摘要:

AbstractTo investigate the effect of chronic sympathectomy on the innervation of a tissue with an extensive intrinsic component, 1‐week‐old rat pups were treated with 50 mg/kg guanethidine for 3 weeks, a treatment shown to produce complete and long‐lasting sympathectomy, and the ileum examined. Changes in the levels of noradrenaline, neuropeptide Y, calcitonin gene‐related peptide, substance P and vasoactive intestinal polypeptide in the external muscle layers containing the myenteric plexus of the ileum were determined between 6 and 20 weeks of age. After sympathectomy, noradrenaline levels were initially depleted (3% of age‐matched controls at 6 weeks,P<0.001, and 18% of age‐matched controls at 12 weeks,P<0.001), but were not significantly reduced at 20 weeks (67% of age‐matched controls). Such increases in noradrenaline content with time after sympathectomy did not occur in the mesenteric vein (levels in 20‐week‐old sympathectomized rats were 2% of the control values (P<0.001). In the myenteric plexus, catecholamine fluorescent nerve fibres were seen in the 12‐week‐old sympathectomized rats, although tyrosine hydroxylase‐immunoreactivity was absent. Guanethidine sympathectomy had no effect on the neuropeptide levels in 6‐week‐old rat ileum but there was a selective increase at 20 weeks; the levels of calcitonin gene‐related peptide and substance P were increased (×3,P<0.001 and ×1.6,P<0.05, respectively) while vasoactive intestinal polypeptide and neuropeptide Y levels were unchanged. Short‐term sympathectomy (destruction of sympathetic nerve terminals by acute 6‐hydroxydopamine treatment) had no effect on noradrenaline or peptide levels in this tissue. The changes in innervation noted after long‐term sympathectomy may represent a part of the adaptive response of the enteric nervous system which permits normal intestinal function in the absence of extrinsic neuronal inputs.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00028-F

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractFollowing treatment of adult rats with nerve growth factor (0.5 mg/rat, three times a week for 3 weeks), the innervation of cardiovascular and urinogenital tract smooth muscle was investigated using immunoassay and immunohistochemical techniques. Substance P and calcitonin gene‐related peptide levels were increased in the vas deferens, but not in the atria or femoral artery. Neuropeptide Y and vasoactive intestinal polypeptide levels were unchanged. In penile tissues, there was a marked increase in the density of substance P‐, calcitonin gene‐related peptide‐, neuropeptide Y‐, tyrosine hydroxylase‐ and vasoactive intestinal polypeptide‐containing nerves innervating the urethra and in SP‐containing nerves in the tunica with little change in the innervation of the deep dorsal vein and artery and corpus cavernosum. In the bladder, there was increased innervation of the detrusor by neuropeptide Y‐ and vasoactive intestinal polypeptide‐containing nerves, but a decrease in innervation by substance P‐containing nerves in the trigone. There were no changes in the density of innervation of the femoral artery after nerve growth factor treatment. Thus, in the mature rat, sensory and sympathetic nerves innervating urinogenital tract smooth muscle appear to be more responsive to exogenous nerve growth factor than those innervating cardiovascular smooth muscle. This may reflect an ongoing requirement of plasticity of innervation in the urinogenital tract of the sexually mature animal.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00029-G

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractThis study identified a 140 kDa polypeptide as a putative specific component of Purkinje cell spines' postsynaptic densities and which began to appear during the critical period of cerebellar cortex synaptogenesis. Mouse cerebellar cortices at postnatal days 5, 7, 9, 11, 15 and young adult, between days 30 and 40, were used to purify subcellular fractions of synaptosomes, synaptic membranes and postsynaptic densities. The purity of the subcellular fractions was assessed by electron microscopy and the protein composition of the different fractions was characterized by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Polypeptides of apparent molecular weights of 25, 26, 27, 30, 33, 37, 43, 45, 52, 64, 74, 85, 94, 110, 125, 130, 165 and 174 kDa were found in the synaptosomal fractions of all the ages studied, even before the critical period of synaptogenesis, at postnatal day 7, when the postsynaptic densities were still nonexistent, indicating that the polypeptides are nonspecific constituents of these structures. On the other hand, a 140 kDa polypeptide was detected in the postsynaptic density fractions at postnatal day 11, immediately after postsynaptic structures began to appear, suggesting the possibility that this protein is a specific component of the cerebellar cortex postsynaptic densities. The 140 kDa polypeptide was electroeluted from the gel and analysed for its amino acid composition by reverse‐phase high‐pressure liquid chromatography. The analysis showed that this protein has a high content of nonpolar amino acid residues, such as leucine, isoleucine, glycine, phenylalanine and valine. A hypothetical model relative to the participation of the 140 kDa protein in the molecular organization of the postsynaptic density is suggested which may contribute to the understanding of the role played by this structure in synaptic function.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00027-E

