bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of ornithine decarboxylase and the polyamines in nervous system development: Short‐term postnatal administration of α‐difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase
Authors: Slotkin T.A. , Whitmore W.L. , Lerea L. , Slepetis R.J. , Weigel S.J. , Trepanier P.A. , Seidler F.J.
Published: April 2003

The role of ornithine decarboxylase (ODC) and the polyamines in development of central and peripheral catecholaminergic neurons was examined through the use of α‐difluoromethylornithine (DFMO), a specific irreversible inhibitor of ODC. Short‐term postnatal administration of DFMO (500 mg/kg daily on days 1–6) to neonatal rats resulted in effective inhibition of ODC and depletion of both putrescine and spermidine in brain, heart and kidney; after cessation of DFMO administration, polyamine levels returned to normal by 10–13 days of age. There were no signs of generalized toxicity of short‐term DFMO treatment, as body weight gains were largely unaffected over the course of study (through weaning). However, development of peripheral sympathetic neurons was severely retarded by DFMO, with persistent and profound deficits of both cardiac and renal norepinephrine; the catecholamine deficiencies were unrelated to effects on end‐organ growth, as cardiac weights were essentially normal whereas kidney weights were adversely affected by DFMO. Development of the adrenal medulla, a peripheral catecholaminergic tissue which displays approximately the same developmental profile as do sympathetic neurons but which does not develop axonal projections, was not slowed by DFMO treatment; similarly, central noradrenergic and dopaminergic neurons, which undergo the majority of axonal outgrowth and synaptogenesis during the second to third postnatal week (just after the period in which polyamines returned to control levels), developed normally as assessed by measurements of transmitter levels, tyrosine hydroxylase activity and synaptosomal uptake of [3H]norepinephrine or [3H]dopamine. Extension of the period of DFMO treatment and consequent depletion of polyamines into the period in which central synaptogenesis occurs does, however, produce slowing of development of brain catecholamine neuronal projections. Thus, the ODC/polyamine system appears to play a critical postnatal role in catecholamine systems specifically undergoing active synaptogenesis.
A comparison of the regional ontogenesis of nicotine‐ and muscarine‐like binding sites in mouse brain
Authors: Falkeborn Y. , Larsson C. , Nordberg A. , Slanina P.
Published: April 2003

The postnatal development of the cholinergic neurotransmitter system was studied in the cortex, hippocampus, midbrain and cerebellum of 3‐, 7‐, 12‐, 17‐ and 30‐day‐old NMRI mice. The concentration of muscarine‐like binding sites determined with [3H]quinuclidinyl benzilate as a ligand increased progressively with age. A similar developmental pattern was found for the activity of a presynaptic marker, choline acetyltransferase (ChAT). When expressed as a percentage of the values for 30‐day‐old mice, however, the muscarine‐like receptors were parallel but preceding the development of ChAT in all the brain regions studied. The concentration of nicotine‐like binding sites studied with [3H]α‐bungaro‐toxin as a ligand gradually increased with age in the cortex, hippocampus and midbrain, with a peak between days 7 and 12, followed by a decrease towards day 30. With [3H]tubocurarine as a ligand, on the other hand, the concentration of nicotine‐like binding sites was in general high at 3 days and gradually decreased with age, suggesting that different subpopulations of nicotine‐like receptors might be determined when the two ligands are used.
The arachnoid granulations of the newborn human: An ultrastructural study
Authors: Gomez Daniel G. , Ehrmann Jorge E. , Potts D. Gordon , Pavese Albert M. , Gilanian Angela
Published: April 2003

Portions of the superior sagittal sinus and lacunae laterales containing arachnoid villi and granulations from 8 full‐term newborn babies were studied by transmission electron microscopy. Arachnoid proliferations from 3 subjects were distended and fixed in vitro by applying a differential pressure of 8 cm H2O to the subarachnoid aspect of the tissues. The remaining cases were fixed in a collapsed state. Distended arachnoid proliferations showed morphologic characteristics associated with similar functional structures in experimental animals: shortened and enlarged interendothelial spaces; micropinocytotic activity and a system of endothelial‐lined tubules. All this is taken as evidence that arachnoid proliferations in newborn babies could already be engaged in cerebrospinal fluid absorption.
Ultrastructural cytochemistry of monoamines in cultured human fetal sympathetic neurons
Authors: Zeevalk Gail Duffy , Cederqvist Lars L. , Lyser Katherine M.
Published: April 2003

The presence and storage of adrenergic neurotransmitter (monoamines) in cultured human fetal sympathetic neurons was investigated by chromate‐dichromate cytochemistry, formaldehyde‐induced fluorescence and potassium permanganate fixation. Monoamines were specifically identified in the neurons by the presence of an electron dense precipitate following cytochemical treatment. Reaction product was found in cell somas and processes in all chromate—dichromate treated cultures. The size range and morphology of the precipitate indicated a vesicular storage site within large dense core vesicles. Neurons fluoresced after treatment with formaldehyde vapors, further confirming the presence of monoamines. When potassium permanganate was employed as the fixative, occasional positive dense core vesicles were found but their frequency was greatly reduced from that seen in the chromate‐dichromate treated cultures. These findings show that cultured human fetal sympathetic neurons retain an adrenergic phenotype during long‐term serum‐free culture. In addition, the storage site for the adrenergic neurotransmitter in the developing neuron is within large dense core vesicles. The lack of dense core vesicles in potassium permanganate fixed material is believed to be due to the depletion of monoamines during fixation.
A chick neural antigen identified by monoclonal antibodies
Authors: Leah John , Gynther Bruce , Kidson C.
Published: April 2003

A monoclonal antibody technique has been used to locate a neural antigen which appears to be involved in developmental processes.

