摘要:

AbstractExplants of transverse slices of the 6‐day‐old rat hippocampus were grown in a serum‐free medium for 2–14 days. Histology performed after various culturing periods demonstrated that these slices maintain a high degree of 3‐dimensional organotypy, while undergoing growth and differentiation of the main cellular elements similar to that seenin vivo. Histological indications of continuing cell proliferation were verified by autoradiography showing a labelling of neuroblasts in the dentate gyrus and of glioblasts at the sites of gliogenesis observedin vivo. Spontaneous bioelectric activity and evoked potentials were recorded, both indicating the development of impulse generation and neuronal connectivity within the explant. Silver impregnation and electron microscopic studies lent further support for the presence of neuronal networks intrinsic to the hippocampus. These findings suggest that within the period studied the hippocampal slice cultures mature in a fashion similar to that seenin situ.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90001-9

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe primary sensory neurons in mouse dorsal root ganglia consist of diversified subpopulations which express distinct phenotypic characteristics such as substance P or calbindin D‐28k. To determine whether neuronal phenotypes are altered or not inin vitrocultures carried out in a defined synthetic medium, dissociated dorsal root ganglion cells from newborn mice were grown in the alpha‐modified minimum essential medium either supplemented with 10% fetal calf serum or serum‐free. About 80% of the neurons survived after 5 days of culture in both media, but only 35% or 65% were rescued after 12 days in serum‐free or fetal calf serum supplemented medium, respectively. The neuronal subpopulations expressing substance P or calbindin D‐28k displayed similar morphological properties in both media and a higher resistance to culture conditions than the whole neuronal cell population, especially in serum‐free medium. It is therefore concluded that a defined synthetic medium offers reproducible conditions to culture dorsal root ganglion cells for at least 5 days, stimulates the expression of substance P and enriches preferentially neuronal phenotypes expressing substance P or calbindin D‐28k, for a longer period of culture.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90002-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to assess the functional role of presynaptic α2‐autoreceptors in noradrenergic transmission in the hippocampus and dopamine‐2 heteroreceptors in cholinergic transmission in the striatum in young, adult, and senescent rats. Male and female Wistar rats (4, 12, and 24 months old) were used and the release of radioactivity from striatal and hippocampal slices that had been loaded either with [3H]choline or with [3H]norepinephrine was measured at rest and in response to field stimulation (2 Hz, 360 shocks). The release was challenged by sulpiride, a selective dopamine‐2 receptor antagonist, and CH‐38083, a selective α2‐adrenoceptor antagonist. The dissociation constant and the number of α2‐adrenoceptors was also determined by binding studies using [3H]yohimbine as ligand in crude membrane preparations of frontal cortex. There were an age‐related changes in α2‐adrenoceptor‐mediated negative feedback modulation of norepinephrine release and in the density and dissociation constant of α2‐adrenoceptors. They were reduced in senescent rats. In contrast the presynaptic modulation of striatal cholinergic transmission by dopamine‐2 receptors was not altered during aging, but the storage capacity of and the release of acetylcholine from cholinergic interneurons was significantly lower.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90003-5

