Neuroendocrine Responses To Psychological Stress: Unmasking The Protective Role Of The Prefrontal Cortex.
Funder
National Health and Medical Research Council
Funding Amount
$346,153.00
Summary
This project seeks to build up a picture of one of the mechanisms that the brain uses to protect our bodies from the potentially harmful effects of psychological stress. When we are subjected to psychological stress one of the consequences is the release of a hormone, corticosterone, into the blood-stream. This can be beneficial in the short-term as it helps our body redistribute its pattern of energy utilization in a way that helps in coping with an unexpected challenge. However, excessive secr ....This project seeks to build up a picture of one of the mechanisms that the brain uses to protect our bodies from the potentially harmful effects of psychological stress. When we are subjected to psychological stress one of the consequences is the release of a hormone, corticosterone, into the blood-stream. This can be beneficial in the short-term as it helps our body redistribute its pattern of energy utilization in a way that helps in coping with an unexpected challenge. However, excessive secretion of corticosterone due to excessive exposure to psychological stress can damage your health. For example, it can make you more susceptible to infection and also accelerate the rate at which your brain ages. The brain possesses certain mechanisms which try to limit the release of corticosterone when you are subjected to psychological stress. Unfortunately these mechanisms are not quite up to doing the necessary job under the conditions in which we live today, i.e. a very high level of psychological stress is a common feature of modern life. Nevertheless we believe that if we can properly understand these protective mechanisms in the brain, it may be possible to develop drugs which can boost their efficiency. In the long term this could greatly reduce ill-health in our society.Read moreRead less
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
One of the main trends in the evolution of the primate brain was the huge expansion of the cortical areas devoted to visual processing. However, the exact role of individual areas remains highly controversial, making detailed physiological and anatomical studies in suitable primate models a key step to elucidating their function in the human brain. In this project, we will address the organization of a poorly known group of visual areas, which is located deep in a part of the brain called the in ....One of the main trends in the evolution of the primate brain was the huge expansion of the cortical areas devoted to visual processing. However, the exact role of individual areas remains highly controversial, making detailed physiological and anatomical studies in suitable primate models a key step to elucidating their function in the human brain. In this project, we will address the organization of a poorly known group of visual areas, which is located deep in a part of the brain called the interhemispheric fissure (the medial complex of visual areas). Preliminary evidence suggests that these areas may provide anatomical shortcuts linking vision, behavioural reactions, and emotion. Suppose, for example, that you are sitting outside reading. Although deep in concentration, you are still able to detect the sudden movement of an approaching object in your peripheral field of vision. In many cases you can react (e.g., by ducking , or raising your arms to protect the face) long before you register what the object actually is. An adrenaline rush often accompanies these quick motor reactions, implying a parallel activation of the autonomic nervous system. While the mechanism by which the brain promotes these quick reactions remains poorly understood, we believe that the medial complex of visual areas holds the key. The aim of this study is to map the anatomical framework underlying our ability to react to sudden stimuli in our peripheral visual field. Such work is fundamental for understanding the functional organization of the brain. It also has the potential to lay the groundwork for developments in areas of applied research, including medicine (e.g. the design of better rehabilitation strategies for people with brain damage) and the cognitive sciences (e.g. a better understanding of the factors that limit human responses to visual stimuli).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
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.
Investigations Of Neural Pathways For Heat Loss And Heat Gain In Thermoregulation And Fever
Funder
National Health and Medical Research Council
Funding Amount
$349,486.00
Summary
This project aims to map the nerve pathways in the brain that participate in the regulation of body temperature in the laboratory rat. The area of the brain that will be studied is the hypothalamic region. We will determine how this region influences the constriction of blood vessels in the skin to reduce heat loss when an animal is exposed to a cool environment, or when it exhibits a fever in response to a bacterial infection. As well, we will compare the nervous pathway that controls the gener ....This project aims to map the nerve pathways in the brain that participate in the regulation of body temperature in the laboratory rat. The area of the brain that will be studied is the hypothalamic region. We will determine how this region influences the constriction of blood vessels in the skin to reduce heat loss when an animal is exposed to a cool environment, or when it exhibits a fever in response to a bacterial infection. As well, we will compare the nervous pathway that controls the generation of heat from fat tissue in response to cold or fever with those controlling blood flow to the skin. These nervous pathways may be critical for maintaining correct body temperature during general anaesthesia, infections or in the aged subjected to temperature extremes. Thus, they are of importance in the health and well-being of much of the population.Read moreRead less
Forebrain Neuroadaptations To Chronic Morphine Treatment
Funder
National Health and Medical Research Council
Funding Amount
$435,956.00
Summary
