Regulation Of Growth Hormone Action By Oestrogen And Selective Oestrogen Receptor Modulators
Funder
National Health and Medical Research Council
Funding Amount
$474,750.00
Summary
Growth hormone (GH) is essential for body growth and development. In adult life, it plays a key role in regulating the ratio of body fat to muscle, thus influencing health. Disruption of GH action decreases muscle mass and increases body fat. These changes lead to reduced muscle strength and fitness, and increase the risk of diabetes, hypertension and cardiovascular mortality. Our laboratory has reported that oestrogens taken orally blunt GH action and cause unfavourable changes in body fat and ....Growth hormone (GH) is essential for body growth and development. In adult life, it plays a key role in regulating the ratio of body fat to muscle, thus influencing health. Disruption of GH action decreases muscle mass and increases body fat. These changes lead to reduced muscle strength and fitness, and increase the risk of diabetes, hypertension and cardiovascular mortality. Our laboratory has reported that oestrogens taken orally blunt GH action and cause unfavourable changes in body fat and muscle. How this happens is not known. As oral oestrogens are widely used in our society, it is important to understand the basis of their impact on GH action. SERMs, or selective oestrogen receptor modulators, are a group of drugs used in the treatment of breast cancer and osteoporosis. These substances mimic oestrogen action in some tissues, and block oestrogen action in others. Whether SERMs interfere with GH action as oestrogens do have not been studied, but such knowledge would have therapeutic significance because of their widespread and long-term use. GH action is mediated by a protein, called the GH receptor, located on the surface of target tissues. We propose that oestrogens and SERMs alter the production and function of this protein to control GH action. Thereby, this project is designed to test, in cultured cells of human origin, how oestrogens and SERMs modulate abundance of the GH receptor and its ability to mediate GH action. This work is anticipated to gain novel insights into the interaction of GH with oestrogens and SERMs. This information may also be useful for the design of new drugs devoid of adverse effects on GH action, and hence would have potentially significant implications in women s health and disease.Read moreRead less
Regulation Of Growth Hormone Action By Sex Steroids: Metabolic Implications For Health And Disease
Funder
National Health and Medical Research Council
Funding Amount
$353,250.00
Summary
Fitness and health is determined by body composition, the amount of fat and lean tissue in the body. Obesity increases the risk of diabetes, blood pressure and heart attacks, while muscle wasting reduces strength and fitness. Body composition is controlled by hormones such as growth hormone (GH) which reduces body fat by stimulating its metabolism (burning) and increases lean tissue by stimulating protein synthesis. These metabolic actions of GH are exerted through the liver. This proposal seeks ....Fitness and health is determined by body composition, the amount of fat and lean tissue in the body. Obesity increases the risk of diabetes, blood pressure and heart attacks, while muscle wasting reduces strength and fitness. Body composition is controlled by hormones such as growth hormone (GH) which reduces body fat by stimulating its metabolism (burning) and increases lean tissue by stimulating protein synthesis. These metabolic actions of GH are exerted through the liver. This proposal seeks to understand how sex hormones control the amount of body fat and muscle in women and men. Based on previous research in our laboratory, we propose that sex hormones control the action of growth hormone on the liver. We will test the hypothesis that oestrogens impair the ability of the liver to burn fat and build protein in response to GH while male hormones have the opposite effect. The effect of oestrogen occurs only when oestrogen is taken as a tablet because the liver is exposed to high concentrations of this hormone after gut absorption. It causes postmenopausal women to gain fat and lose muscle. Apart from oestrogens, there are many other compounds with oestrogen-like activities such as phytooestrogens (oestrogens found in plants) and SERMs (used for treating osteoporosis). Their effect on the liver and body composition are unknown but important because of their widespread use in the community. The significance of these studies relate to optimising the benefits of oestrogen compounds by defining their metabolic effects on the liver. In men, understanding how male hormones work as anabolic agents may lead to ways of treating protein muscle wasting.Read moreRead less
The Effects Of Zoledronic Acid On Bone Architecture In Premenopausal Women With Breast Cancer Receiving Adjuvant Combined Ovarian Suppression And Aromatase Inhibitor Therapy: A Randomised Controlled Trial.
