  Chronic stress affects nano to microscale structures of the brain
cells/tissues due the suppression of neural growths and reconnections, hence
the neuronal activities. This results in depression, memory loss and even the
death of the brain cells. Our recently developed novel optical technique,
partial wave spectroscopic (PWS) microscopy has nanoscale sensitivity, and
hence, can detect nanoscale changes in brain tissues due to stress. In this
study, we applied this technique to quantify the stress related structural
changes in the corticosterone-treated mouse model of stress. Our results show
that brains from corticosterone-treated mice showed higher nanoscale structural
disorder in the hippocampal region as compared to the brain from normal
(vehicle) mice. The increase in structural alteration correlates with the
duration of the stress. We further quantified the relative changes and the
spatial localization of these changes in this mouse model and found out that
the maximum changes occurred nearly symmetrically in both regions of the
hippocampus. The mRNA for stress-related genes, BDNF and TrkB were also
significantly reduced in the hippocampus of corticosterone-treated mice
compared to that in control mice. These results indicate that chronic
corticosterone treatment induces nanoscale structural alterations in mouse
brain that corresponds to the changes in stress-related gene expression.
