bluuebunny/crossref_metadata_2025 huggingface dataset:
Ontogeny of opiate receptors in the rat medial preoptic area: Critical periods in regional development
Authors: Hammkr Ronald P.
Published: April 2003

Opiate receptor labeling was examined throughout the early postnatal period using autoradiography to localize and quantify [3H]naloxone binding to μ‐type opiate receptors in the medial preoptic area (MPOA). This region begins to exhibit sexual dimorphism of volume and dendritic growth shortly after birth. A distinct concentration of opiate receptor labeling appears on postnatal day 3 in females: this labeling is directly associated with the sexually dimorphic nucleus of the preoptic area (SDN‐POA). SDN‐POA labeling becomes denser through postnatal day 10 in females and the densely labeled area increases in size to encompass and surround the SDN‐POA. These changes in opiate receptor labeling occur only in females, since males show relatively uniform labeling across the region throughout the early postnatal period.

The critical time of formation of dense MPOA opiate receptor labeling may be related to endogenous MPOA opioid function and to the critical period of dendritic growth of SDN‐POA neurons. The timing of these critical periods and their focus in the SDN‐POA are coincident. The possible role of MPOA opiate receptors in modulating growth of MPOA neurons is discussed.
Postnatal development of conduction velocity and fibre size in the rat tibial nerve
Authors: Vejsada Richard , Paleček Jiří , Hník Pavel , Soukup Tomáš
Published: April 2003

The maximum conduction velocity (CV) and fibre diameters (D) were determined in the tibial nerve of developing rats. In 1‐day‐old rats CV of the fastest motor and sensory fibres (assessed separately) was 1.4 m/sec on the average and increased to 35 m/sec by postnatal day 30. The maximum conduction rate in adult rats ranged from 60 to 84 m/sec. Diameters of at least 100 nerve fibres in each age group were measured in electronmicrographs. The calibre of myelinating fibres in 1‐day‐old rats was 0.5–1.5 μm. By day 90 after birth the range of myelinated fibre size extended to 1.5–12.5 μm. The factor relating conduction rate and total fibre diameter of the largest fibres (i.e. the value of CV/D) was found to vary with age, increasing from 1.1 to 6.2 between postnatal days 1 and 90. These results indicate that functional and morphological properties of peripheral nerve fibres in the rat undergo considerable changes during postnatal ontogeny until they reach adult values.
Protein kinase activities associated with ribosomes of developing rat brain. Identification of eukaryotic initiation factor 2 kinases
Authors: Alcazar Alberto , Fando Juan L. , Azuara Carmen , Galea Elena , Salinas Matilde
Published: April 2003

Protein kinases associated with ribosomes in the brains of suckling (4–10 days) and adult (2 months) rats were extracted from ribosomal fraction with 0.5 M KCl. The different protein kinase activities were characterized by their ability to phosphorylate three exogenous substrates: casein, histone IIs and histone IIIs in the presence of different modulators. Ribosomal salt wash fractions contain a high casein kinase activity which was partially inhibited by heparin and stimulated by calmodulin in the presence of Ca2+, indicating the presence of casein kinase I and II and calcium/calmodulindependent kinases. Cyclic AMP and cyclic GMP‐dependent kinases and protein kinase C (calcium/phospholipids‐dependent kinase) were also present. No differences were found in the casein kinase activities of suckling and adult animals, but histone kinase activities were higher in adult than in suckling animals.

To identify initiation factor 2 kinases, purified factor from adult brains was used as a protein marker. In addition to the phosphorylation of both factor subunits α and β by casein kinase I or II, an increased phosphorylation was detected of a subunit in the presence of cyclic AMP, and β subunit, in the presence of Ca2+/calmodulin or Ca2+/phospholipids.

Present results reinforce our hypothesis that, as occurs in other eukaryotic cells, the decreased rate of protein synthesis during brain development may be regulated by phosphorylation of initiation factor 2.
Effects of neonatal undernutrition of rats on the synthesis of phosphatidylcholine and phosphatidylethanolamine by microsomes from gray matter and white matter
Authors: Reddy T. Sanjeeva , Horrocks Lloyd A.
Published: April 2003

Undernutrition of rats during the suckling period produces deficits of glycerophospholipids in white matter but not in gray matter. The synthetic enzymes, CDPethanolamine:diacylglycerol phosphoethanolaminetransferase (EC 2.7.8.1) and CDPcholine:diacylglycerol phosphocholinetransferase (EC 2.7.8.2), were assayed in washed microsomal fractions from moderately and severely undernourished rats at 21 days of age. Deficits in brain weight were 14 and 31%, respectively. The transferase activities in white matter were more than 2‐fold greater than in gray matter. Moderate undernutrition has less effect on total transferase activities but Km values were increased for CDPethanolamine with phosphoethanolamine transferase and for CDPcholine and dicaprin with phosphocholine transferase. Severe undernutrition produced by feeding the dams a diet with 4% protein gave deficits for phosphoethanolamine transferase of 52 and 55% and for phosphocholine transferase of 40 and 46% for gray matter and white matter, respectively. These results are consistent with the deficits of glycerophospholipids in white matter. Additional factors, such as synthetic rates in vivo and a reduction of turnover rates, must be sought for the sparing of the glycerophospholipid content of gray matter during undernutrition.
Effect of exogenous dopamine on hypothalamic dopamine and norepinephrine concentrations in the neonatal brain in rats
Authors: Ohkura Takeyoshi , Lee J. W. , Hagino N.
Published: April 2003

