Radioprotective Effects of Annona Muricata Leaf Extract in the Spinal Cord

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Objective: The spinal cord is often involved in radiotherapy to treat malignancies and is considered as one of the most critical dose-limiting organs. Histopathological changes of radiation-induced spinal cord injury include gliosis, demyelination, and necrosis in the white matter, as well as vascular changes in both white and gray matter. All aerial parts of Annona muricata (AM) are used in traditional medicine practices, and previous studies revealed that AM leaf extract has radioprotective effect against gamma- irradiation. This study aimed to evaluate the possible protective effect of AM leaf extract against ionizing radiation spinal cord injury. Methods: A total of 37 adult female Wistar Albino rats were divided into 4 groups (1 control and 3 intervention groups): Group 1 (control) received 0.01 mL/kg of distilled water by oral gavage once a day for 7 days, group 2 (AM group) received 300 mg/kg of AM leaf extract by oral gavage once a day for 7 days, group 3 (IR group) received a single dose of spinal cord radiation (20 Gy) after a 7-day treatment with 0.01 mL/kg of physiologic serum (saline), and group 4 (AM + IR group) received 300 mg/kg of AM leaf extract by oral gavage once a day for 7 days, with spinal cord radiation (20 Gy) applied 1 hour after the last gavage. After the sacrificing, spinal cords were dissected out, embedded in paraffin, and stained with Hematoxylin-Eosin, and 11 parameters were microscopically examined and scored. Results: AM administration prior to irradiation (IR) lowered the histopathological scores for all parameters that were verified in the IR group at most severe levels: inflammatory cells infiltration, edema, neuron swelling, gliocytes hyperplasia, spinal cord cavitation (loosened tissue structure), pyknotic nuclei, vacuolar denaturation, and loss of Nissls substance. Necrosis was present in IR group and was higher compared to Control and AM treated groups. We noticed that necrosis was present in the AM group too and was higher compared to the control. Conclusion: The data of our study suggest that pretreatment with 300 mg/kg of AM leaf extract prior to IR reduce inflammatory cells infiltration, edema, and neuron swelling. This supports the fact that AM-proposed anti-inflammatory property may contribute to neuroprotection. Similarly, AM was documented to have efficient protection on neural cells from apoptosis or necrosis.