Wataru Aoi a,, Shigekuni Hosogi b, Naomi Niisato b,d, Noriko Yokoyama b, Hiroki Hayata b, Hiroaki Miyazaki b, Katsuyuki Kusuzaki b,d, Takuya Fukuda c, Michiaki Fukui c, Naoto Nakamura c, Yoshinori Marunaka b,d,
Institutions
a Laboratory of Health Science, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto 606-8522, Japan
b Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
c Department of Endocrinology and Metabolism, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan d Japan Institute for Food Education and Health, Heian Jogakuin (St. Agnes’) University, Kyoto 602-8013, Japan
Abstract
Propolis, a resinous mixture collected from plants by the Apis mellifera bee, contains high level nutrient 26 factors including vitamins, polyphenols, and amino acids that would be expected to improve insulin sen- 27 sitivity. Insulin resistance would secondarily cause elevation of blood pressure and increase the risk of 28 cardiovascular diseases. The purpose of this study is to investigate the effect of propolis extracts on blood 29 glucose levels and blood pressures in an early developmental stage of insulin resistance in Otsuka Long- 30 Evans Tokushima Fatty (OLETF) rats. OLETF rats (10 weeks old) were divided into three different groups: 31 normal diet, 0.1% propolis diet, and 0.5% propolis diet. After 8 weeks, blood glucose levels, blood pres- 32 sures, plasma metabolic factors and hormones, and interstitial fluid pH were measured. Casual blood glu- 33 cose levels were decreased associated with a reduction of plasma insulin levels in both propolis diet 34 groups compared with normal diet group. Propolis decreased systolic blood pressure with no significant 35 changes in plasma aldosterone levels. We also found that interstitial fluid pH in ascites, liver, and skeletal 36 muscle was higher in rats fed propolis diet than rats fed normal diet. These data suggests that dietary 37 propolis improves insulin sensitivity and blood pressures in the early stage of the process in development 38 of insulin resistance, which may be mediated by suppression of metabolic acidosis.
* THESE STATEMENTS HAVE NOT BEEN EVALUATED BY THE FOOD AND DRUG ADMINISTRATION. THIS IS NOT INTENDED TO DIAGNOSE, TREAT CURE OR PREVENT ANY DISEASE.