Hypothalamic dopamine (DA) and norepinephrine (NE) concentrations were studied in the neonatal rats after acute (postnatal day 4) or chronic (postnatal days 1–10) DA injections (0.5 mg in 5% dextrose in 0.45% saline). Acute injection of DA twice on postnatal day 4 resulted in an increase of hypothalamic DA and NE concentrations 16 hr later. Chronic treatment with the DA (twice in a day) for 10 days resulted in a reduction of NE concentration in the hypothalamus. The results of these studies suggest that the amount and duration of exposure to exogenous DA during postnatal development may result in divergent effects on hypothalamic catecholamine concentration.
Some electrophysiological properties of cultured rat cerebral cortical neurons dissociated from fetuses at various gestational ages
Authors: Brodie Chaya , Bak Asia , Sampson S. R.
Published: April 2003

Neurons from dissociated cerebral cortex of fetal rat of different gestational ages were grown in culture for up to 4 weeks. Studies of membrane and action potentials, input resistance, neuron size and neurite outgrowth showed that neurons from 7‐day fetuses develop rapidly both electrophysiologically and morphologically, but are maintained for only about 2 weeks. In contrast, neurons from 14 to 17 day fetuses mature slowly, but can be maintained for at least 4 weeks. Neurons from both young and old fetuses show an increase in resting Em with age, the maximum value of −60 to −65 mV being attained by about 2 weeks. While neurons can be maintained in serum‐free medium, their membrane electrical properties deteriorate with time. Thus, appropriate development of neurons in culture depends upon both the age of the starting tissue and the presence of adequate, but still undefined factors found in animal serum for at least the first several days in culture.
Early cytoarchitectonic development of the anlage of the basal nucleus of meynert in the human fetus
Authors: Kračun Ivica , Rösner Harald
Published: April 2003

The present study describes a short period of cytoarchitectonic development of the anlage of the basal nucleus of Meynert between 9 and 15 weeks of gestation (crown‐rump length 42–120 mm). On the basis of temporo‐spatial reconstruction of the cytoarchitectonic pattern within the basal telencephalon it was evident that magnocellular aggregations of the basal telencephalon contain the most differentiated cells in the whole prosencephalon of the 15‐week‐old human fetus. At this stage of development many magnocellular islands can be observed in the sublenticular region. However, it seems that they are in antero‐posterioral continuation and the real number of magnocellular islands is much smaller than observed in a single section. The most voluminous magnocellular aggregations are situated around the temporal limb of the anterior commissure and below the ventral pallidal surface in the 15th week of gestation. Between 12 and 15 weeks of gestation, at the most rostral levels, the distinct cell group appeared with unique cytoarchitectonic properties (‘albino cell group’). This cell group is situated close to the ventral putaminal surface within the capsula externa fibres and it corresponds to the subputaminal nucleus of Ayala.
Postnatal maturation of brain cholinergic systems in the precocial murid Acomys cahirinus: Comparison with the altricial rat
Authors: Pintor Annita , Alleva Enrico , Michalek Hanna
Published: April 2003

The spiny mouse (Acomys cahirinus) is the only precocial murid species. It has some neuroanatomical peculiarities such as a relatively thin cerebral cortex and a large hippocampus. The levels of choline acetyltransferase. membrane‐bound acetylcholinesterase and muscarinic receptor sites (measured as [3H]quinuclidynil benzilate binding) were assessed in the whole brain on days 1, 7, 14, 21, 28 and 80 (adult), and compared with those of Wistar rats of the corresponding ages. At birth choline acetyltransferase was significantly higher in spiny mice than in rats but the adult levels were similar, with an overall increase of about 5.2‐ and 14‐fold for the former and the latter species, respectively. Membrane‐bound acetylcholinesterase level and maximal density of muscarinic receptor sites in spiny mice were considerably higher at birth, in contrast adult levels were significantly lower than in rats with a respective overall increase of about 1.5‐ and over 4.5‐fold. The high degree of maturity attained at birth by spiny mice partially depends on the long gestation period. However, if we consider postconception age, the maturation of choline acetyltransferase appears to be delayed at birth in the spiny mice, probably in relation to the lack of external stimulation during intrauterine life. In the cerebral cortex, hippocampus and striatum of adult spiny mice, when compared with the rats, there were similar levels of choline acetyltransferase but lower levels of membrane‐bound acetylcholinesterase and, in the cerebral cortex, lower density of muscarinic receptor sites.
Regional and cellular differences in rat brain protein synthesis in vivo and in slices during development
Authors: Shahbazian F.M. , Jacobs Myron , Lajtha Abel
Published: April 2003

We compared the rate of protein synthesis in immature and adult rat brain In vivo to that in brain slices. After the incorporation of a flooding dose of [14C]valine, In vivo and in brain slices, the label in proteins was measured in CNS regions and in neuron‐ and glia‐enriched fractions. In regions In vivo in the adult, incorporation rates in corpus callosum were lower than in other regions, which were similar: in the young, cerebellum showed the highest rates and hypothalamus and cord the lowest. Since hypothalamus and cord were low in the young, there was no change during development in these two areas; in other areas incorporation rates in young were 2–3 times higher than in adult brain proteins. Incorporation rates in slices were lower than In vivo. In the young, cerebellum, olfactory bulb, and cord were close to In vivo, and other areas in slices from young incorporated at 60–90% of In vivo rates. In adult slices incorporation was 5–15% of that In vivo except in olfactory bulb, where it was 30%. In the cellular fractions, incorporation In vivo in young was close in the neuronal and glial fractions; in adults incorporation rates in neurons were higher, as the decrease in development was less in neurons than astrocytes. In slices in young, astrocytes incorporated amino acids at 100% of the In vivo rates, neurons at 60%; in adult slices, incorporation was at only 4–7% of the In vivo rate.

