Organization of primary afferent and local-circuit synapses in the olfactory glomerulus

Odorant molecules are transduced by olfactory receptor cells whose axons join to form the olfactory nerve which distributes across the surface of the olfactory bulb (OB). Axons exit the nerve layer to terminate within the glomerular neuropil of the OB. While there appears a gross topography between the epithelium and OB4, it is clear that extensive topographic reorganization of axons occurs within the olfactory nerve. To better understand the mechanisms that may contribute to the establishment of glomerular-specific fascicles and functional domains within the OB, we have investigated axonal organization within the nerve and the intraglomerular distribution of primary afferent synapses using light, confocal and electron microscopy.Sprague-Dawley rats, 30 to 50 days postnatal, were anesthetized, lightly perfused with 0.9% NaCl and the OBs removed. Crystals of the lipophilic dye, Dil, were inserted into the olfactory nerve layer and the tissue placed in 4% paraformaldehyde at room temperature for 10 - 30 days.</jats:p

Protein kinase C delta mediates cerebral reperfusion injury in vivo

Protein kinase C (PKC) has been implicated in mediating ischemic and reperfusion damage in multiple organs. However, conflicting reports exist on the role of individual PKC isozymes in cerebral ischemic injury. Using a peptide inhibitor selective for deltaPKC, deltaV1-1, we found that deltaPKC inhibition reduced cellular injury in a rat hippocampal slice model of cerebral ischemia [oxygen-glucose deprivation (OGD)] when present both during OGD and for the first 3 hr of reperfusion. We next demonstrated peptide delivery to the brain parenchyma after in vivo delivery by detecting biotin-conjugateddeltaV1-1 and by measuring inhibition of intracellular deltaPKC translocation, an indicator of deltaPKC activity. Delivery of deltaV1-1 decreased infarct size in an in vivo rat stroke model of transient middle cerebral artery occlusion. Importantly, deltaV1-1 had no effect when delivered immediately before ischemia. However, delivery at the onset, at 1 hr, or at 6 hr of reperfusion reduced injury by 68, 47, and 58%, respectively. Previous work has implicated deltaPKC in mediating apoptotic processes. We therefore determined whether deltaPKC inhibition altered apoptotic cell death or cell survival pathways in our models. We found that deltaV1-1 reduced numbers of terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling-positive cells, indicating decreased apoptosis, increased levels of phospho-Akt, a kinase involved in cell survival pathways, and inhibited BAD (Bcl-2-associated death protein) protein translocation from the cell cytosol to the membrane, indicating inhibition of proapoptotic signaling. These data support a deleterious role for deltaPKC during reperfusion and suggest that deltaV1-1 delivery, even hours after commencement of reperfusion, may provide a therapeutic advantage after cerebral ischemia