Pathways For Estrogen Feedback To Gonadotropin Releasing Hormone Neurons
Funder
National Health and Medical Research Council
Funding Amount
$466,980.00
Summary
Gonadotropin releasing hormone (GnRH) is the brain hormone that drives the reproductive process. In the female, a surge in the secretion of GnRH is the trigger for ovulation. An understanding of the mechanisms that regulate the secretion of GnRH is, therefore, extremely important if we are to decipher abnormalities that lead to infertility. Understanding of the ovulatory process is also important for the development of new (possibly simpler) means of contraception. Our research is intended to pr ....Gonadotropin releasing hormone (GnRH) is the brain hormone that drives the reproductive process. In the female, a surge in the secretion of GnRH is the trigger for ovulation. An understanding of the mechanisms that regulate the secretion of GnRH is, therefore, extremely important if we are to decipher abnormalities that lead to infertility. Understanding of the ovulatory process is also important for the development of new (possibly simpler) means of contraception. Our research is intended to provide a full understanding of the brain circuits that provide input to the GnRH neurons. In particular, we will focus on the microcircuitry in the preoptic area, where GnRH cells are found. In addition to providing a full understanding of the circuits that are primarily involved in regulating GnRH secretion, this work will provide a substrate upon which we can expand knowledge of how factors such as emotion and stress can impact on the reproductive process.Read moreRead less
Functional Modulation Of Ovine And Human Somatotropes By In Vitro Application Of Leptin
Funder
National Health and Medical Research Council
Funding Amount
$227,036.00
Summary
Obesity is a common disorder in developed countries and a prevalent condition which is often stigmatized. Actuarial data indicate that life expectancy is reduced when body-mass index (body mass in kg-square of the height in metres) is 20% or more above the ideal (obesity is >28% above ideal). Growth hormone (GH) from pituitary gland is the major anabolic hormone to increase muscle and reduce fat. A significant reduction in GH is found in obesity. Indeed, visceral fat mass is primary negative ....Obesity is a common disorder in developed countries and a prevalent condition which is often stigmatized. Actuarial data indicate that life expectancy is reduced when body-mass index (body mass in kg-square of the height in metres) is 20% or more above the ideal (obesity is >28% above ideal). Growth hormone (GH) from pituitary gland is the major anabolic hormone to increase muscle and reduce fat. A significant reduction in GH is found in obesity. Indeed, visceral fat mass is primary negative statistical determinant of GH secretion in middle age men and women. It is clear that the reduction in GH is due to a low sensitivity of GH cells to GH-releasing hormone (GHRH) from brain. It is therefore necessary to understand the change of pituitary GH cells in obesity. A recently identified, fat cell secreted, polypeptide (leptin) is demonstrated to reduce food intake and increase energy expenditure. Receptors for leptin have been found in pituitary gland, mainly in GH secreting cells. In our preliminary experiments, leptin reduces GH secretion by decreasing GHRH receptor synthesis. Meanwhile, this leptin treatment increased the receptors for GH-releasing peptide (GHRP), a synthetic peptide stimulating GH secretion. We aim to investigate the effect of leptin on cultured ovine and human GH cells by studying important cell functions including hormone and receptors synthesis, intracellular signaling molecules, membrane ion channels and cellular secreting machinery. The results will clarify the mechanism underlying GH deficiency in obese patients. We will also test the effect of synthetic GHRP in combination with leptin in vitro. The relationship between GHRP and leptin on the functional modification of GH cells will also be studied. It is likely to see that GHRP reduces the inhibitory effect of leptin on GH cells. This may end up an effective therapeutical use of GHRP (oral available) in the treatment of obesity.Read moreRead less