The results show that developmental changes in protein metabolism occur in all brain areas and brain cells, with metabolic rates in young 2–3 times that in adult. Incorporation in vitro is less than In vivo: it is close in immature tissue, but is greatly decreased in adult. Although developmental and postmortem differences in rates of synthesis affect most areas and cells, regional and cellular heterogeneity can be found.
Ontogeny of flash‐evoked potentials in unanesthetized rats
Authors: Rigdon Greg C. , Dyer Robert S.
Published: April 2003

The effects of age and stimulation frequency (0.2/sec, 1.0/sec, 2.0/sec, or 4.0/sec) on flashevoked potentials (FEPs) were investigated in awake, unsedated, unrestrained rats. Animals were tested daily from postnatal day (PND) 8 to PND 20, and every 3 or 4 days thereafter until PND 41. On PND 9, a single negative wave (N1a) was observed following 0.2/sec flash presentation. Animals tested on PND 10 exhibited a positive wave (P2) following the return of peak N1a to baseline. On PND 13 another negative wave (N1) appeared on the leading shoulder of peak N1a. Peak N1 became the dominant negative wave on PND 14. Peak N1a merged into N1 and had disappeared by PND 19. Peak N3 was first observed as a negative shift following peak P2 on PND 15. Peaks N2 and P3 were not observed in the group average waveforms until PND 34. Peak latencies decreased through the fifth postnatal week. Peak amplitudes increased with age until after eye opening (PND 15), but were variable thereafter. No FEPs were observed following higher than 0.2/sec flash presentation until PND 13. Increasing stimulation frequency decreased N1 and P2 peak amplitudes, but had no effect on peak latencies.
Glycinergic systems in the brain stem of developing and adult mice: Effects of taurine
Authors: Kontro Pirjo , Oja Simo S.
Published: April 2003

The release of glycine from slices of the brain stem and binding of strychnine to brain stem membranes were characterized in adult and developing mice. Spontaneous glycine efflux was markedly facilitated by homoexchange with exogenous glycine and moderately by heteroexchange with taurine. Potassium stimulation released more glycine from brain stem slices from adult than from 7‐day‐old mice. Potassium‐stimulated glycine release was also potentiated by glycine and by the novel anticonvulsant taurine derivatives. One population of strychnine‐binding sites was found in both mature and immature brain stem. The number of binding sites increased with age, whereas the affinity of the sites for strychnine remained the same. The glycine inhibition was stronger in adult than in developing mice. In the presence of taurine the affinity for strychnine decreased without any change in the maximal binding capacity, suggesting a competitive type of inhibition. The binding constant and maximal binding capacity of strychnine increased in the presence of NaCl (200 mM) both in adult and 7‐day‐old mice. The calculated IC50 values for displacement of strychnine binding by glycine, taurine and β‐alanine were higher in the presence than in the absence of sodium. The results show that the evoked release of glycine and the number of binding sites of strychnine increase during postnatal development in the mouse but that their characteristics do not change.
Development of axonal‐oligodendroglial relationships and junctions during myelination of the optic nerve
Authors: Wiggins Richard C. , Chongjie Guo , Delaney Courtney , Samorajski Thaddeus
Published: April 2003

The early stages of myelination were examined in optic nerves of rats aged 12–15 days. The initial association between oligodendroglial processes and bare axons involves no junctional specialization, as the axoglial extracellular space remains unaltered. Following ensheathment by a collar of glial cytoplasm, at least one full rotation of mesaxon was evident before compact myelin formed. Furthermore, myelin was generally evident before a second rotation was completed. In longitudinal sections, an axoglial junction was always observed beginning on the first paranodal loop, continuing through to the last (or outermost) loop. Thus, the formation of myelin and elaboration of a junctional complex in the paranodal region follow a promyelination phase and appear to be synchronous (and possibly related) events. Although the paranodal plasmalemma and axolemma are in close apposition, there is a material in the extracellular space that precipitates phosphotungstic acid, a characteristic that appears to be featured in a number of different types of cell junctions.
Effects of Trembler mouse serum and laminin on oligodendrocyte proliferation and differentiation in culture
Authors: Hantaz‐Ambroise Djennet , Vigny Marc , Alliot Françoise
Published: April 2003

Oligodendrocytes in primary cultures derived from rat embryo spinal cord were examined in control medium and in Trembler mouse serum (TMS)‐supplemented medium. The Oligodendrocytes were identified on the basis of the synthesis and surface expression of galactocerebrosides revealed by a monoclonal antibody directed against this component. We noticed two effects of TMS compared to control mouse serum. First, our results revealed that in TMS medium there is a mitogenic response of galactocerebroside (GalC)‐positive cells. Second, in the presence of TMS, Oligodendrocytes do not develop processes as they do in the presence of normal mouse serum. When laminin, a basal lamina component was added to TMS medium, GalC+ Oligodendrocytes decreased in number and differentiation was normal. Possible explanations of the effects of TMS and laminin on oligodendrocyte proliferation and differentiation are discussed.
Cathepsin D and 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase in developing human foetal brain
Authors: Mahajan R. G. , Mandal S. , Mukherjee K. L.
Published: April 2003

