摘要:

AbstractThe effect of ethanol on the development of the main olfactory bulb (OB) was examined by light and electron microscopy in 21‐day‐old Swiss mice (CD‐1), exposed to ethanol from embryonic day 13 to postnatal day 21. Two control groups were included in the study to rule out changes due to malnourishment: a normal control group, whose dams were fed rodent lab chow throughout the study and a pairfed group, whose dams were fed the same amount of liquid diet as the dams in the ethanol group but with sucrose replacement of ethanol. Somatic growth, measured by length and body weight, was retarded to the same degree in ethanol and pairfed mice, indicating a similar level of malnourishment in both groups without an additional ethanol effect. The most striking change in olfactory bulb development was the stunted growth of this structure in the ethanol‐exposed animals with reductions in the volume of the glomerular. external plexiform and granular cell layers. The laminar organization and cellular cytoarchitecture were not substantially altered by ethanol or malnourishment except for a retarded migration of the periglomerular cells in the ethanol‐treated group. Examination of synaptogenesis in the external plexiform layer (EPL) of olfactory bulb from 21‐day‐old mice in the three groups revealed no treatment‐related changes in synaptic structure, appositional length or ratios of the two dominant type of EPL synapses, which are formed between dendrites of the output neurons (mitral and tufted cells) and granule cells. However, morphometric analysis revealed elevated densities of both synaptic types in the ethanol‐exposed group but with no change in the total synaptic number per olfactory bulb. The results suggest that ethanol exposure of mice after the latter half of gestation and during the postnatal period primarily affects the growth of the olfactory bulb probably by decreasing neuronal cell growth, and/or proliferation but has little affect on other aspects of maturation such as formation of cortical structure, differentiation and synaptogenesis.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90026-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractPerformance in the hippocampal eight arm maze was studied in mice after early exposure to phenobarbital (PhB). since previous studies suggested that these animals suffered neural deficits in the hippocampus. For prenatal exposure pregnant mothers were fed 3 g PhB/kg milled food on gestation days 9–18. Neonates were injected daily with 50 mg PhB/kg. on postnatal days 2–21. After a week of water deprivation, the animals were tested at age 50 days for 5 days preceded by 1 day of habituation. Deficits in eight arm maze performance were demonstrated in early treated mice on every testing day. For example, on day 5 of testing the number of correct entries during the first eight attempts in the prenatally treated group were 12% below control level (P<0.01), the respective reduction in the neonatal group was 10% (P<0.001). The number of trials needed to enter all arms on day 5 was 27% above control level among prenatally treated mice (P<0.001), and 13% in neonatally treated mice (P<0.05). It took prenatal PhB animals twice the time to reach criterion than their controls (P<0.001) and four times as long for neonatally treated mice (P<0.001).

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90027-9

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractNeurogenesis in the magnocellular basal telencephalic nuclei of the rat was examined with [3H]thymidine autoradiography. The experimental animals were the offspring of pregnant females given two injections of [3H]thymidine on consecutive embryonic (E) days (E12–E13, E13–E14, … E21–E22). On postnatal day (P) 60, the percentage of labeled cells and the proportion of cells originating during 24 h periods were quantified at several anatomical levels throughout the magnocellular basal telencephalic nuclei. The neurons of the horizontal limb of the diagonal band originate mainly between E13 and E16 in a combined rostral‐to‐caudal and lateral‐to‐medial gradient. The neurogenetic gradients in the horizontal limb are continued by generation patterns of cells in the vertical limb of the diagonal band‐medial septal complex, the large cells in the polymorph layer of the olfactory tubercle, and the large cells of the anterior amygdaloid area. The substantia innominata originates between E13 and E17 in combined caudal‐to‐rostral and lateral‐to‐medial gradients. The globus pallidus originates between E13 and E17 in combined caudal‐to‐rostral, ventral‐to‐dorsal and medial‐to‐lateral gradients. The entopeduncular nucleus originates between E12 and E14 in a ‘sandwich’ gradient where neurons in the core of the nucleus are older than those in either the anterior or posterior ends. There is an overall superficial (ventral) to deep (dorsal) neurogenetic gradient between the magnocellular basal nuclei present at any given rostrocaudal level. An important finding is that neurogenetic gradients in the individual components of the magnocellular basal nuclei are alike (with the possible exception of the entopeduncular nucleus) indicating they are part of a single system. Finally, evidence is presented that neurogenetic gradients in the magnocellular basal telencephalic neurons can be correlated with their anatomical projections to the cerebral cortex.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90028-0

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractModifications of glycosaminoglycans were studied during rat cerebellum ontogenesis. Levels of both hyaluronic acid and sulphated glycosaminoglycans increase during development but not at the same rate as cerebellar size or proteins. As in the rest of the brain, cerebellar hyaluronic acid concentration decreases during development but not, as expected, in parallel with the loss of tissue water content. In contrast to forebrain, the concentration of cerebellar sulphated glycosaminoglycans decreases at a slow rate. The correlation, suggested by several authors, between glycosaminoglycans concentration and tissue hydratation, cell migration and myelination were not confirmed in developing rat cerebellum.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90029-2