Hybridomas were prepared using chick embryo sympathetic neurons as an immunogen and one clone, H3, was found to secrete antibodies which bound to neurons of the peripheral and central nervous system. The antibodies bound to both membrane and cytoplasmic sites of neurons but only to cytoplasmic sites of glial cells. When added to newly prepared cultures of embryonic sympathetic neurons the H3 antibodies impaired both neurite outgrowth and long‐term neuronal viability. No such effect was seen when the antibodies were added to established, differentiated neurons.
Factors influencing astrocyte growth and development in defined media
Authors: Michler‐Stuke Angelika , Wolff Joachim R. , Bottenstein Jane E.
Published: April 2003

A previously described serum‐free, defined medium (G2 medium) containing transferrin, selenium, hydrocortisone, biotin, fibroblast growth factor (FGF) and fibronectin developed for the growth of human and rat derived glioma cells was investigated for its ability to support proliferation of astrocytes in primary cultures of neonatal rat cerebrum. These cells were able to grow in G2 medium. Enhanced proliferation and repeated subcultivation were obtained after adding insulin and/or epidermal growth factor (EGF) to the G2 medium at concentrations of 5 μg/ml and 10 ng/ml, respectively.

In these modified media (called G4 and G5 medium) astrocytes showed a higher degree of morphological differentiation as compared to serum supplemented medium. Cell type specificity was determined by immunocytochemical staining of glial fibrillary acidic (GFA) protein, which could already be demonstrated 5 days after plating cells. G4 and G5 represent the first serum‐free defined media in which astrocytes proliferate and differentiate without preceding or intermediate contact to serum supplemented medium. Modification of the culture substratum by adding hyaluronic acid and chondroitin sulfate A to G4 medium (G2 medium + insulin) enhanced proliferation of astroglial cells by a factor of about 1.5. In the presence of epidermal growth factor no response to the altered culture dish surface was observed and the addition of fibronectin, otherwise a stringent plating requirement, was no longer necessary.
Reductions in the plating efficiency of the fetal neural precursor cells following maternal alcohol consumption
Authors: Kennedy L.A. , Elliot M.J. , Laverty W.H.
Published: April 2003

Maternal alcohol abuse has been associated with reduced neural cell number and abnormal cell differentiation and organization in many regions of the developing mammalian brain. Experiments were conducted to determine whether changes in the neural precursor cells could be detected in primary culture following maternal alcohol consumption during the early proliferative period of the fetal brain growth spurt. Alcohol was administered to pregnant mice in the drinking water from days 11 to 19 of gestation. There was no alcohol‐related increase in the incidence of fetal mortality or malformation, but fetal body and brain weights were reduced. When disaggregated cells from the day 19 fetal neopallium were grown in culture, there was a reduction in the number of astroglial colonies yielded in 42% of alcohol‐exposed brains. This effect was expressed as a reduction in the absolute plating efficiency (APE) of the neural precursor cells. The APE was reduced as much as 80% in severely affected brains. There was no alcoholrelated difference in the in vitro morphogenesis of the astroglial colonies. Observations of the proliferative neural cells in situ suggest that there is an impaired recruitment of all neural cell types, but that the reduced APE reflects primarily a proportionate increase in the number of immature neurons among the cells obtained from the fetal neopallium. It appears that a prolongation of mitosis may be resulting in a general developmental delay in the fetal neocortex.
Tissue repair in the embryonic rat spinal cord following exposure to N‐ethyl‐N‐nitrosourea
Authors: Houle John D. , Das Gopal D.
Published: April 2003

The cytotoxic effects of N‐ethyl‐N‐nitrosourea (ENU) and the potential for recovery from this damage in the developing rat spinal cord was investigated. Emphasis was placed on determining the severity and location of initial cell necrosis and the subsequent reorganizational changes in the damaged tissues. Pregnant rats were injected i.v. with a single dose of ENU (60 mg/kg) on one of days 12–16 of gestation. At 6, 12, 24 and 48 h post‐injection one pregnant rat from each gestational stage was anesthetized, the embryos were removed, fixed and processed for embedding in paraplast or epon‐araldite. Transverse sections from embryos killed at 6 h revealed extensive necrosis throughout the neuroepithelium in accordance with the temporal‐spatial patterns of neurogenesis. At this dose level the post‐mitotic neuroblasts appeared unaffected. Regeneration of the damaged neural tissue as defined by the restoration of the neuroepithelial cell layer and removal of necrotic debris proceeded quickly, and within 48 h a near‐normal cytoarchitecture was observed. The embryonic age at time of ENU injection had no apparent influence on the actual sequence of tissue repair in the spinal cords although the events were slightly delayed within embryos exposed to ENU on days 12 or 13 of gestation.
A genetic taxonomy of hyperkinesis in the dog
Authors: Ginsburg Benson E. , Becker Robert E. , Trattner Alice , Bareggi Silvio R.
Published: April 2003