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe neurotrophic peptide Org 2766 accelerates the regeneration of peripheral nerves. Although the mechanism of action of this neuropeptide is not yet understood, functional, pharmacological, and morphological evidence has demonstrated that Org 2766 exerts its beneficial effect during the early stages of nerve regeneration. The induction of some members of the Immediate Early Gene (IEG) family such asc‐junandc‐fosis one of the first molecular events following peripheral nerve damage. The Fos and Jun proteins act as a transcription factor and may stimulate the expression of a number of genes implicated in nerve regeneration. We examined whether Org 2766 stimulates nerve regeneration by enhancing or prolonging the expression ofc‐fosmRNA. Following a crush lesion of the sciatic nerve, the expression ofc‐fosmRNA was induced in the spinal cord and in the damaged nerve at 30 min following injury in untreated animals as demonstrated with Northern blot. No effect of the crush lesion was observed in dorsal root ganglia (DRG). The induction ofc‐fosmRNA in the damaged nerve was more robust as compared to the relatively small induction observed in the spinal cord. Within situhybridization an increase inc‐fosmRNA expression both in the dorsal and in the ventral horn of the spinal cord was demonstrated at 30 min post‐lesion. In the distal sciatic nerve portion the expression ofc‐fosmRNA was predominantly localized around Schwann cell nuclei at 30 min after nerve crush.The effect of Org 2766 treatment on the expression ofc‐fosmRNA was investigated using semiquantitative dot blots. Dot blots containing RN A samples of DRG, spinal cord or sciatic nerve of control animals, saline treated and Org 2766 treated animals isolated 15 min, 30 min, l hr, 1 day and 2 days following nerve crush were scanned densitometrically. No significant effect of Org 2766 on the expression ofc‐fosmRNA was detected. We conclude that Org 2766 does not stimulate peripheral nerve regeneration by affecting the expression of thec‐fosmRNA following sciatic nerve crush. The putative effect of Org 2766 on other immediate early transcription factors of thefosandjunfamily is currently under investigation.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90004-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractSeven monkeys (Macaca mulatta) were laparotomized under general anesthesia (halothane, nitrous oxide, oxygen). Fetal hypoxia was induced in four monkeys by occlusion of the umbilical cord with a hydraulic occluder for 5–6 min. Three sham‐operated fetuses served as controls. After unclamping, the fetuses were allowed to reperfuse for 20–30 min. To monitor hypoxia, the fetal electrocardiogram was recorded continuously. Hypoxic insult was associated with a decrease in fetal heart rate during the occlusion. After reperfusion, fetuses were immediately sacrificed and neocortex regions dissected on ice, frozen on dry ice and stored at −70°C. Dopamine, 3,4‐dihydroxyphenylacetic acid, homovanillic acid, serotonin, and 5‐hydroxyindoleacetic acid were assayed by high performance liquid chromatography with electrochemical detection (HPLC/EC) in hippocampus, caudate nucleus and cortical regions. In the hippocampus, there was a significant increase in 5‐hydroxyindoleacetic acid concentration. In prefrontal cortex, there was a trend toward an increase in serotonin but no effects on dopamine and homovanillic acid concentrations. Dopamine, serotonin and metabolites were not altered in the caudate nucleus. These data demonstrate that fetal hypoxia followed by reperfusion produced an increase in serotonin concentration measured within the hippocampus and selected cortical areas known to be targets of hypoxic injury.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90005-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIt has been reported that an inverse relationship exists between nicotine intake and the incidence of Alzheimer's Disease (AD). Although nicotine has been reported to induce c‐fos, in the present study it was shown that this induction does not alter the accumulation of a number of transcripts associated with AD. Altered splicing patterns of Amyloid Precursor Protein (APP) and changes in neurotrophin and glucose transporter expression have been implicated in AD and behavioral deficits in rats. The effects of subacute administration of nicotine (12 mg/ml at 2.3 μl/hr for 14 days) on the abundance levels of APP, glucose transporter(GLUT) and neurotrophin transcripts were determined by rtPCR in the hippocampus, cortex, and striatum of aged (22–24 months) male Wistar rats. No significant differences between saline and nicotine infused rats were detected for APP abundance levels or ratio of the various isoforms. However, both groups had a higher level of APP transcripts containing the Kunitz Protease Inhibitor (KPI) domain in the hippocampus than in either the cortex or striatum. The mean percentages of APP 695 for the two groups were 75% in the hippocampus and 82 and 81% in the cortex and striatum, respectively (P<0.01). No changes in the abundance of GLUT1, GLUT3, nerve growth factor (NGF) or brain derived neurotrophic factor (BDNF) transcripts were detected. However, since both APP and GLUT1 are thought to be regulated post‐transcriptionally, the present results do not rule out a change at the protein level. Further work will be required to determine whether nicotine can influence the expression of these proteins which affect neuronal function.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90006-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThis study has evaluated the possible role of serotonin, a potential morphogen, in the regulation of vasoactive intestinal polypeptide (VIP) gene expression in the target neurons of the suprachiasmatic nucleus (SCN) before and after the onset of the serotonin neurotransmitter function. VIP gene expression was quantified byin situhybridization of the corresponding mRNA on cryostat sections with subsequent film autoradiography and densitometry. The content of VIP mRNA was measured in the SCN in fetuses at the 21st embryonic day (E21) and in postnatal rats at day 11 (P11) following chronic depletion of serotonin byp‐chlorophenylalanine, an inhibitor of serotonin synthesis. This inhibitor was daily injected to pregnant rats for E13–20 or to postnatal animals for P2–10. Results of this study indicate that prenatal serotonin depletion caused a significant increase in VIP mRNA content in the SCN compared to control fetuses. On the contrary, the same treatment performed postnatally did not change VIP mRNA levels in the SCN. These data suggest that the VIP gene expression in differentiating target neurons of the SCN might be under serotonin inhibitory control during prenatal neurogenesis, prior to the onset of the serotoninergic neurotransmission.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90007-8

