title: Beneficial effects of calcitriol on hypertension, glucose intolerance, impairment of endothelium-dependent vascular relaxation, and visceral adiposity in fructose-fed hypertensive rats.
abstract: Besides regulating calcium homeostasis, the effects of vitamin D on vascular tone and metabolic disturbances remain scarce in the literature despite an increase intake with high-fructose corn syrup worldwide. We investigated the effects of calcitriol, an active form of vitamin D, on vascular relaxation, glucose tolerance, and visceral fat pads in fructose-fed rats. Male Wistar-Kyoto rats were divided into 4 groups (n = 6 per group). Group Con: standard chow diet for 8 weeks; Group Fru: high-fructose diet (60% fructose) for 8 weeks; Group Fru-HVD: high-fructose diet as Group Fru, high-dose calcitriol treatment (20 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding; and Group Fru-LVD: high-fructose diet as Group Fru, low-dose calcitriol treatment (10 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding. Systolic blood pressure was measured twice a week by the tail-cuff method. Blood was examined for serum ionized calcium, phosphate, creatinine, glucose, triglycerides, and total cholesterol. Intra-peritoneal glucose intolerance test, aortic vascular reactivity, the weight of visceral fat pads, adipose size, and adipose angiotensin II levels were analyzed at the end of the study. The results showed that the fructose-fed rats significantly developed hypertension, impaired glucose tolerance, heavier weight and larger adipose size of visceral fat pads, and raised adipose angiotensin II expressions compared with the control rats. High- and low-dose calcitriol reduced modestly systolic blood pressure, increased endothelium-dependent aortic relaxation, ameliorated glucose intolerance, reduced the weight and adipose size of visceral fat pads, and lowered adipose angiotensin II expressions in the fructose-fed rats. However, high-dose calcitriol treatment mildly increased serum ionized calcium levels (1.44 ± 0.05 mmol/L). These results suggest a protective role of calcitriol treatment on endothelial function, glucose tolerance, and visceral adiposity in fructose-fed rats.
authors.affiliation: Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan.
authors.forename: Chu-Lin
authors.initials: CL
authors.lastname: Chou
authors.affiliation: Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan.
authors.forename: Cheng-Yoong
authors.initials: CY
authors.lastname: Pang
authors.affiliation: Institutes of Life Sciences, Pharmacology & Toxicology, and Medical Sciences, Tzu Chi University, Hualien, Taiwan; Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America.
authors.forename: Tony J F
authors.initials: TJ
authors.lastname: Lee
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Te-Chao
authors.initials: TC
authors.lastname: Fang
mesh_terms: D050154:Adiposity / Q000187:drug effects; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002117:Calcitriol / Q000008:administration & dosage* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005632:Fructose / Q000009:adverse effects*; D018149:Glucose Intolerance / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D005951:Glucose Tolerance Test; D006973:Hypertension / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D056128:Obesity, Abdominal / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D051381:Rats; D011921:Rats, Inbred WKY; D014664:Vasodilation / Q000187:drug effects; D014815:Vitamins / Q000008:administration & dosage* / Q000494:pharmacology
chemical_list: D014815:Vitamins; D000804:Angiotensin II; D005632:Fructose; D002117:Calcitriol