ABSTRACT
Within neurons of several regions of the CNS, mature dendrite architecture is attained via extensive reorganization of arbor during the developmental period. Since dendrite morphology determines the firing patterns of the neuron, morphological refinement of dendritic arbor may have important implications for mature network activity. In the neocortex, a region of brain that is sensitive to activity-dependent structural rearrangement of dendritic arbor, the proportion of AMPA receptors increases over the developmental period. However, it is unclear whether changes in AMPA receptor expression contribute to maturation of dendritic architecture. To determine the effects of increasing AMPA receptor expression on dendrite morphology and connectivity within the neocortex, and to determine whether these effects are dependent on specific AMPA receptor subunits, we overexpressed the AMPA glutamate receptor subunit 1 (GluR1) and glutamate receptor subunit 2 (GluR2) in cultured rat neocortical neurons at the time that AMPA receptors would normally be incorporated into synapses. Following expression of GluR1 or GluR2 we observed increases in the length and complexity of dendritic arbor of cortical neurons, and a concurrent reduction in motility of spines. In addition, expression of either subunit was associated with an increased density of excitatory postsynaptic puncta. These results suggest that AMPA receptor expression is an important determinant of dendrite morphology and connectivity in neocortical neurons, and further, that contrary to other regions of the CNS, the effects of AMPA receptors on dendrite morphology are not subunit-specific.
Subject(s)
Cerebral Cortex/cytology , Dendritic Spines/physiology , Neurons/cytology , Receptors, AMPA/metabolism , Analysis of Variance , Animals , Calcium/metabolism , Cells, Cultured , Dendrites/physiology , Dendrites/ultrastructure , Dendritic Spines/drug effects , Disks Large Homolog 4 Protein , Embryo, Mammalian , Female , Green Fluorescent Proteins/genetics , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Male , Membrane Proteins/genetics , Membrane Proteins/metabolism , Neurons/classification , Neurons/physiology , Pregnancy , Pseudopodia/drug effects , Pseudopodia/physiology , Rats , Rats, Sprague-Dawley , Receptors, AMPA/genetics , Transfection/methodsABSTRACT
In this article up-to-date, nephron-sparing therapy for renal cell cancer such as radical tumor nephrectomy, partial resection or enucleation is summarised. The results of open and laparoscopic partial nephrectomy and tumor enucleation are presented. Problems and complications associated with the techniques are reviewed. There are as yet no randomized, controlled trials and most published studies show retrospective data. Further new alternative techniques in nephron-sparing therapy like cryosurgery and radiofrequency ablation are presented.
