[Effect of propolis on insulin resistance in fructose-drinking rats].
Propolis, a honeybee product, contains a variety of biologically active substances. The present study was designed to investigate the effects of propolis on insulin resistance induced by fructose-drinking rats (FDR; type 2 diabetic animal model). Male Wistar rats (6 weeks old) received 15% fructose solution in drinking water for 8 weeks. FDR showed significant increases in plasma levels of insulin, Homeostasis Model Assessment ratio (HOMA-R, an index of insulin resistance), body weight, and systolic blood pressure but not blood glucose levels, when compared with control rats. Brazilian propolis extract (100 and 300 mg/kg, p.o.) treatment for 8 weeks significantly decreased the plasma level of insulin, HOMA-R, and body weight, increased plasma triglyceride levels without affecting blood glucose and total cholesterol levels, and tended to decrease systolic blood pressure. In isolated and perfused mesenteric vascular beds of FDR, propolis treatment resulted in a significant reduction of sympathetic nerve-mediated vasoconstrictor response to periarterial nerve stimulation (PNS; 8 Hz) and tended to increase the calcitonin gene-related peptide (CGRP) nerve-mediated vasodilator response to PNS, compared with those in untreated FDR. However, propolis treatment did not significantly affect norepinephrine-induced vasoconstriction and CGRP-induced vasodilation. These results suggest that propolis could be an effective functional food to prevent the development of insulin resistance.
Department of Clinical Pharmaceutical Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University. 1-1-1 Tsushima-naka, Okayama City 700-8530, Japan.
Yoshito
Y
Zamami
Shingo
S
Takatori
Toshihiro
T
Koyama
Mitsuhiro
M
Goda
Yukiko
Y
Iwatani
Shima
S
Doi
Hiromu
H
Kawasaki
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D015740:Calcitonin Gene-Related Peptide / Q000502:physiology; D004195:Disease Models, Animal; D005632:Fructose / Q000008:administration & dosage*; D006943:Hyperglycemia / Q000517:prevention & control*; D066298:In Vitro Techniques; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008638:Mesenteric Arteries / Q000294:innervation; D011429:Propolis / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D013564:Sympathetic Nervous System / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D007328:Insulin; D005632:Fructose; D011429:Propolis; D015740:Calcitonin Gene-Related Peptide