Morphological characterization of medium spiny neuron development in vitro

Abstract

Medium Spiny Neurons (MSNs) are the primary cell type of the striatum, a structure critically involved in motivation, memory, and movement. MSN structure and function are altered in Parkinson’s and Huntington’s disease as well as following repeated exposure to drugs of abuse. One site on the MSN that changes in all of these diseases is the dendritic spine, a sub-micron protrusion responsible for receiving excitatory (glutamatergic) signals. Dendritic spines undergo structural and functional changes during development, normal aging, and disease. To date, no studies have specifically characterized the developmental changes undergone by MSN dendritic spines and investigation into the molecules that regulate MSN dendritic spines has been limited to in vivo manipulations in adults or characterization of global knockout of specific molecules. Research into MSN dendritic spine development and plasticity mechanisms were likely limited by the absence of an in vitro primary neuronal culture system that produced MSNs with mature in vivo-like characteristics. The experiments detailed in this thesis describe the development and characterization of such a system as well as a morphological analysis of MSN development in culture. MSNs cultured using this technique develop gross morphological characteristics similar to in vivo cells. They also develop high densities of dendritic spines with a high variety of mature morphologies and have synaptic and intrinsic physiological characteristics like MSNs in vivo. This work represents a significant contribution to the field, supporting future research into the molecules that regulate MSN development and plasticity in both normal and disease models.