Involvement of p38α in Kainate-Induced Seizure and Neuronal Cell Damage

We investigated how p38α mitogen-activated protein kinase (p38) is related to kainate-induced epilepsy and neuronal damages, by using the mice with a single copy disruption of the p38 α gene (p38α^+/?). Mortality rate and seizure score of p38α^+/? mice administered with kainate were significantly reduced compared with the case of wild-type (WT) mice. This was clearly supported by the electroencephalography data in which kainate-induced seizure duration and frequency in the brain of p38α^+/? mice were significantly suppressed compared to those of WT mice. As a consequence of seizure, kainate induced delayed neuronal damages in parallel with astrocytic growth in the hippocampus and ectopic innervation of the mossy fibers into the stratum oriens in the CA3 region of hippocampus in WT mice, whose changes were moderate in p38α^+/? mice. Likewise, kainate-induced phosphorylation of calcium/calmodulin-dependent kinase II in the hippocampus of p38α ^+/? mice was significantly decreased compared to that of WT mice. These results suggest that p38α signaling pathway plays an important role in epileptic seizure and excitotoxicity.     

PHYSICOCHEMICAL STUDIES OF TASTE RECEPTION VI: Interpretation of Anion Influences on Taste Response

Monolayers of lipids from bovine tongue epithelium were preparedas a model system for the gustatory receptor membrane to clarifythe effects of anions on the taste response. Changes in thesurface potential of the monolayers were measured by use ofthe ionizing-electrode method under the presence of sodium andcalcium salts carrying various species of anions in the aqueousphase. The organic and chaotropic anions showed the suppressiveeffect on the surface potentials as compared with Cl^–or NO₃^-. The influences of anion species on the surface potentialwere similar to those on the taste response recorded from glossopharyngealnerve of the frog. This suggested that the effects of anionson the taste response could be explained in terms of the electricalpotential at the interface between the receptor membrane andstimulating solution. Analysis of data on the surface potentialrevealed that a conformational change of the monolayers causedby non-electrical interaction between the monolayers and anionsis responsible for the suppressive effect.