Chelyshev Y A, Muhamedshina Y O, Povysheva T V, Shaymardanova G F, Rizvanov A A, Nigmetzyanova M V, Tiapkina O V, Bondarenko N I, Nikolskiy E E, Islamov R R
Kazan State Medical University, Kazan, Russia; Kazan (Volga Region) Federal University, Kazan, Russia.
Kazan State Medical University, Kazan, Russia.
Neuroscience. 2014 Nov 7;280:328-39. doi: 10.1016/j.neuroscience.2014.09.004. Epub 2014 Sep 16.
Exposure to microgravity has been shown to result in damaging alterations to skeletal muscle, bones, and inner organs. In this study, we investigated the effects of microgravity by using a hindlimb unloading model (HUM) in mice. The characteristics of the lumbar spinal cords of HUM mice 30 days after hindlimb unloading were examined. Morphometric analysis showed reductions of the total area, gray matter, and white matter by 17%, 20%, and 12%, respectively. Myelinated fibers in the white matter showed prominent myelin destruction. Analysis of the number of glial fibrillary acidic protein (GFAP+)/S100 calcium-binding protein B (S100B-), GFAP+/S100B+, and GFAP-/S100B+ astrocytes in the ventral horn (VH), central channel area (CC), dorsal root entry zone (DREZ), main corticospinal tract (CST), and ventral funiculi (VF) showed that the number of GFAP+/S100B- astrocytes was increased in the DREZ and CST of HUM mice. Additionally, GFAP+/S100B+ cell numbers were significantly decreased in the VH and CST but did not differ in the CC or DREZ of HUM mice, as compared with the control. The numbers of GFAP-/S100B+ cells were significantly reduced only in the VH of HUM mice. Moreover, the number of ionized calcium-binding adaptor molecule 1 (Iba1+) microglia cells was significantly increased in the CC and DREZ of HUM mice. In control mice, homeobox protein HoxB8 (HoxB8+) cells were found only in the CC; in contrast, HoxB8+ cells were observed in all studied areas in HUM mice, with the greatest number found in the CC. Genome-wide transcriptome analysis of the lumbar spinal cords of HUM mice showed decreased expression of genes encoding myelin, extracellular matrix, cytoskeleton, and cell adhesion proteins. Real-time polymerase chain reaction (PCR) confirmed reductions in the expression of mpz, pmp2, pmp22, and prx genes, which are involved in myelination, as well as decreases in the levels of genes encoding extracellular matrix molecules, including glycoproteins (matrix gla protein (MGP), osteoglycin (OGN), microfibrillar associated protein 5 (MFAP), and collagen, type IV, alpha 1 (COL4A)), proteoglycans (perlecan (heparan sulfate proteoglycan) (HSPG)), and metalloproteinases (lysyl oxidase (LOX)). Thus, our results showed that hindlimb unloading caused decreases in gray and white matter areas, changes in gene expression, alterations in myelination, and phenotypic modifications in glial cells in the lumbar spinal cords of mice.
已证明暴露于微重力环境会导致骨骼肌、骨骼和内部器官发生损害性改变。在本研究中，我们通过使用小鼠后肢卸载模型（HUM）来研究微重力的影响。检查了后肢卸载30天后HUM小鼠腰脊髓的特征。形态计量学分析显示，总面积、灰质和白质分别减少了17%、20%和12%。白质中的有髓纤维显示出明显的髓鞘破坏。对腹角（VH）、中央管区域（CC）、背根进入区（DREZ）、主要皮质脊髓束（CST）和腹侧索（VF）中胶质纤维酸性蛋白（GFAP+）/S100钙结合蛋白B（S100B-）、GFAP+/S100B+和GFAP-/S100B+星形胶质细胞数量的分析表明，HUM小鼠的DREZ和CST中GFAP+/S100B-星形胶质细胞数量增加。此外，与对照组相比，HUM小鼠VH和CST中的GFAP+/S100B+细胞数量显著减少，但在CC或DREZ中无差异。GFAP-/S100B+细胞数量仅在HUM小鼠的VH中显著减少。此外，HUM小鼠CC和DREZ中离子钙结合衔接分子1（Iba1+）小胶质细胞数量显著增加。在对照小鼠中，仅在CC中发现同源框蛋白HoxB8（HoxB8+）细胞；相反，在HUM小鼠的所有研究区域均观察到HoxB8+细胞，其中CC中数量最多。对HUM小鼠腰脊髓进行全基因组转录组分析显示，编码髓鞘、细胞外基质、细胞骨架和细胞粘附蛋白的基因表达降低。实时聚合酶链反应（PCR）证实，参与髓鞘形成的mpz、pmp2、pmp22和prx基因表达减少，以及编码细胞外基质分子的基因水平降低，包括糖蛋白（基质γ-羧基谷氨酸蛋白（MGP）、骨甘蛋白（OGN）、微原纤维相关蛋白5（MFAP）和IV型胶原α1（COL4A））、蛋白聚糖（基底膜聚糖（硫酸乙酰肝素蛋白聚糖）（HSPG））和金属蛋白酶（赖氨酰氧化酶（LOX））。因此，我们的结果表明，后肢卸载导致小鼠腰脊髓灰质和白质区域减少、基因表达变化、髓鞘形成改变以及神经胶质细胞表型修饰。
