Spinal CCK1 Receptors Contribute to Somatic Pain Hypersensitivity Induced by Malocclusion via a Reciprocal Neuron-Glial Signaling Cascade

Recent studies have shown that the incidence of chronic primary pain including temporomandibular disorders (TMD) and fibromyalgia syndrome (FMS) often exhibit comorbidities. We recently reported that central sensitization and descending facilitation system contributed to the development of somatic pain hypersensitivity induced by orofacial inflammation combined with stress. The purpose of this study was to explore whether TMD caused by unilateral anterior crossbite (UAC) can induce somatic pain hypersensitivity, and whether the cholecystokinin (CCK) receptor-mediated descending facilitation system promotes hypersensitivity through neuron-glia cell signaling cascade. UAC evoked thermal and mechanical pain hypersensitivity of the hind paws from day 5 to 70 that peaked at week 4 post UAC. The expression levels of CCK1 receptors, interleukin-18 (IL-18) and IL-18 receptors (IL-18R) were significantly up-regulated in the L4 to L5 spinal dorsal horn at 4 weeks post UAC. Intrathecal injection of CCK1 and IL-18 receptor antagonists blocked somatic pain hypersensitivity. IL-18 mainly co-localized with microglia, while IL-18R mainly co-localized with astrocytes and to a lesser extent with neurons. These findings indicate that the signaling transduction between neurons and glia at the spinal cord level contributes to the descending pain facilitation through CCK1 receptors during the development of the comorbidity of TMD and FMS.PerspectiveCCK1 receptor-dependent descending facilitation may mediate central mechanisms underlying the development of widespread somatic pain via a reciprocal neuron-glial signaling cascade, providing novel therapeutic targets for the clinical treatment of TMD and FMS comorbidities.     

中枢神经系统内缝隙连接的研究进展

缝隙连接是介导相邻细胞间交流的直接通道,缝隙连接结构和功能的异常与中枢神经系统疾病的发生、发展关系密切。研究中枢神经系统内的缝隙连接可能为中枢神经系统疾病的治疗开拓新靶点。     

甲基强的松龙对大鼠脊髓损伤后星形胶质细胞的影响

目的 观察大鼠脊髓损伤后甲基强的松龙(MP)对星形胶质细胞(AS)增殖和胶质纤维酸性蛋白(GFAP)表达的影响.方法 雄性SPF级10周龄大鼠48只,制成脊髓右侧半横断损伤模型,分为MP组和对照组,每组24只.术后每4 d进行1次行为学(BBB)评分.MP组通过尾静脉注射MP溶液,对照组同时注射等量生理盐水,两组大鼠分别在3 d、7 d、14 d、28 d处死,应用免疫组化技术观察GFAP的表达,并做灰度值测定和GFAP阳性细胞计数.结果 与对照组相比,MP组在损伤后21 d内行为学方面无显著性差异,在25 d后MP组优于对照组.脊髓损伤后3 d和7 d,MP组活性化AS数目明显少于对照组,14 d后无显著性差异;3 d、7 d、21 d时,MP组胶质性瘢痕中GFAP表达量均明显低于对照组,28 d时两组无显著性差异.结论 急性脊髓损伤后大剂量MP冲击疗法能减少AS活化的数目,减少胶质性瘢痕的形成,并能促进后肢功能的恢复.     

抑制脊髓损伤后星形胶质细胞增殖和胶质瘢痕形成的研究进展

对星形胶质细胞（AS）的性质和功能、脊髓损伤后的AS病理变化和作用、抑制AS增殖和胶质瘢痕形成的实验方法等方面进行综述。认为,AS激活后的不同分化时期对脊髓损伤修复具有一定的积极作用;但成熟以后,AS可以分泌有害因子,形成化学性胶质屏障,严重影响神经再生和阻碍轴突延长。脊髓损伤后AS被激活,静止态、活化态和增殖态往往并存,形成原因复杂,目前采取单一的方法很难有效控制AS增殖和胶质瘢痕形成。     

Functional Characterization of At-Level Hypersensitivity in Patients With Spinal Cord Injury

At-level and above-level hypersensitivity was assessed in patients with chronic complete thoracic spinal cord injury (SCI). Patients were classified using somatosensory mapping (brush, cold, pinprick) and assigned into 2 groups (ie, patients with at-level hypersensitivity [SCIHs, n = 8] and without at-level hypersensitivity [SCINHs, n = 7]). Gender and age-matched healthy subjects served as controls. Quantitative sensory testing (QST), electrically- and histamine-induced pain and itch, laser Doppler imaging, and laser-evoked potentials (LEP) were recorded at-level and above-level in SCI-patients. Six of 8 SCIHs, but 0 of 7 SCINHs patients suffered from neuropathic below-level pain. Clinical sensory mapping revealed spreading of hypersensitivity to more cranial areas (above-level) in 3 SCIHs. Cold pain threshold measures confirmed clinical hypersensitivity at-level in SCIHs. At-level and above-level hypersensitivity to electrical stimulation did not differ significantly between SCIHs and SCINHs. Mechanical allodynia, cold, and pin-prick hypersensitivity did not relate to impaired sensory function (QST), axon reflex flare, or LEPs. Clinically assessed at-level hypersensitivity was linked to below-level neuropathic pain, suggesting neuronal hyperexcitability contributes to the development of neuropathic pain. However, electrically evoked pain was not significantly different between SCI patients. Thus, SCI-induced enhanced excitability of nociceptive processing does not necessarily lead to neuropathic pain. QST and LEP revealed no crucial role of deafferentation for hypersensitivity development after SCI.

