Blood-Brain Barrier Disruption and Edema in Xenopus: Methods for Analysis.

The blood-brain barrier (BBB) isolates the brain from pathogens, toxins, and environmental compounds, and it preserves homeostatic control of the neural microenvironment. Thus, it is critical for normal function of the central nervous system throughout vertebrates and in many invertebrate taxa. Disruption or leakage at the BBB is a hallmark of neural injury and many neurodegenerative disorders. This chapter offers a method to assess the integrity of the BBB in live Xenopus tadpoles, by examining the spread of fluorescein introduced by intraventricular injection. Edema often accompanies disruption of the BBB, appearing as an increase in the amount of water present in brain tissue. The chapter, therefore, also includes a method for quantifying brain water weight, which can then be used to evaluate edema. These protocols should be useful for studies modeling neurodegenerative or neurodevelopmental disorders in amphibians.