THE AUTONOMIC, SOMATIC AND CENTRAL NEURAL RESPONSES TO DEEP AND SUPERFICIAL PAIN IN HUMAN SUBJECTS
Funder
National Health and Medical Research Council
Funding Amount
$375,750.00
Summary
Pain is a subjective experience, the intensity of which can be readily influenced by personal experience. Despite this, pain originating from a particular part of the body will usually be described by all individuals as having similar character. For example, pain arising from the skin is commonly described as being sharp or burning and is usually easy to localise, whereas pain arising from muscle is commonly dull, throbbing and diffuse. In addition to producing sensory changes, pain also evokes ....Pain is a subjective experience, the intensity of which can be readily influenced by personal experience. Despite this, pain originating from a particular part of the body will usually be described by all individuals as having similar character. For example, pain arising from the skin is commonly described as being sharp or burning and is usually easy to localise, whereas pain arising from muscle is commonly dull, throbbing and diffuse. In addition to producing sensory changes, pain also evokes changes in blood pressure, heart rate and motor activity (often in an attempt to remove the source of the pain). The proposed research aims to characterise the cardiovascular and motor patterns associated with pain originating in skin and in muscle and to examine the brain regions that produce these changes. More specifically, microelectrodes will be used to investigate changes in peripheral nerve activity during transient painful skin and muscle events in awake human subjects. In a separate investigation functional magnetic resonance imaging will be used to determine brain sites that are activated by skin or muscle pain.Read moreRead less
Although chronic pain is a serious clinical problem, treatments for its alleviation have largely failed, in part because they have not been tailored to the specific origin of the pain. This proposal focuses on rheumatoid arthritis, a common and incurrable source of chronic pain. This study will investigate how specific changes in spinal cord nerve cells contribute to chronic arthritic pain. The outcomes will help identify new targets to treat chronic pain in rheumatoid arthritis.
Analysis Of Functional Role Of The BDNF Precursor In Sensory Neurons
Funder
National Health and Medical Research Council
Funding Amount
$457,267.00
Summary
Neurotrophins, which are generated from their precursors, are essential for the survival and function of the nervous system. One of neurotrophins, brain derived neurotrophic factor (BDNF), is made in sensory neurons and transported towards nerve terminals. Mutation of a single amino acid in the precursor of BDNF disrupts this transport. This project will examine whether the precursor of BDNF has any function within sensory nerves. We will examine whether the precursor of BDNF gets into the nerve ....Neurotrophins, which are generated from their precursors, are essential for the survival and function of the nervous system. One of neurotrophins, brain derived neurotrophic factor (BDNF), is made in sensory neurons and transported towards nerve terminals. Mutation of a single amino acid in the precursor of BDNF disrupts this transport. This project will examine whether the precursor of BDNF has any function within sensory nerves. We will examine whether the precursor of BDNF gets into the nerve via its receptors and whether it plays any role in the development of pain and maintenance of neuropathic pain after nerve injury. Successful execution of the project will eludicate mechanisms of pain, especially neuropathic pain, and will provide important information to assist in the design of drugs for neurological diseases.Read moreRead less
This is a study of the senses which arise from our muscles and which tell us where our different body parts are, at any point in time. These senses, collectively called proprioception, are also involved in the automatic, unconscious control of our muscles. So, ultimately, they allow us to stand and to move freely with precision and confidence, even in the dark. One of these senses, the sense of effort or of heaviness, is believed to be generated within the brain. It intensifies when we become fa ....This is a study of the senses which arise from our muscles and which tell us where our different body parts are, at any point in time. These senses, collectively called proprioception, are also involved in the automatic, unconscious control of our muscles. So, ultimately, they allow us to stand and to move freely with precision and confidence, even in the dark. One of these senses, the sense of effort or of heaviness, is believed to be generated within the brain. It intensifies when we become fatigued. These experiments will be concerned with finding out more about how this works. We have a method that uses magnetic stimulation of the brain to change its control of our muscles. Using it we will learn how this sense is generated. When we close our eyes and move our limbs we realise that we know exactly where they are at any point in time. It remains uncertain exactly how this information is generated within the nervous system. One idea, arising from some recent experiments which we want to test, is that as we move the limb, the skin over the moving parts is stretched and stretch-sensitive nerve endings in the skin provide us with information about the movement. Alternatively, perhaps it is the effort we exert to maintain limb position against the force of gravity which tells us where the limb is. In another recent study we have found that when a muscle has become painful from excessive exercise or from some local strain injury, our ability to control the muscle and so move the limb is no longer as effective. We want to study the underlying nervous mechanisms responsible for the changes in movement control. Are they designed to spare the muscle while it recovers from injury? How are they brought about? All of this work is important for a better understanding of ourselves, for a better clinical diagnosis when something goes wrong and for improved treatment of diseased or injured muscles.Read moreRead less
Does The Complement System Contribute To Neuropathic Pain?
