Prion Protein Is a Key Determinant of Alcohol Sensitivity through the Modulation of N-Methyl-D-Aspartate Receptor (NMDAR) Activity

The prion protein (PrP) is absolutely required for the development of prion diseases; nevertheless, its physiological functions in the central nervous system remain elusive. Using a combination of behavioral, electrophysiological and biochemical approaches in transgenic mouse models, we provide strong evidence for a crucial role of PrP in alcohol sensitivity. Indeed, PrP knock out (PrP−/−) mice presented a greater sensitivity to the sedative effects of EtOH compared to wild-type (wt) control mice. Conversely, compared to wt mice, those over-expressing mouse, human or hamster PrP genes presented a relative insensitivity to ethanol-induced sedation. An acute tolerance (i.e. reversion) to ethanol inhibition of N-methyl-D-aspartate (NMDA) receptor-mediated excitatory post-synaptic potentials in hippocampal slices developed slower in PrP−/− mice than in wt mice. We show that PrP is required to induce acute tolerance to ethanol by activating a Src-protein tyrosine kinase-dependent intracellular signaling pathway. In an attempt to decipher the molecular mechanisms underlying PrP-dependent ethanol effect, we looked for changes in lipid raft features in hippocampus of ethanol-treated wt mice compared to PrP−/− mice. Ethanol induced rapid and transient changes of buoyancy of lipid raft-associated proteins in hippocampus of wt but not PrP−/− mice suggesting a possible mechanistic link for PrP-dependent signal transduction. Together, our results reveal a hitherto unknown physiological role of PrP on the regulation of NMDAR activity and highlight its crucial role in synaptic functions

Dielectric and pyroelectric properties of sintered discs of sodium meta vanadate

The dielectric and pyroelectric properties of poled and unpoled sintered discs of sodium meta vanadate were investigated in the temperature range from room temperature to 450°C. Dielectric constant and loss tangent anomalies were found around 375–390°C, while in pyroelectric coefficient, two anomalies were noticed at 250±25°C and 360±50°C respectively

Changes in valency state of ions in CuMn<SUB>2</SUB>O<SUB>4</SUB> at high temperatures

Thin films of copper manganite with three different molar ratios of CuratioMn viz 1:1, 1:2 and 1:3 have been deposited on quartz plates. The electrical conductivity of these thin films has been studied as a function of temperature. The energy of activation for electrical conduction in these compounds is found to increase from 0.20 eV to about 0.62 eV above 600&#176; K. Differential thermal analysis of bulk sample of copper manganite also shows a small endothermic change at 600&#176; K, while thermogravimetric analysis does not show any change in weight. It has been concluded from these results that the stable form of the ionic configuration of copper manganite at low temperatures, i.e. Cu1+[Mn3+Mn4+]O4 changes at high temperatures to Cu2+[Mn2 3+]O4