192 results found
Sirinathsinghji DJ, Morris BJ, Wisden W, et al., 1990, Gene expression in striatal grafts-I. Cellular localization of neurotransmitter mRNAs, Neuroscience, Vol: 34, Pages: 675-686, ISSN: 0306-4522
his study utilized the technique of in situ hybridization histochemistry to identify cells expressing neurotransmitter mRNAs in embryonic striatal tissue grafts implanted into the ibotenic acid-lesioned rat neostriatum. Synthetic 32P- or 35S-labelled oligodeoxyribonucleotide probes specific for prosomatostatin, proneuropeptide Y. proenkephalin, prodynorphin and preprotachykinin mRNAs and a 32P-labelled cRNA probe specific for glutamate decarboxylase mRNA were used to study the regional and cellular changes in these mRNA levels in the normal, lesioned and grafted neostriatum. The levels of neuropeptide Y mRNA and somatostatin mRNA were substantially increased in the striatal grafts compared with the intact control striata. The levels of glutamate decarboxylase mRNA in the grafts also appeared to be slightly elevated over those in the control striata. However, the levels of proenkephalin mRNA, prodynorphin mRNA and preprotachykinin mRNA were significantly lower in the grafts. The increased levels of neuropeptide Y mRNA and somatostatin mRNA in the grafts were due both to an increase in the number of labelled cells and to an increase in the cellular levels of each neuropeptide mRNA. In contrast, the cellular levels of proenkephalin mRNA, prodynorphin mRNA and preprotachykinin mRNA in the grafts were comparable, or elevated relative, to those in the intact striata but the density of cells expressing each of these mRNAs was reduced. Since neuropeptide Y and somatostatin are known to be present in medium to large aspiny striatal neurons (interneurons) and enkephalin, dynorphin and tachykinin peptides and GABA are localized in medium spiny striatal projection neurons, the above findings would indicate that there is a divergence in the levels of activity between these two neuronal populations in the striatal grafts. Our data suggest that the levels of gene expression and hence the functional neurotransmitter-synthesizing and releasing activity in the grafted neuron are diff
Ymer S, Draguhn A, Wisden W, et al., 1990, Structural and functional characterization of the gamma 1 subunit of GABA-A/benzodiazepine receptors, EMBO J, Vol: 9, Pages: 3261-3267, ISSN: 0261-4189
The GABAA receptor gamma 1 subunit of human, rat and bovine origin was molecularly cloned and compared with the gamma 2 subunit in structure and function. Both gamma subunit variants share 74% sequence similarity and are prominently synthesized in often distinct areas of the central nervous system as documented by in situ hybridization. When co-expressed with alpha and beta subunits in Xenopus oocytes and mammalian cells, the gamma variants mediate the potentiation of GABA evoked currents by benzodiazepines and help generate high-affinity binding sites for these drugs. However, these sites show disparate pharmacological properties which, for receptors assembled from alpha 1, beta 1 and gamma 1 subunits, are characterized by the conspicuous loss in affinity for neutral antagonists (e.g. flumazenil) and negative modulators (e.g. DMCM). These findings reveal a pronounced effect of gamma subunit variants on GABAA/benzodiazepine receptor pharmacology.
WISDEN W, MORRIS BJ, DARLISON MG, et al., 1989, DIFFERENTIAL DISTRIBUTION IN BOVINE BRAIN OF DISTINCT GAMMA-AMINOBUTYRIC ACIDA RECEPTOR ALPHA-SUBUNIT MESSENGER-RNAS, Publisher: PORTLAND PRESS, Pages: 566-567, ISSN: 0300-5127
Wisden W, McNaughton LA, Darlison MG, et al., 1989, Differential distribution of GABAA receptor mRNAs in bovine cerebellum--localization of alpha 2 mRNA in Bergmann glia layer, Neurosci Lett, Vol: 106, Pages: 7-12
Using in situ hybridization histochemistry, we have demonstrated that 3 alpha subunit mRNAs of the GABAA receptor are present in different cell populations of the bovine cerebellum. While the alpha 1 mRNA is the most abundant and is present in granule cells, Purkinje cells and stellate/basket cells, the alpha 2 mRNA appears to be confined to the Bergmann glial cell layer. The alpha 3 mRNA is only expressed in the Golgi cells. This differential distribution of GABAA receptor mRNA subtypes suggests a previously unrecognized complexity of GABAergic transmission in the cerebellum.
Wisden W, Morris BJ, Darlison MG, et al., 1989, Localization of GABA-A receptor alpha-subunit mRNAs in relation to receptor subtypes, Brain Res Mol Brain Res, Vol: 5, Pages: 305-310, ISSN: 0169-328X
The distribution of 3 GABAA receptor alpha-subunit mRNAs in various regions of bovine brain has been investigated using in situ hybridization. Whereas the alpha 2- and alpha 3-transcripts are of low abundance in all regions except striatum, the alpha 1-transcript is considerably enriched in the inferior colliculus, olfactory bulb and substantia nigra, and appears to be correlated with benzodiazepine type I receptor localization.
