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Completed Project

3D Reconstructions of Neurons: Testing Structural Plasticity of CA3 Hippocampal Pyramidal Neurons in Response to Postnatal Maternal Exercise

Sanaya Shikari ’21 and Professor Bojana Zupan (Psychological Science)

One of the most consistently observed effects of chronic stress on the hippocampus, mediated through high levels of systemic glucocorticoids, is structural alterations of the branching of pyramidal cell dendrites. Data suggests that exercise can normalize many effects of stress, including dendritic restructuring (Trinchero et al., 2019). Interestingly, we have previously found that postnatal maternal exercise can also ameliorate many behavioral effects of stress in her adult offspring. In order to assess whether increased resiliency to chronic stress in runner-dam offspring is associated with structural changes in the hippocampus, male mice born from dams that either had post-parturition access to a running wheel or a standard housing cage underwent a chronic unpredictable stress (CUS) paradigm for 21 days. Following CUS, mice were perfused, and brains were Golgi stained to study dendritic arborization in the CA3 region of the dorsal and ventral hippocampus. 

For this project, Golgi-stained neurons were visualized under a brightfield light microscope, and 3D reconstructions of neurons of interest were created using Neurolucida. The process included delineating and reconstructing the axon, dendrites, and soma of a neuron, thereby creating a digital, geometric model of the cell. The 3D reconstructions were used to visualize and morphometrically analyze several intricate neuronal structures. A currently ongoing Sholl analysis will reveal the dendritic length and the number of dendritic intersections that occur at fixed distances from the soma in concentric spheres, which will allow us to determine whether postnatal maternal exercise can rescue dendritic arborization from the effects of chronic stress. If structural differences are found between our groups, we will assess gene and protein expression patterns in these brain regions to probe for associated molecular changes which may drive the observed dendritic restructuring.