Three peaks of proteinases were observed with hemoglobin, bovine serum albumin and casein as substrates at the pH of 3.5, 6.5 and 8.5, in prenatal human cerebral cortex. Cathepsin D (EC 3.4.23.5) was the most prominent, with hemoglobin as the preferred substrate. The enzyme was partially purified by Concanavalin A — Sepharose affinity chromatography and the nature of the active site was assessed with proteinase inhibitors. Inhibitor studies showed that similar to pepstatin A, benzethonium chloride was also strongly inhibitory to the enzyme. The distribution of cathepsin D, a neuronal marker, and 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase (EC 3.1.4.37), a oligodendroglial marker in foetal brain regions with increasing gestation revealed that neurogenesis and gliogenesis occur concomitantly from earlier periods of gestation. Glial marker acquisition was particularly high in medulla and in spinal cord between 20 and 25 weeks of gestation.
Neuronal aggregation and neurotransmitter regulation: Partial purification and characterization of a membrane‐derived factor
Authors: Adler Joshua E.
Published: April 2003

Cell membrane contact induces marked differential changes in neurotransmitter expression. In cultures of virtually pure dissociated sympathetic neurons, when such contact is provided by either high cell densities or addition of membranes derived from specific tissues, there is a marked increase in cell‐specific content of substance P and de novo induction of choline acetyltransferase. To identify molecular mechanisms underlying regulation of transmitter expression by neuronal aggregation and membrane contact, we have begun to isolate and characterize a membrane‐associated factor responsible for stimulation of choline acetyltransferase activity. The factor was found in substantial quantities in membranes from adult rat spinal cord as well as from sympathetic and sensory ganglia. Ionic mechanisms were employed to extract transmitter‐inducing activity from spinal cord membranes in soluble form. The solubilized factor was then partially purified by ion exchange and gel filtration chromatography. It appears to be an extrinsic (non‐integral) protein with an apparent molecular weight of 27. It is inactivated by trypsin and chymotrypsin, but is only moderately sensitive to heat inactivation, retaining activity at 60°C but not at 90°C. Neuronal perikaryal contact via aggregation represents a critical mechanism by which neurons themselves may influence phenotypic expression. Membrane localization of the factor provides a means by which cell contact may regulate transmitter expression.
Cytochrome c oxidase during human fetal development
Authors: Moggio Maurizio , Bresolin Nereo , Scarpini Elio , Adobbati Laura , Prelle Alessandro , Gallanti Andrea , Bet Luciano , Fortunato Francesco , Pellegrini Giulio , Scarlato Guglielmo
Published: April 2003

Histochemical, biochemical and immunologic analysis of cytochrome c oxidase (COX) in skeletal muscle, heart and kidney during human fetal development was performed. COX histochemical activity was present only in few muscle fibres from the 11th to the 20th week of gestation. At the same developmental stage intrafusal muscle fibres, heart and kidney already showed strong activity. At the 28th week of gestation muscular COX activity was present in about 90% of the fibres. Tissue biochemical analysis confirmed these histochemical findings. Histochemical and biochemical findings compared to the immunocytochemical results and ELISA indicate that COX activity parallels the progressive synthesis of the enzyme in each tissue.
Ontogeny of the metencephalic, mesencephalic and diencephalic content of catecholamines as measured by high performance liquid chromatography with electrochemical detection
Authors: Parés‐Herbuté N. , Tapia‐Arancibia L. , Astier H.
Published: April 2003

Developmental changes in norepinephrine (NE), dopamine (DA) and epinephrine (E) contents of the rat metencephalon, mesencephalon and diencephalon, have been measured by high performance liquid chromatography with electrochemical detection, from fetal stages (E15 or E17 to E21) to postnatal days (P0 to P30) and compared to the adult levels. The data show a biphasic pattern in NE changes of the three brain areas, with a first increase in the late prenatal period, followed by a further development from PO to P18, thus reaching the adult levels. A similar pattern of development is found for the mesencephalic and diencephalic DA contents. The E levels of the diencephalon are very low in comparison to the NE and DA concentrations, but present a gradual increase from E17 to P18. The results correlate with the development of catecholamine systems in brain area as measured by other methodological approaches.
Developing rat cerebellum—III Effects of abnormal thyroid states and undernutrition on gangliosides
Authors: Vitiello F. , Clos J. , Di Benedetta C. , Gombos G.
Published: April 2003

Alteration of rat postnatal cerebellar development produced by undernutrition, thyroxine treatment and thyroid deficiency also involves ganglioside deposition. The distribution of the different ganglioside types is apparently unaffected but quantitative alterations are present that reflect the reduction of cell number and cell process surface in the adult, and either acceleration or slowing down or reduction of cell formation and maturation occurring during cerebellar development in the three experimental situations.
Effects of glycosaminoglycans and proteinase inhibitors on astroglia‐induced detachment of cultured rat cerebellar neurons
Authors: Gilad Gad M. , Dahl Doris , Gilad Varda H.
Published: April 2003

