Hepatitis C, interferon alfa, and depression.
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Biomedical subjects
D Zdilar
Publications and source records attributed to D Zdilar.
Novel receptor protein tyrosine phosphatase (RPTPrho) and acidic fibroblast growth factor (FGF-1) transcripts delineate a rostrocaudal boundary in the granule cell layer of the murine cerebellar cortex.
We have identified a novel receptor-like protein tyrosine phosphatase (RPTPrho) transcript whose expression in the cerebellar cortex is restricted to the granule cell layer of lobules 1-6. Acidic fibroblast growth factor (FGF-1) mRNA follows a similar cerebellar expression pattern. Together, the two markers define a sharp boundary in lobule 6, slightly caudal to the primary fissure. Anterior and posterior compartments became discernible only during postnatal weeks two and six, for RPTPrho and FGF-1, respectively. A rostrocaudal boundary in lobule 6 of the murine cerebellar cortex has also been identified morphologically by the effects of the meander tail mutation. The position of the RPTPrho and FGF-1 boundary on the rostrocaudal axis of the cerebellar cortex was close to, but not coincident with, the caudal extent of the disorganized anterior lobe of meander tail and the rostral extent of Otx-2 expression. The restricted pattern of FGF-1 and RPTPrho implies that these molecules may have specific signaling roles in the tyrosine phosphorylation/dephosphorylation pathway in the anterior compartment of the adult cerebellar cortex.
Animals↗
Uncoupling of GABAA/benzodiazepine receptor alpha 1, beta 2, and gamma 2 subunit mRNA expression in cerebellar Purkinje cells of staggerer mutant mice.
The mammalian GABAA/benzodiazepine (GABAA/BZ) receptor is comprised of several subunit isoforms: alpha 1-6, beta 1-13, gamma 1-3 and delta. In the present studies, the expression of alpha 1, beta 2, and gamma 2 subunit mRNAs was examined in cerebellar Purkinje cells and deep cerebellar neurons of staggerer mutant mice during postnatal development. In control animals, the three subunit mRNAs were present at high density in Purkinje cells which, in adult animals, form a monolayer at the interface of the granule cell and molecular layers. The number of Purkinje cells in the staggerer cerebellar cortex is reduced; the majority of those that remain are retained within the granule cell layer and are unable to receive normal afferent synapses from granule cells. The three subunit mRNAs were ex pressed at similar levels in both staggerer and control Purkinje cells until postnatal day 9. After this time, although the alpha 1 subunit mRNA was maintained at control levels in staggerer Purkinje cells, the expression of beta 2 and gamma 2 subunit mRNAs decreased, and was largely absent by postnatal day 20. The loss of beta 2 and gamma 2 mRNA expression in staggerer was specific to Purkinje cells, since all three mRNAs were present throughout postnatal development in other brain regions, including the deep cerebellar nuclei. The present studies indicate that in cerebellar Purkinje cells, the GABAA/BZ receptor alpha 1, and beta 2, and gamma 2, subunit mRNAs are regulated by distinct mechanisms which are differentially affected by the staggerer mutation.
Aging↗
Differential expression of GABAA/benzodiazepine receptor beta 1, beta 2, and beta 3 subunit mRNAs in the developing mouse cerebellum.