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractStimulation of lipid peroxidationin vivo(in experimental epilepsy and closed cranio‐cerebral injury, as models for endogenous stimulation of lipid peroxidation) affects catalytic activity, substrate specificity of mitochondrial monoamine oxidases and increases their susceptibility to trypsinolysis. It is suggested that increased susceptibility to trypsinolysis reflects an appearance of new hydrophilic site(s) in monoamine oxidase molecules which may be responsible for an involvement of the modified enzymes in the deamination of other important nitrogenous compounds (such as γ‐aminobutyric acid) with subsequent impairment of a ratio between inhibition and excitation processes in the brain.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90008-6

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe plasticity of the sympathetic and sensory innervation of the rat uterus was examined, before and after puberty, in controls and in animals where primary sensory nerves had been destroyed by neonatal capsaicin treatment. Immunohistochemical and histochemical methods were used in association with nerve density measurements and biochemical assays. The main findings were as follows: (1) Puberty was associated with a marked increase in the weight of the uterine horn, uterine cervix and parametrial tissue. This was unaffected by capsaicin treatment. (2) The sympathetic innervation of the uterine horn and parametrial tissue was reduced following puberty as revealed by a decrease in the density of noradrenaline‐containing nerves and a marked decrease in the tissue concentration of noradrenaline. Sympathetic nerves supplying the uterine cervix and the blood vessels of the uterus appeared to be unaffected by puberty. (3) In contrast, the sensory supply of the uterus by substance P and calcitonin gene‐related peptide‐containing nerves increased in parallel with uterine growth during puberty resulting in no change in nerve density and only a slight reduction in peptide concentration. (4) Neonatal capsaicin treatment caused a long‐lasting depletion of substance P‐ and calcitonin gene‐related peptide‐containing nerves. In the uterine horn and parametrial tissue, capsaicin‐resistant calcitonin gene‐related peptide, but not substance P, still increased with tissue weight during puberty, indeed, in the uterine horn, the relative increase was greater than in controls. (5) Sensory denervation resulted in an increase in the non‐vascular sympathetic supply of the uterus, although there was a regional variation in the time course of the response. Perivascular sympathetic nerves were unaffected by capsaicin treatment. The pattern of change in non‐vascular noradrenaline‐containing nerves associated with puberty was similar in nature to controls. Thus, there is considerable plasticity in the innervation of the uterus both during puberty and following sensory denervation. A complex pattern of change occurs with differential responses in vascular and nonvascular nerves and in different regions of the uterus. Such differences may be due in part to the different origins of individual nerve populations and/or to their relative sensitivities to sex hormones.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90009-4

出版商:Wiley    

年代:2003

数据来源: WILEY

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90010-8

出版商:Wiley    

年代:2003

数据来源: WILEY