Neurons in mixed primary embryonic CNS cultures degenerate secondary to their detachment from the substratum. The present study demonstrates that in primary cultures of postnatal cerebellum, detachment of neurons can be prevented by antiproliferative drugs which inhibit the growth of astroglia. Several types of proteinase inhibitors did not affect the process of detachment. However, among several types of glycosaminoglycans, heparan sulfate and to a lesser degree heparin, could reversibly inhibit neuron detachment without causing morphological changes of astroglia. The enzymes heparitinase and heparinase caused neuron detachment but only within the first 24–48 hr after plating and not in older cultures. We conclude: (1) cerebellar interneurons in culture are not dependent on astroglia for their survival; (2) astroglia are most probably responsible for neuron detachment via a membrane associated activity and (3) heparan sulfate‐like glycosaminoglycans are important in neuronsubstratum attachment.
Embryogenesis of the avian iris sphincter muscle: in vivo and in vitro studies
Authors: Peirone Saverio M. , Sisto‐Daneo Laura , Filogamo Guido
Published: April 2003

The histogenesis of iris sphincter muscle was studied in birds. Chick embryo iris “anlagen”, aged from 3 days (st. 18 H.H.) to hatching, were examined. At the 4th day (st. 24 H.H.), nerve fibers were observed in the mesenchyme of the inferotemporal quadrant of the optic cup near the colobomic fissure. Among the mesenchymal cells, there were cells characterized by AChE activity, presence of desmin filaments, exhibiting ACh receptors, and ultrastructurally similar to the presumptive skeletal myoblasts. One day later (st. 27 H.H.), these myoblasts could be cultivated. The formation of myotubes began between 10 and 12 days. From 9 to 14 days, cells left the anterior epithelium of the iris to give rise to the smooth iris muscle; during this evolution some epithelial cells fused with the myotubes taking part in the histogenesis of striated muscle. The possibility of a neurogenic determination for the iris skeletal muscle is discussed.
Effects of tunicamycin on the avoidance reaction of epidermis by sensory neurites in co‐cultures
Authors: Fichard Agnes , Verna Jean‐Marc , Saxod Raymond
Published: April 2003

In 7‐day chick embryo dorsal root ganglia and epidermis or dermis co‐cultures, nerve fibres establish contacts with dermis while avoiding epidermis. Previous results have indicated that factor(s) secreted by epidermis could be involved in this avoidance reaction. The present study demonstrates that the avoidance reaction is abolished when epidermal cells are treated by the N‐linked glycoproteins synthesis inhibitor, tunicamycin. The same result is obtained after monensin treatment. The epidermal cell viability, development and total protein secretion are not significantly affected by tunicamycin, as demonstrated by trypan blue exclusion, electron microscopy and SDS‐PAGE electrophoresis after 35S‐methionine labelling. It has thus been concluded that the avoidance factor is glycoproteic in nature. It is also suggested that this factor possibly contains chondroitin‐6‐sulphate moieties.
Prenatal phenytoin exposure decreases neuronal membrane order in rat offspring hippocampus
Authors: Vorhees Charles V. , Rauch Scott L. , Hitzemann Robert J.
Published: April 2003

Pregnant Sprague‐Dawley CD rats were administered 0 or 200 mg/kg of phenytoin by gavage on days 7–18 of gestation, with controls pair‐fed to the phenytoin exposed dams. At birth, litter sizes were standardized to 10, balancing for sex, and were reared by their biological dams until either day 3 or 28. At each of these ages half of the litters from each group were used to determine synaptic plasma membrane order in selected brain regions (cerebellum, cortex, hippocampus) by fluorescence polarization using the probe 1,6‐diphenyl‐1,3,5‐hexatriene (DPH). No significant differences in membrane anisotropy were noted in 3‐day‐old phenytoin offspring, but a reduction in anisotropy in 28‐day‐old phenytoin offspring hippocampal regions was observed. The effect was specific in that no changes were found in the cerebellum or cortex at this age. The magnitude of the change corresponded to an approximately 3–5°C increase in temperature and to changes produced by other known membrane disordering agents, such as ethanol. The data, together with previous findings of memory impairments in phenytoin offspring, support an association between the hippocampal membrane disordering effect and functional impairments produced by prenatal phenytoin exposure.
Substance P‐like immunoreactivity in human prenatal hippocampal formation
Authors: Del Fiacco M. , Diana A. , Floris A. , Quartu M.
Published: April 2003

Presence and localization of substance P‐like immunoreactive neuronal structures in human hippocampal formation during prenatal stages of ontogenesis are reported. In fetuses at 16 and 17 weeks of gestation immunoreactivity is very scarce and represented only by sporadic fibres in Ammon's horn and the entorhinal area. In specimens at 25 and 26 weeks of gestation, more or less intensely labelled perikarya of different morphology are easily detectable in deep layers of Ammon's horn and the hilus of fascia dentata. Immunoreactive beaded fibres are also present at this stage. The possibility of the existence of a substance P‐containing extrinsic projection to Ammon's horn is pointed out.
Acidic and basic fibroblast growth factor levels in spinal cord cultures are not regulated by alterations in heparan sulfate proteoglycan expression
Authors: Whittemore Scott R. , White Linda A. , Sanon Henry R.
Published: April 2003