Funder
National Health and Medical Research Council
Funding Amount
$122,714.00
Summary
In premenopausal women, a new treatment method that reduces oestrogen levels to almost zero significantly reduces the risk of breast cancer recurrence. However, this is likely to cause substantial bone loss leading to fractures. Using a new imaging technique (HR-pQCT), the effects of profound oestrogen deprivation on bone structure in premenopausal women will be studied. The ability of zoledronic acid, a drug that reduces bone loss, to prevent these adverse bone effects will also be examined.
Oestrogens And The Metabolic Process: Regulatory Interaction With The GH-IGF-system In Health And Disease
Funder
National Health and Medical Research Council
Funding Amount
$547,970.00
Summary
Growth hormone (GH) plays a key role in controlling body metabolism, fat and muscle in adult life. The female hormone oestrogen controls how much GH is secreted and how well it acts. Drugs that act like or interfere with the action of oestrogen are used increasing for the treatment of many conditions e.g. growth, cancer and osteoporosis. This proposal examines their impact on cardiovascular and physical health.
The Metabolic Effects Of Oestrogens And SERMs: Regulatory Interactions With The GH-IGF-system In Health And Disease
Funder
National Health and Medical Research Council
Funding Amount
$379,142.00
Summary
This project extends work aimed at understanding how GH and sex hormones work together to optimise physical health in women and men. It addresses the benefits and safety of oestrogen compounds in relation to their effects on body fat and muscle (body composition). Oestrogen compounds are among the most widely used medicines and include tradition oestrogens (female hormone) and synthetic oestrogens called SERMs. Oestrogens are used in young women as oral contraception and in the postmenopause for ....This project extends work aimed at understanding how GH and sex hormones work together to optimise physical health in women and men. It addresses the benefits and safety of oestrogen compounds in relation to their effects on body fat and muscle (body composition). Oestrogen compounds are among the most widely used medicines and include tradition oestrogens (female hormone) and synthetic oestrogens called SERMs. Oestrogens are used in young women as oral contraception and in the postmenopause for replacement therapy. Body composition is an important determinant of fitness and health. Obesity reduces fitness and increases the risk of diabetes and heart attacks while muscle loss causes weakness and frailty. GH is a major regulator of body composition; it acts by breaking down fat and building muscle mass. We discovered that oestrogens, when taken as a tablet interferes with the action of GH and causes detrimental changes in body composition. On the positive side, we have exploited the GH blocking action to treat acromegaly. This is a debilitating disease of excessive GH production from a pituitary tumour and for which available drug treatments are very expensive and require injection. The effects of SERMs on body composition are unknown. SERMs are interesting compounds because they act like oestrogens in some but as oestrogen blockers in other tissues. These are widely used in the treatment of breast cancer and osteoporosis. The extent to which they interfere with the action of GH has not been studied. They may exert additional effects because they act on the pituitary gland to reduce the secretion of GH. They may also prove to be effective in acromegaly which could extend their usefulness to men. In summary, the work will provide important information on the long-term benefits of SERMs in patient groups that tend to be frail. It may also prove to be a simple and inexpensive treatment for acromegaly.Read moreRead less
Anti-Estrogens - A Potential Treatment For Bipolar Affective Disorder In Women?
