Opening the Blood-Brain Barrier in the Substantia Nigra of Rat Brain with Focused Ultrasound and Microbubbles

Parkinson disease is a slowly progressive parkinsonian syndrome that begins insidiously, but gradually worsens in severity. Normally, the blood vessels of the brain present a blood-brain barrier (BBB), which is a biochemical barrier combined with a high selective structure that not only impedes the absorption of damaging molecules, but also the delivery of drugs. Recently, focused ultrasound (FUS) with microbubbles (MB) has been used to achieve local blood-brain barrier opening to increase penetration of therapeutic drugs into the brain. This paper presents a protocol to open the BBB with 2 MHz focused ultrasound during the presence of microbubbles and using craniotomies in Wistar rats; it was determined the required power to effectively produce BBB disruption without tissue damage. The opening of the BBB was made at the substantia nigra, which will be used to release a specific drug for Parkinson disease. The results show that with low power (3 W) the BBB was reversibly open at the targeted zone.