Bcl-2/Bax基因表达对低剂量电离辐射诱导小鼠睾丸生精细胞凋亡的影响

EFFECT OF Bcl-2/Bax GENE EXPRESSION ON APOPTOSIS OF SPERMATOGENIC CELLS OF MOUSE TESTES INDUCED BY LOW DOSE RADIATION

应用密度梯度离心法分离小鼠睾丸组织不同类型生精细胞 ,流式细胞术检测其细胞凋亡 ,免疫组织化学方法观察生精细胞Bcl 2和Bax蛋白表达。结果表明 ,0 .0 2 5～ 0 .2GyX射线全身照射后 ,小鼠睾丸组织生精细胞凋亡具有明显的细胞种类规律性。在较低剂量 (0 .0 2 5和 0 .0 5Gy)时 ,以精原细胞凋亡为主 ,随剂量增加 (0 .0 75～ 0 .2Gy)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。Bax蛋白表达主要见于精原细胞和精母细胞 ,前者阳性率高于后者 ,并且随照射剂量增加 ,阳性率逐渐升高 ,而精子细胞和精子阳性率较低 ;Bcl 2蛋白表达主要见于精子细胞和精子 ,而精原细胞和精母细胞阳性率较低。提示 ,Bcl 2和Bax基因表达的相互调节是低剂量电离辐射选择性诱导生精细胞凋亡的重要原因之一 ,这也为深入探讨低剂量电离辐射诱导生精细胞适应性反应的凋亡机制 ,提供了更深层次实验证据。

The different kinds of spermatogenic cells were separated using density gradient centrifugation and their apoptosis and Bcl 2 and Bax protein expression were measured with flow cytometry and immunohistochemical method, respectively. The results showed the apoptosis in all kinds of spermatogenic cells induced by low dose radiation (LDR) had a obvious regularity. When the doses were 0.025 and 0.05 Gy, spermatogone apoptosis was dominant. With the increase of irradiation dose (0.075～0.2 Gy), spermatocytes also showedan apoptotic change, but the apoptotic percentage of spermatogonia was significantly higher than that of spermatocytes. Moreover, the apoptosis of spermatids and spermatozoa scarcely occurred after LDR. Bax protein was primarily expressed in spermatogonia and spermatocytes, and the former was significantly higher than that of the latter after LDR. With the increase of irradiation dose, Bax protein expression showed a upgrading tendency, but that of spermatids and spermatozoa scarcely occurred. Bcl 2 protein was primarily expressed in spermatids and spermatozoa, but the Bcl 2 protein expressions of spermatogonia and spermatocytes scarcely occurred after LDR. These results imply that the interacting regulation of Bcl 2 and Bax gene expression might be involved in selective apoptosis of spermatogenic cells induced by LDR, which provided an experimental evidence for further exploring the apoptotic mechanism of adaptive response of spermatogenic cells by LDR.