Evaluation of a Vivo-Morpholino Delivery Method to the Brain and the Affect on Physical Activity

Evaluation of a Vivo-Morpholino Delivery Method to the Brain and the Affect on Physical Activity *David P. Ferguson MS, Emily E. Schmitt MS, J. Timothy Lightfoot PhD FACSM Biology of Physical Activity Lab, Texas A&M University, College Station, TX, 77843 *To be judged in the doctoral category Physical inactivity has been shown to be correlated to various disease and conditions. Therefore, there is interest in the genetic mechanisms that control daily physical activity. Vivo-morpholinos are a new molecular biology tool that allows for the transient silencing of specific genes in an animal model, thereby allowing for a systematic method to turn off potential candidate genes involved in the regulation of physical activity. Vivo-morpholinos have not been shown to be effective at silencing genes in the brain due to the fact that the vivo-morpholino cannot cross the blood brain barrier. To counteract this, a tail vein injection (55 ul total volume; 11mg/kg vivo-morpholino; 6.5ug/kg RMP7) was given on three consecutive days containing the bradykinin analog RMP7 and a vivo-morpholino targeting Vmat2 to male C57/LJ mice (n=6). RMP7 has been shown to increase blood brain barrier permeability while Vmat2 is a dopamine transporter and is thought to be involved in the regulation of voluntary physical activity. Control animals received either RMP7 plus saline (n=6) or RMP7 plus a vivo-morpholino “scramble” control (n=6). Physical activity was measured by wheel running. Results showed there was not a significant (p=0.24) knockdown in Vmat2 in the brain with RMP7 administration as compared to control animals. Interestingly there was a significant (p=0.001) knockdown in daily physical activity in the Vmat2 treated animals compared to the control group. RMP7 may still be a viable option for vivo-morpholino delivery in the brain; however an increased dosage may be required