The Relationship Between Norepinephrine And Aluminum Immunotoxicity

In vivo experiment, Wistar rats were used as experimental animals. 60 healthy rats (110g～120g) were randomly divided into 4 groups, and were orally exposed to 0 (control group, C group), 64.18 (low dose group, L group), 128.36 (middle dose group, M group) and 256.72 (high dose group, H group) mg/kg body weight aluminum trichloride (AlCl₃) in drinking water for 120 days, respectively. And sub-chronic Al intoxication model was built successfully. The spleen lymphocyte proliferation, immune cytokines, T lymphocyte subsets, NE levels in serum and hypothalamus, corticotropin release hormone (CRH), adrenal cortex hormone (ACTH) and cortisone (Cort) content in serum, the cAMP content in spleen lymphocyte, the density ofβ₂-AR on spleen lymphocyte membrane and expression level ofβ₂-AR mRNA were detected to study the influence of aluminum exposure on immune state and NE level of rats and to find the relationship between NE level and the immune state of aluminum exposed rats.In vitro experiment, the spleen lymphocyte of 1-month-old rats was obtained. The culture solutions were added with AlCl₃ of 0 (control group, W-C group), 1/20 IC₅₀ (low dose group, W-L group), 1/10 IC₅₀ (middle dose group, W-M group) and 1/5 IC₅₀ (high dose group, W-H group), respectively. The detection of in vitro proliferation of rats'spleen lymphocyte, immune cytokines and T lymphocyte subsets were detected, and the results showed that aluminum with concentration of 1/10 IC₅₀ could inhibit lymphocyte immune function in vitro. The lymphocyte with this concentration was chosen and added with NE of 0 (control group, N-C group), 10-10 (low dose group, N-L group), 10-9 (middle dose group, N-M group) and 10-8 (high dose group, N-H group) mol/L, respectively. And the spleen lymphocyte proliferation, immune cytokines, T lymphocyte subsets, the cAMP content in spleen lymphocyte, the density ofβ₂-AR on spleen lymphocyte membrane and expression level ofβ₂-AR mRNA were detected to study the regulation function of NE on aluminum immunotoxicity. The experiment results showed as follows:The result of the vivo experiment indicated that:1. The aluminum contents in serum, spleen and brain tissue of sub-chronic aluminum poisoned rats were all extremely significantly higher than C group; the expression rate of CD3⁺, CD4⁺, CD8⁺ T lymphocyte, proportionality of CD4⁺/CD8⁺, IL-2 and TNF-αcontents from lymphocyte secretion were all significantly lower than C group, which showed that aluminum could inhibit the immune function of rats. 2. The NE content in serum, the density ofβ₂-AR on spleen lymphocyte membrane, expression level ofβ₂-AR mRNA and cAMP content in lymphocyte of sub-chronic aluminum poisoned rats were all significantly higher than C group, which showed that aluminum could increase the peripheral NE level, activate the approach ofβ₂-AR-cAMP, and inhibit immune function directly.3. The NE content in the brain tissues of sub-chronic aluminum poisoned rats was significantly lower than C group, while the CRH, ACTH and Cort contents in serum were all significantly higher than C group, which showed that aluminum could inhibit the NE re-englobement of presynaptic membrane, raise the extracellular NE level, and inhibit immune function indirectly by activating the HPA axle.4. The correlation analysis results between NE level in the spleen of sub-chronic aluminum exposed rats and proliferation rate of T/B lymphocyte, IL-2 and TNF-αcontent in spleen, the expression rate of CD3⁺, CD4⁺ T lymphocyte and proportionality of CD4⁺/CD8⁺ were all significantly negatively correlated, which showed that NE was closely related to aluminum immunotoxicity, and extracellular high-level NE could aggravate immunosuppression induced by aluminum.The result of the vitro experiment indicated that:1. Exposed to aluminum for 24 h in vitro, the IC₅₀ of AlCl₃ to rat splenic lymphocytes detected by MTT was 5.52 mmol/L, and 95% confidence interval was 4.76 mmol/L～6.38 mmol/L.2. With the increasing of the aluminum, the proliferation rate of T/B lymphocyte of rats, the expression rate of CD3⁺, CD4⁺, CD8⁺ T lymphocyte, proportionality of CD4⁺/CD8⁺, IL-2 and TNF-αcontent from lymphocyte secretion were all gradually decreased. And the W-M and W-H groups were significantly lower than C group, while the difference between W-L group and with W-C group was not significant. The results proved further that aluminum could inhibit the function of lymphocyte. Because W-M group could cause remarkable immunosuppression, W-M group was chosen as the research object for future experiment.3. With the increasing of aluminum, the density ofβ₂-AR and expression level ofβ₂-AR mRNA on lymphocyte of rats were higher than that in W-C group and the W-M and W-H groups were significantly higher than that in W-C group. And the inhibition of lymphocyte immune function was accompanied. The results showed that theβ₂-AR approach was one of the aluminum immunotoxicity mechanisms.4. With the increasing of NE, the cAMP content in lymphocyte was significantly higher than that in N-C group, and the proliferation rate of T lymphocyte of rats, the expression rate of CD3⁺, CD4⁺, CD8⁺ T lymphocyte, proportionality of CD4⁺/CD8⁺, IL-2 and TNF-αcontents from lymphocyte secretion were all significantly lower than that in N-C group. B lymphocyte proliferation rate had no significant change compared with N-C group. The results showed that theβ₂-AR-cAMP approach could be used to aggravate the inhibitory effect of aluminum on T lymphocyte, but it would have no remarkable influence on B lymphocyte.