Effects Of Leptin On Follicle Growth And Ovulation
Funder
National Health and Medical Research Council
Funding Amount
$196,470.00
Summary
Leptin is a recently discovered hormone which is very important in controlling body weight. Extremely obese, or extremely underweight women, find it difficult to become pregnant, and leptin is probably the connection between weight and fertility. This may be a particularly important factor in polycystic ovary syndrome (PCOS), a distressing condition which affects 5% of women and causes both obesity and infertility. Exciting new research suggests that leptin also affects the immune system, and pr ....Leptin is a recently discovered hormone which is very important in controlling body weight. Extremely obese, or extremely underweight women, find it difficult to become pregnant, and leptin is probably the connection between weight and fertility. This may be a particularly important factor in polycystic ovary syndrome (PCOS), a distressing condition which affects 5% of women and causes both obesity and infertility. Exciting new research suggests that leptin also affects the immune system, and previous NH and MRC funding has enabled us to demonstrate that the immune system plays a crucial role in maintaining normal ovarian function. The nutritional status of the body, the immune system and the reproductive system all interact, and leptin appears to be the connecting link between these three major systems. We propose that leptin plays a major role in the ovary, and wish to determine how leptin mediates the effects of bodyweight and the immune system on ovarian function. Laboratory rats will be treated with leptin, their food intake and weight recorded, and a few weeks later the rats will have their ovaries removed. We will find out whether ovaries respond to leptin, or whether the ovarian response changes according to the menstrual cycle: perhaps leptin is very important just before ovulation, but it does not affect menstruation? Do any ovarian cells make leptin? Will leptin stimulate ovaries to produce more oestrogen or progesterone, or ovulate more eggs? We will also identify immune system cells in the ovary, and note whether leptin affects them. We will be able to relate all this data to weight and diet. Increased understanding of leptins' effect on the ovary has the potential to lead to new, improved treatments for PCOS or for unexplained cases of infertility. It is also possible that in the future a weight-loss regime might be developed which takes a womans monthly cycle into account, therefore making weight-loss more efficient and attainable.Read moreRead less
Progesterone Receptor-mediated Coordination Of Oocyte-oviduct Communication During Ovulation
Funder
National Health and Medical Research Council
Funding Amount
$86,128.00
Summary
Infertility affects 1 in 6 couples, often due to failed release of an egg from the ovary. The hormone progesterone is essential for this process. Our goal is to determine how progesterone signals the egg to ensure its correct release into the oviduct where fertilization may occur. To identify these signals, experiments will analyse ovary cells and eggs of mice, including mice that do not respond to progesterone. The results will provide much needed information about female reproductive health.
Polycystic ovary syndrome (PCOS) affects 5-10% of women worldwide, yet its origins remain unknown. Androgens are implicated in the development of PCOS, but the decisive, invasive studies needed to confirm and elucidate their roles are not feasible in women. Hence, using our innovative mouse models of androgen resistant female mice, this study will determine the role of androgens in PCOS aiming to better understand, and identify new treatments for this common female reproductive disorder.
Hormonal Control Of Serotli Cell Maturation And Function
Funder
National Health and Medical Research Council
Funding Amount
$512,898.00
Summary
This project will determine the key roles of androgen in the Sertoli cell, a unique highly specialised cell that provides essential nutritional and structural support for sperm production. Androgen acts via the androgen receptor (AR), which is vital for initiating and maintaining sperm development. In current NHMRC-funded research we successfully established new mouse models designed to study AR, in particular its regulation of gene expression, in the Sertoli cell. We revealed that genomic AR ac ....This project will determine the key roles of androgen in the Sertoli cell, a unique highly specialised cell that provides essential nutritional and structural support for sperm production. Androgen acts via the androgen receptor (AR), which is vital for initiating and maintaining sperm development. In current NHMRC-funded research we successfully established new mouse models designed to study AR, in particular its regulation of gene expression, in the Sertoli cell. We revealed that genomic AR activity within Sertoli cells is essential for 'induction' of complete sperm development. Ongoing work will develop unique 'inducible' transgenic models that will allow, for the first time, selective analysis of Sertoli AR in both 'developing' and 'adult' testes. Our innovative models will allow AR function to be switched on or off at any stage of development, providing unique opportunity to determine the key AR-regulated factors and pathways controlling induction, maintenance or restoration of sperm production. In past NHMRC research we created a novel transgenic model to study another major reproductive hormone, FSH. Using the hormone-deficient background of 'hpg' mice, we found that androgen and FSH act synergistically in the developing 'meiotic' germ cells that form sperm. Using the latest microarray gene technology we generated datasets of androgen-regulated genes with or without FSH activity, which combined with our unique transgenic AR and FSH models, will be used to identify key pathways, including those enhanced by androgen-FSH synergism, in the early testicular response. Our research will provide new knowledge of the precise roles and pathways of testicular AR actions, to ultimately identify key genetic and regulatory factors as targets for significantly improved therapy for male infertility, gonadal tumours, or contraception.Read moreRead less
