Pre-treatment with simvastatin prevents the induction of diet-induced atherosclerosis in a rabbit model

Ketamine treatment upon memory retrieval reduces fear memory in marmoset monkeys

Emotionally arousing experiences are retained very well as seen in posttraumatic stress disorder (PTSD). Various lines of evidence indicate that reactivation of these memories renders them labile which offers a potential time-window for intervention. We tested in non-human primates whether ketamine, administered during fear memory reactivation, affected passive (inhibitory) avoidance learning. For the consolidation of contextual emotional memory, the unescapable foot-shock paradigm in a passive avoidance task with two compartments (dark vs illuminated) was used. After entering the dark compartment, marmoset monkeys received four random foot-shocks (1 mA, 4 s) within 15-min. This stressful exposure increased the saliva cortisol and heart rate and impaired REM-sleep (p<0.05). One week later the monkeys were re-exposed to the stressful situation for the reconsolidation of the fearful experience. During the re-exposure the monkeys were treated with ketamine (0.5 mg/kg) or saline. In week 3, the monkeys were placed in the experimental setting to test their memory for the fearful experience. In contrast to the vehicle-treated monkeys, who avoided the dark compartment, the ketamine-treated monkeys entered the dark compartment that was previously associated with the fearful experience (p<0.05). Post-mortem analysis of the hippocampus showed that ketamine-treated animals exhibited less doublecortin positive neurons and BrdU-labeled cells in the dentate gyrus. This study reveals that a single low dose of ketamine, administered upon fear retrieval in monkeys, reduce contextual fear memory and attenuate neurogenesis in the hippocampus. These are important findings for considering ketamine as a potential candidate to target traumatic memories in PTSD.

The Effect of Simvastatin on Gut Microbiota and Lipid Metabolism in Hyperlipidemic Rats Induced by a High-Fat Diet

The objective of this study was to investigate the effects of simvastatin (SIM) on lipid metabolism disorders and gut microbiota in high-fat diet-induced hyperlipidemic rats. The obtained results revealed that feeding rats with SIM (20 mg/kg/day) significantly decreased serum lipid level and inhibited hepatic lipid accumulation and steatosis. Histological analysis further indicated that SIM reduced lipid deposition in adipocytes and hepatocytes in comparison with that of the HFD group. The underlying mechanisms of SIM administration against HFD-induced hyperlipidemia were also studied by UPLC-Q-TOF/MS-based liver metabonomics coupled with pathway analysis. Metabolic pathway enrichment analysis of liver metabolites with significant difference in abundance indicated that fatty acids metabolism and amino acid metabolism were the main metabolic pathways altered by SIM administration. Meanwhile, operational taxonomic units (OTUs) analysis revealed that oral administration of SIM altered the composition of gut microbiota, including Ruminococcaceae (OTU960) and Lactobacillus (OTU152), and so on. Furthermore, SIM treatment also regulated the mRNA levels of the genes involved in lipid and cholesterol metabolism. Immunohistochemistry (IHC) analysis of the liver-related proteins (CD36, CYP7A1 and SREBP-1C) showed that oral administration of SIM could regulate the levels of the protein expression related to hepatic lipid metabolism.

Simvastatin protects against acetaminophen-induced liver injury in mice

The present study aimed to investigate the effect of simvastatin on acetaminophen (APAP) hepatotoxicity in a mouse model. Male C57BL/6 mice were allocated into the following groups: control, APAP, APAP+SIM10, APAP+SIM20, APAP+SIM100 and APAP+SIM200 groups. The mice in the APAP group were treated with saline intraperitoneally (i.p.) 72 h before and 24 h or 72 h after APAP challenge (i.p., 400 mg/kg of APAP). The simvastatin-treated groups were treated with different doses of simvastatin i.p. (10, 20, 100 and 200 mg/kg/day) as in the APAP group. After 24 h or 72 h of APAP challenge, blood and liver samples were collected to detect hepatic injury and liver regeneration. The results showed that low doses of simvastatin (10 and 20 mg/kg) could significantly reverse the histological change and decrease hepatic injury. Simvastatin also reduced the serum cytokine levels and transcriptional levels of tumor necrosis factor-α and interleukin-6 in the liver. The malonyldialdehyde and myeloperoxidase levels significantly decreased in the simvastatin treatment groups compared with the APAP group. Simvastatin restored the decrease in superoxide dismutase, catalase, glutathione and glutathione peroxidase activities induced by APAP hepatotoxicity. In addition, simvastatin inhibited hepatic C/EBP-homologous protein expression and hepatocyte apoptosis. However, simvastatin had no effect on liver regeneration after APAP hepatotoxicity. Moreover, high doses could aggravate APAP-induced liver injury. In conclusion, low doses of simvastatin had a significant therapeutic effect in APAP-induced liver injury by inhibiting oxidative stress, inflammation and apoptosis. However, high doses of simvastatin had adverse hepatotoxicity.