بررسي اثر ميريستين بر عملكرد انقباضي آئورت سينه‌اي در موش صحرايي ديابتي‌شده با استرپتوزوتوسين

Evaluation of the Effect of Myricetin on Contractile Reactivity of Thoracic Aorta in Streptozotocin-Diabetic Rats

زمينه و هدف: بيماري ديابت قندي با گذشت زمان با افزايش وقوع بيماري‌هاي قلبي- عروقي همراه است. باتوجه به خاصيت آنتي‌اكسيداني فلاونوئيد ميريستين، هدف تحقيق حاضر بررسي اثر تجويز اين ماده بر پاسخ انقباضي و رفع انقباضي آئورت سينه‌اي ايزوله در مدل تجربي ديابت قندي و تعيين نقش استرس اكسيداتيو در موش صحرائي بود. موادّ و روش‌ها: دراين مطالعه‌ي تجربي، موش‌هاي صحراييِ نر به چهار گروه كنترل، كنترل تحت تيمار با ميريستين (1 ميلي‌گرم بر كيلوگرم)، ديابتي و ديابتي تحت تيمار با ميريستين (1 ميلي‌گرم بر كيلوگرم) تقسيم‌شدند. ميريستين 10 روز پس از تزريق استرپتوزوتوسين به‌مدت 3 هفته (داخل صفاقي) و روزانه تجويزشد. درانتها، پاسخ انقباضي حلقه‌هاي آئورت سينه‌اي به كلرور پتاسيم و فنيل‌افرين و شل‌شدگي به استيل كولين با استفاده از بساط بافت ايزوله مورد سنجش‌قرارگرفت و ميزان مالون دي آلدئيد (MDA) و نيتريت در بافت آئورت تعيين‌شد. يافته‌ها: حداكثر پاسخ انقباضي آئورت سينه‌اي در گروه ديابتي تحت تيمار با ميريستين به كلرور پتاسيم به‌طور غير معنادار و به فنيل‌افرين به‌طور معنادار كمتر از گروه ديابتي بود.

Background and Aim: Diabetes mellitus is accompanied with higher incidence of cardiovascular disorders. Due to antioxidant activity of the flavonoid myricetin, this study was conducted to evaluate its effect on contractile and relaxation response of thoracic aorta in diabetic rats and to determine the role of oxidative stress. Materials and Methods: In this experimental study, male Wistar rats were divided into 4 groups, i.e. control, myricetin-treated control (1 mg/kg), diabetic, and myricetin-treated diabetic groups (1 mg/kg). Myricetin was daily administered (i.p.) ten days after streptozotocin injection for 3 weeks. At the end of study, contractile reactivity of thoracic aortic rings to KCl and phenylephrine and relaxation response to acetylcholine was determined using isolated tissue setup. In addition, malondialdehyde (MDA) and nitrite were assessed in aortic tissue. Results: Myricetin -treated diabetic group showed a non-significantly lower maximum contraction to KCl and a significantly lower maximum contraction to phenylephrine (p<0.05) as compared to diabetic group. Meanwhile, maximum relaxation response of rings to acetylcholine was significantly higher in myricetin-treated diabetic group as compared to diabetics (p<0.05). In addition, there was also a lower contractile response to PE in myricetin-treaded control and a higher relaxation response for myricetin-treated control group versus controls (p<0.05). In addition, significant reduction of MDA and nitrite (p<0.05) were observed in treated-diabetic rats. Conclusion: Administration of myricetin could decrease contractile response to PE and enhance relaxation response in aortic tissue of diabetic rat and this may be beneficial in prevention of long-term vascular complications of diabetes and part of its effect is via reducing oxidative stress.