Improved dynamic monitoring of transcriptional activity during longitudinal analysis in the mouse brain.

Bioluminescence imaging has proven to be a highly sensitive technique for assessing transcriptional activity toward understanding gene regulation patterns; however, application of this technique is limited for brain research. In particular, the poor spatiotemporal resolution is a major hurdle for monitoring the dynamic changes of transcriptional activity in specific regions of the brain during longitudinal analysis of living animals. To overcome this limitation, in this study, we modified a lentivirus-based luciferase glucocorticoid receptor (GR) reporter by inserting destabilizing sequence genes, and then the reporter was stereotaxically injected in the mouse infralimbic prefrontal cortex (IL-PFC). Using this strategy, we could successfully pin-point and monitor the dynamic changes in GR activity in IL-PFC during normal stress adaptation. The modified reporter showed a 1.5-fold increase in temporal resolution for monitoring GR activity compared to the control, with respect to the intra-individual coefficients of variation. This novel method has broad applications, as it is readily adaptable to different types of transcription factor arrays as well spanning wide target regions of the brain to other organs and tissues.