9 research outputs found
Increased expression of Aquaporin 4 in the rat hippocampus and cortex during trimethyltin-induced neurodegeneration
Trimethyltin chloride (TMT) is a neurotoxicant producing neuronal degeneration and reactive astrogliosis in the mammalian central nervous system, especially the hippocampus. A previous magnetic resonance imaging investigation in TMT-treated rats evidenced dilation of lateral ventricles, also suggesting alterations in blood-brain barrier permeability and brain edema. Aquaporin 4 (AQP4), a glial water channel protein expressed mainly in the nervous system, is considered a specific marker of vascular permeability and thought to play an important role in brain edema (conditions). We studied AQP4 expression in the hippocampus and cerebral cortex of TMT-treated rats in order to explore the molecular mechanisms involved in brain edema occurring in these experimental conditions. Real-time PCR and western blotting data showed significant up-regulation of both AQP4 mRNA and protein levels starting 14 days after TMT treatment in the hippocampus and cortex. Parallel immunofluorescence studies indicated intense astrogliosis and AQP4 immunoreactivity diffusely pronounced in the hippocampal and cortex areas starting 14 days after TMT intoxication. In order to study the effects of TMT on vascular integrity, double-label immunofluorescence experiments for rat immunoglobulin G (IgG) and rat endothelial cell antigen-1 (RECA-1) or neuronal nuclei (NeuN) (endothelial and neuronal markers respectively) were performed. The results indicated, at 21 and 35 days after treatment, the presence of rat IgG in paravasal parenchyma and in some neuronal cells of the hippocampus and cortex. The extravasated IgG staining was temporally correlated with over-expression of neuronal vascular endothelial growth factor (VEGF) and the active phosphorylated form of its neuronal receptor (VEGFR-2P), suggesting that these factors may cooperate in mediating vascular leakage
Reelin is transiently expressed in the peripheral nerve during development and is upregulated following nerve crush
Reelin is an extracellular matrix protein which is critical for the
positioning of migrating post-mitotic neurons and the laminar
organization of several brain structures during development. We
investigated the expression and localization of Reelin in the rodent
peripheral nerve during postnatal development and following crush
injury in the adult stage. As shown with Western blotting, immunocytochemistry
and RT-PCR, Schwann cells in the developing peripheral
nerve and in primary cultures from neonatal nerves produce and
secrete Reelin. While Reelin levels are downregulated in adult stages,
they are again induced following sciatic nerve injury. A morphometric
analysis of sciatic nerve sections of reeler mice suggests that Reelin is
not essential for axonal ensheathment by Schwann cells, however, it
influences the caliber of myelinated axons and the absolute number of
fibers per unit area. This indicates that Reelin may play a role in
peripheral nervous system development and repair by regulating
Schwann cell–axon interactions
Aquaporin 4 (AQP4) expression and blood brain barrier damage in an experimental model of neurodegeneration induced by trimethyltin
Trimethyltin (TMT) is well know
Cathepsin D Plays a Crucial Role in the Trimethyltin-Induced Hippocampal Neurodegeneration Process
Trimethyltin chloride (TMT) is known to produce
neuronal damage in the rat hippocampus, especially in the
CA1/CA3 subfields, together with reactive astrogliosis. Previous
studies indicate that in cultured rat hippocampal neurons
the Ca2 cytosolic increase induced by TMT is correlated
with apoptotic cell death, although some molecular aspects
of the hippocampal neurodegeneration induced by this neurotoxicant
still remain to be clarified. Cathepsin D (Cat D) is a
lysosomal aspartic protease involved in some neurodegenerative
processes and also seems to play an important role in
the processes that regulate apoptosis. We investigated the
specific activity and cellular expression of Cat D in the rat
hippocampus in vivo and in cultured organotypic rat hippocampal
slices. The role of Cat D in cell death processes
and the mechanisms controlling Cat D were also investigated.
Cat D activity was assayed in hippocampus homogenates
of control and TMT-treated rats. In order to visualize the
distribution of Cat D immunoreactivity in the hippocampus,
double-label immunofluorescence for Cat D and Neu N,
GFAP, OX42 was performed. In addition, in order to clarify the
possible relationship between Cat D activity, neuronal calcium
overload and neuronal death processes, organotypic
hippocampal cultures were also treated with a Cat D inhibitor
(Pepstatin A) or Calpain inhibitor (Calpeptin) or an intracellular
Ca2 chelator (BAPTA-AM) in the presence of TMT. TMT
treatment in rat hippocampus induced high levels of Cat D
activity both in vivo and in vitro, in glial cells and in CA3
neurons, where a marked TMT-induced neuronal loss also
occurred. Cat D is actively involved in CA3 neuronal death
and the protease increase is a calcium-Calpain dependent
phenomeno
Aquaporin 4 expression in the rat hippocampus and cortex during trimethyltin-induced neurodegeneration
Trimethyltin (TMT) is a .....
Aquaporin 4 expression in the rat cortex and hippocampus during TMT induced neurodegeneration
Trimethyltin is an organotin.....
Aquaporin 4 expression increases in the rat hippocampus and cortex during trimrthyltin-induced neurodegeneration
Trimethyltin (TMT) ia a neurotoxicant...