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractQuantitative analysis of the density of1and β2/3GABAAreceptor subunits was performed at the electron microscope level after indirect pre‐embedding immunogold labeling with subunit‐specific antibodies of rat cerebellar granule cell cultures grown for 4 or 8 days and in the presence or absence of the GABAAreceptor agonist 4,5,6,7‐tetrahydroisoxazolo[5,4c]pyridin‐3‐ol (THIP). THIP (150 μM) induced a 2‐fold increase in the number of α1and β2/3subunits in both cell bodies and processes in 4‐day‐old cultures. Extending the culture period to 8 days led to a polarization of the receptor expression, since the increase in the number of subunits selectively was observed in the processes. Moreover, a general subcellular differentiation of the receptor population was observed in all culture conditions, since the ratio between the two subunits (β2/3;α1) was four times higher in cell bodies compared to processes. A detailed analysis of the less mature (4‐day‐old) cultures revealed the existence of two populations of neurons exhibiting differences in the average number of receptors. During maturation neurons with few receptors developed into cells with a higher density of receptors resulting in a single population of the latter neurons, a process enhanced by exposure to THIP. This may indicate that receptor development is a discontinuous process with individual neurons following different temporal patterns. In double‐labeling experiments, a spatially close association of the α1and β2/3subunits could be seen, but the subunits were more frequently found separated from each other. In spite of the fact that exposure of the neurons to THIP increased the total number of receptor subunits, its presence apparently prevented formation of receptors with this subunit composition. Interestingly, receptor subunit clusters, consisting ofα1alone, were more frequently observed than composite (1and β2/3) clusters. This substantiates the view that receptors not having α1and β2/3subunits in the same complex may exist.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00024-B

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractOnly L‐ and N‐type high voltage‐activated calcium currents (HVA ICa) have been demonstrated in identified embryonic spinal motoneurons. However, pharmacological experiments suggest that other HVA ICa, including P‐type, govern neurotransmitter release at the adult neuromuscular junction. We sought to analyse if embryonic motoneurons express these other ICa, using the whole‐cell voltage‐clamp method on motoneurons purified by a new metrizamide‐panning technique from E15 rat embryos. In addition to L‐type dihydropyridine‐sensitive and N‐type ω‐GVIA‐sensitive currents, motoneurons express two other HVA ICa. One has properties related to the P‐type channel currents described in Purkinje cells: it is inhibited by the peptide ω‐agatoxin‐IVA with a maximal effect at 100–200 nM. The inhibited current has a characteristic sustained component during depolarizing test pulses. Furthermore, 50–100 nM concentration of ω‐agatoxin‐IVA reduce the increase in cytoplasmic calcium concentration observed after depolarization. The other HVA ICais resistant to saturating concentrations of verapamil, ω‐conotoxin GVIA and ω‐agatoxin‐IVA which block L, N and P‐type HVAICa, respectively. These results suggest that it is now possible to dissect, using a simple method of purification, the properties of the ICain embryonic mammalian motoneurons and to provide pharmacological evidence for multiple calcium channels which may be involved in regulation of their activity during development.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00026-D

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractRetinoic acid (RA), a natural metabolite of vitamin A, influences the survival and neurotransmitter phenotype of several classes of vertebrate neurons during development. We now report that RA induces a subpopulation of NTera 2/clone D1 (NT2) human embryonal carcinoma cells to differentiate into postmitotic cells with cholinergic properties (NT2‐N cells). After growth for 6 days in the presence of RA (10 μM) low levels of the acetylcholine‐synthesizing enzyme choline acetyltransferase (ChAT) were detected in NT2 cell cultures. ChAT activity in the NT2 cell cultures continued to increase for at least an addition 22 days to a final activity of 50 pmol ACh synthesized/min/mg protein. Immunohistochemical staining of RA‐treated cultures demonstrated that only those cells with a neuronal morphology (NT2‐N cells) expressed the human ChAT protein. Since such cells comprised a small proportion (∼20%) of the population, the ChAT activity per neuronal cell was estimated to approach 250–300 pmol ACh/min/mg protein. Cultures composed of>95% NT2‐N cells had significantly lower ChAT specific activities and this could be increased by either ciliary neurotrophic factor or leukemia inhibitory factor, but not by nerve growth factor. We conclude that NT2 cells provide a system in which to study the molecular events that underlie neurotransmitter choice during the differentiation of human cholinergic neurons.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00025-C