Footshock-Induced Urinary Bladder Hypersensitivity: Role of Spinal Corticotropin-Releasing Factor Receptors

Stress-induced hyperalgesia (SIH), a common clinical observation associated with multiple painful diseases including functional urinary disorders, presently has no mechanistic explanation. Using a footshock treatment, a classic stressor, to magnify physiological responses in a model of urinary bladder pain, we examined one potential group of mediators of SIH, the corticotropin-releasing factor (CRF)-related neuropeptides. Exposure to a footshock treatment produced bladder hypersensitivity in female Sprague-Dawley rats, manifested as significantly more vigorous visceromotor responses (VMRs) to urinary bladder distension (UBD) compared with rats that were exposed to a non-footshock treatment. This bladder hypersensitivity was significantly attenuated by blocking spinal CRF₂ receptors but not CRF₁ receptors. Furthermore, spinal administration of urocortin 2, a CRF₂ receptor agonist, augmented UBD-evoked VMRs in a way similar to what was observed after exposure to Footshock, an effect significantly attenuated by pretreatment with spinal aSVG30, a CRF₂ receptor antagonist. Surprisingly, neither spinal administration of CRF nor the CRF₁ receptor antagonist antalarmin had an effect on bladder nociceptive responses. The results of the present study not only provide further support for a role of stress in the exacerbation of bladder pain but also implicate spinal urocortins and their endogenous receptor, the CRF₂ receptor, as potential mediators of this effect.PerspectiveThis study presents evidence that spinal urocortins and CRF₂ receptors are involved in stress-induced hypersensitivity related to the urinary bladder. This provides a basis for investigating how urocortins mediate SIH, ultimately leading to more effective treatment options for patients with painful bladder syndromes as well as stress-exacerbated chronic pain.     

Antioxidants Improve Oxaliplatin-Induced Peripheral Neuropathy in Tumor-Bearing Mice Model: Role of Spinal Cord Oxidative Stress and Inflammation

Chemotherapy-Induced Peripheral Neuropathy (CIPN) is a common, difficult-to-treat, and dose-limiting side effect associated with Oxaliplatin (OXA) treatment. In this study, we evaluated the effect of three antioxidants - namely N-acetylcysteine, α-lipoic acid and vitamin E – upon nociceptive parameters and antitumor efficacy of OXA in a tumor-bearing Swiss mice model. Oral treatment with antioxidants inhibited both mechanical and cold allodynia when concomitantly administrated with OXA (preventive protocol), as well as in animals with previously established CIPN (therapeutic protocol). OXA increased Reactive Oxygen Species (ROS) production and lipoperoxidation, and augmented the content of pro-inflammatory cytokines (IL-1β and TNF-α) and expression of the astrocytic marker Gfap mRNA in the spinal cord. Antioxidants decreased ROS production and lipoperoxidation, and abolished neuroinflammation in OXA-treated animals. Toll-like receptor 4 (Tlr4) and inflammasome enzyme caspase-1/11 knockout mice treated with OXA showed reduced levels of pro-inflammatory cytokines (but not oxidative stress) in the spinal cord, which were associated with resistance to OXA-induced mechanical allodynia. Lastly, antioxidants affected neither antitumor activity nor hematological toxicity of OXA in vivo. The herein presented results are provocative for further evaluation of antioxidants in clinical management of chemotherapy-induced peripheral neuropathy.PerspectiveThis study reports preventive and therapeutic efficacy of orally administrated antioxidants (N-acetylcysteine, α-lipoic-acid and Vitamin-E) in alleviating oxaliplatin-induced peripheral neuropathy in tumor-bearing mice. Antioxidants’ anti-nociceptive effects are associated with inhibition of ROS-dependent neuroinflammation, and occur at no detriment of OXA antitumor activity, therefore indicating a translational potential of these compounds.     