Among children who have difficulty inhibiting gross motor activity and focusing on learning tasks requiring them to do this, some are helped by central nervous system stimulants such as amphetamine, while others with identical symptoms are not. Similar variations in response to pharmacological agents are seen in other syndromes, suggesting that multiple biological mechanisms are involved and that these are selectively responsive to pharmacological manipulations. Diagnosis, therefore, involves not only the identification of the condition, but knowledge of the mechanisms by means of which it can be brought about, as well as some means of identifying these. Since such variations often have a genetic basis, their identification and characterization by genetic and pharmacogenetic approaches permit the investigator to avoid confounding biological variation with statistical error and, ultimately, to suit the treatment to the mechanism when there is no final common path permitting a single intervention specific to a given syndrome. Because such researches are difficult with human patients, we have been attempting to identify animal models with analogous symptoms to human conditions and homologous mechanisms underlying these. The present paper is one in a series describing a dog model for hyperkinesis.
Myelinogenic cycle and myelination status of the brain of the catfish, Heteropneustes fossilis
Authors: Yusuf Harun K.M. , Islam M. Sayedul
Published: April 2003

The lipid composition of the brain of the catfish, Heteropneustes fossilis (Bloch) was studied over the age period of 2–12 months, during which time the body weight increased from 2.5 to 33 g. The brain weight increased from 28 to 84 mg between 2 and 9 months of age, with a further increase of only 7 mg during the following three months. The concentration of cholesterol increased slowly up to 5 months of age, from which time the concentration began to increase rapidly and attained adult values at 8 months. The concentration of total lipid‐P increased steadily up to the age of 7 months and remained almost constant thereafter. In contrast, there was very little increase in the concentration of the galactolipids (cerebroside + sulphatide) until month 5, after which the concentration increased rapidly to reach the adult level at 8 months of age. The concentration of cholesterol esters decreased during development; however, there occurred a transient rise at 5 months of age, which continued up to 8 months. These data indicate that the period between months 5 and 8 is one of active myelination in the brain of this species. The mole ratio of cholesterol, phospholipids, and galactolipids in the adult fish brain was 31:53:1, much higher than that in adult mammalian brain. Moreover, within the phospholipids, ethanolamine phosphoglyceride comprised < 10%, as against the corresponding value in the mammals of about 40%. These data therefore suggest a low level of myelination in the brain of catfish, as compared to that in higher species.
Morphological maturation and survival of chicken and rat embryonic neurons on different culture substrata
Authors: Faltin J. , Lodin Z. , Hartman J. , Foucaud B. , Gombos G. , Sensenbrenner M.
Published: April 2003

Neuronal cells from chicken and rat embryonic cerebral hemispheres were plated at a low cell concentration and cultured either on collagen or on a supporting continuous glial layer for periods of up to 21 days. The glial layer was either homologous or heterologous with regard to the animal species; the survival and maturation of the neuronal cells in these different conditions were investigated by light and electron microscopy.

Neuronal cells cultured on collagen formed aggregates similar to those formed by neuronal cells plated at high cell density as described in a previous paper; a few aggregated neurons formed processes after 24 h and, only after 48 h of culture, more fibres had developed; the majority of the cells progressively degenerated between days 7 and 21 of culture. In contrast to this, neuronal cells cultured on a supporting glial layer, whether homologous or heterologous, progressively differentiated: neuronal perikarya remained well separated from each other and many processes were already formed after 24 h; later on, networks of fibres developed. At the electron microscopic level, microtubules and neurofilaments were present at a high density in the cells and fibres; immature synapses could be found, but infrequently. Differentiated cells were represented mostly by neurons; oligodendroglial cells were absent, and myelinated fibres could not be detected.

The highest positive effect on the maturation and survival of neuronal cells was observed in the presence of a layer of glial cells from the same species. These results emphasize the essential role of glial cells for the neuronal maturation in the absence of contact between neuroblasts.
Delayed development of GFA immunoreactivity in the parietal cortex during thyroid hormone deficiency
Authors: Granholm A.‐Ch , Dahl D. , Siegel R. A. , Björklund H. , Seiger Å
Published: April 2003

The influence of neonatal hypothyroidism on the development of immunoreactivity to glial fibrillary acidic protein (GFA) was studied in parietal cortex of rats treated from birth with the antithyroid agent propylthiouracil (PTU) for 3 or 8 weeks. Density of GFA immunoreactivity was evaluated in cryostate sections reacted with an antiserum specific for GFA. Three weeks postnatally, the density of GFA‐immunoreactive structures in the cortical layers II‐V was 70% lower in PTU‐treated animals than in controls injected with the solvent. This marked difference between the groups was, however, not seen in either the molecular layer, layer VI or white matter. The inhibited development of GFA immunoreactivity was not persistent in animals treated with PTU for 8 weeks continuously. Plasma from animals treated with PTU for 1,2,3 and 8 weeks was collected and the TSH level in each group compared with samples from age‐matched controls and newborn pups. The treatment with PTU resulted in a more than 10‐fold increase in TSH level after 1 week of injections. In longterm groups of 8 weeks, the TSH level decreased in the PTU‐treated animals, but stayed considerably higher than control values throughout the experiments.

