Apoptosis Of Intervertebral Disc Cells In Different Ages Of Human Body And The Expression Of Bcl-2, Bax Protein

Ojective. To investigate apoptosis of intervertebral disc cells and gene regulation in different ages of human body.Metheds. The intervertebral disc cells in different ages of human body were examined by hematoxylin and eosin staining, TdT-mediated dUTP nick-labeling(TUNEL) and Bcl-2, Bax protein immunohistochemical method.Results. (1) Hematoxylin and eosin staining: In embryonal and infantile stages, not-ochordal cells are the mainly kind of cells in different ages of human intervertebral disc, but cartilaginoid cells are the mainly kind of cells in adults. From the later stage of embryo, the number of nucleus pulposus cells reduce gradually with the age, arrive the old-age stage nucleus pulposus cells already few(P<0.05).(2) TUNEL: The TUNEL positived cells of nucleus pulposus cells can be seen immediately after child bearing, and in each age. The mean optical density of the stained granules of TUNEL increase year by year(P<0.05). From the later stage of embryo to adulthood, the rate of TUNEL positive cells reduce to the lowest gradually in the whole life, then increase with the age(P<0.05).(3) Bcl-2 protein immunohistochemical labeling: A higher expression of Bcl-2 protein could be seen in the later stage of embryo, but reduce gradually with the age (P<0.05). The rate of Bccl-2 protein positive cells also be reported the same trend (P<0.05).(4) Bax protein irnmunohistochemical labeling: A higher expression of Bax protein could be seen from the later stage of embryo but reduce gradually with the age(P<0.05); the expression of Bax protein increase with the age in adulthood, but it is not very obvious. From the later stage of embryo to adults, the rate of Bax protein positive cells reduce gradually with the age(P<0.05); the rate of Bax protein positive cells increase year by year from adults to old-age(P<0.05).Conclusion. It is through apoptosis that nucleus pulposus cells of intervertebral disc died, the number of cells decrease obviously. Apoptosis of nucleus pulposus cells might be Bax-dependent, and because of the lower expression, Bcl-2 can't obstruct the occurrence of apoptosis.