低剂量辐射诱导小鼠生精细胞凋亡及p53基因表达的适应性反应

目的研究低剂量X射线照射诱导小鼠睾丸生精细胞凋亡及p53基因表达的适应性反应。方法通过不连续泛影葡胺密度梯度离心法分离睾丸组织不同种类生精细胞，采用碘化丙啶荧光探针标记细胞，流式细胞术检测各类生精细胞凋亡，免疫组化法观察生精细胞p53蛋白表达。结果当1．0、2．0或3．0Gy（攻击剂量，D2）照射前6h给予75mGy（诱导剂量，D1）预照射时明显减轻D2对精原细胞和精母细胞的凋亡损伤作用，而对精子细胞和精子影响不明显。当D2照射前6h给予D1预照射时明最减少精原细胞和精母细胞p53基因表达阳性率，而对精子细胞和精子影响不明显。结论低剂量X射线照射可选择性诱导小鼠睾丸精原细胞和精母细胞凋亡的适应性反应，并与D1和D2间隔时间及D2剂量有关。同时，可诱导精原细胞和精母细胞p53基因表达的适应性反应，推测其在低剂量辐射诱导生精细胞凋亡适应性反应分子机制中起重要的调控作用。

Adaptive Response of Spermatogenic Cell Apoptosis and p53 Gene Expression Selectively Induced by Irradiation with Low Dose X-Ray in Mice

Objective The adaptive response of spermatogenic cell apoptosis and p53 gene expression induced by whole-body low dose radiation (LDR) with X-rays was studied in male Kunming mice. Methods Different kinds of spermatogenic cells were separated using density gradient centrifugation and their apoptotic percentagcs were analysed using flow cytometry (FCM) stained with propodium iodide. At meantime, p53 protein was measured with immunohistochemical SABC. Results When inductive dose (D1) was 75 mGy 6 h before irradiation with the challenging doses (D2) of 1.0, 2.0 or 3.0 Gy, the apoptotic percentages of the spermatogonia and spermatocytes in the D1+D2 groups were declined rapidly as compared with those in the D2 groups, and the apoptotic percentages of spermatids and spermatozoa showed no significant changes. When inductive dose (D1) was 75 mGy 6 h before irradiation with the challenging doses (D2) of 1.0, 2.0 or 3.0 Gy, the percentages of p53 protein positive of spermatogonia and spermatocytes in the D1+D2 groups were declined rapidly as compared with those in the D2 groups, and the positive percentages of spermatids and spermatozoa showed no significant changes. Conclusion The adaptive response of apoptosis and p53 protein expression in spermatogonia and spermatocytes could be selectively induced by irradiation with low dose X-ray. The apoptotic adaptive response induced by LDR could closely relate to the D2 doses and interval time between D1 and D2, so we speculated that p53 gene plays a great role in molecular mechanisms of adaptive response on spermatogenic cell apoptosis induced by LDR.