ABSTRACT
D-galactose (D-gal) administration was proven to induce cognitive impairment and aging in rodents' models. Geraniol (GNL) belongs to the acyclic isoprenoid monoterpenes. GNL reduces inflammation by changing important signaling pathways and cytokines, and thus it is plausible to be used as a medicine for treating disorders linked to inflammation. Herein, we examined the therapeutic effects of GNL on D-gal-induced oxidative stress and neuroinflammation-mediated memory loss in mice. The study was conducted using six groups of mice (6 mice per group). The first group received normal saline, then D-gal (150 mg/wt) dissolved in normal saline solution (0.9%, w/v) was given orally for 9 weeks to the second group. In the III group, from the second week until the 10th week, mice were treated orally (without anesthesia) with D-gal (150 mg/kg body wt) and GNL weekly twice (40 mg/kg body wt) four hours later. Mice in Group IV were treated with GNL from the second week up until the end of the experiment. For comparison of young versus elderly mice, 4 month old (Group V) and 16-month-old (Group VI) control mice were used. We evaluated the changes in antioxidant levels, PI3K/Akt levels, and Nrf2 levels. We also examined how D-gal and GNL treated pathological aging changes. Administration of GNL induced a significant increase in spatial learning and memory with spontaneously altered behavior. Enhancing anti-oxidant and anti-inflammatory effects and activating PI3K/Akt were the mechanisms that mediated this effect. Further, GNL treatment upregulated Nrf2 and HO-1 to reduce oxidative stress and apoptosis. This was confirmed using 99mTc-HMPAO brain flow gamma bioassays. Thus, our data suggested GNL as a promising agent for treating neuroinflammation-induced cognitive impairment.
Subject(s)
Acyclic Monoterpenes , Cognitive Dysfunction , Galactose , Humans , Mice , Animals , Galactose/toxicity , Proto-Oncogene Proteins c-akt/metabolism , Neuroinflammatory Diseases , NF-E2-Related Factor 2/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Oxidative Stress , Aging/metabolism , Cognitive Dysfunction/drug therapy , Antioxidants/pharmacology , Disease Models, Animal , Inflammation/drug therapyABSTRACT
Research is currently under way to produce tissue engineered corneal endothelium transplants for therapeutic use in humans. This work requires the use of model animals, both for the supply of corneal endothelial cells (CECs) for experimentation, and to serve as recipients for test transplants. A variety of species can be used, however, a number of important advantages can be gained by using sheep as transplant recipients. The purpose of the present study was therefore to develop a method for culturing sheep CECs that would be suitable for the eventual construction of corneal endothelium grafts destined for sheep subjects. A method was established for culturing sheep CECs and these were compared to cultured human CECs. Results showed that cultured sheep and human CECs had similar growth characteristics when expanded from corneal endothelium explants on gelatin-coated plates, and achieved similar cell densities after several weeks. Furthermore, the markers zonula occludens-1, N-cadherin and sodium potassium ATPase could be immunodetected in similar staining patterns at cell boundaries of cultured CECs from both species. This work represents the first detailed study of sheep CEC cultures, and is the first demonstration of their similarities to human CEC cultures. Our results indicate that sheep CECs would be an appropriate substitute for human CECs when developing methods to produce tissue engineered corneal endothelium transplants.
Subject(s)
Cell Culture Techniques , Endothelium, Corneal/cytology , Adolescent , Animals , Biomarkers/metabolism , Cadherins/genetics , Cadherins/metabolism , Cell Count , Cells, Cultured , Endothelium, Corneal/metabolism , Fluorescent Antibody Technique, Indirect , Humans , Real-Time Polymerase Chain Reaction , Sheep , Sodium-Potassium-Exchanging ATPase/genetics , Sodium-Potassium-Exchanging ATPase/metabolism , Tissue Engineering , Zonula Occludens-1 Protein/metabolismABSTRACT
The corneal endothelium is a monolayer of epithelial cells that lines the posterior surface of the cornea and is essential for maintenance of corneal transparency. Wound healing within the corneal endothelium typically occurs through cell spreading and migration rather than through proliferation. The mechanisms that control corneal endothelial cell migration are unclear. In this study we demonstrate that cultures of corneal endothelial cells display reduced migration in scratch wound assays, and reduced levels of E-cadherin mRNA, following suppression of ligand-activated Eph receptor signalling by treatment with lithocholic acid. Two Eph receptors, EphA1 and EphA2, were subsequently detected in corneal endothelial cells, and their potential involvement during migration was explored through gene silencing using siRNAs. EphA2 siRNA reduced levels of mRNA for both EphA2 and N-cadherin, but increased levels of mRNA for both EphA1 and E-cadherin. No effect, however, was observed for EphA2 siRNA on migration. Our results indicate a potential role for Eph receptor signalling during corneal endothelial cell migration via changes in cadherin expression. Nevertheless, defining a precise role for select Eph receptors is likely to be complicated by crosstalk between Eph-mediated signalling pathways.
