ABSTRACT
Background Chemical modification of RNA is a recent hotspot in the field of epigenetics, but the specific mechanism of chemical modification of RNA in aluminum neurotoxicity has not been fully reported. Objective To investigate the alterations of fat mass and obesity-associated protein (FTO), that demethylates N6-methyladenosine (m6A), and brain-derived neurotrophic factor (BDNF) in different brain regions of rats and rat adrenal pheochromocytoma differentiated cells (PC12 cells) following aluminum exposure. Methods Animal experiment: Twenty-four healthy male SD rats were randomly divided into a control group (normal saline) and 10, 20, and 40 μmol·kg−1 exposure groups according to body weight, with 6 rats in each group. Maltol aluminum [Al(mal)3] was injected intraperitoneally every other day for 3 months. Cell experiment: PC12 cells were divided into a control group and 100, 200, and 400 μmol·L−1 exposure groups exposed to Al(mal)3 for 24 h. After exposure, the learning and memory ability of rats was measured by water maze experiment, and the protein expression levels of FTO and BDNF in rat cortex (n=6) and hippocampus (n=6) samples as well as in PC12 cells (n=5) were determined by Western blotting. Results The results of water maze test showed that the escape latency of the 40 μmol·kg−1Al(mal)3 group was higher than those of the control group, the 10 μmol·kg−1Al(mal)3 group, and the 20 μmol·kg−1Al(mal)3 group on day 3, 4, and 5 of training (P<0.05). The retention time of the target quadrant of the 40 μmol·kg−1Al(mal)3 group was also reduced compared with that of the control group (P<0.05), indicating that aluminum exposure damaged the learning and memory ability of the rats. The Western blotting results showed that in the cortex, compared with the control group, the protein expression levels of FTO and BDNF in the aluminum treated groups were decreased (P<0.05). In the hippocampus, compared with the control group, the protein expression levels of FTO and BDNF in the 20 μmol·kg−1 and the 40 μmol·kg−1Al(mal)3 groups were decreased (P<0.05). In PC12 cells, compared with the control group, the protein expression levels of FTO and BDNF in the aluminum treated groups were decreased (P<0.05). Conclusion Aluminum-induced learning and memory impairment is related to a simultaneous reduction of FTO and BDNF protein expressions, suggesting that m6A methylation may be involved.
ABSTRACT
Objective To investigate the protective effect of thalidomide on acute lung injury (ALI) induced by paraquat (PQ) poisoning in rats and its possible mechanism. Methods Sixty SPF Wistar rats were randomly divided into six groups with 10 rats in each group. The rat model of PQ poisoning was reproduced by intraperitoneal injection of PQ solution 20 mg/kg (PQ model group), and the rats were treated by intraperitoneal injection of gradient thalidomide (50, 100, 200 mg/kg treatment groups) 30 minutes later continuously for 3 days. The normal saline (NS) control group and thalidomide control group (thalidomide 200 mg/kg) were established. After 3 days, the abdominal aorta blood was collected, and the superoxide dismutase (SOD) activity was determined by hydroxylamine method, serum malondialdehyde (MDA) content was determined by thiobarbituric acid method. The rats were sacrificed for lung tissue, the levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were determined by enzyme-linked immunosorbent assay (ELISA). The phosphorylation levels of p65 and inhibitor-α of nuclear factor-κB (NF-κB) (IκB-α), which were the NF-κB signaling pathway proteins, were determined by Western Blot. The pathological changes in lung tissue were observed under light microscope by hematoxylin-eosin (HE) staining. Results Under microscope, obvious congestion of pulmonary interstitial and alveolar septum, a large number of inflammatory cells infiltration and thickened alveolar wall were observed after 3 days of PQ poisoning, and the congestion of pulmonary interstitial and alveolar septum, edema and inflammatory cells infiltration in the lung tissue were significantly reduced after treatment of 50, 100, 200 mg/kg thalidomide, but compared with NS control group, there was still a small amount of edema fluid, inflammatory cells and erythrocytes in the lungs tissue. Compared with the NS control group, serum MDA content and the levels of TNF-α and IL-6, and the phosphorylation of p65 and IκB-α in lung tissue were significantly increased after PQ exposure, and the activity of serum SOD was significantly decreased. Treatment with 50, 100, 200 mg/kg thalidomide could significantly reduce the levels of MDA, TNF-α, IL-6, and phosphorylation of IκB-α and p65, and increase SOD activity, in a dose-dependent manner, and the levels were significantly different from PQ model group [MDA (mmol/L): 8.26±1.20, 6.72±1.18, 5.51±1.44 vs. 9.02±1.03, TNF-α (ng/mg): 3.00±0.14, 1.84±0.18, 1.58±0.11 vs. 3.30±0.14, IL-6 (ng/mg): 1.26±0.04, 1.06±0.04, 0.97±0.08 vs. 1.97±0.07, p-p65/p65: 6.01±0.35, 3.64±0.15, 2.89±0.18 vs. 6.34±0.23, p-IκB-α/IκB-α: 2.27±0.13, 2.14±0.22, 1.52±0.14 vs. 2.96±0.20, SOD (kU/L): 195.7±19.3, 207.1±25.6, 225.8±23.1 vs. 188.2±26.6, all P < 0.05]. There was no significant effect on lung by 200 mg/kg thalidomide alone. Conclusion Thalidomide has a protective effect on ALI induced by PQ poisoning in rats in a dose-dependent manner, the mechanism may be achieved by reducing the level of oxygen free radicals, reducing the inflammatory factor and inhibiting the IκB-α/NF-κB signal pathway activation.