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

Abstract

Objective To evaluate the expression and significance of Beclin-1 and microtubule-associated 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 expression 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 ( ayerage 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 ). Beclin-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. Key words: Intervertebral disc degeneration; Aging; Autophagy; Beclin-1; MAPLC3