Vasomotor Ganglionic Transmission: The Preganglionic Peptide And The Second Gear
Funder
National Health and Medical Research Council
Funding Amount
$451,896.00
Summary
Blood pressure depends on nerve signals that travel from the central nervous system to blood vessels. In the middle of this pathway is a relay station - the sympathetic ganglion cell. Transmission through this relay station has recently been shown to have not only a fixed but also a variable component - the 'second gear'. The project tests if and how three likely candidate peptide molecules, one in the nerves, two in the bloodstream, control this 'second gear' and hence regulate blood pressure.
Role Of The Hypothalamus, Oxidative Stress And Angiotensin In Chronic Stress
Funder
National Health and Medical Research Council
Funding Amount
$535,333.00
Summary
Stress can trigger life threatening cardiovascular events and its impact is much greater when blood pressure is raised. We seek to determine which chemical type of brain neuron and which region is responsible for amplifying the responses to repeated stress in an animal model that closely resembles the human form of the disease. We will focus specifically on the hypothalamus which controls the sympathetic nervous system.
Roles Of The Peptide Hormone, Ghrelin, In The Spinal Cord
Funder
National Health and Medical Research Council
Funding Amount
$414,326.00
Summary
This study investigates the control of internal organs of the body, the heart, blood vessels, intestine and bladder. We have made the new and surprising discovery that ghrelin, previously known to be a hormone, is probably also a neurotransmitter in the spinal cord. This raises the possibility that drugs that act on ghrelin receptors in the spinal cord could be used to treat high blood pressure or other problems of internal organs.
What Triggers Complex Regional Pain Syndrome After Minor Injury?
Funder
National Health and Medical Research Council
Funding Amount
$958,898.00
Summary
Most people recover from minor trauma but some develop very disabling, difficult to treat, costly pain syndromes. We can identify those at high risk of developing such a syndrome after wrist fracture. By comparing inflammation, immune system function, stress, brain function and behaviour between high and low risk patients, we will take a major step towards understanding, preventing and treating these syndromes.
PREMOTOR SYMPATHETIC CONTROL OF BLOOD PRESSURE DURING PSYCHOLOGICAL STRESS: HYPOTHALAMUS VERSUS MEDULLA.
Funder
National Health and Medical Research Council
Funding Amount
$153,616.00
Summary
Health and well being depend in large part on a strong and efficient autonomic nervous system. The autonomic nervous system controls blood pressure, heart rate, gastrointestinal function, immune responses and certain forms of pain. Negative emotions can have a strong impact on autonomic function. We have all experienced the sweaty hands, pounding heart and intestinal discomfort when the mail arrives and bad news is expected or when we face a deadline for which we are not prepared. This is known ....Health and well being depend in large part on a strong and efficient autonomic nervous system. The autonomic nervous system controls blood pressure, heart rate, gastrointestinal function, immune responses and certain forms of pain. Negative emotions can have a strong impact on autonomic function. We have all experienced the sweaty hands, pounding heart and intestinal discomfort when the mail arrives and bad news is expected or when we face a deadline for which we are not prepared. This is known as psychological stress and it is usually associated with anxiety. Unfortunately, it is also the most common form of stress in modern urban life. There are clear indications that when these autonomic changes become chronic they can lead to hypertension, weak immune responses and gastric ulcers. In people already suffering from cardiovascular diseases they can also precipitate cardiac and cerebrovascular accidents. Clearly, the link between psychological stress and the autonomic nervous system needs to be explored in more detail. This project looks at the organization of the neural network in the brain and spinal cord that controls these responses. It uses a simple model of psychological stress in the conscious rat and recent non invasive techniques to record blood pressure and look at neuronal activity. We think that we have identified a group of neurons that may be controlling very specifically this response. It is located in the hypothalamus. The aim of this project is to further test the role of these neurons and find out what is controlling them. They will also be compared to another group of neurons that also controls blood pressure but apparently not in relation to psychological stress. The possibility that the cardiovascular response to psychological stress might be mediated by a specific group of neurons in the brain is a very exciting finding. It could lead to new therapeutic applications for acting against the short and long term effects of stress.Read moreRead less
Inhibition Of Fear Memories By Extinction: Neural Substrates.
