell processes within the outer plexiform layer was also altered and normal synaptic connections were not made. In spite of these changes in the constituents of the outer plexiform layer, the normal position of the synaptic layer was not affected by the loss of horizontal cells. These results rule out the possibility that horizontal cells provide a structural barrier which is an absolute requirement for establishing the location of the outer plexiform layer. Rather, these cells may be more involved in cell differentation and synaptogenesis.
GABA mediated excitation in immature rat CA3 hippocampal neurons
Authors: Cherubini E. , Rovira C. , Gaiarsa J. L. , Corradetti R. , Ari Y. Ben
Published: April 2003

Intracellular recordings from rat hippocampal neurons in vitro during the first postnatal week revealed the presence of spontaneous giant depolarizing potentials (GDPs). These were generated by the synchronous discharge of a population of neurons. GDPs reversed polarity at −27 and −51 mV when recorded with KCl or K‐methylsulphate filled electrodes, respectively. GDPs were blocked by the GABAA receptor antagonist bicuculline (10 μM). Iontophoretic or bath applications of GABA (10–300 μM) in the presence of tetrodotoxin (1 μM), induced a membrane depolarization or in voltage clamp experiments an inward current which reversed polarity at the same potential as GDPs. The response to GABA was blocked in a non‐competitive manner by bicuculline (10 μM) and did not desensitize.

GABA mediated GDPs were presynaptically modulated by N‐methyl‐d‐aspartate (NMDA) and non‐NMDA receptors. Their frequency was reduced or blocked by NMDA receptor antagonists and by the rather specific non‐NMDA receptor antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX). The frequency of GDPs was enhanced by glycine and d‐serine (10–30 μM) in a strychnine insensitive manner. This effect was blocked by AP‐5, suggesting that it was mediated by the allosteric modulatory site of the NMDA receptor.

These observations suggest that most of the ‘excitatory’ drive in immature neurons is mediated by GABA acting on GABAA receptors; furthermore excitatory amino acids modulate the release of GABA by a presynaptic action on GABAergic interneurons.
Comparison of the developmental changes of the brainstem auditory evoked response (BAER) in taurine‐supplemented and taurine‐deficient kittens
Authors: Vallecalle‐Sandoval M.‐H. , Heaney G. , Sersen E. , Sturman J.A.
Published: April 2003

A similar development of the brainstem auditory evoked response is present in taurine‐supplemented and taurine‐deficient kittens between the second postnatal week and the third month of life. Between birth and the second postnatal week kittens from mothers fed the 1% taurine diet showed earlier maturation of the brainstem auditory evoked response as indicated by lower threshold, shorter P1 latency and shorter central conduction time when compared to the kittens from mothers fed the 0.05% taurine diet. These results suggest an important role of taurine in the anatomical and functional development of the auditory system.
Ontogeny of β‐adrenergic receptor‐mediated cyclic AMP generating system in primary cultured neurons
Authors: Ma Fu‐Hai , Ohkuma Seitaro , Kishi Masataka , Kuriyama Kinya
Published: April 2003

The developmental changes in the β‐adrenergic receptor/cyclic AMP generating system were examined using mouse cerebral cortical neurons in primary culture. During neuronal growth in vitro, the number of binding sites for [3H]dihydroalprenolol (DHA) showed a tendency to increase (Bmax), while the affinity (Kd) for [3H]DHA did not show any noticeable changes. Basal and isoproterenol‐stimulated adenylate cyclase activities as well as the activation of adenylate cyclase by 5′‐guanylylimidodiphosphate (GppNHp), NaF and forskolin showed progressive and parallel increases during neuronal growth on a polylysine‐coated surface. The treatment of primary cultured neurons with islet‐activating protein (IAP), one of the pertussis toxins, attenuated the inhibitory effect of carbachol, a muscarinic agonist, on isoproteronol‐induced activation of adenylate cyclase activity. These results indicate that primary cultured neurons possess a cyclic AMP generating system coupled with β‐adrenergic and muscarinic receptors, which is regulated via stimulatory and inhibitory GTP‐binding proteins, respectively. The results described above also suggest that the β‐adrenergic receptor, stimulatory and inhibitory types of GTP‐binding proteins and adenylate cyclase may develop in a parallel fashion during neuronal growth on a polylysine‐coated surface.
A comparison of substance P peptide and preprotachykinin mRNA levels during development of rat medullary raphe and neostriatum
Authors: Walker Paul D. , Green Todd L. , Jonakait G. Miller , Hart Ronald P.
Published: April 2003

