Proliferation, Adult Neuronal Stem Cells and Cells Migration in Pallium during Constitutive Neurogenesis and after Traumatic Injury of Telencephalon of Juvenile Masu Salmon, Oncorhynchus masou.

A study of the lateral pallium in zebrafish and the visual tectum of the medaka revealed a population of adult neuroepithelial (NE) cells supported from the early stage of development to various postembryonic stages of ontogenesis. These data emphasize the importance of non-radial glial stem cells in the neurogenesis of adult animals, in particular fish. However, the distribution, cell cycle features, and molecular markers of NE cells and glial progenitors in fish are still poorly understood at the postembryonic stages of ontogenesis. Fetalization predominates in the ontogenetic development of salmon fish, which is associated with a delay in development and preservation of the features of the embryonic structure of the brain during the first year of life. In the present work, we studied the features of proliferation and the migration of neuronal precursors in the pallial proliferative zone of juvenile Oncorhynchus masou. The aim of the study is a comparative analysis of the distribution of glial-type aNSCs markers, such as vimentin and glial fibrillar acid protein GFAP, as well as the proliferation marker BrdU and migratory neuronal precursor doublecortin, in the pallial zone of the intact telencephalon in juvenile O. masou normal and after mechanical injury. The immunohistochemical IHC labeling with antibodies to vimentin, GFAP and doublecortin in the pallium of intact fish revealed single, small, round and oval immunopositive cells, that correspond to a persistent pool of neuronal and/or glial progenitors. After the injury, heterogeneous cell clusters, radial glia processes, single and small intensely labeled GFAP+ cells in the parenchyma of Dd and lateral part of pallium (Dl) appeared, corresponding to reactive neurogenic niches containing glial aNSCs. A multifold increase in the pool of Vim+ neuronal precursor cells (NPCs) resulting from the injury was observed. Vim+ cells of the neuroepithelial type in Dd and Dm and cells of the glial type were identified in Dl after the injury. Doublecortine (Dc) immunolabeling after the injury revealed the radial migration of neuroblasts into Dm from the neurogenic zone of the pallium. The appearance of intensely labeled Dc+ cells in the brain parenchyma might indicate the activation of resident aNSCs as a consequence of the traumatic process.

Electrophysiological and contractile evidence of the ability of human mesenchymal stromal cells to correct vascular malfunction in rats after ionizing irradiation.

The effect of intravenous administration of human mesenchymal stromal stem cells (hMSC) has been evaluated by means of large-conductance calcium-dependent potassium channel (BK(Ca)) activity measurements in thoracic aorta smooth muscle cells (SMC) obtained from non-fatal whole-body irradiated rats, using the patch clamp technique in whole-cell modification, and the standard acetylcholine (ACh) test to evaluate functional endothelium integrity using SM contractile recordings. Myofilament calcium sensitivity was estimated using simultaneous contractile recordings versus [Ca(2+)](i). Arterial blood was measured in intact and irradiated rats before and after hMSC administration. Stimulation of isolated SMC from the control group of animals with depolarizing voltage steps showed that outward K(+) currents sensitive to the BK(Ca) inhibitor paxilline were expressed. Outward currents in SMC obtained from irradiated animals were significantly reduced on the 30th day of post-irradiation. Irradiation led to a significant elevation in arterial blood pressure and reduced ACh-induced relaxation responses in irradiated rats as compared with the control group. Simultaneous measurements of contractile force and [Ca(2+)](i) showed that myofilament Ca(2+) sensitivity had increased following irradiation. Intravenously injected hMSC effectively restored BK(Ca) current and the amplitude of ACh-induced endothelium-dependent vasodilatation in vascular tissues obtained from post-irradiated rats. SMC obtained from irradiated rats treated with hMSC demonstrated a significantly increased paxilline-sensitive component of outward potassium currents, indicating that BK(Ca) activity had been restored. hMSC administration normalized increased blood pressure and myofilament Ca(2+) sensitivity in irradiated animals. When administered to healthy rats, hMSC were without effects on either of these. This study does not provide any immunohistochemical proof of hMSC engraftment in the host rats. PCR analysis showed that hMSCs were negative for hematopoietic cell markers and positive for hMSC markers. There were no clinical signs of graft-versus-host disease throughout the experimental period of 30 days. The data obtained suggest that hMSC demonstrate a clearly expressed ability to normalize vascular function damaged following irradiation, i.e. to reduce an elevated arterial blood pressure and myofilament Ca(2+) sensitivity, and to repair BK(Ca) function and endothelium-dependent relaxation in vascular tissues obtained from irradiated animals. Thus, hMSC seem to be worthwhile therapeutic approach in cases of ionizing irradiation accident or radiation beam therapy.

Dependence of the coupling of dopamine receptors to G proteins on the protein redox state in the neural plasma membranes of pond snail.

Binding analysis using [3H]dopamine has shown that reduction of protein thiol groups with dithiothreitol (DTT) led to a dual effect on the receptors. First, the amount of dopamine-binding sites on the membranes and their affinity to the ligand were decreased. Second, the affinity of the receptors to [3H]dopamine was enhanced in the presence of GDP. Binding of D(1) antagonist [3H]SCH23390 to dopamine receptors increased following DTT treatment, opposite to the case with D(1) agonist [3H]SKF38393. The displacement of [3H]GDP by GTPgammaS was depressed by dopamine. Stimulation of [3H]GDP binding by dopamine was potentiated after incubation with DTT. Membrane nitrosylation eliminated the reciprocal dependence of GDP and dopamine binding to the membranes. It is suggested that binding of dopamine to the receptors can lead to both stimulation and inhibition of G protein activity, and the ratio of these effects depends on the reduction and oxidation of sulfhydryl groups of membrane proteins. Thiol reduction potentiated inhibitory action of dopamine receptors on coupled G proteins, and nitrosylation led to their uncoupling.