The present study was undertaken to assess both the levels of acidic and basic fibroblast growth factors in spinal cord cultures and to determine how they were presented to responsive cells. Western blots detected a single acidic fibroblast growth factor‐like protein (17 kDa) and two (18 kDa, 24 kDa) basic fibroblast growth factor‐immunoreactive proteins, the levels of which varied with the antibody used. Levels of all three proteins were unaltered in cultures grown in the presence of a mitotic inhibitor, which greatly reduced the number of astrocytes. Cell blots showed increased survival of spinal cord neurons at Mr that corresponded with the three proteins detected immunologically. Solubilized cultures separated on a P100 column showed mitogenic activity for NIH3T3 cells from 17–18 and 24 kDa fractions. Treatment of the cultures with heparitinase did not decrease the levels of acidic and basic fibroblast growth factors detected by Western blots, suggesting that these proteins were not associated with extracellular membrane heparan sulfate proteoglycans. The major fraction of both proteins appeared to be intracellular with a minor amount complexed with extracellular matrix proteins. An inhibitor of xylose‐linked proteoglycan synthesis significantly altered heparan sulfate proteoglycan deposition into extracellular matrix, but did not alter the levels of acidic or basic fibroblast growth factors detected by Western blots, or the levels of choline acetyltransferase, glutamic acid decarboxylase, or aspartate aminotransferase activities. These results indicate that both acidic and basic fibroblast growth factors are stored predominantly intracellularly, with only a minor fraction complexed with extracellular proteins. We suggest that these intracellular proteins may be released following injury in the CNS and mediate a cascade of neuroprotective events.
Lack of thyroid hormones but not their excess affects the maturation of olfactory receptor neurons: A quantitative morphologic study in the postnatal rat
Authors: Paternostro Mark A. , Meisami Esmail
Published: April 2003

To study quantitatively actions of thyroid hormones on maturation of olfactory receptor neurons (ORN), surface density and total number of receptor knobs (1 knob/ORN) were measured in 1 μ sections from septal olfactory epithelium of newborn, 12‐ and 25 day normal, hypo‐ and hyperthyroid rats. Hypothyroidism was induced by adding to drinking water n‐propylthiouracil (0.1% w/v) from birth. Hyperthyroidism was induced by daily injection of pups with T4 (1‐thyroxine, 0.3 μg/g b.w. s.c.). Experimental pups showed all the signs of hypo‐ and hyperthyroidism. Between days 1–25, normal pups showed marked increase in surface area of septal olfactory epithelium (6 ×), total number (12 ×) and surface density (#/mm2, 2 ×) of mature ORNs. Thyroid deficient rats showed, by day 12, marked reductions in epithelial surface area and total number of mature ORNs; these and the surface density deficits became very pronounced by 25 day (30% area, 27% density, 47% # mature ORNs). Hyperthyroid rats, however, did not show an increase in any of these parameters over controls. Although total number of ORNs (mature and immature), as measured by number of nuclei, was also reduced in hypothyroid pups, surface density was not altered, indicating that maturation of ORNs, but not their local accretion is altered in thyroid deficiency. The results indicate that thyroid hormones are essential for normal proliferative expansion of olfactory epithelium and for maturation of ORNs postnatally. These actions of thyroid hormones are not increased or accelerated by excess T4 suggesting saturation of the hormone receptor system at the normal plasma level.
A sensitive period in gestation for nicotine acceleration of neuromuscular maturation
Authors: Rose Kenneth J. , Strand Fleur L.
Published: April 2003

Nicotine, administered to pregnant Sprague‐Dawley rat dams during gestation, altered the maturation of the developing extensor digitorum longus (EDL) muscle‐peroneal nerve complex of the 2‐week‐old offspring. Initial isometric twitch time to peak and rate of rise of tension and tetanus time to peak tension of the group treated with nicotine during gestational (G) days G3–G8 were faster than controls indicating accelerated maturation of EDL muscle. Contractile parameters of the group treated with nicotine during G9–G13, a period immediately prior to muscle innervation, differed little from control. Nicotine administered during G14–G21 significantly increased twitch and tetanus tension and twitch rate of rise. There was little to no effect on motor unit size or number of motor units with nicotine during any of the three prenatal periods. Thus, while late prenatal nicotine administration primarily altered the strength of muscle, early gestational administration of nicotine increased the rate of muscle development suggesting a possible sensitive period for the accelerative action of nicotine on muscle maturation at this time.
Muscle‐derived factors enhance cholinergic neuronal expression in the chick embryo—I. In ovo studies
Authors: Brodie Chaya , Vernadakis Antonia
Published: April 2003

The effects of muscle‐derived factors were studied in the chick embryo in ovo, during early neuroembryogenesis. Limb muscle extract (LME) administration during embryonic period E1–E7 produced a significant increase in choline acetyltransferase activity of both spinal cord and brain in 8‐day‐old chick embryos. Similar treatment failed to induce significant change in the GABAergic phenotypes as assessed by the activity of the enzyme glutamic acid decarboxylase. Administration of limb muscle extract at either embryonic days 1–3 or 4–7 produced a significant increase in choline acetyltransferase activity in the brain, indicating that the critical period of limb muscle extract in the brain to be between embryonic days E1 and E7, a period of neuronal proliferation and differentiation in the brain. On the other hand, LME administration produced no effect on spinal cord choline acetyltransferase activity when given at embryonic days 1–3, whereas it produced a marked increase when given at embryonic days 4–7. Thus, the critical period of limb muscle extract effect in the spinal cord appears to be confined to embryonic days E4–E7, a period of neuronal differentiation and cell death in the spinal cord.

