Investigation into the Vasomotor Signs and Symptoms of the Menopause

Abstract

The mechanism of the menopausal hot flush was investigated.
Physiological changes, as well as changes in plasma and whole blood
pharmacological activity were examined in post-menopausal women, at
rest and during a hot flush, and in a group of pre-menopausal
controls, at rest and during heat induced vasodilatation. The hot
flush was found to be associated with an altered cardiovascular
activity and an increase in skin surface temperatures. There was a
difference in the contractile activity of plasma from post-menopausal
women, at rest and during a hot flush, upon the methysergide blocked
rat fundic strip. This suggested the involvement of a humoral
component in the mechanism of the hot flush. This humoral component
did not appear to be simply due to vasodilatation since there was
no difference in the contractile activity of plasma from premenopausal
women at rest and during heat induced vasodilatation.
17B-oestradiol appeared to affect the responsiveness of both vascular
and non-vascular sympathetically innervated smooth muscle. 178-
oestradiol depressed the responses of the rat isolated vas deferens
to transmural stimulation to noradrenaline and to potassium chloride.
This suggested a direct action of 178-oestradiol upon the smooth
muscle. Furthermore, 17B-oestradiol, given in a dose which is
considered physiological, increased the pressor responses of the
female pithed rat to stimulation of the spinal sympathetic outflow
but left responses to noradrenaline and angiotensin more or less
unaffected. In addition 178-oestradiol given at a higher amount
decreased the pressor responses of the female pithed rat to stimulation
of the spinal sympathetic outflow. The pressor responses to
noradrenaline and angiotensin were again left more or less unaffected.
These results suggested a biphasic action of 178-oestradiol on the
presynaptic site, at the neuroeffector junction of the vascular
smooth muscle. Although the mechanism of the menopausal hot flush
has not been completely elucidated, it appears to involve both a
humoral and a nervous component. Furthermore, the hot flush may be
related to the hormonal changes occurring at the menopause, since
178-oestradiol was found to affect the vascular smooth muscle.

Date of Award	1980
Original language	English
Awarding Institution	Aston University