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractTransferrin is a growth‐promoting plasma protein which is known to occur within developing neurons. Since little information exists on the process by which transferrin is internalized by neurons, we studied this process using dissociated embryonic chicken dorsal root ganglion neurons in culture. Cultured dorsal root ganglion neurons were incubated in the presence of 3.75 nM125I‐transferrin at 37°C, the cultures were extensively washed, the neurons were solubilized in a Triton‐containing buffer and internalized125I‐transferrin was quantified with a gamma counter.125I‐transferrin was internalized in a linear fashion for at least 60 min, and this uptake was abolished by the presence of 1.25 μM unlabeled transferrin. No competition for the uptake of125I‐transferrin was observed in the presence of 1.25 μM ovalbumin, cytochromec, hemoglobin, insulin, horseradish peroxidase, aldolase or the carboxyl‐terminal fragment (‘half‐site’) of transferrin. By contrast, uptake was inhibited by approximately 50% in the presence of the amino‐terminal fragment (‘half‐site’) of transferrin (1.25 μM) or in the presence of concanavalin A (1.25 μM). The binding of transferrin conjugated to fluorescein isothiocyanate to neurons at 4°C and its subsequent internalization at 37°C was demonstrated by fluorescence microscopy of unfixed cells following incubation of the neurons in the presence of the fluorescently labeled protein. Furthermore, the transferrin receptors were visualized immunocytochemically on the surface membranes of dorsal root ganglion neurons using rabbit antibodies directed against transferrin receptors from chicken reticulocytes. From these data, we conclude that transferrin is internalized by neurons via receptor‐mediated endocytosis, and suggest that this protein may serve an important role in the development and survival of dorsal root ganglion neurons.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90030-9

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractSubstance P‐like immunoreactivity (SPLI) has been observed in cell bodies of fetal cranial parasympathetic ganglia of rat. It first appears at day 16 of gestation at the same time as in cranial sensory ganglia. From day 17 to 21, SPLI neurons constitute most, if not all, submandibular‐sublingual and intralingual ganglia, they form 30–40% of otic and pterygopalatine ganglia and numerous such neurons are found in the myenteric plexus of the esophagus as well as in pharyngeal and buccal walls. The immunoreactive material is thinly granular, and its appearance does not change with prenatal development. The immunoreactivity in cell bodies of parasympathetic ganglia decreases at the end of the gestational period, and cannot be evidenced any more in most cells of normal adult ganglia. However, the corresponding SPLI fibers remain intensely immunoreactive. When grafted to rat irides, which have been chemically depleted of intrinsic SPLI fibers, submandibular, otic and pterygopalatine ganglia from pre‐ or postnatal rats rapidly produce a large amount of SPLI fibers on the iris mimicking the pattern of sensory innervation. This proves the presence of SPLI neurons in adult parasympathetic ganglia, at least in experimental conditions.This study of fetuses and grafts demonstrates the existence of neurons in SPLI parasympathetic cranial ganglia which has been underestimated or ignored previously as a result of observations on adult ganglia. The very large proportion of SPLI neurons in the ganglia of the salivary gland might be of importance for the interpretation of experimental studies on the control of salivation. The presence of SPLI in all three types of peripheral ganglia, sensory, sympathetic and parasympathetic, raises the question of its functional significance in the different compartments of the peripheral nervous system.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90031-0

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIn a series of four experiments, the ability of specific catecholaminergic agonists to intensify the ‘transport response’ was investigated in 19‐, 32‐, 36‐ and 40‐day‐old rats. The dopaminergic agonist, apomorphine, was able to intensify the response in a dose‐dependent fashion. The beta‐noradrenergic agonist, isoproterenol, was unable to alter the intensity of the response. These results indicate a central dopaminergic involvement in the transport response.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90032-2

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe level of binding of [3H]serotonin (5‐hydroxytryptamine) to serotonin type 1 receptors (S1) in the visual centres and frontal cortex of control, dark reared and monocularly deprived (one eyelid sutured on postnatal day 10) 3‐month‐old rats were determined and compared to that assayed in 25‐day‐old rats. The two forms of light deprivation affect [3H]serotonin binding in the central visual structures in a different way.Monocular deprivation until the age of 3 months resulted in decreased serotonin binding levels in the retina of both eyes compared to the control group raised under a 12 h light‐dark cycle. Additionally, serotonin binding in the lateral geniculate nucleus contralateral to the closed eye is decreased. Rearing rats in complete darkness from birth to the age of 3 months leads to an increase of serotonin binding in the visual cortex and superior colliculus. Regarding the normal distribution of serotonin type 1 binding sites in the visual system of 3‐month‐old rats, highest serotonin binding is found in the lateral geniculate nucleus followed by the retina, superior colliculus and visual cortex.The differential effect of monocular or total light deprivation upon serotonin type 1 receptors in the different visual nuclei might reflect differences in the morpho‐functional organization of the serotoninergic system along the visual pathway and its involvement in visual information processing.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90033-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractDissociated 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.Oncoatedcoverslips 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. Onuncoatedcoverslips 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.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90034-6

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe distribution of hyaluronectin, an extracellular matrix glycoprotein binding specifically to hyaluronate, was studied by indirect immunofluorescence in the cerebral cortex of the rat embryo. On days 11 and 12 thin strands of immunofluorescent material spanning the entire thickness of the telencephalon were seen. The appearance was similar to that observed with vimentin antisera decorating radial glia. On days 13–15 the primordial plexiform layer of the cerebral cortex was intensely hyaluronectin positive. On day 16 hyaluronectin immunoreactivity was mainly confined to Layer I above and to the intermediate layer below the newly formed cortical plate. It is suggested that in embryonal rat brain HN immunoreactivity is first distributed along radial glia and then accumulates in regions of axonal growth and neuropil formation.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90035-8

出版商:Wiley    

年代:2003

数据来源: WILEY