
Effects of Phytoestrogens on Acetylcholine- and Isoprenaline-Induced Vasodilation in Rat Aorta
Author(s) -
Kiyoshi Yamaguchi,
Hideo Honda,
Chiaki Wakisaka,
Atsushi Tohei,
Hiroshi Kuroda
Publication year - 2001
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.87.67
Subject(s) - ovariectomized rat , endocrinology , genistein , medicine , daidzein , isoprenaline , phytoestrogens , vasodilation , isoflavones , acetylcholine , chemistry , estrogen , stimulation
The influence of the phytoestrogen, isoflavones, on vasodilating responses of the thoracic aorta precontracted with norepinephrine, together with the stimulatory effect on uterine weight (uterotrophic effect), was investigated in ovariectomized rats. In comparison with intact rats, acetylcholine (ACh)-induced vasodilation showed a tendency to be decreased by ovariectomy. On the other hand, isoprenaline (ISO)-induced vasodilation was significantly increased by ovariectomy. Estrogen replacement (17beta-estradiol dipropionate, 300 microg/kg per week, for 1 month) completely restored the impaired ACh- and ISO-induced vasodilation caused by ovariectomy. Dietary isoflavone aglycones (containing 52% genistein, 42% daidzein and 6% glycitein) of 157 mg/kg per day (not 67 mg/kg per day) for 1 month, in addition to the effects of estrogen replacement, completely restored the impaired vasodilation caused by ovariectomy. However, the uterotrophic effect of dietary isoflavones of 157 mg/kg per day was incomplete as compared with that by estrogen replacement. These results indicate that phytoestrogen, isoflavones, certainly possess estrogenic actions on the vasodilating responses caused by ACh and ISO, as well as a weaker uterotrophic effect.