Search results for "Hyperalgesia"
showing 10 items of 78 documents
Pain, Neural Basis of
2001
The term ‘pain’ refers on one hand to a subjective state of suffering, which is a conscious personal experience. On the other hand, pain is the percept that results from the activation of the nociceptive system. This specific sensory system is specialized for the detection of external stimuli and internal tissue states that threaten the integrity of the body. It is a part of the somatosensory system, but its peripheral and central neurons are separate from the tactile system. Functions such as the localization of painful stimuli or the discrimination of pain intensities are subserved by a projection pathway from thin peripheral nerve fibers, via processing centers in the spinal cord and lat…
SETD7 mediates spinal microgliosis and neuropathic pain in a rat model of peripheral nerve injury
2019
Abstract Gene transcription regulation is critical for the development of spinal microgliosis and neuropathic pain after peripheral nerve injury. Using a model of chronic constriction injury (CCI) of the sciatic nerve, this study characterized the role of SET domain containing lysine methyltransferase 7 (SETD7) which monomethylates histone H3 lysine 4 (H3K4me1), a marker for active gene transcription. SETD7 protein expression in the spinal dorsal horn ipsilateral to nerve lesion was increased from one day to 14 days after CCI, concomitantly with the expression of inflammatory genes, Ccl2, Il-6 and Il-1β. The CCI-induced SETD7 expression was predominantly localized to microglia, as demonstra…
Therapeutic Potential of Inhibitors of Endocannabinoid Degradation for the Treatment of Stress-Related Hyperalgesia in an Animal Model of Chronic Pain
2014
The occurrence of chronic stress, depression, and anxiety can increase nociception in humans and may facilitate the transition from localized to chronic widespread pain. The mechanisms underlying chronic widespread pain are still unknown, hindering the development of effective pharmacological therapies. Here, we exposed C57BL/6J mice to chronic unpredictable stress (CUS) to investigate how persistent stress affects nociception. Next, mice were treated with multiple intramuscular nerve growth factor (NGF) injections, which induced chronic widespread nociception. Thus, combination of CUS and NGF served as a model where psychophysiological impairment coexists with long-lasting hyperalgesia. We…
Hyperalgesia: An Emerging Iatrogenic Syndrome
2003
Clinical reports suggest that opioids, intended to abolish pain, can unexpectedly produce hyperalgesia. This paradoxical effect may be mechanistically related to tolerance induced by increasing doses of opioids. Two case reports illustrate a syndrome characterized by increasing pain pursued by escalating opioid doses, which results in a worsening of the clinical picture. Several experimental data may help explain the course of this challenging clinical condition. In escalating opioid doses rapidly, a risk of opioid-induced hyperalgesia should be recognized, as higher doses of opioids may stimulate rather than inhibit the central nervous system by different mechanisms. Alternative procedures…
The gamma(2)-MSH peptide mediates a central analgesic effect via a GABA-ergic mechanism that is independent from activation of melanocortin receptors.
2001
Using the latency for tail-flick after thermal stimulation we have assessed the effects of alpha-, gamma(1)- and gamma(2)-MSH on nociceptive threshold in the mice. Intracisternal injections of gamma(2)-MSH induced a distinct analgesia, while gamma(1)-MSH in the same doses gave only a minor analgesia. Intracisternal alpha-MSH instead gave a short-term hyperalgesia. The effect of gamma(2)-MSH was not blocked by any of the MC(4)/MC(3)receptor antagonist HS014, naloxone or by the prior intracisternal administrations of gamma(1)-MSH. However, the gamma(2)-MSH analgesic response was completely attenuated by treating animals with the GABA(A)antagonist bicuculline. The gamma(2)-MSH analgesic effect…
Inflammatory Pain Promotes Increased Opioid Self-Administration: Role of Dysregulated Ventral Tegmental Area μ Opioid Receptors
2015
Pain management in opioid abusers engenders ethical and practical difficulties for clinicians, often resulting in pain mismanagement. Although chronic opioid administration may alter pain states, the presence of pain itself may alter the propensity to self-administer opioids, and previous history of drug abuse comorbid with chronic pain promotes higher rates of opioid misuse. Here, we tested the hypothesis that inflammatory pain leads to increased heroin self-administration resulting from altered mu opioid receptor (MOR) regulation of mesolimbic dopamine (DA) transmission. To this end, the complete Freund's adjuvant (CFA) model of inflammation was used to assess the neurochemical and functi…
Bone Trauma Causes Massive but Reversible Changes in Spinal Circuitry.
2016
Abstract Bone fracture with subsequent immobilization of the injured limb can cause complex regional pain syndrome (CRPS) in humans. Mechanisms of CRPS are still not completely understood but bone fracture with casting in mice leads to a similar post-traumatic inflammation as seen in humans and might therefore be an analog to human CRPS. In this article we report behavioral and spinal electrophysiological changes in mice that developed swelling of the paw, warming of the skin, and pain in the injured limb after bone fracture. The receptive field sizes of spinal neurons representing areas of the hind paws increased after trauma and recovered over time—as did the behavioral signs of inflammat…
Thermal Thresholds Predict Painfulness of Diabetic Neuropathies
2004
OBJECTIVE—Pathophysiology explaining pain in diabetic neuropathy (DN) is still unknown. RESEARCH DESIGN AND METHODS—Thirty patients with peripheral DN (17 men and 13 women; mean age 52.4 ± 2.5 years) were investigated. Fifteen patients had neuropathic pain, and 15 patients were free of pain. Patients were followed over 2 years and examined at the beginning and thereafter every 6 months. Clinical severity and painfulness of the DN were assessed by the neuropathy impairment score and visual analog scales (VASs). Cold and warm perception thresholds as well as heat pain thresholds were obtained for evaluation of Aδ- and C-fibers. Nerve conduction velocities (NCVs) and vibratory thresholds were …
Thermal hypoaesthesia differentiates secondary restless legs syndrome associated with small fibre neuropathy from primary restless legs syndrome.
2010
This study aimed to assess thermal and mechanical perception and pain thresholds in primary idiopathic restless legs syndrome and secondary restless legs syndrome associated with small fibre neuropathy. Twenty-one patients (age: 53.4 + or - 8.4, n = 3, male) with primary restless legs syndrome and 13 patients (age: 63.0 + or - 8.2, n = 1, male) with secondary restless legs syndrome associated with small fibre neuropathy were compared with 20 healthy subjects (age: 58.0 + or - 7.0; n = 2, male). Differential diagnosis of secondary restless legs syndrome associated with small fibre neuropathy was based on clinical symptoms and confirmed with skin biopsies in all patients. A comprehensive quan…
Transient Receptor Potential Channel Polymorphisms Are Associated with the Somatosensory Function in Neuropathic Pain Patients
2011
Transient receptor potential channels are important mediators of thermal and mechanical stimuli and play an important role in neuropathic pain. The contribution of hereditary variants in the genes of transient receptor potential channels to neuropathic pain is unknown. We investigated the frequency of transient receptor potential ankyrin 1, transient receptor potential melastin 8 and transient receptor potential vanilloid 1 single nucleotide polymorphisms and their impact on somatosensory abnormalities in neuropathic pain patients. Within the German Research Network on Neuropathic Pain (Deutscher Forscbungsverbund Neuropathischer Schmerz) 371 neuropathic pain patients were phenotypically ch…