Mulberry leaf extract restores arterial pressure in streptozotocin-induced chronic diabetic rats.
Free radical-induced vascular dysfunction plays a key role in the pathogenesis of vascular disease found in chronic diabetic patients. Morus alba (MA) leaf extract is promoted for good health especially in diabetic patients. Interestingly, antidiabetic and antioxidant activities of MA have been reported in experimental animals. Thus, the hypothesis of this study was that the long-term treatment with MA could improve vascular reactivity of chronic diabetic rats. To test this hypothesis, we examined the effect of long-term treatment with MA on the vascular responses to vasoactive agents in streptozotocin-induced chronic diabetic rats. The diabetic rats were either orally administered with distilled water, MA (0.25, 0.5 and 1 g/kg per day) or subcutaneously injected with insulin (4 U/kg per day) for 8 weeks. After each treatment, the fasting blood glucose, blood pressure, vascular responses to vasoactive agents and tissue malondialdehyde were examined. Morus alba at the doses of 0.5 and 1 g/kg, which significantly reduced blood glucose level, also significantly decreased the high blood pressure in diabetic rats. Vascular responses of the chronic diabetic rats to vasodilators, acetylcholine (3-30 nmol/kg) and sodium nitroprusside (1-10 nmol/kg) were significantly suppressed by 26% to 44% and 45% to 77% respectively, whereas those to vasoconstrictor, phenylephrine (0.01-0.1 micromol/kg) were significantly increased by 23% to 38% as compared to normal rats. Interestingly, the administration of 0.5 and 1 g/kg MA or 4 U/kg insulin significantly restored the vascular reactivities of diabetic rats. Moreover, 8 weeks of diabetes resulted in the elevation of malondialdehyde content in tissues (liver, kidney, heart, and aorta), and MA treatment significantly lessened this increase. These results provide the first evidence for the efficacy of MA in restoring the vascular reactivity of diabetic rats, the mechanism of which may associate with the alleviation of oxidative stress.
Naowaboot
Jarinyaporn
J
Department of Pharmacology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
Pannangpetch
Patchareewan
P
Kukongviriyapan
Veerapol
V
Kukongviriyapan
Upa
U
Nakmareong
Saowanee
S
Itharat
Arunporn
A
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D002908:Chronic Disease; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D031625:Morus; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D018515:Plant Leaves; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
D001786:Blood Glucose; D007328:Insulin; D010936:Plant Extracts; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D008315:Malondialdehyde