Funder
National Health and Medical Research Council
Funding Amount
$262,958.00
Summary
Nerve injury often results in increased sensitivity to painful stimuli and the perception of innocuous stimuli as painful; it may also result in spontaneous pain. These disorders of pain sensation due to nerve injury are common, debilitating and difficult to treat. They are symptoms of neuropathic pain. Pain is normally signalled to the brain by sensory nerve cells called nociceptors. Following nerve injury, nociceptors are sensitised by chemicals released by inflammatory cells. This contributes ....Nerve injury often results in increased sensitivity to painful stimuli and the perception of innocuous stimuli as painful; it may also result in spontaneous pain. These disorders of pain sensation due to nerve injury are common, debilitating and difficult to treat. They are symptoms of neuropathic pain. Pain is normally signalled to the brain by sensory nerve cells called nociceptors. Following nerve injury, nociceptors are sensitised by chemicals released by inflammatory cells. This contributes to neuropathic pain. We have evidence that inflammatory responses play a key role in initiating neuropathic pain. Other evidence suggests that the immune system contributes to neurological diseases and accompanying pain (e.g. Guillain-Barr syndrome and multiple sclerosis). We plan to test the idea that a component of the immune system known as the complement pathway contributes to the development of neuropathic pain following peripheral nerve injury. The outcome of this work will be a better understanding of the way in which nerve injury leads to chronic disorders of pain, including increased sensitivity to painful stimuli. This will lead in turn to the development of more effective treatments for neuropathic pain.Read moreRead less
Current treatments for chronic pain are limited in their success. This emphasises the need for new insights into the basic mechanisms and nervous system circuitry underlying altered or chronic pain states. Work in animals and patients with chronic pain shows that certain brainstem centres communicate, via descending spinal cord pathways, with small nerve cells in the superficial dorsal horn (SDH) of the spinal cord. These SDH neurones receive and process pain-signalling information from the skin ....Current treatments for chronic pain are limited in their success. This emphasises the need for new insights into the basic mechanisms and nervous system circuitry underlying altered or chronic pain states. Work in animals and patients with chronic pain shows that certain brainstem centres communicate, via descending spinal cord pathways, with small nerve cells in the superficial dorsal horn (SDH) of the spinal cord. These SDH neurones receive and process pain-signalling information from the skin and internal organs, and receive inputs from descending pathways. This descending input can either inhibit or enhance the activity of SDH neurones and subsequent pain perception. Till now it has been difficult to directly examine how descending pain pathways influence the small SDH neurones in the spinal cord. A new approach, which has been developed in our laboratory, now allows us to record from these very small SDH neurones in the spinal cord of an intact deeply anaesthetized mouse. In addition, our technique allows us to examine the recorded SDH neurone s responses to functionally relevant stimuli (brushing or pinching the hindpaw) as well as its physiology and anatomy. This project will use our new techniques to examine the effects of activating descending brainstem pathways that alter the way painful stimuli are processed in the spinal cord. The effects of altered levels of inhibition in the spinal cord will also be studied by using mice with naturally occurring mutations in their inhibitory glycine receptors. We believe a more complete understanding of pain processing mechanisms will be achieved by examining the role of descending pathways in an intact animal preparation. Such data are essential for the development of drug therapies that can successfully target pain syndromes.Read moreRead less
Ion Channels Underlying Inflammatory And Post-inflammatory Visceral Mechanical Hypersensitivity
Funder
National Health and Medical Research Council
Funding Amount
$453,439.00
Summary
Inflammation causes tissue damage that triggers ion channels within sensory nerve fibres to produce greater signals in response to mechanical events, causing acute pain. In chronic pain, although the inflamed tissue has healed, sensory nerve fibres fail to "reset" back to normal. Often chronic pain is more severe than acute pain. This project will identify which ion channels are responsible for signalling acute and chronic visceral pain, explaining why sensory nerve fibres fail to reset.
