Effect of doxycycline and meloxicam on cytokines, brain-derived neurotrophic factor, matrix metalloproteinase-3, tissue inhibitor of metalloproteinase-3 and cyclooxygenase-2 in brain

Prevention of inflammation in early stages will be useful in maintaining vitality of the organism. The objective of this study was to evaluate the effects of doxycycline (DOX) or meloxicam (MLX) monotherapy and combination therapy on the levels of inflammatory mediators in the brain tissues of rats with Escherichia coli lipopolysaccharide (LPS)-induced brain inflammation. Seventy-eight rats were divided into the following groups: control (n=6), LPS (0.5 µg/10 µl intracranial) (n=18), LPS (0.5 µg/10 µl intracranial)+DOX (40 mg/kg intraperitoneal) (n=18), LPS (0.5 µg/10 µl intracranial)+MLX (2 mg/kg intraperitoneal) (n=18) and LPS (0.5 µg/10 µl intracranial)+DOX (40 mg/kg intraperitoneal)+MLX (2 mg/kg intraperitoneal) (n=18) groups. Brain tissues were harvested from all rats in the control group and from six rats each in the four experimental groups at 1, 3 and 6 hr under anaesthesia. The levels of tumor necrosis factor α (TNFα), interleukin 4 (IL-4), IL-6, IL-10, IL-17, brain-derived neurotrophic factor (BDNF), matrix metalloproteinase 3 (MMP-3), tissue inhibitor of metalloproteinase 3 (TIMP-3) and cyclooxygenase 2 (COX-2) in the brain tissues were measured using ELISA kits with ELISA device. LPS administration increased proinflammatory cytokines (TNF, IL-6, IL-17), and MMP-3 levels and decreased anti-inflammatory cytokines (IL-10, IL-4), and BDNF levels. The lowest TNFα levels were detected in the LPS+MLX group (P<0.05). All the drug treatment groups showed decreased IL-17 and COX-2 levels compared to the LPS groups. DOX or MLX monotherapy exerts neuroprotective effects against brain inflammation by decreasing proinflammatory cytokine levels and by increasing anti-inflammatory cytokines levels.