Articles: chronic-pain.
-
Repetitive ischemia with reperfusion (I/R) injury is a common cause of myalgia. Ischemia with reperfusion injuries occur in many conditions that differentially affect males and females including complex regional pain syndrome and fibromyalgia. Our preclinical studies have indicated that primary afferent sensitization and behavioral hypersensitivity caused by I/R injury may be due to sex-specific gene expression in the dorsal root ganglia (DRG) and distinct upregulation of growth factors and cytokines in the affected muscles. ⋯ AUF1 knockdown was able to specifically inhibit repeated I/R-induced gene expression in females potentially downstream of prolactin receptor signaling. Data suggest RNA-binding proteins such as pAUF1 may underlie the sex-specific effects on DRG gene expression that modulates behavioral hypersensitivity after repeated I/R injury through prolactin signaling. This study may aid in finding distinct receptor differences related to the evolution of acute to chronic ischemic muscle pain development between sexes.
-
One-fifth of US adults experience chronic pain, which is associated with increased tobacco and cannabis use. Although bidirectional relationships between tobacco and pain have been demonstrated, pathways between pain, cannabis use, and co-use of cannabis and tobacco are understudied. We aimed to estimate the effects of (1) substance use (exclusive and co-use of cannabis and tobacco) on later pain intensity, and (2) pain intensity on later substance use. ⋯ Compared with no cannabis/tobacco use at T1, co-use (OR: 2.29 [95% CI: 2.09-2.51]), exclusive tobacco use (2.00 [1.86-2.14]), and exclusive cannabis use (1.35 [1.13-1.61]) were all associated with moderate/severe pain at T2. Moderate/severe pain at T1 increased odds of co-use (2.43 [2.22-2.66]), exclusive tobacco (2.12 [1.98-2.28]), and exclusive cannabis use (1.46 [1.29-1.65]) compared with no cannabis/tobacco use at T2, and increased odds of co-use at T2 compared with exclusive cannabis/tobacco use. Findings demonstrated bidirectional relationships between pain and the exclusive use and co-use of cannabis and tobacco and indicate potential synergy in the co-use of cannabis and tobacco with respect to pain.
-
Opioid analgesics are commonly used to treat acute and chronic pain following traumatic injury. Psychiatric comorbidity has been reported to be associated with increased pain and persistent opioid use. Our aims were to determine the extent of post-injury opioid use and assess whether pre-injury antidepressant, benzodiazepine, and z-hypnotic drug use is associated with increased post-injury opioid use. ⋯ This large registry-based study adds to the body of knowledge on opioid use beyond in-hospital care in patients having sustained traumatic injury, a field which is scarcely investigated and not yet fully understood. It suggests that both previous drug therapy and the nature of opioid treatment initiation may affect outcome. This will help guide clinicians in selecting the appropriate pain management in this patient group.
-
Neuropathic pain is pain due to a disease or lesion of the somatosensory system, and can be either spontaneous, evoked or both. Hyperpathia is a type of evoked pain defined by IASP as 'a painful syndrome characterized by an abnormally painful reaction to a stimulus, especially a repetitive stimulus, as well as an increased threshold'. The literature is sparse, and definitions are unclear and inconsistent. ⋯ Hyperpathia is a syndrome of evoked pain. It is poorly defined and little is known about its clinical presentation. Since it is part of pain symptomatology it is important to have a clear definition and understand the pathophysiology behind. This study explored signs of hyperpathia in a heterogeneous group of patients with peripheral neuropathic pain. We used stimulus-response function and repetitive pinprick stimulation to group patients based on the IASP definition. More studies are needed to understand how symptoms and signs coincide.
-
High molecular weight hyaluronan (HMWH) inhibits hyperalgesia induced by diverse pronociceptive inflammatory mediators and their second messengers, in rats of both sexes. However, the hyperalgesia induced by ligands at 3 pattern recognition receptors, lipopolysaccharide (a toll-like receptor 4 agonist), lipoteichoic acid (a toll-like receptor 2/6 agonist), and nigericin (a NOD-like receptor family, pyrin domain containing 3 activator), and oxaliplatin and paclitaxel chemotherapy-induced peripheral neuropathy are only attenuated in males. After gonadectomy or intrathecal administration of an antisense to G-protein-coupled estrogen receptor 30 (GPER) mRNA, HMWH produces antihyperalgesia in females. ⋯ In females, hyperalgesia induced by PKCε agonist, ψεRACK, in control but not in primed nociceptors, was inhibited by HMWH. Inhibitors of 2 GPER second messengers, extracellular-regulated kinase 1/2 and nonreceptor tyrosine kinase, also unmasked HMWH antihyperalgesia in females with oxaliplatin chemotherapy-induced peripheral neuropathy, a condition in which nociceptors are primed as well as sensitized. Our results support GPER-dependent sex dimorphism in HMWH-induced antihyperalgesia for pain induced by pattern recognition receptor agonists, and chronic inflammatory and neuropathic pain, mediated by changes in signaling downstream of PKCε in primed nociceptors.