ABSTRACT
Objective: Based on the tumor-bearing rat model, using rutin, quercitrin, and isoquercitrin from Hedyotis diffusa as the research object, the pharmacokinetics of those three flavonoid glycosides in the pathological state was studied. Methods: Establishing a method for the comparison of the pharmacokinetics of flavonoid extracts in normal rats and tumor-bearing rats, which was analyzed by HPLC-MS/MS in subcutaneous tumor models of SD rat made with tumour cell of Walker-256. Results: Compared with the pharmacokinetics parameters of flavonoid glycosides in normal rats, the Cmax and AUC0-∞ of rutin, quercetin, and isoquercitrin in the tumor-bearing rats were significantly decreased, t1/2z was prolonged, and the metabolic time of three components was prolonged to 24 h, which revealed the effect of pathological condition on the pharmacokinetic characteristics of flavonoid glycosides. Conclusion: The method established in this study is simple, fast, sensitive, and suitable for the pharmacokinetic study of flavonoid glycosides in rats in vivo. The pharmacokinetic characteristics of flavonoids in normal and tumor-bearing rats are different.
ABSTRACT
Implantation of Walker 256 tumor decreases acute systemic inflammation in rats. Inflammatory hyperalgesia is one of the most important events of acute inflammation. The L-arginine/NO/cGMP/K+ATP pathway has been proposed as the mechanism of peripheral antinociception mediated by several drugs and physical exercise. The objective of this study was to investigate a possible involvement of the NO/cGMP/K+ATP pathway in antinociception induced in Walker 256 tumor-bearing male Wistar rats (180-220 g). The groups consisted of 5-6 animals. Mechanical inflammatory hypernociception was evaluated using an electronic version of the von Frey test. Walker tumor (4th and 7th day post-implantation) reduced prostaglandin E2- (PGE2, 400 ng/paw; 50 µL; intraplantar injection) and carrageenan-induced hypernociception (500 µg/paw; 100 µL; intraplantar injection). Walker tumor-induced analgesia was reversed (99.3% for carrageenan and 77.2% for PGE2) by a selective inhibitor of nitric oxide synthase (L-NAME; 90 mg/kg, ip) and L-arginine (200 mg/kg, ip), which prevented (80% for carrageenan and 65% for PGE2) the effect of L-NAME. Treatment with the soluble guanylyl cyclase inhibitor ODQ (100% for carrageenan and 95% for PGE2; 8 µg/paw) and the ATP-sensitive K+ channel (KATP) blocker glibenclamide (87.5% for carrageenan and 100% for PGE2; 160 µg/paw) reversed the antinociceptive effect of tumor bearing in a statistically significant manner (P < 0.05). The present study confirmed an intrinsic peripheral antinociceptive effect of Walker tumor bearing in rats. This antinociceptive effect seemed to be mediated by activation of the NO/cGMP pathway followed by the opening of KATP channels.