Methotrexate (MTX), an antifolate drug, is widely used in chemotherapeutic protocols for metastatic and primary brain tumors and some autoimmune diseases. Its efficacy for brain tumors is limited by the high incidence of central nervous system (CNS) complications. This investigation aimed to observe the morphological effects, including astroglial and microglial responses, following systemic short-term MTX administration in adult rats.

Male Wistar rats received 5 or 10 mg/kg/day of MTX by intraperitoneal route for 4 consecutive days (respectively, MTX5 and MTX10 groups) or the same volume of 0.9% saline solution (control group). On the 5th day, brain samples were collected for hematoxylin-eosin and luxol fast blue staining techniques, as well as for immunohistochemical staining for glial fibrillary acidic protein (GFAP) expression in astrocytes and Iba1 (ionized calcium binding adaptor molecule 1) for microglia in the frontal cortex, hippocampus, hypothalamus and molecular/granular layers of the cerebellum. Morphometric analyses were performed using Image Pro-Plus software. Brain levels of the proinflammatory cytokines TNF-α and IL-1β were determined by ELISA.

No signs of neuronal loss or demyelination were observed in all groups. Increased GFAP and Iba1 expression was found in all areas from the MTX groups, although it was slightly higher in the MTX10 group compared to the MTX5. Both TNF-α and IL-1β levels were decreased in the MTX5 group compared to controls. In the MTX10 group, TNF-α decreased, although IL-1β was increased relative to controls.

MTX administration induced microglial reaction and astrogliosis in several CNS areas. In the MTX5 group, it apparently occurred in the presence of decreased proinflammatory cytokines.

甲氨蝶呤 (MTX) 是一种抗叶酸药物，广泛用于转移性和原发性脑肿瘤以及一些自身免疫性疾病的化疗方案。其对脑肿瘤的疗效受到中枢神经系统 (CNS) 并发症的高发率限制。本研究旨在观察成年大鼠全身短期 MTX 给药后的形态学效应，包括星形胶质细胞和小胶质细胞反应。

雄性 Wistar 大鼠连续 4 天通过腹腔途径接受 5 或 10 mg/kg/天的 MTX（分别为 MTX5 和 MTX10 组）或相同体积的 0.9% 盐水溶液（对照组）。在第 5 天，收集脑样本用于苏木精-伊红和 luxol 快速蓝染色技术，以及用于星形胶质细胞中胶质纤维酸性蛋白 (GFAP) 表达的免疫组织化学染色和小胶质细胞中 Iba1（离子钙结合接头分子 1）的免疫组织化学染色。小脑的额叶皮层、海马、下丘脑和分子/颗粒层。使用 Image Pro-Plus 软件进行形态测量分析。通过ELISA确定促炎细胞因子TNF-α和IL-1β的脑水平。

在所有组中均未观察到神经元丢失或脱髓鞘的迹象。在 MTX 组的所有区域都发现 GFAP 和 Iba1 表达增加，尽管与 MTX5 相比，MTX10 组的表达略高。与对照组相比，MTX5 组的 TNF-α 和 IL-1β 水平均降低。在 MTX10 组中，尽管 IL-1β 相对于对照增加，但 TNF-α 降低。

MTX 给药在几个中枢神经系统区域诱导小胶质细胞反应和星形胶质细胞增生。在 MTX5 组中，它显然是在促炎细胞因子减少的情况下发生的。