大鼠增龄过程中髓核组织Beclin-1和微管相关蛋白轻链3的表达及其意义

Expression and significance of Beclin-1 and microtubule-associated protein 1 light chain 3 in nucleus pulpous of rats during the aging process

目的探讨在增龄过程中SD大鼠髓核组织中Beclin-1和微管相关蛋白轻链3（MAPLC3）的表达及其意义。方法3个月龄、12个月龄、24个月龄SD大鼠各8只，建立青年组、中年组和老龄组大鼠模型，苏木素-伊红（HE）染色检测椎间盘组织的退变；透射电镜检测髓核细胞中自噬体的表达；免疫组织化学染色和逆转录-聚合酶链反应（RT-PCR）法测定髓核组织中Beclin-1和MAPLC3的表达。结果大鼠增龄过程可较好地体现椎间盘的退变变化；不同年龄组大鼠髓核细胞中均有自噬体的表达；Beclin．1和MAPLC3在不同年龄组sD大鼠髓核细胞中均有表达（0．42±0．05，0．47±0．06，0．52±0．05；0．34±0．06，0．39±0．05，0．46±0．09），且老龄组表达均较青年组高（P〈0．01）。Beclin-1和MAPLC3mRNA在不同年龄组SD大鼠髓核组织中均有表达（0．86±0．12，0．93±0．14，1．01±0．13；1．09±0．06，1．15±0．07，1．33±0．11），且老龄组表达较青年组表达明显增高（分别为P〈0．05和P〈0．01）。结论自噬存在于椎间盘退变过程中，且MAPLC3与Beclin-1在椎间盘退变过程中的表达增加，提示自噬活性的增加可能与椎间盘退变的发展进程有关。

Objective To evaluate the expression and significance of Beclin-1 and microtubule-as- sociated protein 1 light chain 3 （ MAPLC3 ） in nucleus pulpous of rats during the aging process. Methods The models of youth, middle-aged and old rats were made with the 3-month, 12-month and 24-months SD rats respectively. The grades of intervertebral disc degeneration were measured with HE staining. The ex- pression of autophagosome in nucleus pulpous was detected under a transmission electron microscope （TEM）. The changes of Beclin-1 and MAPLC3 in nucleus pulpous were assayed by immunocytochemistry and reverse transcription-polymerase chain reaction （RT-PCR）. Results The aging process of rats may reflect the process of intervertebral disc degeneration. There was expression of autophagosome in nucleus pulpous in every group. Beclin-1 and MAPLC3 were expressed in nucleus pulpous cells in each group （ average absorbance values were 0. 42 ± 0. 05, 0. 47 ± 0. 06, 0. 52 ± 0. 05 and 0. 34 ± 0. 06, 0. 39 ± 0. 05, 0.46 ± 0. 09 respectively） and both of them were higher in old group （P 〈 0. 01 ）. Bcclin-1 and MAPLC3 mRNA was expressed in nucleus pulpous in each group （0. 86 ± 0. 12, 0. 93 ± 0. 14, 1.01 ± 0. 13 and 1. 09 ± 0. 06 ,1.15 ± 0. 07, 1.33 ±0. 11 respectively） and both of them were higher in old group （P 〈 0. 05 and P 〈 0.01 respectively）. Conclusion Autophagy resides in the process of intervertebral disc degeneration. The expression of MAPLC3 and Beclinl was up-regulated in nucleus pulpous in different groups and autophagy. Up-regulation of MAPLC3 and Beclinl may be related to the process of the lumbar disc degeneration.