title: Geraniol improves the impaired vascular reactivity in diabetes and metabolic syndrome through calcium channel blocking effect.
abstract: The aim of the present study is to investigate the effect and possible mechanism of action of geraniol on the impaired vascular reactivity of aortic rings isolated from diabetes or metabolic syndrome (MS) -induced rats.
  
  
  
  Male Wistar rats were divided into control, type 1 diabetes and metabolic syndrome (MS) groups. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50mg/kg) and left for 10weeks to develop vascular complications. MS was induced by adding 10% fructose and 3% salt to water and diet for 12weeks. The present study investigated the effect of in vitro incubation with geraniol (10-300μM) on the vasoconstrictor response to phenylephrine (PE) and the vasodilator response to acetylcholine (ACh) as well as its effect on aortae incubated with methylglyoxal (MG) as an advanced glycation end product (AGE). To investigate the mechanism of action of geraniol, different blockers are used, including Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME, 100μM), tetraethylammonium chloride (TEA, 10mM), and indomethacin (INDO, 5μM). Moreover, the effect of calcium chloride (CaCl2) on aortic rings precontracted with PE or potassium chloride (KCl) was examined.
  
  
  
  Thirty minutes incubation with geraniol alleviated the exaggerated vasoconstriction in aortae isolated from diabetic or MS animals or in vitro exposed to MG in a concentration-dependent manner. In addition, geraniol improved the vasodilatation response of diabetic or MS aortae or aortae exposed to MG. In search for the mechanism; geraniol produced concentration-dependent relaxation of both PE and KCl-precontracted aorta. Geraniol relaxation was not affected by L-NAME, INDO or TEA. However, geraniol significantly inhibited voltage dependent and receptor mediated Ca(2+)-induced contraction activated by KCl or PE respectively.
  
  
  
  In conclusion, geraniol ameliorates impaired vascular reactivity in experimentally induced diabetes and MS. The effect may be partially attributed to an endothelium-independent pathway involving blockage of both voltage dependent and receptor operated calcium channel.
authors.affiliation: Department of Pharmacology and Toxicology, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia; Department of Pharmacology, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt.
authors.forename: Hany M
authors.initials: HM
authors.lastname: El-Bassossy
authors.affiliation: Department of Clinical Pharmacy, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia; Department of Clinical Pharmacology, Faculty of Medicine, Beni-Suef University, Beni-Suef, Egypt. Electronic address: berry_ahmed@yahoo.com.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Elberry
authors.affiliation: Department of Pharmacology and Toxicology, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Salah A
authors.initials: SA
authors.lastname: Ghareib
mesh_terms: D000080462:Acyclic Monoterpenes; D000818:Animals; D001011:Aorta / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy*; D004730:Endothelium, Vascular; D066298:In Vitro Techniques; D008297:Male; D024821:Metabolic Syndrome / Q000188:drug therapy*; D051381:Rats; D017208:Rats, Wistar; D013729:Terpenes / Q000494:pharmacology*; D014664:Vasodilation; D014665:Vasodilator Agents
chemical_list: D000080462:Acyclic Monoterpenes; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D013729:Terpenes; D014665:Vasodilator Agents; C007836:geraniol
keywords: Advanced glycation end products; Calcium channels; Diabetes; Geraniol; Nitric oxide; Vascular reactivity