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P Vernier

Publications and source records attributed to P Vernier.

65 records · Page 4Linked to original sources
PubMed1989

Modulation of GFAP mRNA levels following toxic lesions in the basal ganglia of the rat.

GFAP mRNA levels were quantified by Northern blot analysis using a human GFAP (glial fibrillary acidic protein) cDNA probe in association with immunocytochemistry. Ten days after a unilateral lesion of substantia nigra with 6-hydroxydopamine (6-OHDA), GFAP mRNA level is increased 1.4-fold in the ipsilateral striatum; thereafter it declined continuously to reach the control level 4 months later. This effect contrasted with the lower and more sustained increase of preproenkephalin (PPE) mRNA, a marker of neuronal target of nigrostriatal pathway. Following ibotenic acid-induced neuronal degeneration of the neostriatum in the rat, we observed a sharp elevation of the GFAP transcripts (4-fold) as soon as 2 days after the lesion both in the striatum and in the substantia nigra. Whereas in the striatum GFAP mRNA level already declined at 5 days postlesion, it remained stable in the substantia nigra. In comparison GFAP immunoreactivity was slightly delayed. No obvious modification was observed in the contralateral side to the lesion whatever the denervation condition studied. Implication of these results on the understanding and the therapeutic approach of glial scarring is discussed.

Animals↗
PubMed1988

Identification of a human glial fibrillary acidic protein cDNA: a tool for the molecular analysis of reactive gliosis in the mammalian central nervous system.

Two clones encoding human glial fibrillary acidic protein (GFAP) were isolated from a human astrocytoma cDNA library. The clones pHGFAP1 and pHGFAP2 were selected by the combined use of differential colony hybridization and hybridization-selection technique with polyclonal anti GFAP antiserum. The longer one, pHGFAP1, encompasses 3.0 kb and includes the 1.8 kb long 3' untranslated region specific to the human mRNA. Sequence data disclosed an extensive homology within the coding region of human and mouse GFAP cDNAs even in the end domains. Blot hybridization analysis of RNAs from human, rat and mouse brain revealed a single GFAP mRNA species of 3.1, 2.8 and 2.7 kb respectively and Southern blot experiments indicated that this mRNA is most probably transcribed from a unique gene. In situ hybridization performed with biotinylated probes on cultured mouse brain cells suggests both the sorting and the transport of GFAP mRNA throughout the cytoplasm and processes of the astrocytes. As a model of reactive gliosis secondary to degenerative disorders, 6-hydroxydopamine (6-OHDA) lesion of the substantia nigra in the rat was performed. GFAP mRNA increased 1.4 fold in the ipsilateral striatum on day 10 after the lesion. It then declined to the control level 4 months later contrasting with the lower and more sustained increase in preproenkephalin (PPE) mRNA. The interspecies cross-reactivity of the HGFAP probes make them useful as a tool for the molecular analysis of reactive gliosis in various experimental models.

Amino Acid Sequence↗
PubMed1988

Similar time course changes in striatal levels of glutamic acid decarboxylase and proenkephalin mRNA following dopaminergic deafferentation in the rat.

The time course changes in levels of mRNA encoding glutamic acid decarboxylase (GAD) and proenkephalin (PPE) was analyzed in the rat striatum following unilateral lesion of substantia nigra with 6-hydroxydopamine. The levels of both GAD and PPE mRNAs increased after the dopaminergic deafferentation, reaching concomitantly a maximal twofold increase on day 25. Thereafter, the mRNA levels declined; at 4 months, the amount of PPE mRNA remained slightly elevated whereas GAD mRNA had returned to the control value, suggesting the action of a compensatory mechanism. We also observed a rise of glial fibrillary acidic protein mRNA level which reflects a reactive astrocytosis. In contrast, alpha-tubulin mRNA level remained unchanged, indicating that no significant synaptogenesis occurs in this experimental situation. No obvious modification in mRNA levels was detected in the striatum contralateral to the lesion. These results highlight the role of the modulation of gene expression in adaptive processes to dopamine deficiency in striatal efferent pathways. Its relevance to the pathophysiology of Parkinson's disease is discussed.