These findings indicate that the cholinotrophic activity of muscle‐derived factors is not limited to the muscle target tissues but have a general effect on cholinergic neurons in the CNS. Whether these cholinotrophic effects are mediated by a common factor or by different factors is still under investigation.
The nerve growth factor receptor gene is expressed in both neuronal and non‐neuronal tissues in the human fetus
Authors: Ernfors Patrik , Wetmore Cynthia , Eriksdotter‐Nilsson Maria , Bygdeman Marc , Strömberg Ingrid , Olson Lars , Persson Håkan
Published: April 2003

In situ hybridization was used to study expression of β‐nerve growth factor receptor (NGF‐R) mRNA in the early human fetus. In 8‐ to 12‐week old fetuses, high labelling was found over motoneurons along the entire length of the lateral motor column. High levels of NGF‐R mRNA were also seen over most developing nerve cell bodies in both the dorsomedial and ventrolateral part of the dorsal root ganglia. Lower, but clearly specific labelling was detected over a subpopulation of cells in Auerbach's plexus in the intestines. Evidence for a non‐neuronal expression of NGF‐R mRNA came from labelling over a subpopulation of cells in glomeruli of the kidney in a 12‐week old human embryo. Myoblasts in skeletal muscle anlagen were labelled as well as cells along peripheral nerve. The wide‐spread expression of NGF‐R mRNA in the human fetus suggests that the NGF‐R is important for development of a variety of different tissues of both neuronal and non‐neuronal origin.
Tubulin gene expression during synaptogenesis in rat, mouse and chick brain
Authors: Bhattacharya B. , Sarkar P.K.
Published: April 2003

Studies on tubulin gene expression in brains from three different species, viz rat, mouse and chick, varying with respect to their periods of synaptogenesis, show that the rise and fall in the level of tubulin during synaptogenesis is closely parallel to that of tubulin mRNA. In all three species, the onset of synaptogenesis is accompanied by a dramatic rise in the level of tubulin which continues till the midphase and then declines to adult level by the end of synaptogenesis. The chick α‐ and β‐tubulin coding region probes, pT1 and pT2, which have a 80–90% homology with rat/mouse sequences, were employed to determine the overall levels of α‐ and β‐tubulin mRNA in all samples. Quantitation of tubulin mRNA by dot hybridization revealed a closely parallel change in the levels of both α‐ and β‐tubulin mRNA. In analogy with that of tubulin, the mRNA levels in rat and mouse brain increased progressively from birth till postnatal day 5 and that in the chick brain increased from day 7 till day 11 of embryonic development. In all three cases, the peak levels of tubulin mRNA corresponded closely with the midphase of synaptogenesis and declined almost to adult levels by the end of synaptogenesis. The sudden decline in the level of tubulin as well as its mRNA during the middle of synaptogenesis suggests that the repression of tubulin gene expression is neither due to cessation of cell division nor cell differentiation. Instead, it is likely to be due to the autoregulatory property of tubulin which leads to rapid turnover of its own mRNA when a sufficient level of intracellular tubulin accumulates during the midphase of synaptogenesis.
The extracellular matrix of cerebral gray matter: Golgi's pericellular net and nissl's nervösen Grau revisited
Authors: Bignami A. , Asher R. , Perides G. , Rahemtulla F.
Published: April 2003

Glial hyaluronate‐binding protein (GHAP) and a large aggregating chondroitin sulfate proteoglycan (Ag‐Pg) similar to a fibroblast proteoglycan (versican) were localized in bovine, dog and cat central nervous system (CNS) gray matter by indirect immunofluorescence. The distribution of the two hyaluronate‐binding proteins was identical with that of hyaluronate, an extracellular glycosaminoglycan. All substances formed a finely reticulated mesh in the neuropil with a condensation of the stain around large neurons. It is concluded that in gray matter, as in white matter, the extracellular matrix (ECM) contains hyaluronate‐protein aggregates. We suggest that the hyaluronate‐protein aggregates correspond to the pericellular network first described by Golgi.
Regulation of the low affinity receptor for nerve growth factor, p75NGFR, in the olfactory system of neonatal and adult rat
Authors: Turner Christopher P. , Perez‐Polo J. Regino
Published: April 2003

Using MAb192, a monoclonal antibody to the rat low affinity receptor for nerve growth factor (p75NGFR), we determined the expression of p75NGFR in rat neonatal and adult olfactory system. In neonates and adults, we observed discrete p75NGFR‐immunoreactivity (p75NGFR‐ir) in the glomerular layer of the main olfactory bulb. The intensity and organization of glomerular p75NGFR‐ir increased with age. This was in keeping with the general ontogeny of the main olfactory bulb. Generally, granule cells, mitral cells and periglomerular cells of the main olfactory bulb were not specifically stained. However, in early neonates, granule cells close to the lateral olfactory tract exhibited p75NGFR‐ir. Additional specific staining was found in the olfactory receptor neurons of neonatal and adult olfactory neuroepithelium, the olfactory fascicles and in the glomeruli of the accessory olfactory bulb. The intensity, but not the organization, of specific staining in the accessory olfactory bulb increased as the animal matured. We believe that p75NGFR‐ir in the olfactory system is associated with its unique capacity to regenerate its peripheral input to the main olfactory bulb. The presence of p75NGFR‐ir in the accessory olfactory bulb would suggest a broader role for this protein. Here we discuss the implications of these findings with regards to nerve growth factor, other trophic molecules, and their receptors. The data presented provide a foundation for studies involving manipulation of regenerative phenomena while monitoring the expression of neurotrophic factors and their receptors.
Neonatal prazosin exposure reduces ovarian weight and estrogen receptor binding in adult female rats
Authors: Fitch Roslyn Holly , Feder Harvey
Published: April 2003

