Brain derived neurotrophic factor (BDNF) signalling through its high-affinity tropomyosin receptor kinase B (TrkB) is known to have potent effects on motor neuron survival and morphology during development and in neurodegenerative diseases. Here, we employed a novel 1NMPP1 sensitive TrkB^F616 rat model to evaluate the effect of 14 days inhibition of TrkB signalling on phrenic motor neurons (PhMNs). Adult female and male TrkB^F616 rats were divided into 1NMPP1 or vehicle treated groups. Three days prior to treatment, PhMNs in both groups were initially labeled via intrapleural injection of Alexa-Fluor-647 cholera toxin B (CTB). After 11 days of treatment, retrograde axonal uptake/transport was assessed by secondary labeling of PhMNs by intrapleural injection of Alexa-Fluor-488 CTB. After 14 days of treatment, the spinal cord was excised 100 μm thick spinal sections containing PhMNs were imaged using two-channel confocal microscopy. TrkB inhibition reduced the total number of PhMNs by ∼16 %, reduced the mean PhMN somal surface areas by ∼25 %, impaired CTB uptake 2.5-fold and reduced the estimated PhMN dendritic surface area by ∼38 %. We conclude that inhibition of TrkB signalling alone in adult TrkB^F616 rats is sufficient to lead to PhMN loss, morphological degeneration and deficits in retrograde axonal uptake/transport.

已知脑源性神经营养因子 (BDNF) 通过其高亲和力原肌球蛋白受体激酶 B (TrkB) 发出信号，在发育过程中和神经退行性疾病中对运动神经元存活和形态具有强大影响。在这里，我们采用了一种新型的 1NMPP1 敏感TrkB ^F616大鼠模型来评估 14 天抑制 TrkB 信号对膈运动神经元 (PhMN) 的影响。成年女性和男性TrkB ^F616大鼠被分为 1NMPP1 或载体治疗组。治疗前三天，两组的 PhMN 最初都通过胸腔内注射 Alexa-Fluor-647 霍乱毒素 B (CTB) 进行标记。治疗 11 天后，通过胸腔内注射 Alexa-Fluor-488 CTB 对 PhMN 进行二次标记来评估逆行轴突摄取/运输。治疗 14 天后，切除脊髓，使用双通道共聚焦显微镜对含有 PhMN 的 100 μm 厚脊柱切片进行成像。TrkB 抑制使 PhMN 总数减少约 16%，平均 PhMN 体表面积减少约 25%，CTB 摄取受损 2.5 倍，估计的 PhMN 树突表面积减少约 38%。我们得出结论，在成人TrkB ^F616中单独抑制 TrkB 信号大鼠足以导致 PhMN 丢失、形态退化和逆行轴突摄取/运输缺陷。