TY - JOUR
T1 - The hop phytoestrogen, 8-prenylnaringenin, reverses the ovariectomy-induced rise in skin temperature in an animal model of menopausal hot flushes
AU - Bowe, James
AU - Li, Xiao Feng
AU - Kinsey-Jones, James
AU - Heyerick, Arne
AU - Brain, Susan
AU - Milligan, Stuart
AU - O'Byrne, Kevin
PY - 2006/11/1
Y1 - 2006/11/1
N2 - The mechanisms underlying menopausal hot flushes are poorly understood, although it is generally assumed they result from disturbances of thermoregulatory centres in the hypothalamus. 8-Prenylnaringenin (8-PN) has been identified as a potent phytoestrogen in hops (Humulus lupulus) and there are claims that hop-containing preparations can reduce hot flushes. We have investigated the site of action of 8-PN in a rat model of menopausal hot flushes, in which the tail skin temperature (TST) is increased after oestrogen withdrawal induced by ovariectomy. Daily s.c. administration of either 17β-oestradiol (E2; 4 μg/kg) or 8-PN (400 μg/kg) significantly reduced the elevated TST after 2 days of treatment. Subcutaneous co-administration of either E2 or 8-PN with the oestrogen receptor (ER,) antagonist, ICI 182,780 (200 μg/kg), which is thought not to cross the blood-brain barrier, completely blocked the effect of E2 and 8-PN on TST. The ERα- and ERβ-specific agonists, 4,4′,4″- (4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (100 μg/kg) and 2,3-bis(4-hydroxyphenyl)-propionitrile (60 μg/kg) respectively, both significantly reversed the raised TST in ovariectomised rats. These observations suggest that the regulation of the vasomotor response by oestrogens and phytoestrogens is mediated, at least in part, by peripheral mechanisms involving both ERα and ERβ.
AB - The mechanisms underlying menopausal hot flushes are poorly understood, although it is generally assumed they result from disturbances of thermoregulatory centres in the hypothalamus. 8-Prenylnaringenin (8-PN) has been identified as a potent phytoestrogen in hops (Humulus lupulus) and there are claims that hop-containing preparations can reduce hot flushes. We have investigated the site of action of 8-PN in a rat model of menopausal hot flushes, in which the tail skin temperature (TST) is increased after oestrogen withdrawal induced by ovariectomy. Daily s.c. administration of either 17β-oestradiol (E2; 4 μg/kg) or 8-PN (400 μg/kg) significantly reduced the elevated TST after 2 days of treatment. Subcutaneous co-administration of either E2 or 8-PN with the oestrogen receptor (ER,) antagonist, ICI 182,780 (200 μg/kg), which is thought not to cross the blood-brain barrier, completely blocked the effect of E2 and 8-PN on TST. The ERα- and ERβ-specific agonists, 4,4′,4″- (4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (100 μg/kg) and 2,3-bis(4-hydroxyphenyl)-propionitrile (60 μg/kg) respectively, both significantly reversed the raised TST in ovariectomised rats. These observations suggest that the regulation of the vasomotor response by oestrogens and phytoestrogens is mediated, at least in part, by peripheral mechanisms involving both ERα and ERβ.
UR - http://www.scopus.com/inward/record.url?scp=33751531570&partnerID=8YFLogxK
U2 - 10.1677/joe.1.06919
DO - 10.1677/joe.1.06919
M3 - Article
C2 - 17088409
AN - SCOPUS:33751531570
SN - 0022-0795
VL - 191
SP - 399
EP - 405
JO - Journal of Endocrinology
JF - Journal of Endocrinology
IS - 2
ER -