The results described in the present paper indicate a thyroid hormone dependent development of the GFA immunoreactivity in cortex cerebri astrocytes.
The expression of concanavalin a binding glycoproteins during the development of cerebellar granule neurons in vitro
Authors: Webb Michael , Gallo Vittorio , Schneider Annerose , Balazs Robert
Published: April 2003

We present data on the expression of Concanavalin A (ConA) binding glycoproteins by granule cell enriched cultures derived from 8 day postnatal rat cerebellum. Time course studies were conducted over a 12 day culture period. ConA binding glycoproteins were localized on the cell bodies and fibres of the granule neurons using fluorescence microscopy. The fluorescence intensity increased between 4 and 12 days in vitro. Quantitative studies on the capacity of live cells to bind 125I‐iodinated ConA showed that there was a significant increase in the amount of lectin bound between 4 and 8 days in vitro. However, in contrast to previous results on the developing cerebellum in vivo [Zanetta et al. (1978) Brain Res.142, 301–319.], there was no decline in binding capacity after 8 days in culture. Glycoproteins expressed by these cells were analysed by staining SDS polyacrylamide gels with [125I]ConA. A large number of lectin binding proteins were observed which spread over a wide range of molecular weights. Only minor changes were detected in the profile of [125I]ConA binding glycoproteins with the maturation of the cells in culture. The comparison of the findings on granule cells developing in culture and in vivo suggested that an interaction between granule cell axons and their normal target neurons is involved in the regulation of the ConA binding protein content in the cerebellum.
Timecourse of effects of triiodothyronine on mouse cerebellar cells cultured by two different methods
Authors: Messer Anne , Snodgrass Gary L. , Maskin Paul
Published: April 2003

Dissociated cells from week‐old mouse cerebellum were grown on either polylysine coated coverslips or on uncoated coverslips. Polylysine coated coverslips give rise to cultures containing all of the cerebellar cell types except Purkinje cells. Use of uncoated coverslips gives rise to cultures which are depleted of granule cells because the granule cells are unable to adhere to glass without a substrate present. The uncoated coverslip cultures are therefore enriched in glial and other non‐neuronal cells. Effects of triiodothyronine on each type of culture were then examined as a function of time.

On coated coverslips hormone treatment caused a noticeable increase in cell clumping at 1 week, and seemed responsible for a leveling off of the decline in total high‐affinity uptake of γ‐aminobutyric acid, as well as for a small increase in β‐alanine inhibited uptake between 2 and 3 weeks. There was no effect on the overall uptake of thymidine. On uncoated coverslips triiodothyronine treatment significantly increased the thymidine uptake at days 2 and 3, and increased the proportion of Bergmann‐like to velate astrocytes at 1 week. There were, however, no significant differences in GABA uptake at any of the time points examined.

We conclude that in cerebellar cultures lacking Purkinje cells, triiodothyronine affects both the rate of acquisition and the timecourse of morphological changes (possibly reflecting transformation to more differentiated states) of glial cells but not of neurons. These results are consistent with the hypothesis that, in vivo, thyroxine acts indirectly via Purkinje cells to give developmental signals to neuroblasts and/ or neurons.
The phagocytes of neonate rat primary mixed glial cultures
Authors: DuBois J.H. , Hammond‐Tooke G.D. , Cuzner M.L.
Published: April 2003

The phagocytes present in mechanically dissociated neonate rat cerebral hemispheres have been cultured and characterized both qualitatively and quantitatively. They comprise about 10% of the starting cell suspension and persist but do not proliferate in culture. They do not possess neuronal or neuroglial antigens but do express the leukocyte common antigen and readily ingest both latex beads and opsonized erythrocytes. the latter by an Fc receptor‐mediated process. Evidence is presented that these cells are a bona fida component of the neonate central nervous system.
Ephemeral existence of a single catecholamine synthetic enzyme in the olfactory placode and the spinal cord of the embryonic rat
Authors: Foster George A. , Schultzberg Marianne , Dahl Doris , Goldstein Menek , Verhofstad Albert A.J.
Published: April 2003

The distribution of three catecholamine synthetic enzymes (tyrosine hydroxylase, l‐aromatic acid decarboxylase and dopamine β‐hydroxylase), of the catecholamines themselves (dopamine and noradrenaline) and of a marker for neuronal intermediate filaments (neurofilament) was investigated in the embryonic rat using immunohistochemical and histofluorescence methods.

At early stages of gestation (days 11–13), large numbers of tyrosine hydroxylase immunoreactive cells and fibres were apparent in the ventro‐lateral spinal cord, and in and around the olfactory placode. In both cases, tyrosine hydroxylase positive fibres coursed between the proliferative layer and the surrounding mesenchyme, indicating the considerable degree of morphological differentiation. The similar disposition of neurofilament‐like immunoreactivity in the same regions suggested that the tyrosine hydroxylase containing structures were neuronal.

Within 2–3 days of their first manifestation, the tyrosine hydroxylase immunoreactive neurons disappeared. In the spinal cord, this coincided with their migration out of the mantle layer. Over this same period, neither of the other enzymes involved in the synthesis of noradrenaline, namely l‐aromatic acid decarboxylase and dopamine β‐hydroxylase, nor dopamine and noradrenaline themselves, could be detected.

