摘要： 目的·探索垂体腺苷酸环化酶激活肽38（pituitary adenylate cyclase-activating polypeptide 38，PACAP38）对心肌细胞辐照敏感性的影响及对急性放射性心肌损伤的潜在防护作用。方法·采用H9C2大鼠心室肌母细胞和C57BL/6J小鼠应用6 MVX射线在体内外构建放射性心肌损伤的辐照模型。在辐照之前对H9C2细胞和C57BL/6J小鼠进行不同剂量的PACAP38预处理。PACAP38在H9C2细胞中的作用浓度为10
-9 和10
-7 mol/L，在辐照前2 h给予。在小鼠中，分别在辐照前2 h、辐照后24及48 h给予10 μg PACAP38（0.1 μg/μL×100 μL）腹腔注射。体内外放射性心肌损伤辐照模型分为对照组、PACAP38单独处理组、辐照（irradiation， IR）组和PACAP38+IR组。体外实验辐照剂量为2、4、8及12 Gy；体内实验辐照剂量为14 Gy，单次辐照。应用CCK-8实验检测细胞活力；通过克隆形成实验检测辐照敏感性变化；利用苏木精-伊红染色评估小鼠单心脏辐照1个月后心肌组织结构的病理改变。结果·PACAP38预处理H9C2心肌细胞组较单独IR组（12 Gy）的细胞活力显著提高，其中10
-7 mol/L PACAP38+IR组和IR组分别为（98.63±2.70）%和（83.67±0.78）%，差异有统计学意义（
P=0.000）。2 Gy时的细胞存活率在10
-9 和10
-7 mol/L PACAP38预处理后从0.53增加至0.63和0.70，放射增敏比在10
-9和10
-7 mol/L PACAP38处理组分别为0.95和0.91。通过体内研究发现，PACAP38干预对辐照（14 Gy）后小鼠的心肌组织的病理损伤包括心肌细胞变性、嗜酸性增强、细胞质空泡化、细胞核固缩及心肌纤维扭曲均具有显著的缓解作用。结论·PACAP38干预后可明显降低心肌细胞的辐照敏感性，对急性放射性心肌损伤具有一定的防护作用。
关键词: 垂体腺苷酸环化酶激活肽38, 辐照模型, 放射性心肌损伤, 防护作用 Abstract: Objective·To explore the effect of pituitary adenylate cyclase-activating polypeptide 38 (PACAP38) on radiosensitivity of myocardial cells and its potential protective effect on acute radiation-induced myocardial injury.
Methods·The radiation-related cardiac injury models were established by using 6 MV X-ray with H9C2 cardiomyocytes and male C57BL/6J mice which were pre-treated with different doses of PACAP38 prior to radiation exposure. H9C2 cells were treated with 10-9 and 10-7 mol/L PACAP38 2 h before irradiation. 10 μg of 0.1 μg/μL PACAP38 was administered to C57BL/6J mice intraperitoneally at 2 h before irradiation and additional doses were given at 24 h and 48 h after irradiation. In vivo and in vitro myocardial radiation injury models were divided into control group, PACAP38 group, irradiation group (IR) and PACAP38+IR group. The specific irradiation doses in vitro were 2, 4, 8 and 12 Gy. The specific irradiation dose in vivo were 14 Gy, one fraction irradiation. CCK-8 and clonogenesis assays were used to examine cell viability and radiosensitivity, respectively. Hematoxylin and eosin staining was used to evaluate the pathological changes of myocardial tissue in mice after one-month irradiation.
Results·The cell viability of H9C2 cardiomyocytes pretreated with PACAP38 was significantly higher than that of irradiation (12 Gy) alone [10-7 mol/L PACAP38+IR group vs IR group, (98.63±2.70)% vs (83.67±0.78)%, P=0.000]. The survival fraction at 2 Gy increased from 0.53 to 0.63 and 0.70 after 10-9 and 10-7 mol/L PACAP38 pretreatment, and the sensitivity enhancement ratio of 10-9 and 10-7 mol/L PACAP38 pretreatment groups were 0.95 and 0.91, respectively. In vivo studies showed that PACAP38 could significantly alleviate the pathological damage of myocardial tissue after irradiation (14 Gy), including cardiomyocyte degeneration, eosinophilic enhancement, cytoplasmic vacuolation, nuclear pyknosis and myocardial fiber distortion.
Conclusion·PACAP38 can significantly reduce the radiosensitivity of myocardial cells and has a certain protective effect on acute radiation-induced myocardial injury.
Key words: pituitary adenylate cyclase-activating polypeptide 38 (PACAP38), irradiation model, radiation-induced myocardial injury, cardioprotectant PDF全文下载地址:
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