Pretreatment with 3,6′-dithiothalidomide significantly attenuates LPS-induced elevations in TNF-α in vitro
and in vivo. (A) Increasing concentration of LPS in RAW 264.7 cells induced a dose-dependent elevation in TNF-α and nitrite levels. (B) In the same cells, LPS induced increases in media sAPP levels (n = 3); no cell toxicity was observed. (C) Pretreatment of cells with 3,6′-dithiothalidomide lowered the levels of TNF-α and nitrite-induced by LPS (n = 3–4). (D) Likewise, in the absence of toxicity the drug reduced the levels of sAPP. (E) The effects of intraperitoneal administration of LPS ± pretreatment with 3,6′-dithiothalidomide on rat plasma TNF-α levels over a 4-h time course are shown. LPS induced a marked elevation of plasma TNF-α protein (n = 7–9), which was significantly reduced by drug (n = 4–5). (F) Compared to control (n = 6), at 4 h, there was a marked LPS-induced increase in the levels of hippocampus TNF-α mRNA (n = 9). Pretreatment with drug significantly attenuated the LPS-induced expression of TNF-α mRNA (n = 5). (G) In line with LPS-induced systemic elevations in TNF-α, CNS TNF-α levels were likewise significantly elevated. 3,6′-Dithiothalidomide fully ameliorated this increase and restored CNS TNF-α levels to baseline. Data are expressed as mean ± SEM of n observations; levels of statistical significance are indicated as follows: *P < 0.05, **P < 0.01, ***P < 0.001.