Substance P (SP) and the mRNA coding for its precursor peptide, preprotachykinin (PPT), were measured in medullary raphe nuclei (MRN) and neostriatum (NS) over development in order to determine (1) whether PPT mRNA levels correlate with peptide development, and (2) whether changes in PPT mRNA might help to account for the apparent decline in SP seen immunohistochemically in certain brain areas postnatally. Total RNA was quantified in dissected tissue pieces using the sensitive orcinol reaction. When MRN PPT mRNA levels measured by Northern blot analysis were adjusted to total RNA levels, PPT mRNA per MRN increased over development with a profile similar to that seen for SP peptide. Moreover, both peptide and mRNA levels exhibited a similar decline after postnatal day 15. Therefore, developmental regulation of SP biosynthesis in the MRN may, in part, explain previous evidence documenting a postnatal decline in SP there.

In the NS, SP peptide and PPT mRNA increased with a similar profile from E18 through the first post‐natal week. Thereafter, SP increased less rapidly than its mRNA, indicating incongruities in prohormone message and processed peptide in the NS.
The role of taurine in the survival and function of cerebellar cells in cultures of early postnatal cat
Authors: Trenkner E. , Sturman J.A.
Published: April 2003

The role of taurine and β‐alanine was analyzed in kitten cerebellar cultures. Since in contrast to mouse, cats (and primates including man) cannot synthesize sufficient taurine to maintain their body pools, we considered the cat an ideal species for the analysis of the role of taurine during early postnatal cerebellar development under controlled conditions. Unexpectedly, we found that the presence of taurine was toxic to neurons but that compounds, considered to be competitors for the β‐amino acid uptake system, support cell survival and cell function in vitro, the opposite of the results found in mice. This could be explained by the finding that only minute amounts of [3H]taurine were taken up by both cat neurons and glial cells under optimal culture conditions but that in the presence of the taurine analogues β‐alanine and guanidinoethane sulfonic acid (GES) significant amounts of taurine were found in all cell types. These differences between mouse cerebellar cells and cat cerebellar cells in vitro suggest that a reevaluation of the mechanisms that control taurine function in cats and primates is warranted.
Lipid peroxidation in rat cerebral cortex during post‐ischemic reperfusion: Effect of exogenous antioxidants and Ca++‐antagonist drugs
Authors: Vanella A. , Sorrenti V. , Castorina C. , Campisi A. , Di Giacomo C. , Russo A. , Perez‐Polo J.R.
Published: April 2003

Although the role of oxidant‐antioxidant metabolism in total ischemia and reperfusion in the central nervous system and cardiac myocardium have been well studied, less is known about the consequences of partial ischemic episodes. Here we show that reperfusion contributes to free radical formation as judged by conjugated diene formation. Also, antioxidants and Ca++ antagonists were able to reduce free radical formation. These results would suggest that free radical generation following ischemia and reperfusion may result from more than one injury process in cerebral cortex.
Effect of seizure activity and calpain inhibitor I on LTP in juvenile hippocampal slices
Authors: Fitzpatrick John S. , Shahi Kavian , Baudry Michel
Published: April 2003

Kainic acid‐induced seizure activity in adult rats produces an impairment of long‐term potentiation induction in hippocampal slices. As the consequences of seizure activity are different in adult and juvenile rats, we tested the ability of hippocampal slices prepared from kainate‐treated juvenile rats to exhibit long‐term potentiation. Long‐term potentiation was induced by theta‐burst stimulation and was not significantly different in slices prepared from control or kainate‐injected juvenile rats (16–18 postnatal days). Short‐term potentiation, however, was reduced in the kainate‐treated juveniles. Calpain inhibitor I has been shown to prevent long‐term potentiation formation in adult hippocampal slices, and we evaluated its effect on long‐term potentiation in hippocampal slices from juvenile rats. Calpain inhibitor I produced a significant reduction in the degree of long‐term potentiation induced by theta‐burst stimulation in hippocampal slices prepared from 14–20 postnatal day‐old animals. The results are consistent with the notion that, although similar mechanisms participate in the formation of long‐term potentiation in juvenile and adult animals, juvenile animals are much more resistant than adult animals to the consequences of seizure activity.
Serotoninergic reinnervation of regenerating tentacular sensory organs in a pulmonate snail, Cryptomphalus aspersa
Authors: Flores Vladimir , Brusco Alicia , Scicolone Gabriel , Saavedra Jorge Pecci
Published: April 2003

