Role of Prostaglandins in the Vasodilator Effect of the Aqueous Extract from Artemisia annua Plant in Streptozotocin-induced Diabetic Rats

Aims: One of the most important causes of mortality is vascular complications resulting from diabetes mellitus. Herbal medicines are commonly used for the treatment of cardiovascular conditions in diabetes. Artemisia annua (A. annua) as a medicinal plant has vasculature protective effects in diabetic rats. In the present study, the role of prostaglandins in the vasodilator effect of A. annua aqueous extract in diabetic rats has been studied.

Study Design: This animal study was conducted on diabetic rats. Aqueous extract of Artemisia annua was used for diabetic rats. Then, isolated thoracic aortic rings were exposed to indomethacin and after exposure, the contractile responses were measured.

Methodology: The studied animals were male Wistar rats (n=36) which were randomly divided into intact, untreated-diabetic, and A. annua aqueous extract treated-diabetic groups. For the induction of diabetes, streptozotocin was intraperitoneally (i.p.) administered (60 mg/kg). A. annua extract-treated group received i.p. 100 mg/kg of extract for one month. After one month, the dose contractile response of isolated aortic rings to phenylephrine (doses of 10-9-10-4 mol/L) in the absence and presence of indomethacin as a prostaglandins inhibitor was determined using isolated tissue setup.

Results: Comparison of contractile responses before and after adding indomethacin in treated extract diabetic rats, showed that contractile responses of aorta ring with and without endothelium after adding indomethacin significantly increased at all concentrations of phenylephrine (P<0.05–P<0.0001) while indomethacin in diabetic rats did not effect on contractile response.

Conclusions: Since the vasodilator effect of the aqueous extract of A. annua with a concentration of 100 mg/kg of body weight was pronounced even after endothelium removal, it can be claimed that the vasodilator effects of the extract are related to inhibition of prostaglandin generation both indirectly and directly.