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractRat spinal cord (1–24 weeks postnatal) was analysed by HPLC for various species of galactolipids that accumulate in mammalian myelin during development. Cerebral tissue of the same animals was taken as reference. The levels of the major galactolipids, galactosylceramide (GalCer) and its sulfated analog (SGalCer), increased linearly during the first 2 months after birth. At 3 months, constant levels were reached that were approx. 4‐fold (GalCer) and 2.5‐fold (SGalCer) higher than in cerebral tissue of corresponding age. The accumulation of galactoglycerolipids slightly preceded that of galactosphingolipids. Levels of galacto‐glycerolipids were much lower (4% of galactospingolipids in 3‐ and 2.5% in 6‐month‐old spinal cord on weight basis) and decreased upon CNS maturation. During the first postnatal month, the ratio of non‐hydroxy‐ over hydroxy‐species (NFA/HFA) of cerebral GalCer declined from 2.2 to 0.5 whereas the NFA/HFA ratio for cerebral SGalCer increased from 1.0 to 1.8 in the same period. Through development the hydroxy‐species contributed 56–60% to GalCer and 28–41% to SGalCer in spinal cord, whereas in cerebrum of 24‐week‐old rats 73% of GalCer and 48% of SGalCer was α‐hydroxylated in the ceramide moiety. These data point to different developmental programs with respect to galactolipid metabolism of oligodendrocytes in high‐ (spinal cord) as compared to low‐myelinated (cerebral) areas of rat CNS.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00006-3

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractIn late infantile and juvenile forms of neuronal ceroid lipofuscinosis, commonly known as Batten disease (BD), ATP synthase subunit c accumulates in the lysosomes of neural cells. By using polyclonal antibodies, raised against bovine liver subunit c and an image analysis system for the quantification of antibody‐linked alkaline phosphatase reaction, we have demonstrated that polymorphonucleocytes (PMN) from a late infantile and a juvenile BD patient stored several‐fold more subunit c as compared to normal PMN.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00011-5

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractThe development of neurons utilizing γ‐aminobutyric acid (GABAergic neurons) in prosencephalon and telencephalon from chicken embryonic days 4–14 (E4–E14) was studied by means of immunohistochemistry. Furthermore, routine histology and transmission electron microscopy, respectively, were performed in order to study the morphological development in the designated area. The main finding is that development of GABAergic neurons in the chick telencephalon is rapid; the GABA neurons are appearing in bulk at day 8, being “overexpressed” at days 10–11, decreasing in numbers thereafter and achieving mature morphology on day 14, which is considerably faster than in the rodent.Morphological analysis revealed that the prosencephalon mainly consisted of a thin layer of undifferentiated neuroblasts in the E4 embryo. By E6, the prosencephalon had increased in thickness and occasional cells outside the neuroepithelium showed a more mature morphology with a few cells weakly staining positive for GABA. At E8, the prospective granular and subventricular layers had developed. At E14, the appearance of the telencephalon is approximating that of the adult since both ependymal cells and morphologically mature neurons can be seen.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00010-E

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractFast axonal transport of radiolabeled protein was examined in lumbar and tail dorsal root ganglion (DRG) neurons at progressive stages of bullfrog tadpole metamorphosis. Accumulation of [35S]methionine‐labeled protein proximal to a lumbar peripheral nerve ligature (at a fixed distance from the DRG) increased as tadpoles advanced from premetamorphosis through prometamorphosis to metamorphic climax. The rate of increase was steeper when expressed as a percentage of protein synthesized in the neurons of origin than when expressed as a percentage of total DRG protein synthesis. Further, the increase was not secondary to a rise in protein synthesis. In contrast, fast axonal transport decreased in DRG neurons of the tail at the onset of metamorphic climax, when tail resorption is initiated. The stage‐related increase in protein transport in lumbar nerves is due, at least in part, to an increased rate of transport. As determined from optically detected anterograde organelles in individual lumbar nerve axons, an approximate doubling of the fast transport rate occurred between the premetamorphic stage and metamorphic climax. In addition, the rates of organelle transport in lumbar axons of adult bullfrogs were significantly greater than in corresponding axons of tadpoles at metamorphic climax, further suggesting that organelle velocity is a developmentally regulated parameter of fast axonal transport.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00007-4

出版商:Wiley    

年代:1999

数据来源: WILEY