Potential role of microglia in axonal regeneration following facial nerve injury
- 주제(키워드) Microglia , Facial nerve injuries , Nerve Regeneration , PLX5622
- 주제(DDC) 570
- 발행기관 아주대학교
- 지도교수 김병곤
- 발행년도 2023
- 학위수여년월 2023. 8
- 학위명 석사
- 학과 및 전공 일반대학원 의생명과학과
- 실제URI http://www.dcollection.net/handler/ajou/000000032866
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Although CNS neurons fail to regenerate injured axons, PNS neurons can spontaneously regenerate following injury. For example, patients with facial nerve paralysis frequently experience spontaneous recovery without any treatment. It is still not fully understood what the differences between CNS and PNS neurons are in their regenerative programs. Recent studies have begun to reveal that interactions between neurons and non-neuronal cells may play a role in axonal regeneration. Previous studies in my lab demonstrated that sciatic nerve injury elicits neuron-macrophage interactions in dorsal root ganglia and activated perineuronal macrophages promote axonal regeneration. In contrast to the peripheral sensory neurons, neuronal cell bodies of the peripheral motor nerves lie in the CNS and are surrounded by microglia cells rather than macrophages. It has been reported that microglial cells can also exhibit a pro-regeneration phenotype in the immature nervous system. Therefore, it is conceivable that microglial cells could interact with the motor neurons in the spinal cord to support spontaneous axonal regeneration of the peripheral motor nerves. The present study was conducted to test the hypothesis whether the microglial cells could also contribute to the regeneration of the injured facial motor nerves. We found that microglial cells surrounding the facial motor neurons were highly activated in the facial motor nucleus (FMN) located in the brainstem following facial nerve crush injury (FNC). To test the hypothesis, microglial cells were depleted using PLX5622, a colony-stimulating factor 1 receptor inhibitor. The PLX5622 treatment substantially attenuated the injury-induced increase in the number of perineuronal microglia in the FMN, whereas astrocytic activation was not affected. In the PLX5622 treatment group, recovery of the eye closure and vibrissa movement was significantly delayed compared to the control AIN-76A-feeding group. Retrograde tracing of regenerating facial motor neurons using FluoroGold revealed a decrease in the regenerating facial motor neurons by almost 50%. The results corroborate the notion that microglial cells in the CNS also play an essential role in spontaneous axon nerve regeneration. We propose that manipulating pro-regenerative microglial activation would have implications in axon regeneration following CNS injuries such as stroke and spinal cord injury.
more목차
Ⅰ. INTRODUCTION 1
A. Mechanism of spontaneous axon regeneration in the PNS neurons 1
B. Neuron-nonneuronal cell interaction in axonal regeneration 2
C. Anatomical structure of the facial nerve 4
D. Characteristics of the facial nerve injury model 4
E. Potential role of microglia in CNS neuroprotection and regeneration 6
F. PLX5622 is depleted microglia in the brain 7
G. Aim of this study 8
Ⅱ. MATERIALS AND METHODS 10
1. Animals and surgical procedure 10
2. Primary culture of bone marrow-derived macrophages 11
3. Primary microglia culture 11
4. Behavior tests 12
5. Fluorogold injection 13
6. Tissue processing and immunohistochemistry 14
7. Quantification 15
8. Statistical analysis 15
Ⅲ. RESULTS 19
1. Microglial cells are significantly activated in the facial motor nucleus after facial crush nerve injury 19
2. PLX5622 feeding efficiently suppressed the microglia in the facial motor nucleus 23
3. Microglia suppression delayed facial nerve regeneration 30
Ⅳ. DISCUSSION 36
REFERENCES 38
국문요약 46
