Therapeutic effects of low-intensity transcranial ultrasound on neurological recovery in rat models of MCAO with varying injury severities

BACKGROUND: Low-intensity transcranial ultrasound (LITUS) is a safe, non-invasive neuromodulation method shown to improve neurological function after ischemic stroke in middle cerebral artery occlusion (MCAO) rats models. Given that the degree of severity of ischemic damage may influence treatment outcomes, it is important to investigate the therapeutic performance of LITUS in various injury models to provide a comprehensive understanding to support its clinical application. METHODS: Sixty adult male SD rats were randomly divided into four groups: Sham (S), MCAO only (M), MCAO + high-intensity transcranial ultrasound (HITUS) injury + LITUS treatment (MHL), and MCAO + LITUS treatment (ML), with 15 rats per group. MCAO models were verified by 9.4 T MRI. LITUS was administered to MHL and ML groups for 20 min daily over 14 days. Behavioral tests, blood biomarkers, and molecular analyses (Western blot, qPCR, immunofluorescence) were used to evaluate neurological function, inflammation, and neurovascular changes. RESULTS: LITUS significantly improved neurological, motor, and cognitive functions in MCAO rats with varying injury severities. Treated animals showed better body weight recovery, lower Longa scores, improved motor coordination, and enhanced exploratory and recognition behavior. Mechanistically, LITUS reduced peripheral inflammation, downregulated iNOS expression, and regulated glucose, lipid, and homocysteine levels, supporting systemic homeostasis. It also promoted hematopoiesis and upregulated angiogenic markers (VEGF-A, eNOS, CD31), enhancing vascular regeneration in the ischemic cortex. Furthermore, LITUS activated the BDNF/nNOS signaling pathway, facilitating neurogenesis and neuronal repair. These findings suggest that LITUS exerts multi-target protective effects through coordinated regulation of inflammation, metabolism, angiogenesis, and neuroregeneration, offering strong therapeutic potential for stroke recovery. CONCLUSION: LITUS treatment can improve neurological and motor dysfunction in MCAO rats with varying degrees of injury. The potential underlying mechanism of LITUS is through the regulation of the level of inflammation and promoting angiogenesis and neurogenesis.