Fig. 1
From: Metformin reduces morphine tolerance by inhibiting microglial-mediated neuroinflammation
Metformin inhibited morphine-induced inflammation in microglial BV-2 cells. Cells were pretreated with metformin (4, 20, or 100 μM) for 15 min before the challenge of morphine (200 μM). BV-2 cells were collected and analyzed 6 h after morphine was given. a–c Metformin suppressed the expression of pro-inflammatory factors induced by morphine in BV-2 cells in a dose-dependent manner (n = 4). The levels of IL-1β, IL-6, and TNF-α mRNA were determined using real-time quantitative polymerase chain reaction (PCR). Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was used as an invariant control. d Metformin inhibited the phosphorylation of p38 induced by morphine treatment in BV-2 cells in a dose-dependent manner (n = 4). e Metformin suppressed TLR-4 mRNA expression induced by morphine in BV-2 cells in a dose-dependent manner (n = 4). The level of TLR-4 mRNA was determined with real-time quantitative PCR. (*p < 0.05; **p < 0.01 Bonferroni post hoc tests)