松果体及褪黑素对大鼠胸腺CD4+/CD8+T细胞分化发育的影响

目的：探讨松果体和褪黑素对胸腺T细胞分化发育的影响。方法：实验组为松果体摘除组和松果体摘除 褪黑素组。ABC法染胸腺CD4^ 、CD8^ 细胞。流式细胞术测定胸腺和血液T淋巴细胞CD4^ 、CD8^ T亚类。结果：松果体摘除后胸腺明显萎缩，并随时间延长而加剧，补充褪黑素后胸腺重量逐渐恢复。松果体摘除后胸腺和血液中CD4^ T细胞百分比无明显波动；胸腺CD8^ T细胞比例上升，但血液CD8^ T细胞比例则下降；补充褪黑素后胸腺CD4^ T细胞在低剂量组略有下降，而高剂量组则显著升高，胸腺和血液CD8^ T呈下降趋势，双阳性细胞比例恢复正常，双阴性细胞比例则上升。结论：松果体能显著影响CD8^ T细胞的分化发育和释放，降低血液CD8^ T细胞的比例。补充褪黑素能缓解相关影响。

Effects of pineal gland and melatonin on CD4+/CD8+ T cell subsets development in rat thymus

Objective: To investigate the effect of pinealectomy and melatonin on the T cells development in thymus. Methods: SD rats were divided into 5 groups: normal control, sham-operation control, pinealectomy (Px), pinealectomy+melatonin 7.5 mg/kg, and pinealectomy+melatonin 15 mg/kg group. The animals were sacrificed on 4 or 8 weeks after operation. CD4~+ and CD8~+ T cells in thymus were dyed with immunocytochemical ABC methods and measured by computer image analysis. The percentage of CD4~+ and CD8~+ T cells subset in thymus and blood were tested by flow cytometry. Results: Pinealectomy reduced the rat thymus weight, and treatment with melatonin restored it. The variation of CD4~+ T cells in thymus and blood was not obvious after Px. The percentage of CD8~+ T cells in thymus increased but decreased in blood. The percentage of CD8~+ T cells in thymus and blood both decreased. The CD4~+ and CD8~+ T cells restored to normal and CD4~- and CD8~- T cells were raised. Conclusion:Pinealectomy can notably influence the T cell subsets development in thymus, decease CD8~+ T cells in blood. Melatonin administration can recover the above mentioned changes.