Drug addiction is caused by long term changes in brain areas that normally produce the drives that sustain normal behaviours such as eating, drinking and sex. Addictive drugs effectively hijack these brain areas so that behaviours relating to drug taking become associated with feeling good. In some individuals, over time the pattern of drug taking becomes compulsive and no longer can be controlled. This transition is now known to be due to drugs causing physical changes to certain groups of nerv ....Drug addiction is caused by long term changes in brain areas that normally produce the drives that sustain normal behaviours such as eating, drinking and sex. Addictive drugs effectively hijack these brain areas so that behaviours relating to drug taking become associated with feeling good. In some individuals, over time the pattern of drug taking becomes compulsive and no longer can be controlled. This transition is now known to be due to drugs causing physical changes to certain groups of nerve cells in the brain. The affected nerve cells are responsible for causing new behaviours that appear once addiction is established. Addiction is not exclusive to humans. Animals will self-inject the same addictive drugs that humans use, and show many other kinds of addictive behaviours that parallel aspects of human addiction. Studying the effects of addictive drugs on rats and other animals has been very important in working out where and how drugs work. We now have a very good idea of which parts of the brain are affected by drugs, and it turns out that most addictive drugs act in the same places. We also now know for all of the major drugs, exactly which parts of nerve cells they affect. However, this turns out to be only the first step as the nerve cells that directly respond to drugs can affect other whole networks of nerve cells. This study is going to look at how morphine, a drug that is related to heroin, affects nerve cells in a part of the brain that helps cause addiction. It is going to work out which of the many pathways in this brain region are affected by morphine treatments that cause addiction in rats. It will then see what is happening to single nerve cells in the affected pathways. If we can understand more about these processes it may become possible to come up with new ways to treat addiction. We will also understand much more about the production of powerful emotional and behavioural drives so many of us find hard to control.Read moreRead less
Role Of SOCS 3 In Regulating Oligodendroglial Phenotype In Health And Disease
Funder
National Health and Medical Research Council
Funding Amount
$419,187.00
Summary
The response of nerve cells, known as oligodendrocytes, to an inflammatory insult dictates the severity of demyelinating diseases such as multiple sclerosis (MS). We have previously discovered that a key protein in this response is the cytokine leukaemia inhibitory factor (LIF) which, by activating the LIF receptor expressed on these cells, limits their death and reduces the clinical impact on animal models of MS. However, the therapeutic benefit of LIF is incomplete and we do not completely und ....The response of nerve cells, known as oligodendrocytes, to an inflammatory insult dictates the severity of demyelinating diseases such as multiple sclerosis (MS). We have previously discovered that a key protein in this response is the cytokine leukaemia inhibitory factor (LIF) which, by activating the LIF receptor expressed on these cells, limits their death and reduces the clinical impact on animal models of MS. However, the therapeutic benefit of LIF is incomplete and we do not completely understand the mechanisms by which LIF exerts these effects. To maximise the treatment potential of LIF we need to understand how LIF receptor signaling is modulated in the nervous system. An important protein known to regulate the activity of LIF and of other cytokines in other organs of the body is the suppressor of cytokine signaling 3 (SOCS 3) molecule. We have recently shown that the expression of SOCS 3 is increased in an animal model of MS, indicating that it is likely to modulate the activity of LIF in this context. We plan to investigate the nature of this regulation. SOCS 3 might limit the efficacy of LIF but it could also limit the deleterious effect of unbridled LIF receptor signaling. To distinguish between these possibilities, we plan to study the impact of demyelinating disease in animals in which SOCS 3 is either deleted or overexpressed in oligodendrocytes. In this way, we should be able to learn how to optimise the therapeutic potential of LIF in MS and related nervous system diseases.Read moreRead less
Brain Pathways For Neurally-mediated Fever: From Vagal Afferent To Sympathetic Output To Brown Adipose Tissue Via Brain
Funder
National Health and Medical Research Council
Funding Amount
$405,223.00
Summary
Fever is one of the immune defence reactions to the invasion of microorganisms such as bacteria and viruses. Fever reflects increased heat production and decreased heat loss. Systems regulating heat production and heat loss are under brain control. To trigger fever, the immune system must alert the brain to the presence of infection. The general view of how the alerting system triggers fever is that it develops in sequential steps. Macrophages ingest microorganisms, and then regulatory proteins ....Fever is one of the immune defence reactions to the invasion of microorganisms such as bacteria and viruses. Fever reflects increased heat production and decreased heat loss. Systems regulating heat production and heat loss are under brain control. To trigger fever, the immune system must alert the brain to the presence of infection. The general view of how the alerting system triggers fever is that it develops in sequential steps. Macrophages ingest microorganisms, and then regulatory proteins (cytokines) are released. The cytokines enter the blood stream and are transported to the brain. Recently, the existence of another signalling pathway has been demonstrated. The pathway is via a special peripheral sensory nerve, the abdominal vagal sensory nerve. However, special neural pathways in the brain have not yet been clarified, even though several neural relay stations have been proposed. To elucidate neural pathways transmitting information of infection to the brain, both input and output of the pathway need to be specified. Specific outputs other than body temperature have not been determined, so far. I have recently developed a new reflex model, in which I focus on sympathetic nerves supplying the specialised fat tissue as an output as well as the vagus sensory nerve as an input. The fat tissue, brown adipose tissue (BAT), generates heat. When the vagus sensory nerve is stimulated electrically, BAT sympathetic nerve is activated. We were very exited when we discovered the potency of the combination in our rat model. We are now ready to elucidate brain pathways for neurally-mediated fever, using our new reflex model. Signalling to the brain via the nervous system is faster than via the blood stream, and thus must be very important for the earliest phase of fever. Understanding the neural pathways by which the brain perceives peripheral infection and triggers fever may promote beneficial aspects of the acute-phase immune reaction.Read moreRead less