Funder
National Health and Medical Research Council
Funding Amount
$234,250.00
Summary
Anxiety disorders [e.g., Post Traumatic Stress Disorder (PTSD)] are the most prevalent type of psychopathology in the industrialised world. They are associated with characteristic behavioural (e.g., heightened startle) and autonomic (e.g., cardiovascular) reactions. These disorders are often characterised as an inability to regulate the emotion of fear. Significant progress has been made in understanding the neural and cellular processes involved in the establishment of fear memories, but relati ....Anxiety disorders [e.g., Post Traumatic Stress Disorder (PTSD)] are the most prevalent type of psychopathology in the industrialised world. They are associated with characteristic behavioural (e.g., heightened startle) and autonomic (e.g., cardiovascular) reactions. These disorders are often characterised as an inability to regulate the emotion of fear. Significant progress has been made in understanding the neural and cellular processes involved in the establishment of fear memories, but relatively little is known about the mechanisms by which fear memories can be inhibited or suppressed. Understanding this latter process is a key to the development of effective treatments for anxiety disorders such as PTSD where the patient suffers from persistent, intrusive, unwanted trauma memories. A common experimental procedure for reducing learned fear is to repeatedly expose the subject to a fear-eliciting stimulus but without any aversive outcome. This procedure leads to a progressive loss, or extinction, of the fear reactions elicited by the stimulus. Historically, the extinction of fear was thought to be due to an erasure of the fear memory. However, recent evidence shows that extinction inhibits, rather than erases, the fear memory. Because the fear memories remain intact, some structure(s) in the brain must inhibit activity in the fear pathway. This project uses extinction of conditioned fear reactions in rat subjects to determine the structure(s) in the brain that inhibit fear memories and their behavioural and cardiovascular expression. It brings together the expertise of four well-established researchers and uses a combination of behavioural, physiological, immunohistochemical, tract tracing, and lesion approaches to achieve this aim. The proposed experiments will reveal the structure(s) in the brain that control the inhibition of fear, as well as the site(s) of this inhibition in the fear pathwayRead moreRead less
DEVELOPMENT OF CARDIOVASCULAR CONTROL DURING SLEEP IN HUMAN INFANTS AFTER PRETERM BIRTH
Funder
National Health and Medical Research Council
Funding Amount
$358,537.00
Summary
Infants spend the major part of their life in sleep, and the period between birth and 6 months of age sees dramatic changes in their sleep organisation. Coincidently, there are dramatic developmental changes in the infant's heart and blood pressure control systems, and the ability to compensate for stress such as falls of blood pressure (hypotension) or in the level of oxygen in the blood (hypoxaemia). In infants born preterm, the risks of hypoxaemia, and even death are significantly greater dur ....Infants spend the major part of their life in sleep, and the period between birth and 6 months of age sees dramatic changes in their sleep organisation. Coincidently, there are dramatic developmental changes in the infant's heart and blood pressure control systems, and the ability to compensate for stress such as falls of blood pressure (hypotension) or in the level of oxygen in the blood (hypoxaemia). In infants born preterm, the risks of hypoxaemia, and even death are significantly greater during sleep than during wakefulness, but why this is so is uncertain. This study will examine the ability of infants to respond to stress during sleep. Four groups of infants will be examined: healthy infants born at normal gestation; healthy infants born prematurely (preterm); preterm infants who have experienced mild hypoxaemia soon after birth; and preterm infants who have suffered more severe hypoxaemia because of lung disease. Infants will be studied in a sleep laboratory during day-time sleep, and their ability to control blood pressure will be determined. By contrasting the effectiveness of blood pressure control between the infant groups we aim to determine whether preterm infants have lasting problems as a result of their premature birth, or their exposure to hypoxaemia. By contrasting infants in sleep and wakefulness, we aim to assess whether the risks of poorer blood pressure control are greater in sleep.Read moreRead less
Effects Of Ghrelin Receptor Ligands On Cardiovascular Function
Funder
National Health and Medical Research Council
Funding Amount
$516,207.00
Summary
Ghrelin is a hormone that is known to control food intake and growth hormone release. Our recent work shows that compounds that mimic ghrelin�s actions influence blood pressure by their effects in the brain, the spinal cord and on arteries. We will investigate the potential of such compounds to treat blood pressure disorders
Changes In Pelvic Autonomic Neurons After Spinal Nerve Injury
Funder
National Health and Medical Research Council
Funding Amount
$176,734.00
Summary
This project is about the effects of spinal injury on autonomic neurons that control the bladder, lower bowel and reproductive organs. One of the consequences of some types of spinal injury is that there are no signals being sent from the spinal cord to the nerve cells outside the cord, and this leads to poor bladder control, impotence, etc. We are mimicking this problem experimentally by damaging the spinal nerves that carry these signals. We have found that after this type of damage the pelvic ....This project is about the effects of spinal injury on autonomic neurons that control the bladder, lower bowel and reproductive organs. One of the consequences of some types of spinal injury is that there are no signals being sent from the spinal cord to the nerve cells outside the cord, and this leads to poor bladder control, impotence, etc. We are mimicking this problem experimentally by damaging the spinal nerves that carry these signals. We have found that after this type of damage the pelvic autonomic neurons make many new connections between each other, and the types of new connections depend on which spinal nerves have been injured. This leads to the question: are these new connections good or bad? ie are they helpful in trying to get organ control back to normal or will they stop the correct connections from the spinal cord from being made in the future? This project addresses these questions by using sophisticated techniques for staining and visualising individual nerve fibres growing out from the spinal cord. We will track how well these fibres grow back and connect with the pelvic autonomic neurons. In particular, we will see whether they make correct connections, and if these connections are influenced by the new fibres that have grown between the autonomic neurons in the interim period. We will also do physiological tests to see if the new connections have the correct function. The ultimate aim of these studies is not only to understand more about regeneration, but to see what determines whether the correct connections have been made - and ideally, to give us insight into how we can make regeneration work more quickly and accurately. We believe that this work is an important adjunct to other studies on spinal injury, which mostly focuses on regaining voluntary motor control (e.g. walking); however loss of bladder, bowel and reproductive function is another important quality of life issue for spinal injury patients.Read moreRead less