Date of this Version
Ultrasound in Medicine & Biology, Volume 40, Issue 5, May 2014, Pages 965-978
Though intrinsically of much higher frequency than open-field blast overpressures, high-intensity focused ultrasound (HIFU) pulse trains can be frequency modulated to produce a radiation pressure having a similar form. In this study, 1.5-MHz HIFU pulse trains of 1-ms duration were applied to intact skulls of mice in vivo and resulted in blood-brain barrier disruption and immune responses (astrocyte reactivity and microglial activation). Analyses of variance indicated that 24 h after HIFU exposure, staining density for glial fibrillary acidic protein was elevated in the parietal and temporal regions of the cerebral cortex, corpus callosum and hippocampus, and staining density for the microglial marker, ionized calcium binding adaptor molecule, was elevated 2 and 24 h after exposure in the corpus callosum and hippocampus (all statistical test results, p<0.05). HIFU shows promise for the study of some bio-effect aspects of blast-related, non-impact mild traumatic brain injuries in animals.