Guan-fu base A(Guan-fu base A)

Activation of satellite glial cells (SGCs) in the dorsal root ganglia (DRG) is involved in mechanical and thermal hyperalgesia. The upregulated P2Y₁₂ receptor expressed in SGCs of the DRG participates in the nociceptive transmission of neuropathic pain. Guanfu base A (GFA) has been reported to exhibit antiarrhythmic and anti-inflammatory effects. In this study, we explored the effects of GFA on P2Y₁₂ receptor-mediated mechanical and thermal hyperalgesia in chronic constriction injury (CCI) rats. Sprague-Dawley rats were randomly divided into sham operation group (Sham), CCI operation group (CCI), CCI rats treated with guanfu base A group (CCI + GFA) and control rats treated with GFA group (Ctrl + GFA). Mechanical withdrawal threshold and thermal withdrawal latency were measured. P2Y₁₂ expression in L4-L6 dorsal root ganglion (DRG) was detected by quantitative real-time PCR and Western blot. After CCI treatment, mechanical and thermal hyperalgesia and the expression values of P2Y₁₂ receptor mRNA and protein in DRG were increased. Dual-labeling immunofluorescence showed that the coexpression of P2Y₁₂ receptor and glial fibrillary acidic protein (GFAP) in the DRG of CCI rats was increased compared to sham rats. GFA relieved mechanical and thermal hyperalgesia in the CCI rats, decreased the expression of P2Y₁₂ mRNA and protein and phosphorylation of p38 MAPK in the DRG, and increased the ADP-downregulated cAMP concentrations in HEK293 cells transfected with P2Y₁₂ plasmid. After CCI rats were treated with GFA, the coexpression of P2Y₁₂ receptor and GFAP in the DRG was significantly decreased compared to the untreated CCI group. Thus, downregulating the P2Y₁₂ receptor relieved mechanical and thermal hyperalgesia in the CCI rats.

Guanfu base A·HCl (GFA·HCl) solution, approved by the China Food and Drug Administration (CFDA) in 2005, has been used in the treatment of arrhythmia. However, the poor targeting and absorption of GFA·HCl have severely affected its clinical application. In this study, a nanolipid-based, Guanfu base A (GFA) delivery system was designed to improve the deficiency of GFA·HCl and realize better clinical effect. The GFA-loaded solid nanolipids (GFASN) with a core/shell structure, composed of Poloxamer 188, lecithin, and medium-chain fatty acid, were prepared using a high-pressure homogenate emulsification method. Results showed that GFASN possessed well morphology and stability during the process of lyophilization and rehydration at 220-260 nm. Safety evaluation revealed that ear vein injection of GFASN (14 mg/kg) were safe enough and of good biocompatibility. More importantly, GFASN can better alleviate the arrhythmia of rats, especially in ventricular ectopia and ventricular tachycardia, than GFA·HCl solution. Pharmacokinetic behaviors and targeting evaluation in mice demonstrated that nanolipids can help GFA achieve longer circulation time in blood and better heart specificity. Collectively, these promising findings suggested that this kind of nanolipids was an ideal delivery carrier for GFA in the treatment of cardiovascular disease.