Synaptic Environment Of Nociceptive Inputs To The Spinal Cord
Funder
National Health and Medical Research Council
Funding Amount
$499,860.00
Summary
Pain affects everyone at some stage in their life. Usually, the pain subsides by itself as the underlying cause is resolved. Thus, the damaged tissue heals or we move away from a potentially injurious stimulus and we become free of pain. However, pain can persist for two main reasons: the underlying cause cannot be treated adequately and the painful stimulus continues; or the pain is maintained long after the primary stimulus has resolved. This ongoing pain often is resistant to alleviation by c ....Pain affects everyone at some stage in their life. Usually, the pain subsides by itself as the underlying cause is resolved. Thus, the damaged tissue heals or we move away from a potentially injurious stimulus and we become free of pain. However, pain can persist for two main reasons: the underlying cause cannot be treated adequately and the painful stimulus continues; or the pain is maintained long after the primary stimulus has resolved. This ongoing pain often is resistant to alleviation by common analgesics. Therefore, a major aim of the pharmaceutical industry is the development of new drugs to target persistent pain. This requires a thorough understanding of how the nerves that detect painful stimuli transmit that information into the spinal cord, and then on to the brain, where we construct a conscious perception of the pain. Various kinds of painful stimuli, such as tissue damage, noxious chemicals, or extreme temperatures, are detected by different types of nerves. Each nerve type can be identified by its characteristic chemical profile. Recently, we found that some of these nerves probably do not transmit their messages to the spinal cord in the way everyone had thought. This means that there must be an alternative way for many types of painful stimuli to be transmitted into the spinal cord. In this project, we will use a sophisticated suite of modern microscopic and electrical recording techniques to find out what this alternative mechanism is. Our central idea is that most types of painful stimuli simultaneously activate two types of sensory nerves. These nerves then connect with specific nerve cells in the spinal cord before painful information is relayed to the brain. Our proposal suggests a new mechanism for understanding how pain can develop from being an acute defensive reaction to a chronic problem. In turn, this should lead to improved strategies for developing and testing new analgesic drugs.Read moreRead less
Mechanisms Of Activation Of Vascular Afferent Nociceptors To The Gut
Funder
National Health and Medical Research Council
Funding Amount
$542,890.00
Summary
We have recently identified the nerve fibres responsible for detecting pain from the gut. In this project we will study exactly how these nerve cells are activated by movements of the gut wall, by changes in blood vessel diameter and how this can be studied most efficiently We will use this information to develop simple preparations in which to study these sensory nerves in animal and adult tissue to test which drugs may affect their excitability and hence be useful in treating gut pain.
The role of the immune system in pain is emerging from recent discoveries, and may hold the key to novel pain treatments. Most people experience brief gut infections from food or contagion without long-term consequences. Many others suffer symptoms for years afterwards - probably the best example of immune-based pain. Our project investigates how immune cells communicate with sensory nerves, and how these communications change from both angles after gut infection or inflammation.