Gamma aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian cerebellum. Cerebellar granule, Purkinje, and deep nuclear neurons are known to receive GABAergic afferents. Since GABA exerts its inhibitory effects via GABA receptors, it is of interest to determine the temporal relationship between the formation of GABAergic synapses and the expression of genes coding for the GABA receptor. In a previous study, we have examined the developmental expression of binding sites for [3H]muscimol, which binds with high affinity to the beta subunits of the GABAA/benzodiazepine (GABAA/BZ) receptor. In the present study, [35S]cRNA probes were used to examine the appearance and distribution of GABAA/BZ beta 1, beta 2, and beta 3 subunit mRNAs in the developing C57BL/6 mouse cerebellum by in situ hybridization. In the adult cerebellum, the distribution of the three subunit mRNAs was clearly different, despite considerable overlap, and their temporal expression differed throughout postnatal development. The beta 1 hybridization signal appeared within the cerebellar cortex during the second postnatal week as a discrete band at the interface of the molecular and granule cell layers. Grains were distributed diffusely over small densely staining cells surrounding the Purkinje cells; relatively few grains were visible over Purkinje cell bodies themselves. This distribution may reflect an association with Bergmann glia or basket cells. The beta 2 and beta 3 hybridization signals were present considerably earlier than that of the beta 1 mRNA. The beta 2 signal was present at birth in the molecular/Purkinje cell layer; as development progressed, the signal became increasingly intense over both granule and Purkinje cells. At birth, the beta 3 subunit mRNA was present in the external germinal and molecular layers, later becoming largely localized within the granule cell layer. Dense beta 2 and beta 3 cRNA probe labeling was present over the adult granule cell layer. Moderate levels of beta 2 signal were seen over Purkinje cell bodies; considerably less labeling was observed with the beta 3 probe. The adult distribution of beta 2 and beta 3 cRNA probes showed good spatial correspondence with the known GABAA receptor beta subunit markers, [3H]-muscimol and the mAb 62-3G1 antibody, each being present within the granule cell layer. Our results indicate that the temporal expression of GABAA/BZ receptor beta subunit messages within a given cell type may be independently regulated, and that acquisition of the beta 2 and beta 3 mRNAs occurs before these cells become integrated into mature synaptic circuits.
Animals↗
Ontogeny of GABAA/benzodiazepine receptor subunit mRNAs in the murine inferior olive: transient appearance of beta 3 subunit mRNA and [3H]muscimol binding sites.
The GABAA/benzodiazepine receptor consists of at least four subunits, alpha, beta, gamma and delta, each comprised of several variants. The developmental expression of the alpha 1, beta 1-3, gamma 2 and delta subunits was studied in the murine inferior olivary nucleus by in situ hybridization with antisense cRNA probes. The postnatal appearance and distribution of [3H]flunitrazepam and [3H]muscimol binding sites, alpha and beta subunit-specific ligands respectively, were also studied autoradiographically. The beta 3 subunit was transiently expressed in each of the subnuclei of the inferior olive: The signal was strong at birth, increased throughout postnatal week 1 and rapidly declined thereafter to low adult levels. A similar pattern of labeling was observed with [3H]muscimol. Detectable levels of alpha 1 subunit mRNA hybridization signal and [3H]flunitrazepam binding sites were also present in the inferior olive at birth, decreasing thereafter. Low to moderate levels of beta 1, beta 2, and gamma 2 subunit mRNAs were present in olivary neurons throughout postnatal development, while delta mRNAs were largely absent. It has been reported previously that, during the 2nd postnatal week, the ratio of climbing fiber terminals to Purkinje cells is reduced from 3:1, as observed in neonates, to the 1:1 relationship observed in the adult cerebellar cortex. Our results raise the possibility that the subunit composition of the GABAA/benzodiazepine receptor in inferior olivary neurons undergoes changes during development, and that this process may be related to the elimination of multiple climbing fiber innervation of cerebellar Purkinje cells.
Animals↗
Stability of GABAA/benzodiazepine receptor alpha 1 subunit mRNA expression in reeler mouse cerebellar Purkinje cells during postnatal development.
A [35S]cRNA probe was used for the visualization of GABAA/benzodiazepine (GABAA/BZ) receptor alpha 1 subunit mRNA in developing reeler mutant mouse cerebellum. A clear hybridization signal was observed throughout the malformed reeler cerebellum from birth. Labeling was associated with Purkinje cell bodies located in three subcortical masses. Additional labeled Purkinje cells were observed within the granule cell layer and at their normal position at the interface between the molecular and granule cell layers. All reeler Purkinje cells had comparable levels of grain density, regardless of their location within the cerebellar cortex. These results indicate that Purkinje cell malpositioning, and the resulting absence of a major complement of afferents throughout development, does not impair the expression of mRNA coding for the alpha 1 subunit of the GABAA/BZ receptor.
