Effects of rapamycin and 3-MA on motor behavior and autophagy related protein LC3 in PD model mice

Abstract

Objective To investigate the effects of rapamycin which is an autophagy inducer and 3- adenine (3-MA) which is an autophagy inhibitor on motor behavior and autophagy related protein LC3 in C57BL/6 mice of Parkinson's disease(PD). Methods 40 C57BL/6 male mice were randomly divided into control group and experimental groups which consist of MPTP model group, rapamycin group and 3-MA group, with 10 in each group. Mice in experimental groups received intraperitoneal injection with MPTP to establish PD models, and mice in control group received intraperitoneal injection with the same amount of saline solution for 1 week. Mice in rapamycin group received intraperitoneal injection with rapamycin and mice in 3-MA group received intraperitoneal injection with 3-MA at the same time when MPTP was injected.Animal behavior detections were carried out on the 1th, 7th and 14th day after the last injection.After the last injection, mice were sacrificed and sections of midbrain nigra were gained for the detection of expression of autophagy specificity protein LC3 by Western Blot. Results Compared with MPTP model group, rapamycin could improve the general condition and behavioral manifestation of mice in pole test((14.89±1.14)s vs (16.24±1.39)s, P<0.05; (15.18±1.36)s vs(17.93±1.11s), P<0.01), traction test((1.7±0.5) vs (1.2±0.4), P<0.05; (1.5±0.5)vs (1.1±0.3), P<0.05)and open field test which contained total activity distance((5 875.3±1148.9)cm vs (5 061.5±773.1)cm, P<0.05; (5 753.2±1 106.7)cm vs (4 669.3±969.1)cm, P<0.01)and average speed((19.29±2.35)cm/s vs (16.47±3.01)cm/s, P<0.05; (18.71±2.71)cm/s vs (15.80±2.50)cm/s, P<0.01), while 3-MA aggravated behavioral deficits of mice in pole test(19.92±1.61s vs 17.93±1.11s, P<0.05), and both total activity distance((3 879.7±575.0)cm vs (4 669.3±969.1)cm, P<0.05)and average speed((13.34±1.87)cm/s vs(15.80±2.50)cm/s, P<0.05)in open field test were decreased.The results of Western Blot confirmed that rapamycin could increase the expression of LC3-Ⅱ, however 3-MA could reduce the expression of LC3-Ⅱ. Conclusion This study confirmed that rapamycin could alleviate behavioral symptoms of PD model mice and increase the level of LC3 in midbrain nigra, while 3-MA could exacerbate behavioral symptoms in PD model mice and decrease the level of LC3 in midbrain nigra.Thus it can be speculated that drugs which can regulate autophagy may be potential treatment protocols for PD. Key words: Rapamycin; 3-MA; Parkinson’s disease; LC3; Autophagy