Exposure of estrogen treated adult female guinea pigs to the alpha‐1 antagonist prazosin has been shown to reduce levels of estrogen binding in the hypothalamus and preoptic area. To further investigate this interaction between the noradrenergic and neuroendocrine axes, newborn female rat pups received an s.c. implant of prazosin (0.0125 mg/day for 5 days) or placebo. In adulthood, subjects were sacrificed by perfusion with DMSO on the morning of proestrous. Tissue analysis of the medial preoptic area, corticomedial amygdala, and mediobassal hypothalamus revealed that cytosolic estrogen binding was significantly reduced in all three areas for the prazosin treated group as compared to controls. Ovarian weight was also significantly reduced in the prazosin treated group, although uterine weight was unaffected. Interestingly, prazosin treated females showed a post‐pubertal increase in body weight characteristic of ovariectomized females, while controls showed no such increase.

These results support the existence of a significant developmental interaction between the noradrenergic system and the neuroendocrine axis as measured by ovarian weight and estrogen binding in the brain.
Postnatal laminar development of cholinergic receptors, protein kinase C and dihydropyridine‐sensitive calcium antagonist binding in rat visual cortex. Effect of visual deprivation
Authors: Kumar Ashok , Schliebs Reinhard
Published: April 2003

The postnatal ontogeny of 3H‐pirenzepine and 3H‐oxotremorine‐M binding to M1‐ and M2‐muscarinic acetylcholine receptors, respectively, as well as 3H‐nicotine binding to neuronal nicotinic acetylcholine receptors, 3H‐phorbol‐12,13‐dibutyrate binding to protein kinase C and 3H‐PN200‐110 binding to dihydropyridine‐sensitive calcium channels was studied in individual layers of the visual cortex in both normally raised and monocularly deprived rats (one eyelid sutured at the age of 11 days) using quantitative receptor autoradiography. Postnatal ontogeny of M1‐muscarinic receptors is similar in each visual cortical layer reaching the highest receptor density at the age of 15 days, whereas M2‐muscarinic binding sites increase gradually from day 7 up to day 34. Highest 3H‐nicotine binding is reached in all visual cortical layers at postnatal day 15 followed by a considerable decrease in binding sites until day 25. Phorbol ester binding rises considerably from birth until the age of 15 days reaching nearly the adult value in the upper layers, whereas in layers V and VI a marked decrease in binding levels until adulthood can be observed. The developmental course of 3H‐PN200‐110 binding sites is similar in all visual cortical layers and exhibits a moderate rise in binding sites between postnatal days 7 and 15. Monocular deprivation results in permanent changes in the developmental profiles of phorbol ester as well as calcium antagonist binding sites, whereas the alterations in muscarinic and nicotinic cholinergic receptors folloing monocular deprivation are only of transient nature. The data presented suggest that acetylcholine plays a modulatory role during a certain period of early postnatal maturation of the visual cortex by affecting both cholinergic receptors and associated second messenger cascades.
Differences in vimentin distribution in glial cells in culture revealed with an antibody against a phosphorylated epitope
Authors: Ciesielski‐Treska Jaroslava , Ulrich Gabrielle , Aunis Dominique
Published: April 2003

We have previously described that spatial and temporal changes in the organization of vimentin that are correlated with protein kinase C (PKC)‐induced phosphorylation of vimentin can be detected with the mouse monoclonal antibody B3 in cultures of amoeboid microglia [Ciesielski‐Treska et al. (1991) J. Neurosci. Res.29, 362–378]. The antibodies were generated to native form of vimentin‐containing filaments and antibody B3 reveals a restricted immunostaining of vimentin in glial cells from human, rat and mouse origin. In the present study we show the distribution of epitope B3 analyzed by immunofluorescence within defined populations of rat glial cells. Relatively high immunoreactivity was found in Type 1 astrocytes, Type 2 astrocytes and oligodendrocytes had low immunoreactivity. Although the results suggested that in Type 1 astrocytes the phosphorylated epitope is prominent, its phosphorylation was not found to be cell cycle‐dependent, and appeared unrelated to the organizational changes of intermediate filaments associated with the morphological conversion of polygonal to stellate astrocytes. As expected, the immunofluorescence was increased by exposition of astrocyte cultures to an activator of PKC, confirming our previous conclusion that the immunoreactivity of the epitope B3 depends on PKC‐mediated phosphorylation. In addition, the finding that the immunofluorescence of vimentin was more homogeneous in quiescent, serum‐deprived astrocytes and also in astrocytes exposed to an inhibitor of protein synthesis, cycloheximide, may suggest that phosphorylation of the epitope B3 depends on a protein factor present in fetal calf serum. The immunofluorescence studies on cultures enriched in Type 2 astrocytes and in oligodendrocytes indicate that the epitope B3 is hypophosphorylated in glial cells of this lineage and becomes dephosphorylated after terminal differentiation of oligodendrocytes. These observations suggest that in Type 2 astrocytes and in oligodendrocytes the low level of phosphorylation of vimentin could be related to the down regulation in vimentin expression.