摘要:

AbstractThe activity and properties of brain γ‐glutamyltransferase (EC 2.3,2.2) were studied in 7‐, 14‐and 90‐day‐old rats. The enzyme activity was highest in the pons‐medulla and lowest in the cerebellum in each age group. The activity of glycylglycine, 10 protein amino acids, GABA and taurine as acceptor of the γ‐glutamyl group was studied with 7‐day‐old and adult rats. The best acceptors were glycylglycine, lysine and methionine and the poorest taurine, valine and isoleucine. The relative acceptor activity of lysine changed most during development.Kmfor the γ‐glutamyl donor,γ‐glutamyl‐p‐nitroanilide, with glycylglycine was about 3 mM in all experimental groups. It did not change during development butVincreased about fivefold in all brain areas studied. A mixture of serine and borate strongly inhibited γ‐glutamyltransferase in each age group. Potassium and magnesium ions had no measurable effect on the enzyme activity but sodium ions were stimulatory.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90013-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractAcute maternal ethanol administration (two i.p. injections of 2.9 g ethanol/kg maternal body wt) to C57B1/6J mice during gastrulation stages of embryogenesis (gestational day 7) induces a spectrum of brain and facial malformations characteristic of those seen in the human Fetal Alcohol Syndrome. Scanning electron microscopic and light microscopic analyses of the brains of embryos of gestational days 11–14 demonstrate ventro‐medial forebrain deficiencies of varying degrees of severity in affected specimens. Even at the mild end of the spectrum, reductions in the size of the septal nuclei and the shape of the third ventricle are observed. As the severity of the effect increases, the septal nuclei disappear altogether, resulting in midline fusion of the corpora striata (basal ganglia). In such cases, the third ventricle is totally absent anteriorly (preoptic area) and significantly narrowed at more posterior levels, adjacent to the ventromedial nuclei. In addition, the hippocampal primordium is absent at levels which include the corpora striata, and septation of the cerebral cortex is incomplete. More posteriorly, at the level of the posterior commissure, the hippocampal primordium is present, but greatly reduced in size, and the entire brain is distinctly narrower in width. Still further posteriorly, at levels of the metencephalon which include the tectum and cerebellar plate, the cerebral aqueduct is significantly expanded, fusion of midline (raphe) structures is incomplete and the cerebellar plate does not extend as far medially as it does normally. Interestingly, these abnormalities are analogous to those observed in the holoprosencephaly series of malformations.The results of the present study support our hypothesis that severe forms of the Fetal Alcohol Syndrome mimic certain aspects of the holoprosencephaly spectrum, and indicate that special attention should be paid to possible deficiencies in the septal nuclei and basal ganglia of children born to women who abuse alcohol. The fact that gross brain malformations can be induced in this animal model at a time corresponding to the third week of human gestation (a time when most women remain unaware of pregnancy) is of significance in terms of the possible prevention of alcohol‐induced birth defects and mental deficiency in man.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90014-5

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractSeveral plasma proteins have previously been demonstrated to be within cells (presumed neurons) in the developing brain of various species. The possibility that the plasma proteins α‐fetoprotein (AFP) albumin and transferrin may be synthesized by developing brain and choroid plexus has been investigated in fetal rats of 18 to 22 days gestation. Samples of these tissues and of liver were incubated in Krebs solution containing [3H]leucine at 37°C for 1 h. Radioactively labelled AFP, albumin and transferrin were extracted and separated by immunoprecipitation. Incorporation of [3H]leucine into the plasma proteins was demonstrated in both fetal brain and choroid plexus. Incorporation was completely blocked by cycloheximide. It is concluded that fetal brain and choroid plexus synthesize AFP, albumin and transferrin and that secretion of these proteins by developing brain and choroid plexus cells probably contributes to the high concentration of plasma proteins in fetal csf.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90015-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractSpontaneous alternation behavior is related to the integrity of the hippocampus. Our earlier studies demonstrated hippocampal deficits after early phenobarbital (PhB) exposure. In the present study, we examined spontaneous alternation of mice who had been exposed to PhB prenatally or neonatally. Prenatal PhB was administered transplacentally: pregnant females were fed 3 g PhB/kg milled food on gestation days 9–18. Neonates were treated directly with daily injections of 50 mg PhB/kg on postnatal days 2–22. The animals were tested for spontaneous alternation in a T maze at the ages of 22, 28, 35 and 42 days. The test was conducted at each age for two consecutive days. A maximum of four alternations were allowed on the first day, and one alternation on the second day. Animals treated neonatally had reductions in alternation from the control group for every age group. Looking at the mean of the four trials on the first day there was a reduction of 35% at age 22 (P<0.001), 8% at age 28, 21% at age 35 (P<0.05) and 36% at age 42 (P<0.02). On the second day the respective reductions were 32, 19, 24 and 36% (P<0.05). The differences in alternation between animals treated with PhB prenatally and the control group were too small to reach statistical significance. Subsequently a more sensitive test, delayed spontaneous alternation (30 s), was applied to an additional group of animals at age 42 which had been prenatally exposed to PhB: 31% reduction from the control group was found on day 1 (P<0.001), and 34% on day 2 (P<0.02). The greater differences after neonatal as opposed to prenatal administration could be related to the more extensive hippocampal damage that was found in adults after neonatal treatment.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90016-9

