Department of Anatomy, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea; Department of Biochemistry and Molecular Biology, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh.
Department of Fisheries Biology and Genetics, Patuakhali Science and Technology University, Patuakhali, 8602, Bangladesh.
Neurochem Int. 2021 Mar;144:104957. doi: 10.1016/j.neuint.2021.104957. Epub 2021 Jan 12.
Centella asiatica is a 'medhya-rasayana (nootrophic or memory booster)' herb that has been indicated in Ayurveda for improving memory function and treating dementia disorders. Although the neuroprotective effects of C. asiatica have been reported in earlier studies, the information on whether this nootropic herb could promote early differentiation and development of axon and dendrites in primary hippocampal neurons is currently limited.
To investigate the effects of C. asiatica and asiatic acid, one of the principal active constituents of C. asiatica, on the various stages of neuronal polarity, including early neuronal differentiation, axonal outgrowth, dendritic arborization, axonal maturation, and synaptic formation.
Embryonic rat hippocampal neurons were incubated with C. asiatica leaf extract (CAE) or asiatic acid. After an indicated time, neurons were fixed and immunolabeled to visualize the neuronal morphology. Morphometric analyses for early neuronal differentiation, axonal and dendritic maturation and synaptogenesis were performed using Image J software. Neuronal viability was determined using trypan blue exclusion assay.
CAE at varying concentrations ranging from 3.75 to 15 μg/mL enhanced neurite outgrowth with the highest optimal concentration of 7.5 μg/mL. The effects of CAE commenced immediately after cell seeding, as indicated by its accelerating effect on neuronal differentiation. Subsequently, CAE significantly elaborated dendritic and axonal morphology and facilitated synapse formation. Asiatic acid also facilitated neurite outgrowth, but to a lesser extent than CAE.
These findings revealed that CAE exerted its modulatory effects in every stage of neuronal development, supporting its previously claimed neurotrophic function and suggest that this natural nootropic and its active component asiatic acid can be further investigated to explore a promising solution for degenerative brain disorders and injuries.
积雪草是一种“medhya-rasayana（益智或记忆增强剂）”草药，在印度阿育吠陀中被用于改善记忆功能和治疗痴呆症。尽管积雪草的神经保护作用在早期研究中已有报道，但关于这种益智草药是否能促进原代海马神经元的早期轴突和树突分化和发育的信息目前还很有限。
研究积雪草及其主要活性成分积雪草酸对神经元极性各个阶段的影响，包括早期神经元分化、轴突生长、树突分枝、轴突成熟和突触形成。
用积雪草叶提取物（CAE）或积雪草酸孵育胚胎大鼠海马神经元。在指定的时间后，固定神经元并进行免疫标记以可视化神经元形态。使用 Image J 软件对早期神经元分化、轴突和树突成熟以及突触发生进行形态计量分析。用台盼蓝排斥试验测定神经元活力。
浓度为 3.75 至 15μg/ml 的 CAE 增强了突起生长，最佳浓度为 7.5μg/ml。CAE 的作用在细胞接种后立即开始，表现为加速神经元分化的作用。随后，CAE 显著地塑造了树突和轴突形态，并促进了突触形成。积雪草酸也促进了突起生长，但程度低于 CAE。
这些发现表明 CAE 对神经元发育的各个阶段都发挥了调节作用，支持了其先前声称的神经营养功能，并表明这种天然益智药及其活性成分积雪草酸可以进一步研究，以探索治疗退行性脑疾病和损伤的有希望的方法。
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