Chronological morphological changes in central nervous system induced by chronic electrical sensorimotor cortex stimulation in rats

运动皮质刺激(MCS)已被用作治疗各种疾病的一种选择，如内科顽固性疼痛、中风后偏瘫和运动障碍。然而，其影响的确切机制仍不清楚。本研究通过观察星形胶质细胞的变化来探讨长期慢性MCS的影响。将四极刺激电极植入成年大鼠感觉运动皮质的硬脑膜，分别持续刺激3h、1周、4周、8周。应用小胶质细胞(Iba1免疫组织化学染色)、星形胶质细胞(GFAP免疫组织化学染色)和神经元变性组织化学(FJB染色)观察长期慢性MCS后的形态变化。IBA1染色和FJB染色未见Iba1阳性的小胶质细胞改变或神经元变性。连续MCS后，刺激侧大脑皮质和丘脑GFAP阳性星形胶质细胞增大，数量增多。这些结果表明，慢性电刺激可以持续激活星形胶质细胞，并导致形态和数量的变化。这些变化可能参与了MCS诱导的神经可塑性效应的机制。

Motor cortex stimulation (MCS) has been utilized as a treatment option for various disorders such as medically refractory pain, poststroke hemiplegia, and movement disorders. However, the precise mechanisms underlying its effects remain unknown. In this study, the effects of long-term chronic MCS were investigated by observing the changes in astrocytes. A quadripolar stimulation electrode was implanted on the dura over the sensorimotor cortex of adult rats, and the cortex was continuously stimulated for three hours, one week, four weeks, and eight weeks. Immunohistochemical staining of microglia (ionized calcium-binding adaptor molecule 1 (Iba1) immunoreactive staining) and astrocytes (glial fibrillary acidic protein (GFAP) -immunoreactive staining), and neuronal degeneration histochemistry (Fluoro-Jade B (FJB) staining) were carried out to investigate the morphological changes following long-term chronic MCS. Iba1 staining and FJB staining showed no evidence of Iba1-positive microglial changes or neurodegeneration. Following continuous MCS, GFAP-positive astrocytes were enlarged and their number increased in the cortex and the thalamus of the stimulated hemisphere. These findings indicate that chronic electrical stimulation can continuously activate astrocytes and result in morphological and quantitative changes. These changes may contribute to the mechanisms underlying the neuroplasticity effect induced by MCS.