摘要:

AbstractThe 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, namelyl‐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.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90050-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractBinding sites for vasoactive intestinal polypeptide (VIP) and the content of immunoreactive VIP were measured in the foetal and neonatal mouse brain cortex and primary cultures of foetal murine brain‐cortical neurons and astrocytes. The amount of cortical VIP binding sites and the concentration of immunoreactive VIP were low before birth, but increased postnatally reaching adult level at about 3 weeks of age. In cultures, a similar rise in neuronal binding sites occurred after 10 days, whereas the VIP concentration remained lower than in adult brain cortex. No binding sites or immunoreactive VIP could be detected in cultured astrocytes. The VIP binding sites were heterogeneous both in developing brain cortex and cultured neurons, and consisted of two classes of binding sites. The high affinity constants (2.5–2.9 nM) as well as low affinity constants (50–76 nM) were unchanged during the development, whereas the number of binding sites increased. In cultured neurons the binding constants were similar to those found in the adult mouse brain cortex. The peptide specificity for the VIP binding was similar in brain cortex and neuronal culture. In conclusion, the maturation of murine brain cortical neurons is accompanied by the development of synaptosomal VIP receptors in support of the neurotransmitter function of VIP.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90051-6

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractAstroglial cells from cerebral hemispheres of newborn rats were cultured for 5 days in Waymouth's MD 705/1 medium containing 10% fetal calf serum. Thereafter, cells were grown in a chemically defined medium consisting of basal Waymouth's medium supplemented with insulin (5 μg/ml) and fatty acid free bovine serum albumin (0.5 mg/ml). The cells underwent morphological and biochemical development over a period of 28 days. The changes in the amount of glial fibrillary acidic protein indicated a development of gliofilaments. The level of S100 protein increased during the entire culture period, while glutamine synthetase activity remained low and relatively constant. The addition of an astroglial growth factor, partially purified from bovine brain soluble extract, stimulated the morphological maturation of the astroglial cells. The cells extended cytoplasmic processes and resembled mature astrocytes. At the ultrastructural level an increase in free ribosomes was observed and the intermediate filaments became organized into large bundles. The amount of glial fibrillary acidic protein was not significantly increased, but the level of S100 protein and the glutamine synthetase activity were greatly enhanced. Our results indicate that astroglial cells undergo limited maturation in the chemically defined medium and that this process is positively affected by the astroglial growth factor.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90052-8

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractExogenous mixtures of bovine brain gangliosides (BBG) initiated a rapid series of sequential changes in surface activity in Neuro‐2a neuroblastoma cells. These changes were characterized by the formation of microvilli, ridge‐like projections and ruffled membranes within l min of BBG exposure. A maximum number of microvilli was reached after 10 min exposure and disappeared by 30 min. Ruffled membranes were most prominent within 5 min, but were still present after 60 min. These surface changes were accompanied by the formation of a thick subcortical meshwork of microfilaments which formed the cores of the microvilli and ruffled membranes. The simultaneous treatment of cells with BBG and an agent known to disrupt microfilaments (cytochalasin D) inhibited the formation of both microvilli and ruffles. In contrast, the simultaneous application of BBG and agents affecting microtubule polymerization (Colcemid and taxol) did not inhibit the formation of these surface structures. Treatment of Neuro‐2a cells with cyclic AMP (cAMP) analogs (dibutyryl cAMP and 8‐bromo cAMP) induced a similar series of surface changes which were inhibited by cytochalasin D. Furthermore, these surface changes may be specific to cAMP since neither cGMP analogs (dibutyryl cGMP and 8‐bromo cGMP) nor 5′AMP induced surface changes. We propose that the initial membrane response to exogenous gangliosides is mediated by a microfilament‐dependent mechanism. The basic similarities in surface responses elicited by BBG and cAMP analogs suggest that the effects of gangliosides on surface activity may be induced in part by a cAMP‐dependent mechanism.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90053-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractA subpopulation of amacrine cells which have the ability to take up exogenous serotonin occur in the rabbit retina at all stages during postnatal development. However, during the initial stages of the retina's development some serotonin‐accumulating neurons are also associated with the outer plexiform layer in the form of interplexiform and/or bipolar and/or horizontal cells. These neurons could have an additional function of their own or simply be misplaced serotonin‐accumulating neurons destined to degenerate in the process of synaptogenesis.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90054-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractWe have studied the concentration of calmodulin and phosphodiesterase (cAMP highKm) in five different parts of the rat central nervous system (hemispheres, cerebellum, diencephalon, brain stem and spinal cord) during postnatal development (5, 10, 15, 20, 30 and 45 days after birth). The concentration of the enzyme and its regulatory protein were independent, so that no correlation could be established between them. In most structures, calmodulin concentration tended to decrease with age, while phosphodiesterase increased or remained at similar values during the time studied.The calmodulin inhibitor trifluoperazine, inhibited phosphodiesterase activity to different degrees, depending on the structure, and age. Hemispheres, diencephalon and brain stem showed maximal inhibition (approximately 95‐65% of control). In these structures, inhibition was higher in older animals. By contrast, cerebellum and spinal cord PDE was less inhibited by trifluoperazine (65‐50% of control), and inhibition was independent of age. The validation of a method for both calmodulin and phosphodiesterase assay, using a modification of established methods, is also reported.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90055-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

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

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90056-5

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe postnatal development of nicotine‐like binding sites in the cortex, hippocampus, midbrain and cerebellum of 3‐, 7‐, 12‐, 17‐ and 30‐day‐old mice was studied. Two different nicotinic cholinergic ligands, namely [3H]acetylcholine ([3H]ACh) and [3H]nicotine ([3H]NIC) were used to detect the nicotine‐like binding sites inin vitrobinding assays. The postnatal development of the binding sites of [3H]NIC increased gradually with age in all brain regions studied. The [3H]ACh binding, on the other hand, showed a marked peak on day 12 in the cerebellum and midbrain but did not change notably with age in the hippocampus and cortex, except for a slight temporary increase in the cortex on day 7. The time‐course for the appearance of nicotinic binding sites as observed with [3H]ACh was found to be rather similar to that earlier described for [3H]alpha‐bungarotoxin binding sites, whereas that for [3H]NIC differed from that described for other nicotinic ligands.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90057-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIn response to enhanced functional activity, only the larger neurons of the myenteric plexus incorporate thymidine. Their number, too, is increased. This phenomenon is not accompanied by proliferation.

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90058-9

出版商:Wiley    

年代:2003

数据来源: WILEY

ISSN:0736-5748    

DOI:10.1016/0736-5748(85)90059-0

出版商:Wiley    

年代:2003

数据来源: WILEY