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe expansor secundariorum is a smooth muscle of the chicken wing which receives a dense noradrenergic innervation and contains high concentrations of trophic activity for sympathetic neurons. Expansor cells were dissociated in trypsin and grown to confluency in standard nutrient medium. Medium that had been conditioned by expansor cells contained trophic activity for chick sympathetic nerves which differed from the activity which is found within the muscle prior to culture, in that it was effective on a different neuronal subpopulation. Furthermore, unlike the factor(s) foundin vivo, the trophic activity of the conditioned medium was not enhanced by NGF and could be partially inhibited by mouse NGF antibodies. Both the production of total trophic activity in the conditioned medium and the activity which differed from that in the muscle extract, increased rapidly and to the same extent between 24 and 48 h culture. Greater concentrations of trophic activity were present in medium conditioned by smooth muscle cells than by skin cells. The conditioned medium was able to support more neurons from 11 and 18 day incubated embryos than a saturating dose of NGF. Neither this effect nor the additive effect of conditioned medium with expansor muscle extract could be attributed to the presence of neurite promoting factors. We conclude that the cultured muscle produces neuronotrophic activity that is similar to the activity found in denervated but not innervated muscle.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90017-0

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractBoth tyrosine hydroxylase and dopamine‐beta‐hydroxylase immunocytochemistry indicated the survival of catecholamine neurons and processes in 7‐day‐old organotype cultures of the locus coeruleus. Cultures of this age were transplanted in the 4th ventricle of adult rats via the cisterna magna. Two months after transplantation microscopic observations revealed that the transplant developed with a defined neural organization. Following tyrosine hydroxylase immunocytochemistry, immunoreactive cells were identified within the transplants. These results indicate that organotype cultures of the locus coeruleus survive within the 4th ventricle of adult rats.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90018-2

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe influence of GABA on cerebellar granule cells in culture was followed morphometrically duringin vitrodevelopment by growing the cells in the absence or presence of 50 μM GABA. The presence of GABA in the culture media increased the number of neurite‐extending cells by 50% after 7 days in culture. At the ultrastructural level GABA treatment led to an increased density of neurotubules, rough endoplasmic reticulum, Golgi apparatus, coated vesicles and other vesicles, whereas structures such as mitochondria and smooth endoplasmic reticulum were not affected by GABA. The density of free ribosomes showed a more pronounced tendency to decrease as a function of the culture period (1–7 days) when the cells were grown in the presence of GABA as compared to control cultures. The results strongly indicate that GABA in addition to being an important neurotransmitter serves as a trophic factor in the development of at least certain types of neurons.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90019-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractSome properties of the uridine‐5′‐diphospho‐N‐acetylgalactosamine:hematosideN‐acetylgalactosaminyltransferase were studied in retina tissue from chick embryos at 7 and 14 days of development. TheVmaxwas about 6‐fold higher in retinas from 14 day embryos than in retinas from 7 day embryos. No differences were found either in the apparent Michaelis constant for both donor nucleotide and acceptor glycolipid, or in the optimal detergent concentration, or in the stability upon storage at −14°C or heating at 50°C. Mixtures of homogenates of retinas from 7 day and from 14 day embryos gave the activity values expected for samples free of effectors diffusible and in excess. From experiments of partial delipidation of retina homogenates and reconstitution with lipid from retina homogenates from one or the other age, no indications were found that the activity was modulated by developmental changes in the lipid environment of the enzyme. Taken together, the results suggest that the increase of activity during development was not due to qualitative changes in the catalytic characteristics of the enzyme.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90020-0

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe effects of the administration of GM1monosialoganglioside internal ester, AGF2, on the dopaminergic reinnervation of the striatum in rats with unilateral hemitransection has been studied. AGF2increases the apparentVmaxand the density of tyrosine‐hydroxylase‐positive nerve terminals in the striatum of the lesioned side, without modification of the tyrosine‐hydroxylase activity in the unlesioned side. AGF2, at lower doses, is more active than its parent natural molecule GM1. AGF2has a larger half‐life and a higher distribution volume than GM1, and undergoes a slow hydrolysis in the serum releasing the original natural compound GM1. Mannitol and dexamethazone, often used to prevent swelling of the brain after injury, or isoaxonine, proposed to stimulate neurite growth are unable to reproduce the effects of AGF2on the recovery of striatal tyrosine‐hydroxylase activity after hemitransection. The data are compatible with the view that AGF2, through its conversion into GM1, facilitates the collateral sprouting of the nigro‐striatal dopaminergic neurons.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90021-2

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractTo determine whether or not the effects of thyroxine on the cells of the external granular layer of rat cerebellum are direct or indirect, Purkinje cell‐free dissociated cell cultures from 5‐day‐old rat cerebellum in serum‐free medium were treated with triiodothyronine (T3) at concentrations of 20–3000 ng/ml. Cultures were assayed for uptake and synthesis of γ‐aminobutyric acid (GABA) after 3 weeks, and for thymidine incorporation at 1, 2, 3 and 4 days. Specific (per mg protein) activity of glutamic acid decarboxylase and of GABA uptake into neurons was reduced by the more physiologic (50 or 500 ng/ml) concentrations of T3, probably due to a non‐neuronal increase in overall protein synthesis, since the total per culture values seem unaffected by hormone. Thymidine uptake was significantly increased only at the highest (unphysiologic) concentration of T3 on the second day after treatment. None of the label appeared to be in the nuclei of the neuronal cells at any of the times and concentrations tested.These results are consistent with the hypothesis that T3 does not have a direct effect on the proliferation of neurons derived from the external granular layer, although it does seem to affect some non‐neuronal cells. T3 also does not seem to enhance differentiated GABA functions (uptake or synthesis) beyond the levels achieved using insulin, progesterone, putrescine, selenium and transferrin.

ISSN:0736-5748    

DOI:10.1016/0736-5748(84)90022-4

出版商:Wiley    

年代:2003

数据来源: WILEY