| Objective:1,To investigate the expression and effect of apoptosis-related Caspases-9 and Caspases-3 in experimental autoimmune myasthenia gravis(EAMG) rats .2,To investigate the expression of Caspases-9 and Caspases-3 in thymus of EAMG rats after nasal immune tolerance and its mechanism.Methods:Female Lewis rats(6-8 weeks) were injected subcutaneously at four spots with the synthetic peptide Rα97-116 in complete Freund's adjuvant(CFA) and boosted on day 30 and 60 with the same peptide in incomplete Freund's adjuvan(tIFA) to iduce the rat model of EAMG , and with phosphate buffer saline(PBS) in the control group. Clinical manifestation was evaluated by the body weight and Lennon clinical score. Disease was further confirmed by 3,5 Hz repetitive nerve stimulation (RNS) for positive decremental response and ELISA for the plasma AchR-Ab(IgG) titers. The model Lewis rats of EAMG group and nasal tolerance group were droped with PBS and Rα97-116(V108A) respectively in nasal cavity on day 71to 80 daily, Clinial score and body weight were evaluated after 10 days post nasal administration. All experiment rats were sacrificed on the 81th day. The apoptosis thymocytes in rat thymus of three groups were counted by TUNEL methods and the expressions of caspases-9 and Caspases-3 in the thymus were studied by immunohistochemical(IHC). AchR-Ab(IgG) in plasma were detected by ELISA.Results:1,Signs of EAMG occurred in 73.3% of Lewis rats in the EAMG group ,which was confirmed by the Lennon clinical score>1 grade, the positive decremental response D5 >10% of 3,5 Hz RNS and the ratio >2.1 of the plasma AchR-Ab(IgG) titers to the normal control group. The achievement ratio of EAMG model was 73.3%.2,On the 10th day after Lewis rats received nasal tolerance with Rα97-116(V108A) , the body weight of rats in the nasal tolerance group were increased significantly compared with the EAMG group(p﹤0.05).3,On the 10th day after Lewis rats received nasal tolerance with Rα97-116(V108A), The difference of average clinical score between nasal tolerance group and EAMG group was significant (P<0.05).4,Compared with the EAMG group , the amount of anti-AChR IgG in nasal tolerance group decreased (p﹤0.05) after the 10th day nasal tolerance with Rα97-116(V108A).5,Numbers of apoptosis thymocytes in EAMG group were less than those of control group and tolerance group respectively (P<0.05),there were not significant difference between nasal tolerance group and control group (p>0.05).6,The expression of Caspases-9 and Caspases-3 in thymocytes of EAMG group was down-regulated, comparing with the control group (p< 0.05).7, The expression of Caspases-9 and Caspases-3 in thymocytes were obviously increased after nasal tolerance with Rα97-116(V108A), there were not significant difference between nasal tolerance group and control group (p>0.05). Conclusions:1,The abnormity of apoptosis thymocytes maybe one of the mecheanisms of EAMG; caspases-9 and caspases-3 play an important role in this process of EAMG.2,Nasal immune tolerance with Rα97-116(V108A)could ameliorate muscle weakness symptoms of EAMG rats and can enhance the apoptosis thymocytes of the EAMG group,Whose mechanism of therapy might be related to passway of apoptosis. The apoptosis of auto-react lymphocyte maybe participate the mechanism of nasal immune tolerance.
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