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Endocrine tissues such as the pituitary, thyroid and adrenal
glands together with the ovaries or testes make a major contribution
to maintaining a state of equilibrium and health in many physiological
systems. This is particularly true of the cardiovascular system
as hormones regulate the function of both the heart and blood
vessels. Hormonal imbalances play an important part in a number
of cardiovascular diseases.
The adrenal gland plays a critical role in regulating vascular
wellbeing. The adrenal steroids it produces have a pivotal
place in regulating many aspects of health and disease. For
instance, excess production of aldosterone by the adrenal
gland can contribute to salt and water retention by the kidney.
This can lead to increased blood pressure, or in patients
with heart failure it can make the symptoms more severe. Adrenal
corticosteroids such as cortisol contribute to the regulation
of inflammatory processes through effects on circulating blood
cells and cells of the blood vessel wall. However, excess
cortisol can increase the risk of diabetes developing. Understanding
how adrenal hormones such as aldosterone and cortisol are
regulated has helped define new approaches to treatment of
a number of diseases. But there is still much to learn about
adrenal function. For example, DHEA (dehydroepiandrosterone)
is the most abundant steroid synthesized by the adrenal gland
yet we still do not know its full physiological role. Levels
of this hormone decline with age, but we do not understand
why or what the consequences are for long-term health.
A second area that needs urgent medical research is the
hormonal mechanisms that protect women from heart disease
until the menopause. Because of this protection many women
are complacent about the risks of developing heart disease
even though it is the most common cause of death over the
long-term. Oestrogen was thought to be the female defence
mechanism. But large-scale clinical trials with hormone replacement
therapy (HRT) showed this was not the explanation. Further
research on the protective mechanisms women benefit from early
in life may provide new insights into preventing heart disease
in women. This may also be translated into new treatments
for men.
The William Harvey Research Foundation needs funds
to undertake new research on (i) the regulation and functions
of adrenal hormones such as DHEA, and (ii) the hormonal mechanisms
that protect women from heart disease up to the menopause.
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