Effect of tetramethylpyrazine on reserpine-induced gastric lesion in rats

Tetramethylpyrazine ameliorates indomethacin-induced gastric ulcer in rats: Impact on oxidative, inflammatory, and angiogenic machineries

Available antiulcer medications reveal partial efficacy and numerous adverse reactions. Tetramethylpyrazine (TMP) was known for its potential antioxidant, anti-inflammatory and angiogenic properties. The aim of current study was to investigate the potential gastroprotective effect of TMP against indomethacin-induced gastric ulcer in rats with possible underlying mechanisms. TMP was tested at 3 doses (15, 30 & 60 mg/kg/d po) three days before indomethacin challenge (25 mg/kg ip). Gastric tissue was evaluated morphologically and histopathologically. Oxidative statuses were assessed via glutathione content (GSH), malondialdhyde (MDA) and catalase (CAT) activity, while TNFα and IL-6 were measured as inflammatory mediators. Gastric PGE2 was investigated in addition to vascular endothelial growth factor (VEGF). TMP was effective (at 30 and 60 mg/kg/d) in promoting mucus secretion and preventing histopathologic changes induced by indomethacin. Mechanistically, TMP significantly enhanced GSH content and CAT activity while reducing lipid peroxidation as expressed by MDA concentration. Moreover, TMP effectively reduced TNFα, IL-6 and intracellular adhesion molecule (ICAM-1) concentrations. On the other hand, TMP enhanced both COX-1 and PGE2 and encouraged angiogenesis via increasing VEGF expression. In conclusion, TMP possesses a protective effect against indomethacin-induced gastric ulcer. This could be explained - at least partly - by its antioxidant, anti-inflammatory and angiogenic effects.

Determination of ibuprofen in dog plasma by liquid chromatography and application in pharmacokinetic studies of an ibuprofen prodrug in dogs

A liquid chromatography (LC) method for the determination of ibuprofen in dog plasma is described. Chromatographic separation was performed on a Diamonsil C18 column with a C18 guard column using a binary mixture of acetonitrile and 0.02 mol/l phosphate buffer (pH 6.5) (35:65, v/v) delivered at a flow rate of 1.2 ml/min. The linear range for ibuprofen was from 1.0 to 40.0 microg/ml with a limit of quantitation of 1.0 microg/ml. Within-run accuracy and precision ranged from -0.1% to 4.0% and from 1.1% to 5.5% and between-run accuracy and precision ranged from -1.1% to 4.7% and from 1.3% to 7.0%, respectively. The mean extraction recoveries of ibuprofen determined over the concentrations of 1.0, 10.0, and 40.0 microg/ml were (100.5+/-1.8)%, (99.8+/-1.0)%, and (99.2+/-2.3)%. The developed LC method greatly simplified the sample preparation and adopted mild conditions to prevent the possible hydrolysis of the prodrug and was successfully applied to the pharmacokinetic studies of an ibuprofen prodrug in dogs.

Protection by tetramethylpyrazine in acute absolute ethanol-induced gastric lesions

Acute oral administration of absolute ethanol (1.0 ml/kg) to fasting rats produced extensive necrosis of the gastric mucosa within 1 h. Pretreatment 30 min before administration of ethanol with oral tetramethylpyrazine (TMP) prevented this necrosis. Gross examination of the gastric mucosa of rats that received TMP showed fewer gastric lesions than that of rats who did not receive TMP. TMP pretreatment in rats exhibited superoxide scavenging activity in absolute ethanol-induced lipid peroxidation in gastric mucosal homogenates. TMP added in vitro to gastric homogenates made from control rats also showed scavenging activity. We conclude that the gastric protective mechanism of TMP could be attributed, at least in part, to its ability to inhibit lipid peroxidation and hence indirectly protect the gastric mucosa from oxidative stress.