Ultrasound/Microbubble-Mediated Tetramethylpyrazine For Neuroprotection Against Cerebral Ischemia/Reperfusion-Injured Rat Brain

The traditional Chinse medicine tetramethylpyrazine (TMP) has shown great promising for neuroprotection against brain injury induced by cerebral ischemia/reperfusion (I/R). In the present work, the neuroprotection effect of TMP combined with ultrasound (US)-activated microbubble (MB) destruction was investigated in a rat middle cerebral artery occlusion (MCAO) model. By using various biochemical and imaging analysis methods (e.g., Evans Blue extravasation, small animal fluorescent imaging, 2,3,5-triphenyltetrazolium chloride staining, histological evaluation, MRI and immunofluorescence staining), the combined neuroprotection effect was comprehensively evaluated with reference to the capability of blood-brain barrier (BBB) opening, the reduction of infarct volume, and the inhibition of proliferation and activation of astrocytes in the peri-infarct area. During all the data analyses, statistical significance was identified as p < 0.05. The results showed that: (1) with the help of US-activated MB destruction (referred as US/MB), significant BBB opening effect was be achieved so that more TMP could be delivered into brain tissues, and the BBB opening capability would enhanced with the increasing acoustic energy; (2) TMP could protect I/R injury in the MCAO model by reducing the infarct volume (about 12.8%) and increasing Nissl-positive neurons (about 25.8%), and the application of US-activated MB activity would further reduce the infarct volume (about 18.4%) and increase Nissl-positive neurons (about 40.4%); and (3) the mechanisms underlying the combined neuroprotection effect could be attributed to two factors: the suppression of inflammation through inhibiting the expression of glial fibrillary acidic protein (GFAP) and the enhancement of neural cell maturity achieved by improving neuronal nuclear (NeuN) protein expressing. Current results suggested that the combined use of TMP and US-activated MB destruction may provide a promising treatment strategy for acute ischemic stroke induced by cerebral I/R injury. (C) 2021 Elsevier Ltd. All rights reserved.