Department of Pharmacology and Therapeutics, State University of Maringá, Maringá, Paraná, Brazil.
Department of Morphophysiological Sciences, State University of Maringá, Maringá, Paraná, Brazil.
J Chem Neuroanat. 2019 Nov;101:101683. doi: 10.1016/j.jchemneu.2019.101683. Epub 2019 Sep 6.
We previously found that fish oil (FO) facilitated memory recovery in the absence of pyramidal neuron rescue after transient, global cerebral ischemia (TGCI). Fish oil preserved the expression of microtubule-associated protein 2 (MAP-2), suggesting a relationship between dendritic plasticity and memory recovery that is mediated by FO after TGCI. The present study examined whether postischemic treatment with FO prevents ischemia-induced loss of dendritic processes in remaining pyramidal neurons. The effects of FO on neuroplasticity-related proteins were also examined after TGCI. Rats were subjected to TGCI (15 min, four-vessel occlusion model) and then received vehicle or FO (300 mg/kg docosahexaenoic acid) once daily for 7 days. The first dose was administered 4 h postischemia. Golgi-Cox staining was used to evaluate dentrict morphology in the pyramidal neurons of hippocampus (CA1 and CA3 subfields) and prefrontal cortex (PFC). Neuronal nuclei protein (NeuN), brain-derived neurotrophic factor (BDNF), growth-associated protein 43 (GAP-43), synaptophysin (SYP), and postsynaptic density protein 95 (PSD-95) levels were measured by Western blot in both structures. Fifteen minutes of TGCI reduced consistently the length of dendrites, number of dendritic branches and dendritic spine density (average of 25%, 43%, 32%, respectively) 7, 14, and 21 days postischemia, indicating that they did not recover spontaneously. This outcome of TGCI was reversed by FO treatment, an effect that was sustained even after treatment cessation. The NeuN and BDNF protein levels were reduced in both the hippocampus and PFC, which were recovered by FO treatment. GAP-43 protein levels decreased after ischemia in the PFC only, and this effect was also mitigated by FO. Neither SYP nor PSD-95 levels were altered by ischemia, but PDS-95 levels almost doubled after FO treatment in the ischemic group. These data support our hypothesis that synaptic plasticity at the level of dendrites may at least partially underlie the memory-protective effect of FO after TGCI and strengthen the possibility that FO has therapeutic potential for treating the sequelae of brain ischemia/reperfusion injury.
我们之前发现，鱼油（FO）在短暂的全脑缺血（TGCI）后促进了记忆的恢复，而没有挽救锥体神经元。鱼油保留了微管相关蛋白 2（MAP-2）的表达，这表明在 TGCI 后，树突可塑性和记忆恢复之间存在着与 FO 介导的关系。本研究探讨了缺血后给予 FO 是否可以防止缺血诱导的剩余锥体神经元中树突过程的丢失。还研究了 FO 对神经可塑性相关蛋白的影响。大鼠接受 TGCI（15 分钟，四血管闭塞模型），然后每天接受载体或 FO（300mg/kg 二十二碳六烯酸）一次，共 7 天。第一剂在缺血后 4 小时给予。Golgi-Cox 染色用于评估海马（CA1 和 CA3 亚区）和前额叶皮层（PFC）锥体神经元的树突形态。通过 Western blot 测量两种结构中的神经元核蛋白（NeuN）、脑源性神经营养因子（BDNF）、生长相关蛋白 43（GAP-43）、突触小体相关蛋白（SYP）和突触后密度蛋白 95（PSD-95）的水平。15 分钟的 TGCI 一致降低了缺血后 7、14 和 21 天的树突长度、树突分支数量和树突棘密度（分别平均为 25%、43%和 32%），表明它们没有自发恢复。FO 治疗逆转了 TGCI 的这一结果，即使在治疗停止后，这种效果仍能持续。海马和 PFC 中的 NeuN 和 BDNF 蛋白水平降低，FO 治疗后恢复。缺血后 PFC 中的 GAP-43 蛋白水平降低，FO 也减轻了这种影响。缺血后 SYP 和 PSD-95 水平没有改变，但缺血组 FO 治疗后 PSD-95 水平几乎增加了一倍。这些数据支持我们的假设，即树突水平的突触可塑性至少部分解释了 FO 在 TGCI 后对记忆的保护作用，并加强了 FO 治疗脑缺血/再灌注损伤后遗症的可能性。