Hunt SP, Wisden W, Morris BJ, et al., 1989, In situ hybridization in the vertebrate nervous system., Neuropeptides: a Methodology, Editors: Fink, Harmer, Publisher: John Wiley & Sons Ltd, Pages: 55-82
Morris BJ, Wisden W, Dunnett SB, et al., 1989, Cellular localisation of somatostatin mRNA and neuropeptide Y mRNA in foetal striatal tissue grafts, Neurosci Lett, Vol: 103, Pages: 121-126, ISSN: 0304-3940
Using in situ nucleic acid hybridisation histochemistry, we have studied the expression of somatostatin mRNA and neuropeptide Y mRNA in grafts of embryonic striatal neurones implanted into the ibotenic acid-lesioned rat neostriatum. Tissue sections of the grafted striatum were incubated with either 32P- or 35S-labelled complementary oligodeoxyribonucleotide probes specific for somatostatin mRNA and neuropeptide Y mRNA, exposed with X-ray film and dipped in Ilford K-5 emulsion. Neither somatostatin mRNA nor neuropeptide Y mRNA was detectable in the ibotenic acid-lesioned striatum indicating a pronounced degeneration of somatostatin- and neuropeptide Y-containing neurones. However, in the striatal grafts the levels of somatostatin mRNA and neuropeptide Y mRNA were substantially increased over those in the control intact striata. The results suggest that in the grafts, somatostatin mRNA and neuropeptide Y mRNA were expressed in a higher proportion of primordial striatal neurones and there was also an increased level of expression of each neuropeptide gene per individual neurone (reflecting a higher synthetic activity of such neurones) compared to the intact mature striatum. These data demonstrate the sensitivity of the in situ hybridisation technique to study patterns of gene expression in developing neuronal tissues after transplantation.
Wisden W, Morris BJ, Darlison MG, et al., 1989, Differential distribution in bovine brain of distinct GABA-A receptor alpha subunit mRNAs., Biochem Soc Trans (London), Vol: 17, Pages: 566-567
Wisden W, Morris BJ, Darlison MG, et al., 1989, Differential distribution in bovine brain of distinct GABA-A receptor alpha subunit mRNAs., Biochem Soc Trans (London), Pages: 566-567
Darlison MG, Barnard EA, Bateson AN, et al., 1989, The structure and expression of the GABA-A receptor as deduced by molecular genetic studies., In Molecular Biology of Neuroreceptors and Ion Channels, Editors: Maelicke, Publisher: Springer-Verlag, Heidelberg, Pages: 83-99
Levitan ES, Schofield PR, Burt DR, et al., 1988, Structural and functional basis for GABAA receptor heterogeneity, Nature, Vol: 335, Pages: 76-79, ISSN: 0028-0836
When gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in vertebrate brain, binds to its receptor it activates a chloride channel. Neurotransmitter action at the GABAA receptor is potentiated by both benzodiazepines and barbiturates which are therapeutically useful drugs (reviewed in ref. 1). There is strong evidence that this receptor is heterogeneous. We have previously isolated complementary DNAs encoding an alpha- and a beta-subunit and shown that both are needed for expression of a functional GABAA receptor. We have now isolated cDNAs encoding two additional GABAA receptor alpha-subunits, confirming the heterogeneous nature of the receptor/chloride channel complex and demonstrating a molecular basis for it. These alpha-subunits are differentially expressed within the CNS and produce, when expressed with the beta-subunit in Xenopus oocytes, receptor subtypes which can be distinguished by their apparent sensitivity to GABA. Highly homologous receptor subtypes which differ functionally seem to be a common feature of brain receptors.
Wisden W, Morris BJ, Darlison MG, et al., 1988, Distinct GABAA receptor alpha subunit mRNAs show differential patterns of expression in bovine brain, Neuron, Vol: 1, Pages: 937-947, ISSN: 0896-6273
Specific oligonucleotide probes have been used to visualize the regional and cellular distribution of the mRNAs encoding three structurally distinct GABAA receptor alpha subunits in bovine brain. In situ hybridization analysis showed that these transcripts differ in distribution and in relative abundance. In frontal cortex the alpha 1 and alpha 2 transcripts are most abundant in layers II-IV, whereas the alpha 3 mRNA is most abundant in layers V and VI. In the hippocampal complex, the alpha transcripts are differentially distributed in the entorhinal cortex and subiculum. The alpha 2 transcript is enriched in the dentate gyrus and CA4/CA3 regions of the hippocampus. In the cerebellum, essentially only the alpha 1 transcript is detectable in granule cells, Purkinje cells, and stellate/basket cells. These results suggest that the different alpha subunits represent components of distinct GABAA receptor subtypes.
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