Funder
National Health and Medical Research Council
Funding Amount
$239,250.00
Summary
Bipolar Affective Disorder (BPAD) or Manic-Depressive Illness is a serious mental illness with high morbidity and mortality. The cause of the illness is still unclear and the underlying neurochemical changes are different for the manic phase compared with the depressive phase. The current treatments for BPAD are limited in scope and not biochemically well understood. There are gender differences in the presentation and outcomes for BPAD which adds to the complexity of the illness. We are proposi ....Bipolar Affective Disorder (BPAD) or Manic-Depressive Illness is a serious mental illness with high morbidity and mortality. The cause of the illness is still unclear and the underlying neurochemical changes are different for the manic phase compared with the depressive phase. The current treatments for BPAD are limited in scope and not biochemically well understood. There are gender differences in the presentation and outcomes for BPAD which adds to the complexity of the illness. We are proposing a study to develop a new type of treatment for the manic phase of BPAD and are exploring the use of anti-estrogens in women with mania. The background to our proposed study comes from a few case reports suggesting that anti-estrogen agents such as progesterone and tamoxifen may be useful adjuncts to treatment. We conducted a small pilot study comparing the addition of oral tamoxifen with oral progesterone and placebo in 10 women with mania and found that the women who received tamoxifen made significantly better improvements in their manic symptoms over a 28-day trial. The research study we are now proposing is a larger, three-arm, double blind, placebo controlled, 28-day adjunctive study in women with mania to expand and clarify our pilot study findings. Patients in our proposed study would receive either 40mg per day tamoxifen or 20mg per day progesterone or placebo in addition to standardised lithium medication. We will measure enzyme activity (protein kinase C) and estrogen-progesterone levels to understand more about the mechanisms of action by these new hormone treatments. BPAD is a crippling disorder and if we are successful, then tamoxifen treatment may be an important new treatment. This proposed study will also shed new light on some of the neurochemical mechanisms underlying BPAD as well as opening up the new area of hormone treatments for serious mental illness.Read moreRead less
SOFT And TEXT Premenopausal Randomised Adjuvant Endocrine Breast Cancer Trials.
Funder
National Health and Medical Research Council
Funding Amount
$722,380.00
Summary
SOFT and TEXT trials enrolled premenopausal women with hormone-sensitive early breast cancer to assess if post-operative hormone treatment that included ovarian function suppression plus tamoxifen, or an aromatase inhibitor exemestane, could improve outcomes. Initial results indicate fewer breast cancer recurrences with the treatment combination of ovarian suppression plus exemestane as compared with tamoxifen, and follow-up of women in these trials can show if overall survival can be improved.
The Mechanism Of Growth Hormone Receptor Activation
Funder
National Health and Medical Research Council
Funding Amount
$679,500.00
Summary
Growth hormone GH excess or deficit results in considerably shortened lifespan. While cardiovascular disease is a major element in this mortality, GH status has also been linked to kidney disease and diabetic retinopathy. Importantly, GH produced locally in breast cells and prostate cells transform s these cells, creating cancers. We aim to define how GH activates its receptor, to facilitate a GH antagonist which results from understanding how GH activates its cell surface receptor.
Validating A New Model For Growth Hormone Receptor Activation
Funder
National Health and Medical Research Council
Funding Amount
$472,500.00
Summary
Growth hormone is an important hormone therapeutic for treating dwarfism. Recently, many new therapeutic applications for growth hormone have been discovered, particularly in relation to its anabolic actions. These include post surgery recovery, enhanced bone fracture healing, Crohns disease, dilated cardiomyopathy, infertility and ageing. The hormone exerts these actions through its receptor, which is a class1 cytokine receptor, similar to many receptors important in regulating immunity, inflam ....Growth hormone is an important hormone therapeutic for treating dwarfism. Recently, many new therapeutic applications for growth hormone have been discovered, particularly in relation to its anabolic actions. These include post surgery recovery, enhanced bone fracture healing, Crohns disease, dilated cardiomyopathy, infertility and ageing. The hormone exerts these actions through its receptor, which is a class1 cytokine receptor, similar to many receptors important in regulating immunity, inflammation, metabolism and cancers. In principle, if we can find out how the GH receptor works, this information would help in designing drugs to treat many immune and inflammatory disorders. With current NHMRC support we have developed a model which describes how GH activates the receptor at a molecular level. The model involves two pre-associated receptors at the cell surface binding to the hormone, with the result that the receptors are rotated relative to each other, and this brings the two JAK2 signalling units attached tothe receptor inside the cell into alignment, so they can activate each other. We can activate the receptor without hormone by artificially rotating it. This model is a prediction based on several techniques, but lacks proof of rotation. There are also a number of issues relating to the need for rigidity in the receptors, so the torque can be transmitted into the cell, since many believe there is no rigidity just above the membrane. We predict there is , but need to prove this. This information is vital for designing small orally active mimics of growth hormone, and for developing GH antagonists, likely to be useful for breast and colon cancer. Finally, we have evidence that the specificity of receptor signalling can be changed by mutating the outer part of the receptor (novel). We believe this can be used to change the activity spectrum of GH, hence decrease side effects, by developing analogs which activate one pathway or the other.Read moreRead less