Several ontogenetic studies performed in different species suggest a developmental role for 5‐HT neurons. The 5‐HT system interconnecting the CNS and the tentacular sensory organs in pulmonates is a suitable model for studying the postulated developmental role of 5‐HT neurons. In this paper we describe the behavior of the 5‐HT fibers during the early stages of blastema reinnervation, primordium formation and differentiation of regenerating tentacular sensory organs in the pulmonate snail Cryptomphalus aspersa. Our results show that the regeneration process allows the development of a normal pattern of 5‐HT innervation of the regenerated sensory organs and suggest that 5‐HT could be involved in reciprocal developmental interactions with regenerating tentacular tissues.
Neurochemical changes of long‐term adrenalectomy in rat brain: Effects on neurotransmitter amino acids
Authors: Zonta N. , Ferrario P. , Di Giulio A.M. , Zecca L. , Gorio A. , Mantegazza P.
Published: April 2003

The levels of five amino acids together with glutamine synthetase activity, were measured in brain regions of rats with bilateral adrenalectomy, performed in newly weaning rats on postnatal day 22 and sacrificed 3 months later. Adrenalectomy caused a general decrease of glutamine concentration in three hippocampal regions (CA1‐CA2, CA3, CA4‐dentate gyrus), in hypothalamus, striatum and cerebellum. This reduction, which was particularly significant in hippocampus and cerebellum, was paralleled by a decrease of glutamine synthetase activity. Treatment with corticosterone reversed the effect of adrenalectomy. Little or no change was observed in the tissue levels of taurine, aspartic, glutamic or gamma‐amino butyric acids.
The developing chick brain shows a dramatic increase in the ω‐conotoxin binding sites around the hatching period
Authors: Azimi‐Zonooz A. , Litzinger M.J.
Published: April 2003

ω‐Conotoxin CVIA, a 27 amino acid neuropeptide toxin believed to target voltage sensitive calcium channels (Cruz et al., 1987, Biochemistry26(3), 820–824) was bound to developing chick brain at embryonic day 9‐post hatch day 10. A two‐fold increase was observed in ω‐Conotoxin binding sites around chick hatching, embryonic days 18–20. Depolarization induced 45Ca fluxes also increased around hatching. ω‐Conotoxins block ⩾‐80% of these 45Ca fluxes throughout development. Competition binding did not detect large differences in the binding affinity of sites during development. We conclude from these data that the increases in ω‐Conotoxin binding sites and 45Ca fluxes around chick hatching are related to one of the presynaptic mechanisms of neuronal maturation necessary for normal neuronal function and chick behavior after hatching.
Microcephalic cerebrum with hypomyelination in the pygmy mouse (pg)
Authors: Sugisaki Tetsuro , Beamer Wesley G. , Noguchi Tetsuya
Published: April 2003

To determine whether somatomedin has a direct action on cerebral development instead of an indirect action of a growth hormone, we examined the central nervous system of the pygmy mouse (pg), a mutant with normal somatomedin activity. Our findings are: (A) the weights of the pg/pg cerebrum and cerebellum weighed were significantly less than those of the normal controls (pg/+), 14 and 15% less, respectively; (B) the total DNA content was reduced by 17% in the cerebrum and cerebellum of the pg/pg mouse; (C) the total RNA content was also reduced in the cerebrum and cerebellum, proportional to the reduction in DNA; (D) CNPase activity was reduced selectively in the cerebrum of the pg/pg mouse by 25%; and (E) the pg/pg mice exhibited a strikingly reduced level of activity with an indistinct diurnal periodicity. Therefore, the present findings suggest that the action of somatomedin on the pro‐liferation and maturation of glial cells might be a necessary precondition to myelin formation.
Developmental and strain‐specific heterogeneity of rat adrenal chromaffin cells recognized by a monoclonal antibody against intact chromogranin B
Authors: Hansen Barbara , Lietzke Rolf , Unsicker Klaus , Westermann Reiner
Published: April 2003

