Sympathetic Control Of Cutaneous Blood Flow And Blood Pressure In Human Spinal Cord Injury
Funder
National Health and Medical Research Council
Funding Amount
$242,002.00
Summary
While spinal cord injury can cause devastating changes in the nervous system paralysis and loss of sensation relatively little is known about changes to the sympathetic nervous system. The sympathetic nervous system is intimately involved in the ongoing control of blood pressure, blood flow and temperature control. Loss of sympathetic control can occur following spinal cord injury. Interruption of descending pathways can result in partial or complete loss of sympathetic outflow from the thoracol ....While spinal cord injury can cause devastating changes in the nervous system paralysis and loss of sensation relatively little is known about changes to the sympathetic nervous system. The sympathetic nervous system is intimately involved in the ongoing control of blood pressure, blood flow and temperature control. Loss of sympathetic control can occur following spinal cord injury. Interruption of descending pathways can result in partial or complete loss of sympathetic outflow from the thoracolumbar segments. Complete decentralization can result in autonomic dysreflexia (autonomic hyperreflexia), in which sensory stimuli originating below the lesion evoke a reflex increase in sympathetic drive to the blood vessels, causing them to constrict. Because of this, blood pressure may rise suddenly and remain at such high levels that stroke and (occassionally) cardiac arrest may occur. This phenomenon, autonomic dysreflexia, is considered a medical emergency. The typical subjective signs of autonomic dysreflexia include a throbbing headache, tingling in the head or nasal congestion; sweating and flushing above the lesion are clinical signs that prompt medical staff to measure blood pressure and to locate the source of sensory irritation (usually a distended bladder or impacted colon, sometimes a pressure sore or ingrown toenail). Commonly, however, subclinical episodes go undetected, and this phenomenon of silent dysreflexia is of increasing concern. This project will develop means of assessing the integrity and state of the sympathetic nervous system below a lesion in patients with spinal cord injury and characterize the firing properties of reflexly activated sympathetic neurones.Read moreRead less
Network Interactions Between Cardiovascular Control Neurons In The Brainstem Underlie Sympathetic Tone
Funder
National Health and Medical Research Council
Funding Amount
$268,328.00
Summary
High blood pressure is a very significant risk factor for many common cardiovascular diseases. Blood pressure is normally tightly regulated by groups of neurons in the brainstem; although we know that this part of the brain becomes dysfunctional in patients with high blood pressure, we do not understand why. We have recently discovered that cardiovascular control neurons can influence each other. The project will determine the effect of such communication in the control of blood pressure.
A novel sensory neural circuit has been identified innervating the airways and lungs. The anatomical organisation of this circuit has been described to some extent in previous studies, however there is a significant gap in knowledge with respect to its functional importance. This project will develop methods to address this knowledge gap and in doing so the project will firstly describe how this circuit controls breathing under normal conditions and secondly how this becomes dysregulated during
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.
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