Effects of l-muscone on motor and cognitive function recovery in a mouse model of traumatic brain injury

다국어 초록 (Multilingual Abstract)

Effects of l-muscone on motor and cognitive function recovery in a mouse model of traumatic brain injury By Jang-Hoon Kim Master of Science in Korean Medicine Graduate School of Kyung Hee university Advised by Professor Youngmin Bu & Associate Professor Kyungjin Lee This study investigated the effects of l-muscone, a fragrant component of Moschus, on traumatic brain injury (TBI) using a controlled cortical impact model in mice. l-muscone (0.5 and 5 mg/kg) was orally administered twice daily following TBI induction. The study assessed body weight, brain damage, blood-brain barrier (BBB) integrity, behavioral outcomes, and various protein markers. l-muscone treatment led to significant weight loss on day 4 after TBI but did not reduce brain damage area. However, it improved motor function in the balance beam test and cognitive function in the novel object recognition test. While l-muscone showed a trend toward reducing BBB disruption, the effect was not statistically significant. Western blot analysis revealed that l-muscone increased ZO-1 expression, a key tight junction protein, but had variable effects on other BBB-related proteins. l-muscone also showed a tendency to increase neuroplasticity markers PSD 95, BDNF and synaptophysin, potentially explaining the functional improvements observed despite the lack of histological protection. These findings suggest that l- muscone may have therapeutic potential in TBI, particularly in improving functional outcomes. However, its heterogeneous effects on tight junction protein expressions and lack of significant impact on inflammatory or neuroplasticity markers, underscore the complicated pathophysiology of TBI. Further research is required to elucidate more direct and precise mechanisms of actions by which l-muscone operates.

국문 초록 (Abstract)

본 연구는 사향의 성분인 l-muscone이 외상성 뇌손상 (TBI)에 미치는 영향을 마우스의 CCI-TBI 모델에서 연구했다. l-Muscone(0.5 및 5 mg/kg)은 TBI 유도 후 하루 두 번 경구로 투여되었다. 본 연구는 체중, 뇌 손상 면적, 뇌혈관장벽(BBB) 손상, 운동실험 (balance beam test), 인지실험 (novel object recognition test, NOR test) 및 다양한 protein marker를 평가했다. 흥미롭게도 l-muscone은 TBI 유발 후 4일째에 체중 감소를 유발했다. l-Muscone은 balance beam test 및 NOR test에서 유의한 운동 및 인지 기능 보호 효과를 보였고, 뇌 손상 면적 및 BBB 손상으로 인한 EB 유출을 감소시키지 못했다. l-Muscone은 EB 유출을 줄이는 경향을 보였으나, 그 효과는 통계적으로 유의하지 않았다. Western blot 분석에서는 l-muscone이 BBB 기본 구조에 해당하는 tight junction protein인 ZO-1의 발현을 증가시켰지만, 다른 BBB 관련 단백질에 대해서는 기존 보고와 상이한 효과를 보였다. l-Muscone은 또한 neuroplasticity marker인 PSD 95, BDNF 그리고 synaptophysin을 증가시키는 경향을 보였다. 이러한 결과는 l-muscone이 TBI에서 운동 및 인지 기능을 회복시키는 데 잠재력이 있음을 시사하고, neuroplasticity marker가 관련이 있을 것으로 사료된다. 그러나 l-muscone이 tight junction protein 발현에 있어서 기존과 상이한 결과를 보이고, inflammatory 및 neuroplasticity marker에 대한 유의미한 영향이 없다는 점은 향후 보다 직접적이고 정확한 메커니즘 연구의 필요성을 제기한다.

목차 (Table of Contents)

• 1. Introduction 1
• 2. Materials and Methods 4
• 2.1. Animals and controlled cortical impact-traumatic brain injury induction 4
• 2.2. Grouping and treatment 5
• 2.3. Histological analysis 6
• 2.4. Behavioral tests 7
• 2.4.1. Balance beam test 7
• 2.4.2. Novel object recognition test 7
• 2.5. Evans Blue extravasation assay 8
• 2.6. Western blot analysis 9
• 2.7. Statistical analysis 12
• 3. Results 13
• 3.1. The effect of l-muscone on body weight after TBI 13
• 3.2. The effect of l-muscone on brain damage area 14
• 3.3. The effect of l-muscone on functional deficits 15
• 3.3.1. The effect of l-muscone on motor function 15
• 3.3.2. The effect of l-muscone on cognitive function 15
• 3.4. The effect of l-muscone on Evans Blue extravasation 17
• 3.5. The effect of l-muscone on protein expression 18
• 3.5.1. The effect of l-muscone on the expression of tight junction proteins 18
• 3.5.2. The effect of l-muscone on the expression of aquaporin 4 18
• 3.5.3. The effect of l-muscone on the expression of inflammatory markers 20
• 3.5.4. The effect of l-muscone on the expression of neuroplasticity markers 22
• 4. Discussion. 24
• 5. Conclusion 29
• 6. References 31
• Abstract in Korean 38