It is concluded that some neurons in the olfactory placodal region and the ventrolateral spinal cord temporarily express a single specifically catecholaminergic enzyme, tyrosine hydroxylase, which is not utilized at that time in catecholamine synthesis. It is suggested that the control of transcription of the gene coding for tyrosine hydroxylase is independent of that for other catecholaminergic synthetic enzymes.
Cell proliferation in the embryonic mouse neocortex following acute maternal alcohol intoxication
Authors: Kennedy L.A. , Elliott M.J.
Published: April 2003

Experiments were conducted to examine the effects of ‘binge’ or acute maternal alcohol intoxication during the early proliferative phase of embryonic brain development. Primiparous mice received ethanol as 0, 10, 15 or 20% (v/v) aqueous solutions by gavage on days 13, 14 and 15 of gestation. Mean daily doses were 0.0, 2.58, 4.03 and 5.40 ml/kg, respectively. There was no alcohol‐related reduction in fetal body weight, length or fixed brain weight. Coronal sections (1 μm) of the dorsal roof of the lateral ventricles over the optic chiasma were examined from nine embryonic day 15 brains for each treatment group. The ventricular surface index of mitotic figures, the number and distribution of non‐surface mitotic figures, and the depth of the cortical roof and its constituent layers were determined. There was no alcohol‐related difference in any of these parameters. These results are in contrast to those of a previous experiment using the same mouse strain, in which prolonged or chronic maternal alcohol consumption in the drinking water from days 11 to 19 of pregnancy was associated with a reduction in the surface index, a reduction in the depth of the cortical roof and an increase in the non‐surface mitotic figures. These latter changes, however, occurred in the presence of reduced body weight. Our observations suggest that during this particular developmental period (corresponding to the second trimester of human pregnancy) alcohol‐related reductions in brain growth parallel restrictions in general body growth.
A possible relationship between concentration of microperoxisomes and myelination
Authors: Adamo Ana M. , Aloise Pedro A. , Pasouini J. M.
Published: April 2003

Using catalase activity as a marker enzyme of microperoxisomes we determined the presence of these organelles in rat cerebral cortex (grey matter) and in brain stem (white matter) throughout development.

While in grey matter the values of specific activity of catalase remained constant during all the period studied, in white matter the values increased up to 17 days of age, remained constant up to 31 days and decreased thereafter. Studies carried out in isolated oligodendroglial cells confirmed the results obtained in white matter. The results give support to the hypothesis of a possible relationship between the increase in the population of microperoxisomes and the appearance of myelin.
Cognin distribution during differentiation of embryonic chick retinal cells in vitro
Authors: Hausman R. E. , Katz M. S. , Dobi E. T. , Offermann J.
Published: April 2003

Differentiation of individual retina neurons is closely linked to development of retina function. This differentiation may be intrinsic to the cell or determined by the position of the cell within the developing tissue. Retina cognin, a cell‐cell recognition protein, which may itself mediate positiondependent cell interactions in vivo exhibits a characteristic change in distribution during embryonic chick development. Cognin is progressively lost from the outer retina in a manner which appears position‐dependent. 10 We asked if this change in cognin distribution was actually position‐dependent or intrinsic to the retina cells. Neural retina cells from 8‐day‐old chick embryos were cultured in vitro. Continued differentiation of the cultured cells was demonstrated by neurite outgrowth and characteristic increases in choline acetyltransferase and glutamic acid decarboxylase activity. In such cultures, the characteristic developmentally related disappearance of retina cognin occurred as in vivo. This indicated that this aspect of retina neuronal differentiation was independent of position within the tissue and likely intrinsic to individual cells after 8 days of embryonic development.
Maintenance of neuritic arborization in mitotic neuroblasts identified by neurofilament immunoreactivity
Authors: Asou Hiroaki , Iwasaki‐Mutou Noriko , Hirano Shuske , Dahl Doris
Published: April 2003

The morphology of mitotic cells identified as neuronal precursors by neurofilament immunoreactivity was studied by scanning electron microscopy in primary dissociated cultures of fetal rat cerebral hemispheres. It is shown that neurofilament‐positive neuroblasts maintain their neuritic arborization during cell division suggesting a cytoskeletal function for the neurofilament.
Ependymal lining of infundibular recess in perinatal rats: Relationships with portal capillaries and permeability
Authors: Ugrumov M.V. , Mitskevich M.S. , Halász B. , Kiss J. , Borisova N.A.
Published: April 2003

Structure and permeability of the ependymal lining the infundibular recess were studied in perinatal rats with silver impregnation, electron microscopy, radioautography and tracer techniques. According to our data basal processes of ependymal cells reach the primary portal plexus linking the 3rd ventricle and the hypophysial portal system all through the perinatal period. After birth, some of the processes penetrate into the perivascular space of the primary portal plexus and abut there on the endothelium of capillaries. Ependymal cells of fetuses and neonates are joined by specialized junctions (tight junctions, gap junctions and zonulae adhaerentes). Intraventricularly injected ionic lanthanum crosses the ependymal lining of fetuses both trans‐ and extra‐cellularly everywhere in the infundibular recess. By postnatal day 9 only the rostral portion of the recess remains readily permeable. Caudally, extracellular leakage becomes highly restricted, apparently due to the appearance of circumferential tight junctions. Finally, [3H]dopamine seems to penetrate through the ependymal lining in the same way as ionic lanthanum entering the portal capillaries.