Animals↗
PubMed1987

Cortical ablation fails to influence striatal dopamine target cell supersensitivity induced by nigrostriatal denervation in the rat.

The possible influence of the corticostriatal (glutamatergic) pathway on denervation-induced striatal dopamine target cell supersensitivity has been investigated in the rat by measuring the changes in striatal acetylcholine levels induced by the dopamine agonist pergolide and the basal dopamine D2-receptor density after combined 6-hydroxydopamine-induced lesion of the substantia nigra and cortical ablation. Lesion of the nigrostriatal dopaminergic pathway alone enhanced the ability of pergolide (0.06-1 mg/kg i.p.) to increase acetylcholine levels and increased the maximal density of [3H]spiperone binding sites in the striatum. Similar changes in these biochemical parameters were observed after combined cortical ablation and nigral lesion. Cortical ablation by itself slightly diminished acetylcholine levels and reduced by 30% [3H]spiperone binding site density in the striatum. These results indicate that the corticostriatal tract does not influence striatal dopamine target cell supersensitivity caused by dopaminergic denervation.

Acetylcholine↗
PubMedDate not supplied

Properties of the kainate channel in rat brain mRNA injected Xenopus oocytes: ionic selectivity and blockage.

The properties of kainate receptor/channels were studied in Xenopus oocytes injected with mRNA that was isolated from adult rat striatum and cerebellum and partially purified by sucrose gradient fractionation. Kainate (3-1000 microM) induced a smooth inward current that was competitively inhibited by gamma-D-glutamyl-aminomethanesulfonate (GAMS, 300 microM). In striatal mRNA-injected oocytes, the kainate current displayed nearly linear voltage-dependence and mean reversal potential (Er) of -6.1 +/- 0.5 mV. In cerebellar mRNA-injected oocytes; Er was nearly identical (-5.1 +/- 1.2 mV) but there was marked inward rectification of the kainate current. Ion replacement studies reveal that the kainate channel is selective for cations over anions, but relatively non-selective among small monovalent cations. Large monovalent cations such as tetrabutylammonium are impermeant and induce a non-competitive block of kainate current that is strongly voltage-dependent. Divalent cations are relatively impermeant in the kainate channel and Cd++ and other polyvalent metals were shown to block kainate current by a mechanism that is only weakly voltage-dependent. A model of the kainate channel is proposed based upon these observations.

Animals↗
PubMedDate not supplied

Substance P-immunoreactivity in the dorsal medial region of the medulla in the cat: effects of nodosectomy.

The distribution of substance P in the vagal system of the cat was studied by immunohistochemistry. Substance P-immunoreactive cell bodies and fibres were observed in the nodose ganglion. Numerous substance P-immunoreactive terminals and fibres were localized in their bulbar projection area, i.e. throughout the caudo-rostral extent of the nucleus of the solitary tract. Four subnuclei, among the nine forming the nucleus of the solitary tract, were strongly labelled: interstitial, gelatinosus, dorsal and commissural. The dorsal motor nucleus of the vagus nerve also exhibited numerous substance P-immunoreactive terminals, sometimes closely apposed on the somata of preganglionic neurons. To determine the substance P component of the vagal afferent system a nodose ganglion was removed on one side. The ablation triggered ipsilaterally a large decrease of substance P immunoreactivity in the four subnuclei strongly labelled on normal cats. These results suggest the involvement of substance P-containing vagal fibres in integrative processes of the central regulation of cardiovascular, digestive and respiratory systems, viscerotopically organized throughout these four subnuclei. The nodose ablation also resulted in a decrease of substance P immunoreactivity in the ipsilateral dorsal motor nucleus of the vagus nerve, suggesting monosynaptic vago-vagal interactions.

Animals↗