Effects of Eugenol on Nerve and Vascular Dysfunction in Streptozotocin-Diabetic Rats

Abstract

Hyperglycaemia in diabetes mellitus results in oxidative stress and pro-inflammatory changes which contribute to vascular complications including endothelial dysfunction and peripheral neuropathy. The aim of this study was to examine whether treatment with the dominant ingredient of clove oil, eugenol, which has antioxidant and anti-inflammatory properties, could improve diabetic vascular and nerve function in streptozotocin-induced diabetic rats. Intervention treatment was given for 2 weeks following 6 weeks of untreated diabetes. Dose-ranging studies on diabetic deficits in sciatic nerve motor and saphenous nerve sensory nerve conduction velocities gave ED50 values of 28 mg/kg and 9 mg/kg, respectively, conduction velocity being within the non-diabetic range at a dose of 200 mg/kg. Sciatic nerve endoneurial blood flow was 49% reduced by diabetes and this was completely corrected by 200 mg/kg eugenol treatment. Gastric fundus maximum nitrergic nerve-mediated relaxation was 44% reduced by diabetes; eugenol corrected this deficit by 69%. For renal artery rings, maximum endothelium-dependent relaxation to acetylcholine was 51% reduced by diabetes; eugenol corrected this deficit by 60%, with improvements in both nitric oxide and endothelium-derived hyperpolarising factor (EDHF)-mediated vasorelaxation components. Diabetes increased renal artery sensitivity to phenylephrine-mediated contraction, however, this was unaffected by eugenol treatment. Thus, aspects of both vascular and neural complications in experimental diabetes are improved by eugenol, which could have potential therapeutic implications for diabetic neuropathy and vasculopathy.

Acetylcholine-induced vasodilation in the perfused kidney of the streptozotocin-induced diabetic rat: role of prostacyclin

“…Indeed, in our previous studies the impairment of ACh-induced endothelium-dependent vasodilation in the diabetic perfused kidney was attributed to a decrease in NO or EDHF signaling (Kamata and Hosokawa, 1997b;Kamata and Yamashita, 1999). Moreover, there are reports of impaired NO signaling (Nangle et al, 2006) and EDHF signaling (De Vriese et al, 2000a;Nangle et al, 2006) in diabetic renal arteries.…”

Hypoglycaemic Effect of γ-Irradiated Clove Extract on Alloxan-Induced Diabetic Rats

“…Clove is one of spices that reportedly modulated physiological responses in streptozotocin-induced diabetic rats and reduced glucose level (Nangle et al, 2006 andZari andAl-Attar, 2007). Results in this study obtained a significant low level of insulin and high glucose level due to alloxan administration.…”

“…Cloves are the dried flower buds of Syzygium aromaticum (L.), family Myrtaceae and successfully used for the management of asthma and various allergic disorders in addition to anti carcinogenic properties. Also, clove reportedly modulated physiological responses in streptozotocin-induced diabetic rats (Nangle et al, 2006 andZari andAl-Attar, 2007). Eugenol (4-allyl-2-methoxyphenol) is a naturally occurring phenol essential oil and makes up to 90% of the clove oil.…”

Chebulic acid attenuates ischemia reperfusion induced biochemical alteration in diabetic rats

“…Diabetic rats should be given daily subcutaneous injections of long-acting insulin (2-4 U/rat, Human Mixtard, Abbott India Ltd., Mumbai, India) to maintain blood glucose levels in a desirable range. A relapse period of 2 weeks was give to rats before surgery (Nangle et al, 2006;Kumar & Subramanian, 2008;Tesch & Allen, 2007).…”