[Choline improves lipopolysaccharide-induced central nervous system inflammatory response and cognitive dysfunction in mice]

OBJECTIVE

To assess the effect of choline in ameliorating lipopolysaccharide (LPS)-induced central nervous system inflammation and cognitive deficits in mice and explore the underlying mechanism.

METHODS

Seventy-two mice were randomized into saline control group, LPS group, choline intervention group and choline control group. In the latter two groups, the mice received pretreatment with intraperitoneal injections of choline (40 mg/kg, 3 times daily for 3 consecutive days) prior to microinjection of LPS into the lateral cerebral ventricle to induce central nervous system inflammation; in saline and LPS groups, the mice were pretreated with saline in the same manner before intraventicular injection of artificial cerebrospinal fluid. Choline treatment was administered in the mice till the end of the experiment. The locomotor activity and spatial learning and memory capacity of the mice were examined. The expressions of Iba1 protein and proinflammatory cytokines (TNF-α and IL-β) I the hippocampal dentate gyrus, and the expressions of α 7nAchR, p38 MAPK and phosphorylated p38 MAPK in the hippocampus of the mice were detected.

RESULTS

Water maze test showed that compared with the saline control group, the mice in LPS group exhibited significantly reduced platform crossings (P<0.05), which was significantly increased by choline pretreatment (P<0.05). The mice pretreated with LPS expressed obviously increased levels of IBA-1 protein, TNF-α, and IL-1β in the hippocampus (P<0.01), and choline pretreatment significantly lowered the expressions of IBA-1 protein and IL-1β (P<0.05). The phosphorylation level of p38 MAPK increased significantly after LPS pretreatment (P<0.05), and was reduced by choline pretreatment (P<0.05); α 7nAchR expression increased significantly in choline intervention group as compared with that in the other 3 groups (P<0.05).

CONCLUSION

Choline can probably antagonize LPS-induced hippocampal p38 MAPK phosphorylation in mice via the α 7nAchR signaling pathway to protective against LPS-induced neuroinflammation and cognitive impairment in mice.

[Protective effect of dexmedetomidine against glutamate-induced cytotoxicity in PC12 cells and its mechanism]

OBJECTIVE

To investigate the protective effects of dexmedetomidine (Dex) against glutamate-induced cytotoxicity in PC12 cells and its mechanism.

METHODS

PC12 cells were treated with varying concentrations of dexmedetomidine 1 h before exposure to a high concentration of glutamate. The cell viability was measured by MTT assay, and LDH release, MDA content and SOD activity were measured. The level of ROS was tested by DCFH-DA staining and flow cytometry. The level of intracellular Ca²⁺ was detected by Fluo-8 staining and flow cytometry, and the mitochondrial membrane potential (MMP) was determined with JC-1 staining and flow cytometry.

RESULTS

Within the concentration range of 0.01 to 100 µmol/L, Dex dose-dependently protected PC12 cells against glutamate-induced cytotoxicity. Treatment with 100 µmol/L Dex significantly increased the cell viability to (86.6∓2.2)% of that of the control cells (P<0.01) and decreased LDH release to 1.4∓0.1 folds of the control level (P<0.01). In PC12 cells exposed to glutamate, Dex pretreatment significantly reduced MDA content (P<0.01), enhanced SOD activity (P<0.01), inhibited ROS overproduction (P<0.01), reduced intracellular Ca²⁺ level (P<0.01) and maintained a stable MMP (P<0.01).

CONCLUSION

Dexmedetomidine can protect PC12 cells against glutamate-induced injury possibly in relation with its anti-oxidative activity, inhibitory effect on intracellular calcium overload and protective effect of the mitochondria.