This study is aiming to develop an unique mouse model in which to study the question whether testosterone plays an essential role in female reproductive and general health. It will develop a genetic mouse model for a biological state of complete resistance to the effects of androgens. Such mice and humans are well known among genetic males but this cannot occur naturally among genetic female mammals. By creating such a mouse line, this project will be able to test for the first time indetail whe ....This study is aiming to develop an unique mouse model in which to study the question whether testosterone plays an essential role in female reproductive and general health. It will develop a genetic mouse model for a biological state of complete resistance to the effects of androgens. Such mice and humans are well known among genetic males but this cannot occur naturally among genetic female mammals. By creating such a mouse line, this project will be able to test for the first time indetail whether testosterone has an impotant role in the development and function of the ovary and of other female tissues such as bone, muscle and the brain.Read moreRead less
Neuroendocrine Mechanisms By Which Leptin Regulates Reproduction
Funder
National Health and Medical Research Council
Funding Amount
$447,750.00
Summary
The reproductive system is sensitive to alterations in body weight. In particular, low body weight causes the reproductive system to cease functioning. This is because the brain 'senses' metabolic status and responds by ceasing to secrete the brain hormone that drives the reproductive process. This hormone is gonadotropin releasing hormone that acts on the pituitary gland to control the release of gonadotropins. These, in turn, act on the gonads. How the brain perceives metabolic status is not k ....The reproductive system is sensitive to alterations in body weight. In particular, low body weight causes the reproductive system to cease functioning. This is because the brain 'senses' metabolic status and responds by ceasing to secrete the brain hormone that drives the reproductive process. This hormone is gonadotropin releasing hormone that acts on the pituitary gland to control the release of gonadotropins. These, in turn, act on the gonads. How the brain perceives metabolic status is not known. Leptin is a hormone that is produced by fat and acts on the brain. This appears to be one of the means by which the reproductive system is regulated. Leptin also regulates food intake and other brain processes. Leptin acts on specific cell types in the brain. Some of these may have dual function to regulated appetite as well as reproduction. The present proposal is for work to determine mechanisms within the brain that are altered by leptin. We will also determine which specific mechanisms relate to the regulation of gonadotropin releasing hormone. The work will provide information on how putative appetite regulators might affect the reproductive axis. Such work will provide a platform for design of pharmaceutical means to manipulate the reproductive axis and will impact on the design of drugs that regulate obesity. It is possible that drugs that developed to control obesity may affect the reproductive axis and the project will identify these.Read moreRead less
Androgen Receptor Activity In Normal And Abnormal Human Ovarian Function
Funder
National Health and Medical Research Council
Funding Amount
$416,696.00
Summary
Androgens are hormones normally associated with men, but women also produce androgens and they are essential for normal female health and reproduction. Imbalances in female androgen activity could account for approximately 50% of female infertility, but exactly how androgens behave in women is not well understood. Making too much androgen is the most common hormonal problem experienced by women in their reproductive years, and it affects the ovary in a way that can cause infertility. Women with ....Androgens are hormones normally associated with men, but women also produce androgens and they are essential for normal female health and reproduction. Imbalances in female androgen activity could account for approximately 50% of female infertility, but exactly how androgens behave in women is not well understood. Making too much androgen is the most common hormonal problem experienced by women in their reproductive years, and it affects the ovary in a way that can cause infertility. Women with this problem have polycystic ovary syndrome (PCOS). Gaining weight increases the chance of having problems with fertility and increases the risk of diabetes and heart problems in women with PCOS. The cause of PCOS is unknown, but it can occur in families, which indicates that some genetic factor is involved. On the other hand, the concept that some women do not produce enough androgen is only beginning to emerge and remains a controversial topic among medical experts. Part of the problem with this notion is that normal female androgen levels are very difficult to measure accurately, so no one can say for certain how much is too little. A recent scientific study in female mice indicates that poor androgen action causes infertility early in life because the ovary is ageing too quickly. A similar thing could possibly occur in women, but this has never been scientifically explored. However, we have some early evidence that shows abnormally low androgen levels in infertile women with signs of early aging in the ovary. Our study aims to understand the role that androgens play in normal and abnormal ovarian function. A large part of this study involves investigation of the androgen receptor, a molecule that controls what androgens can do inside body organs. We think that abnormal activity of this receptor will be involved in ovarian diseases that cause infertility in women. This understanding may lead to new means of diagnosing and treating infertility in women.Read moreRead less