We have raised a monoclonal antibody (MAB‐1E10) reactive with the intact forms but not the processing products of the chromaffin cell vesicle protein chromogranin B (CgB). The antibody recognizes rat and human, but not bovine and chick adrenal chromaffin cells. In addition, MAB‐1E10 immunoreactivity was detected in rat PC 12 pheochromocytoma cells and in pituitaries. Several other tissues, including pancreas, small intestine and superior cervical ganglia, which are known to contain CgB in endocrine cells or neurons, respectively, were found not to be reactive with MAB‐1E10. Using short‐term cultures of dissociated adrenal chromaffin cells from Hannover‐Wistar rats, we found that the expression of intact CgB is developmentally regulated. Between embryonic day 19 and postnatal day 40, about 80% of adrenal chromaffin cells — identified by their reactivity with an antibody against the enzyme dopamine‐β‐hydroxylase — were found to be reactive with MAB‐1E10. The proportion of positive cells subsequently decreased to about 5% at postnatal day 90. In the presence of glucocorticoids, this decrease was reduced to about 45% CgB‐positive cells at postnatal day 90. In another rat strain, Sprague‐Dawley rats, the proportion of MAB‐1E10‐immunoreactive chromaffin cells (about 50%) remained constant from birth to adulthood. Our results indicate that CgB is differentially expressed and/or processed in different rat tissues, strains and during development, and furthermore, that expression or processing in rat chromaffin cells might be regulated by glucocorticoids. Intact CgB appears to be a marker for a subpopulation of chromaffin cells, but its function(s) remains to be clarified.
Endothelin modulates dihydropyridine receptor decreased binding in hippocampal slices from normotensive and spontaneously hypertensive rats
Authors: Huguet Francois , Brisac Anne‐Marie , Dubar Michel , Ingrand Pierre , Piriou Alain
Published: April 2003

Previous studies in rats have demonstrated both the link between voltage‐operated calcium channels and endothelin and their cerebral involvement in the pathophysiology of spontaneous hypertension. In the present study, the interaction of endothelin with specific dihydropyridine (DHP) binding sites was investigated using the brain slices model. In rat hippocampal slices, pre‐incubation with Bay K 8644 decreased [3H] (+) PN 200‐110 binding. There was no difference in agonist‐induced decrease of DHP binding in normotensive and spontaneously hypertensive (SH) rats. The effect of Bay K 8644 was partially inhibited by endothelin but not by angiotensin in both normotensive and hypertensive rats. These data compared to those of other studies suggest that DHP binding sites which are regulated by endothelin are post‐synaptic. We conclude that brain slices provide a good in vitro model to study DHP receptor regulation and to explore endothelin interactions with DHP‐sensitive Ca2+ channels.
Excitatory amino acid response in cultured rat striatal neurons results in a developmentally regulated cGMP formation
Authors: Novelli Antonello , di Porzio Umberto
Published: April 2003

Glutamate and its analogues play a central role in excitatory neurotransmission throughout the brain. Their signal in the postsynaptic cells can be transduced by several second messengers. Here we show that in primary cultures of embryonic rat striatum, excitatory amino acid receptor stimulation increases cyclic GMP intracellular concentration and the magnitude of this response depends upon the time in culture. Formation of cyclic GMP appears to be mediated by both N‐methyl‐d‐aspartate (NMDA) and non‐NMDA type excitatory amino acid receptors, it is blocked by specific excitatory amino acid antagonists and requires extracellular Ca++. The effect mediated via the NMDA receptor is also regulated by extracellular Mg++.

These results show that excitatory amino acids make use of cyclic GMP for signal transduction in striatal neurons in vitro. We suggest that cyclic GMP may be an independent second messenger possibly important in the development of a defined population of striatal neurons.
Visualization of taurine, GABA and glutamate in developing feline cerebellum by immunohistochemistry
Authors: Lu Peimin , Imaki Humi , Xu Weimin , Sturman John A.
Published: April 2003

The localization of taurine, GABA and glutamate in developing feline cerebellum was performed using antibodies raised against the amino acids conjugated to bovine serum albumin with glutaraldehyde. Distinct patterns of immunostaining were observed for each of the amino acids. Taurine‐like immunoreactivity reached a peak at 4 weeks after birth, as did GABA‐like immunoreactivity, whereas glutamate‐like immunoreactivity was greatest in the mature cerebellum. Purkinje cells are all taurine‐positive in cerebellum from neonatal animals, whereas in the mature cerebellum they appear to contain only GABA and glutamate, with virtually no taurine, in contrast to observations reported with rodent cerebellum. Ultrastructural studies and immunogold labelling visualized by electron microscopy show that the band of taurine‐like immunoreactivity observed in newborn feline cerebellum is localized within dendrites, axons and glial processes. Granule cells migrating through this region also show prominent taurine‐like immunoreactivity.