These findings suggest that the adenohypophysiotropic neurohormones can penetrate from the cerebrospinal fluid into the portal circulation from the very beginning of the establishment of the hypothalamo‐hypophysial functional relationships during ontogenesis.
Paradoxical sleep deprivation of the mother enhances DNA synthesis in fetal rat brain: Autoradiographic and biochemical evidence
Authors: Zucconi Giglola Grassi , Belia Silvia , Menichini Enrico , Castigli Emilia , Giuditta Antonio
Published: April 2003

Pregnant rats were deprived of paradoxical sleep for 3 days starting on the 18th gestational day. The condition of PS‐D was imposed by confinement on a small platform surrounded by water or by daily injections of clomipramine. Four hours before the killing rats received a s.c. injection of [3H]‐thymidine. The amount of radioactive DNA determined by autoradiography in several regions of fetal brain was found to be markedly increased under both experimental conditions in comparison with the control fetal brain. Considerably more limited effects were observed in kidney. Comparable changes of lower magnitude were obtained by comparing the specific radioactivity of DNA samples purified by chlorophorm extraction and digestion with RNase and proteinase K. The results fully confirm our previous data obtained under similar experimental conditions but based on the analysis of an acid‐washed DNA fraction.
Developmental changes in hypothalamic melatonin levels of male rats
Authors: Catala M. D. , Quay W. B. , Timiras P. S.
Published: April 2003

Hypothalamic melatonin levels of Long‐Evans male rats were studied at three ages (25, 55–60 and 90 days), at four times of the day in the autumn (6:00, 12:00, 18:00 and 24:00), and at two times (12:00 and 24:00) in the spring using radiommunoassay. Melatonin levels increased markedly at noon at 55–60 days of age, compared with the levels at the same time of the day at 25 and 90 days. This increase persisted in autumn and spring. The 24‐hr pattern in hypothalamic melatonin was the inverse of that in the pineal, with the levels at noon higher than those at midnight. This pattern was detectable at 25 days of age although the difference in melatonin between 12:00 and 24:00 hr was not great. The day/ night difference was prominent by 55–60 days of age and disappeared by adulthood (90 days). This 24‐hr pattern was similar in spring and autumn in the three ages studied. Although in the 55–60‐day‐old group the melatonin ratio (noon/midnight) was the same in autumn and spring, the absolute levels of melatonin in spring were significantly lower. The findings are consistent with the general concept of a modulatory role of melatonin in control of hypothalamo‐hypophyseal GnRH and gonadotropin function and the timing of the developmental maturation of this neuroendocrine axis. Demonstration of the mechanism of melatonin's action at the hypothalamic level will be facilitated by further definition of quantitative developmental changes.
Early changes of surface morphology in monolayer cultures of neural retina cells. The effect of p‐bromophenacyl bromide
Authors: Suburo Angela M. , de Job Claudia Cei
Published: April 2003

Scanning electron microscopy was used to study the surface morphology of neural retina cells from fetal rats. Dissociated cells were plated on polyornithine and examined after 1.5–3.0 hr in vitro. A quantitative analysis of the proportion of cells with and without processes was made and the former were classified according to the length and number of their processes.

Treatment with p‐bromophenacyl bromide (BPB), a selective inhibitor of phospholipase A2 (PLA2), induced significant changes on the early surface activity of retinal cells. An inhibitory effect on cell process formation was observed in monolayers grown for 2 hr in the presence of BPB: process formation was also inhibited when high concentrations (10−6 M or more) were applied as a 30 min pulse, whereas a similar pulse of a lower concentration (10−7 M) stimulated the appearance of cells with short processes. These observations suggest that PLA2 or some other BPB‐reactive substance is involved in the extension of neural cell processes.
Temporal development of gaba agonist induced alterations in ultrastructure and gaba receptor expression in cultured cerebellar granule cells
Authors: Hansen Gert H. , Belhage Bo , Schousboe Arne , Meier Eddi
Published: April 2003

The temporal development of the effect of THIP (4,5,6,7‐tetrahydroisoxazolo[5,4‐c]pyridin‐3‐ol) on the ultrastructure composition and GABA receptor expression in cerebellar granule cells was investigated by quantitative electron microscopy (morphometric analysis) and GABA binding assays. It was found that the cytoplasmic density of smooth endoplasmic reticulum was decreased, while the cytoplasmic density of rough endoplasmic reticulum, Golgi apparatus, vesicles and coated vesicles was greatly enhanced after exposure of the cells to THIP (150 μM) for only 1 hr. In cerebellar granule cells exposed to THIP (150 μM) for 3 hr low affinity GABA receptors were induced. These findings show that the effect of THIP on the ultrastructure composition and GABA receptor expression in cultured cerebellar granule cells may be interrelated and moreover it is likely that the turn‐over of GABA receptors is extremely fast.
Ultrastructural analysis of primary cilium in the embryonic nervous tissue of mouse
Authors: Cohen E. , Meininger V.
Published: April 2003

