[Promoting mechanism of enhancers and transport pathway of large hydrophilic molecular across nasal epithelium studied by ESR and CLSM technologies].

The aim of this study is to investigate absorption-promoting mechanism of enhancers and the transport pathway of large hydrophilous molecular across rat nasal epithelium by electron spin resonance (ESR) and confocal laser scanning microscopy (CLSM) technologies. In the experiment, recombinant hirudin-2 (rHV2) was chosen as a large hydrophilic molecular model drug. After nasal administration in rats the bioavailability of rHV2 with or without various enhancers was compared. The effects of enhancers on membrane lipid fluidity and protein conformation were measured with 5-deoxyl-stearic acid (5-DSA), 16-deoxyl-stearic acid (16-DSA) and 3-maleidoproxyl (MSL) labeling ESR. The effects of enhancers on cytoskeletal F-actin of rat nasal epithelium and FITC-rHV2 transport pathway across rat nasal epithelium were performed by CLSM combined with fluorescence labeling. 0.5% Chitosan (CS), 5% hydroxyl-propyl-beta-cyclodextrin ( HP-beta-CD) and 1% ammonium glycyrrhizinate (AMGZ) were all able to significantly increase the nasal absorption of rHV2. CS could result in the paracellular pathway transport of FITC-rHV2 which seemed related to a transient effect on tight junctions. HP-beta-CD could cause paracellular and transcellular route transport of FITC-rHV2 by influencing upon membrane protein as well as lipid fluidity. AMGZ seemed to enhance the transcellular route transport of FITC-rHV2, and could exert some influence on membrane protein but not on lipid fluidity. So how it brought out this result needs further research. Present experiment may become a useful reference for promoting mechanism of enhancers and the transport pathway of large hydrophilic molecular across nasal epithelium research.