Effect of nicotine on the release of lactate dehydrogenase and the production of tumor necrosis factor-α of cultured macrophage

Background: Nicotine can affect the development of Atherosclerosis (AS). Monocytes/macrophages are the important cells in the AS lesions. Objective: We studied the mechanisms of smoking on AS. The effects of nicotine on macrophage were investigated in this study. Methods: Different concentration of nicotine (6 x 10(-9-5) mol/L), different incubation time (3, 6, 9, 12, 18, and 24 hours) and 7 beta-hydroxycholesterol (50 mu g/ml) were schemed in this study. After exposure of macrophage to those different conditions, lactate dehydrogenase (LDH) activity and tumor necrosis factor-alpha (TNF-alpha) content in the supernatant were assayed. Results: Nicotine (6 x 10(-9)mol/L similar to 6x10(-5)mol/L) treatment resulted in a marked reduction of LDH in the supernatant (131.0 +/- 9.6 U/L, 129.7 +/- 6.2 U/L, 129.4 +/- 5.3 U/L, 134.2 +/- 8.4 U/L, and 138.3 +/- 9.7 U/L vs. 151.3 +/- 8.1 U/L, p < 0.05 respectively, q-test). The same change trend was seen when co-treated with 7 beta-hydroxycholestrol and nicotine (135.7 +/- 7.6 U/L, 135.6 +/- 6.6 U/L, 136.1 +/- 6.7 U/L, 142.9 +/- 4.5 U/L, and 146.4 +/- 4.4 U/L vs. 152.4 +/- 6.2 U/L, P<0.05 respectively, q-test). The peak effects occurred at the nicotine concentration of 6 x 10(-7)mol/L and the first 18-hours incubation. Nicotine (6 x10(-9)mol/L similar to 6 x 10(-6)mol/L) treatment result in the increase of TNF-alpha in the supernatant (0.28 +/- 0.06 ng/mL, 0.32 +/- 0.05 ng/mL, 0.40 +/- 0.07 ng/mL, and 0.30 +/- 0.08 ng/mL vs. 0.17 +/- 0.05 ng/mL, p < 0.05 respectively, q-test). Nicotine (6 x 10(-5)mol/L) treatment have no significant increase compared to the control group (0.21 +/- 0.08 ng/mL vs. 0.17 +/- 0.05 ng/mL, p > 0.05, q-test). The peak effects occurred at the nicotine concentration of 6 x 10(-7)mol/L. Conclusions: Nicotine can produce the beneficial effect on macrophage. Nicotine treatment can activate macrophage to produce TNF-alpha. Thus, nicotine can be a mechanism on the development of atherosclerosis.