Animals↗
Expression of GABAA/benzodiazepine receptor alpha 1-subunit mRNA and [3H]flunitrazepam binding sites during postnatal development of the mouse cerebellum.
Previous studies have shown that the alpha subunit of the GABAA receptor contains the flunitrazepam binding site. In the present study, in situ hybridization and receptor autoradiography were used to examine the temporal and spatial relationships between alpha 1 subunit mRNA and [3H]flunitrazepam binding sites in the developing mouse cerebellum. A [35S]cRNA probe was used to study the expression of GABAA/benzodiazepine receptor alpha 1 subunit mRNA by in situ hybridization. At postnatal day (P) 1, a diffuse band of labeling was observed in the molecular/Purkinje cell layer; subsequently, this band became progressively more concentrated and restricted to the interface between the granular and molecular layers. By P5-P7, high intensity labeling was clearly associated with Purkinje cells. Clusters of grains became visible over basket and stellate cells in the molecular layer between P11 and P13; the internal granule cell layer and the deep cerebellar nuclei showed an increasingly strong hybridization signal during postnatal development. The external germinal layer was devoid of labeling throughout its existence. The developmental distribution of [3H]flunitrazepam binding sites was studied by receptor autoradiography. Cerebellar labeling was detectable at birth, with the highest levels present over the deep cerebellar nuclei, and relatively low levels equally distributed over the molecular and Purkinje cell layers. Cerebellar cortical grain density increased gradually during postnatal weeks 1 and 2, with the molecular, Purkinje and granule cell layers remaining essentially equally labeled. Between P11 and P15, the labeling over the molecular layer increased dramatically, reaching the high adult levels by P20. As with the in situ hybridization studies, there was a complete absence of [3H]flunitrazepam binding sites in the external germinal layer throughout development. These results indicate that, in the Purkinje cell, the production of mRNA and the synthesis of the alpha 1 subunit occur prior to the formation of afferent inhibitory synapses, suggesting that GABAA/benzodiazepine receptor expression precedes, and is independent of GABAergic synaptic input.
Aging↗
[3H]SCH 23390 labels dopamine D-1 receptor sites in the rat kidney.
The binding of [3H]SCH 23390, a selective dopamine D-1 receptor radioligand, to rat kidney cortical membranes was studied. Scatchard analysis revealed a single class of binding sites. Of dopamine, noradrenaline and serotonin, dopamine was the most potent of these to displace [3H]SCH 23390 binding. The selective D-1 ligands SCH 23390 and SK & F 38393 were more potent to displace [3H]SCH 23390 than the selective D-2 ligands S-sulpiride and LY 171555, thus indicating that [3H]SCH 23390 binds predominantly to dopamine D-1 receptor sites.
Animals↗
Absence of [3H]SCH 23390 binding sites in the rat adrenal gland.
The binding of D2-dopamine receptor ligand [3H]spiperone and selective D1-ligand [3H]SCH 23390 to the rat adrenal gland and striatum has been compared. [3H]Spiperone showed specific binding in both tissues revealing a Bmax of 887 fmol mg-1 protein and KD of 0.38 nM, and B of 34 fmol mg-1 protein and KD of 0.66 nM in the striatum and adrenal gland, respectively. On the other hand, [3H]SCH 23390 showed a specific binding to the striatal tissue with Bmax of 747 fmol mg-1 protein and KD of 0.70 nM, while in the adrenal tissue no specific binding was observed. These results apparently indicated only D2-dopamine receptor binding sites being present in the rat adrenal gland.
Adrenal Glands↗