低剂量电离辐射诱导小鼠睾丸生精细胞凋亡及P53基因和蛋白表达

目的:研究低剂量电离辐射对小鼠睾丸生精细胞凋亡及 P53 基因和蛋白表达的影响。方法:应用密度梯度离心法分离不同种类生精细胞, 流式细胞术检测其细胞凋亡, 免疫组化法观察生精细胞P53蛋白表达, 原位杂交法观察其 P53 mRNA水平。结果:0.025-0.2 Gy X射线全身照射后, 生精细胞凋亡具有明显的细胞种类规律性。在较低剂量照射(0.025和0.05 Gy)时, 以精原细胞凋亡为主, 随照射剂量增加(0.075-0.2 Gy)逐渐累及精母细胞, 并且前者凋亡率明显高于后者, 很少累及精子细胞和精子。P53蛋白表达主要见于精原细胞和精母细胞, 并且前者阳性率高于后者, 随照射剂量增加, 其阳性率逐渐升高, 而精子细胞和精子阳性率较低; P53 mRNA表达在较低剂量照射(0.025 Gy)时, 主要以精母细胞和精子细胞为主, 随剂量增加(0.05-0.2 Gy)逐渐累及精原细胞。精原细胞和精母细胞 P53 mRNA表达呈明显的剂量依赖性关系, 但精子细胞表现不明显。结论:低剂量电离辐射可选择性诱导小鼠睾丸生精细胞凋亡, 具有明显的剂量和时程效应关系。提示, 这种选择性诱导凋亡调控机制可能与 P53 基因和蛋白表达相关联。

Apoptosis and expression of P53 mRNA and protein in mouse spermatogenic cells induced by low dose ionizing radiation

AIM: The effect of low dose radiation (LDR) with different doses of X-rays on apoptosis and its related gene P53 expression were studied in spermatogenic cells of male Kunming mouse testis. METHODS: The different kinds of spermatogenic cells were separated using density gradient centrifugation and their apoptosis was measured by flow cytometry. At meantime, P53 protein and P53 mRNA was measured with immunohistochemical SABC and in situ hybridization, respectively. RESULTS: The apoptosis in all kinds of spermatogenic cells induced by LDR had a remarkable regularity. When the doses were 0 025 and 0 05 Gy, spermatogone apoptosis was domaint. With the increase in irradiation dose (0 075-0 2 Gy), spermatocytes also showed an apoptotic change, but the apoptotic percentage of spermatogonia was significantly higher than that of spermatocytes. Moreover, the apoptosis of spermatids and spermatozoa scarely occurred after LDR. P53 protein expressed in spermatogonia and spermatocytes in varying degrees, and the former was significantly higher than that of the latter after LDR. With the increase in irradiation dose, P53 protein expression showed a upregulated tendency, but that of spermatids and spermatozoa scarcely occurred. P53 mRNA primarily expressed in spermatids and spermatocytes when the dose was 0 025 Gy. With the increase in irradiation doses (0 05-0 2 Gy), that of spermatogonia also showed an enhancement. P53 mRNA expression in spermatogonia and spermatocytes showed a remarkable dose-effect relationship. CONCLUSION: The apoptosis of spermatogenic cells was selectively induced by LDR of X-rays, which had remarkable the dose-effect and time-effect relationships. The mechanism of the selective apoptosis in spermatogenic cells by LDR is closely related to the upregulation of P53 .