In the embryonic nervous system, the morphology and spatial organization of the ciliary apparatus in the primordial cells, the neuroepithelial bipolar cells, has been analysed from frontal and horizontal ultrathin sections. Projecting into the ventricular fluid, the primary cilium is located just at the interface between the ventricular fluid and the cytoplasm of these cells. Always associated with a basal body and a centriole, their structural components are nine microtubule doublets equally spaced around the luminal cylinder without central doublet. The cilium is short with a thick base displaying a reduced ciliary necklace and a 9 + 0 pattern. In its tip, the pattern decreases from 7 + 0 to 2 + 0. The basal body differs from the basal body of the motil cilium by internal and external sheets interconnecting triplets from base to apex, the constant existence of an accessory basal foot and the scarcity of a ciliary rootlet. All these characteristics suggest that in the neuroepithelial bipolar cells the ciliary apparatus is a rigid, polarized and transient structure probably important in the possible exchange between the ventricular fluid and the developing nervous system.
Regional protein patterns of the embryonic chick brain: Developmental shifts and the effects of light stimulation
Authors: Zhang J. , Huether G. , Neuhoff V.
Published: April 2003

The developmental changes in the regional protein patterns of the embryonic brain of chick were analysed by micro‐two‐dimensional polyacrylamide gel electrophoresis stained by a highly sensitive procedure with Coomassie Brilliant Blue G‐250 that completely avoids background staining. More than 400 protein spots were resolved in a computerized plot. Many proteins of the various embryonic brain regions varied with age. At least six of these proteins changed remarkably during development. One of them (Mr 14K) was prominent at 6 days and disappeared after 12 days of incubation. One acidic protein (Mr 30K) appeared at 12 days together with two acidic protein spots near tubulin and increased with development. A group of more basic proteins (Mr 94K) was prominent at 6 day incubation and decreased during development. One more basic protein (Mr 20K) was first observed at 18 days of incubation in the metencephalon. It was identified as myelin basic protein, and strikingly increased in all brain regions until hatching. A group of basic proteins with high molecular weight (Mr 94K) appeared at day 12 of incubation, and increased remarkably before hatching. They were identified to be collagen associated with brain capillary vessels. Stimulation by intermittent light in ova from day 10 to day 16 caused a retarded appearance of these collagen proteins, and an increased formation of tubulin in the optic lobe of the developing chick embryo.
Prenatal development of the hippocampus in two strains of inbred mice
Authors: Luzzatto Annarosa Ciofi , Mangano Giorgina , Vonesch Nicoletta
Published: April 2003

In this paper we present some morphological observations on the morphogenesis of the hippocampus in two inbred strains of mice, C57BL/6J (C57) and DBA/2J (DBA), from day 16 (E16) to day 17 (E17) of prenatal life. At E16 some differences in the histoarchitecture of the hippocampal anlage begin to be detectable. At E17 the differences become more relevant, particularly those concerning the lamination pattern. The more relevant differences concern the differentiation of the pyramidal layer, which appears well defined in C57 mice, while in DBA mice there is no clearcut delimitation between the pyramidal layer and the intermediate zone, where numerous migrating neurons are present. These observations may be interpreted in terms of different migration rates for the neurons in the two strains.
Experimental modifications of postnatal differentiation and fate of glial cells related to axo‐glial relationships
Authors: Valat J. , Privat A. , Fulcrand J.
Published: April 2003

The fate of glial cell lines following Wallerian degeneration in the rat optic nerve was analysed after pulse labelling with [3H]thymidine. The rats were unilaterally enucleated at the key stages 2,5,8 and 20 days after birth. Three hours later, they were injected intraperitoneally with [3H]thymidine and killed after 1, 3, 5, 10 and 20 days survival. Oligodendrocytes were the most affected, being unable to differentiate after 2 days enucleation, dying rapidly or transforming into another cell type after 5, 8 and 20 days enucleation. The apparent stability of the astrocyte population is due to an equilibrium between increased differentiation from glioblasts and increased death, the latter being preponderant at the key stage 2 days. Finally, the steady increase in the number of microglia may be due to the transformation from other cells, either glioblasts for the early time intervals or oligodendrocytes later on. It appears, then, that the interrelation between glial cell lines during differentiation is more intricate than previously suspected and is closely dependent, for each line, upon the integrity of axons.
Effects of thyroid hormone on light/dark melatonin synthesis and release by young and maturing rat pineal glands in vitro
Authors: Catala M. D. , Quay W. B. , Timiras P. S.
Published: April 2003

Synthesis and release of melatonin were studied in pineal expiants from 14‐ (young) and 60‐day‐old (‘maturing’) male Long‐Evans rats with or without added thyroid hormone, triiodothyronine (T3), at or near physiological levels and under light and dark conditions. Incubation for 6 hr (1200–1800) was in a synthetic medium; melatonin was measured by radioimmunoassay (RIA). In light, T3 increased melatonin levels in pineal and medium of cultures from either young or maturing animals. In dark, T3 decreased melatonin levels in the pineals of either age, but was without significant effect on levels in the medium. Since it is known from other work that 14‐day‐old rat pineal glands do not yet have a complete sympathetic innervation system, it is here doubly evident that T3 can modulate directly pineal synthesis and release of melatonin, and may not depend upon a mature sympathetic innervation. Light in the studied conditions was permissive from the stimulatory action of T3 on pineal synthesis and release of melatonin in vitro.
Stimulation of neurite outgrowth in vitro by a glycero‐ganglioside
Authors: Cannella Michael S. , Acher Aureliu J. , Ledeen Robert W.
Published: April 2003

