Lisakovska Olha, Labudzynskyi Dmytro, Khomenko Anna, Isaev Dmytro, Savotchenko Alina, Kasatkina Ludmila, Savosko Serhii, Veliky Mykola, Shymanskyi Ihor
Department of Biochemistry of Vitamins and Coenzymes, Palladin Institute of Biochemistry, Kyiv, Ukraine.
Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kyiv, Ukraine.
Front Cell Neurosci. 2023 Mar 20;17:1133400. doi: 10.3389/fncel.2023.1133400. eCollection 2023.
Vitamin D (VD) is a potent para/autocrine regulator and neurosteroid that can strongly influence nerve cell function and counteract the negative effects of glucocorticoid (GC) therapy. The aim of the study was to reveal the relationship between VD status and behavioral, structural-functional and molecular changes associated with GC-induced neurotoxicity.
Female Wistar rats received synthetic GC prednisolone (5 mg/kg b.w.) with or without VD (1000 IU/kg b.w.) for 30 days. Behavioral, histological, physiological, biochemical, molecular biological (RT-PCR, Western blotting) methods, and ELISA were used.
There was no difference in open field test (OFT), while forced swim test (FST) showed an increase in immobility time and a decrease in active behavior in prednisolone-treated rats, indicative of depressive changes. GC increased the perikaryon area, enlarged the size of the nuclei, and caused a slight reduction of cell density in CA1-CA3 hippocampal sections. We established a GC-induced decrease in the long-term potentiation (LTP) in CA1-CA3 hippocampal synapses, the amplitude of high K-stimulated exocytosis, and the rate of Ca-dependent fusion of synaptic vesicles with synaptic plasma membranes. These changes were accompanied by an increase in nitration and poly(ADP)-ribosylation of cerebral proteins, suggesting the development of oxidative-nitrosative stress. Prednisolone upregulated the expression and phosphorylation of NF-κB p65 subunit at Ser311, whereas downregulating IκB. GC loading depleted the circulating pool of 25OHD in serum and CSF, elevated VDR mRNA and protein levels but had an inhibitory effect on CYP24A1 and VDBP expression. Vitamin D supplementation had an antidepressant-like effect, decreasing the immobility time and stimulating active behavior. VD caused a decrease in the size of the perikaryon and nucleus in CA1 hippocampal area. We found a recovery in depolarization-induced fusion of synaptic vesicles and long-term synaptic plasticity after VD treatment. VD diminished the intensity of oxidative-nitrosative stress, and suppressed the NF-κB activation. Its ameliorative effect on GC-induced neuroanatomical and behavioral abnormalities was accompanied by the 25OHD3 repletion and partial restoration of the VD-auto/paracrine system.
GC-induced neurotoxicity and behavioral disturbances are associated with increased oxidative-nitrosative stress and impairments of VD metabolism. Thus, VD can be effective in preventing structural and functional abnormalities in the brain and behavior changes caused by long-term GC administration.
维生素D（VD）是一种强大的旁分泌/自分泌调节因子和神经甾体，可强烈影响神经细胞功能，并抵消糖皮质激素（GC）治疗的负面影响。本研究的目的是揭示VD状态与GC诱导的神经毒性相关的行为、结构功能和分子变化之间的关系。
雌性Wistar大鼠接受合成GC泼尼松龙（5mg/kg体重），伴或不伴VD（1000IU/kg体重），持续30天。采用行为学、组织学、生理学、生物化学、分子生物学（RT-PCR、蛋白质印迹法）方法和酶联免疫吸附测定法。
旷场试验（OFT）无差异，而强迫游泳试验（FST）显示，泼尼松龙治疗的大鼠不动时间增加，主动行为减少，表明有抑郁变化。GC增加了海马CA1-CA3区神经元胞体面积，增大了细胞核大小，并导致细胞密度略有降低。我们发现GC诱导海马CA1-CA3区突触的长时程增强（LTP）、高钾刺激的胞吐作用幅度以及突触小泡与突触质膜的钙依赖性融合速率降低。这些变化伴随着脑蛋白硝化和多聚（ADP）-核糖基化增加，提示氧化亚硝化应激的发生。泼尼松龙上调了NF-κB p65亚基在Ser311位点的表达和磷酸化，而下调了IκB。GC负荷使血清和脑脊液中25OHD的循环池减少，VDR mRNA和蛋白水平升高，但对CYP24A1和VDBP表达有抑制作用。补充维生素D具有抗抑郁样作用，减少不动时间并刺激主动行为。VD使海马CA1区神经元胞体和细胞核大小减小。我们发现VD治疗后突触小泡去极化诱导的融合和长期突触可塑性恢复。VD降低了氧化亚硝化应激强度，并抑制了NF-κB激活。其对GC诱导的神经解剖学和行为异常的改善作用伴随着25OHD3补充以及VD自分泌/旁分泌系统的部分恢复。
GC诱导的神经毒性和行为障碍与氧化亚硝化应激增加和VD代谢受损有关。因此，VD可有效预防长期GC给药引起的脑结构和功能异常以及行为改变。