A glycerol‐containing analog of ganglioside, with sialic acid attached to a diglyceride‐like structure possessing two ether‐linked alkyl chains, was prepared synthetically and applied exogenously to three culture systems; neuro‐2A neuroblastoma cells, PC12 cells and dorsal root ganglia. This resulted in pronounced stimulation of neunte outgrowth in all three, demonstrating that sialo‐lipids(s) lacking ceramide and possessing sialic acid as the sole carbohydrate are able to promote neuritogenesis in approximately the same manner as naturally occurring gangliosides.
Neurochemical development of the striatum in a precocial (guinea pig) and an altricial (rat) species
Authors: Kalaria R. N. , Prince A. K.
Published: April 2003

In this study, the developmental patterns of key neurotransmitter marker enzymes, namely choline acetyltransferase (ChAT), glutamate decarboxylase (GAD), and tyrosine hydroxylase (TH) in the corpus striatum were compared between the guinea pig and rat. In an attempt to assess cell acquisition and differentiation, striatal DNA and protein content were also determined during development in the two species. The most outstanding feature apparent from these investigations was a sequential maturation of the three neurotransmitter‐synthesizing enzymes: TH and GAD first, followed by ChAT in striata of both species. The developmental increase in DNA content suggests that cell acquisition in the rat striatum is approximately 50% at birth, whereas in the guinea pig, the total population is present before birth, and thereafter cell numbers decline. The accretion of protein, reflecting the increase in region size, continued into adulthood in both species. With emphasis on cholinergic neurons, the neurochemical findings are assessed in relation to the morphological descriptions of cellular changes during pre‐ and postnatal development of the striatum.
Composition and synthesis of polyunsaturated fatty acyl groups in the embryonic brain of the trisomy‐16 mouse
Authors: Brooksbank B. W. L. , Martinez M. , Balázs R.
Published: April 2003

The trisomy‐16 (T‐16) mouse is considered to be a promising model for human trisomy‐21 (T‐21) (Down's syndrome, DS). Therefore, the fatty acyl (PUFA) compositions of phosphoglycerides in embryonic brains (days E‐17 and E‐18) of T‐16 mice have been compared with those of balanced heterozygotic embryos from the same litters, in order to determine whether similar abnormalities are present as have been found in foetal DS brain (Brooksbank et al., 1985, J. Neurochem.44, 869–874). The analyses revealed that the ratio of (n‐3) to (n‐6) PUFA was significantly increased in ethanolamine (EPG) and in choline phosphoglycerides, as it is in EPG in the foetal T‐21 brain. However, the abnormality was not so marked in the murine as in the human trisomy, and the (n‐3)/(n‐6) ratio in EPG was primarily elevated on account of decreased proportions of 20:4(n‐6) and 22:4(n‐6), there being no significant increase in (n‐3) PUFA. The PUFA composition of the phosphoglycerides of the corresponding trisomic and balanced placentae was also determined, but no relevant differences could be discerned between the genetically different tissues.

As 6‐desaturase, the rate‐limiting enzyme system in PUFA synthesis, reacts more readily with (n‐3) than with (n‐6) substrates, the shift in (n‐3)(n‐6) ratio of PUFA might be related to an alteration in 6‐desaturase activity in trisomy. Comparison of the specific activity of 6‐desaturase in fresh brain homogenates of T‐16 embryos with those from balanced litter‐mates revealed, however, no differences.
Circadian patterns of serotonin (5‐HT) accumulation after pargyline treatment in the rat hypothalamus during development
Authors: Jimenez Agnes E. , Walker Richard F.
Published: April 2003

The purpose of this study was to determine if developmental changes in serotonin (5‐HT) synthesis occur during maturation of the 5‐HT circadian rhythm in the rat hypothalamus of 10‐ to 35‐day‐old rats. Pargyline (75 mg/kg, s.c.), a monoamine oxidase (MAO) inhibitor, was administered 30 min prior to decapitation. Hypothalamic 5‐HT concentrations after pargyline treatment were measured at six time points over a 24‐hr interval in male and female rat pups at 10, 20, 30 and 35 days of age.

Daily fluctuations in hypothalamic 5‐HT accumulation were detectable as early as 10 days of age in rats of both sexes. Since the influence of MAO on hypothalamic 5‐HT concentrations was eliminated by pargyline treatment, the findings suggest that changes in tryptophan hydroxylase activity contribute significantly to daily and age‐related patterns of 5‐HT accumulation in the rat hypothalamus during development.

Circadian rhythms in hypothalamic norepinephrine (NE) and dopamine (DA) also occurred during development; however, sex differences were not detected for these biogenic amines. Since catecholamine catabolism is not exclusively mediated by MAO, our findings are insufficient to conclude whether or not sex differences actually exist in patterns of these monoamines.