Pulsed Ultrasound Remedies Post-thoracotomy Hypersensitivity and Increases Spinal Anti-inflammatory Cytokine in Rats

The purpose of the experiment was to study the effect of pulsed ultrasound (PUS) on post-thoracotomy pain and local tissue temperature and to correlate the findings with the alteration in spinal anti-inflammatory and pro-inflammatory cytokines. Mechanical sensitivity, subcutaneous temperature and spinal interleukin-10 (IL-10), IL-6 or tumor necrosis factor-alpha (TNF-α) expression were examined in a rat model of experimental post-thoracotomy pain. Group 1 received a sham surgery where thoracotomy was performed except for rib retraction. Group 2 underwent thoracotomy with rib retraction (TRR). Group 3 received the TRR procedure followed by PUS. Group 4 underwent the TRR procedure followed by only the massage with the ultrasound turned off. Compared with group 1 (sham), groups 2–4 showed a decrease in mechanical withdrawal thresholds on postoperative days (PODs) 10 and 11. On PODs 16, 23 and 30, group 3 (TRR+PUS-1) displayed an increase in mechanical withdrawal thresholds compared with groups 2 and 4. Subcutaneous and body temperatures in group 3 were not prominently different from group 1, group 2 (TRR only) or group 4 (TRR+PUS-0). Compared with group 2, group 3 had an increase in spinal IL-10 level on POD 30 and a decrease in spinal IL-6 or TNF-α expression on PODs 16 and 30. We concluded that mechanical hypersensitivity after TRR is postponed by PUS, and its effect continues for 3 wk. A PUS dose not increase local tissue temperature. The beneficial effect of PUS appears related to upregulation of spinal anti-inflammatory cytokine and downregulation of spinal pro-inflammatory cytokines.     

Analgesic Effects of Transcutaneous Ultrasound Nerve Stimulation in a Rat Model of Oxaliplatin-Induced Mechanical Hyperalgesia and Cold Allodynia

This study investigated the effects and underlying mechanisms of therapeutic ultrasound (TUS) in a rat model of oxaliplatin-induced peripheral neuropathy. Animals received a total of eight injections with oxaliplatin (4 mg/kg), administered at 3-d intervals. TUS intervention (1 MHz, 0.5 W/cm²) started on the fifth oxaliplatin administration and continued for 10 consecutive d. Sensory behavioral examinations, protein levels of transient receptor potential channels (TRPM8 and TRPV1) in dorsal root ganglia (DRG) and substance P (SP) in spinal dorsal horn were examined. Results indicated that TUS can reduce mechanical and cold hyper-responsive behaviors caused by repeated administration of oxaliplatin. Oxaliplatin-related increases in protein levels of TRPM8 in DRG and SP in the dorsal horn were also reduced after TUS. Taken together, the results revealed beneficial effects of TUS on oxaliplatin-induced mechanical hyperalgesia and cold allodynia and suggested involvement of TUS biochemicals in suppressing TRPM8 in DRG and SP in spinal cords.     

Hypersensitivity reactions to biological drugs

OBJECTIVES: To review the current evidence regarding hypersensitivity reactions related to the administration of biological drugs in the management of cancer, and to provide the nurse with appropriate interventions related to the management of hypersensitivity reactions. DATA SOURCES: Review articles and research studies from the medical and nursing literature. CONCLUSION: Current evidence is available regarding the types of reactions that are associated with the administration of biological drugs in the management of cancer. Medical and nursing studies that review the most effective management of hypersensitivity reactions related to the administration of biological drugs. A review of "best practice" is offered in this article regarding the management of hypersensitivity reactions related to the administration of biological drugs. IMPLICATIONS FOR NURSING PRACTICE: Nurses play a key role in the early identification of hypersensitivity reactions. Management of hypersensitivity reactions must be rapid for optimal patient outcomes.     

Hypersensitivity to pain in congenital blindness

Vision is important for avoiding encounters with objects in the environment that may imperil physical integrity. We tested whether, in the absence of vision, a lower pain threshold would arise from an adaptive shift to other sensory channels. We therefore measured heat and cold pain thresholds and responses to suprathreshold heat stimuli in 2 groups of congenitally blind and matched normal-sighted participants. We also assessed detection thresholds for innocuous warmth and cold, and participants’ attitude toward painful encounters in daily life. Our results show that, compared to sighted subjects, congenitally blind subjects have lower heat pain thresholds, rate suprathreshold heat pain stimuli as more painful, and have increased sensitivity for cold pain stimuli. Thresholds for nonpainful thermal stimulation did not differ between groups. The results of the pain questionnaires further indicated that blind subjects are more attentive to signals of external threats. These findings indicate that the absence of vision from birth induces a hypersensitivity to painful stimuli, lending new support to a model of sensory integration of vision and pain processing.     

Hypersensitivity reactions to parenteral lipid solutions

 In cancer patients, hypersensitivity reactions to adjunctive medications are easily mistaken for cytostatic toxicities. We report on three patients with systemic reactions (flush, dyspnea, tachycardia, hypotension, back pain) to a lipid emulsion containing long chain fatty acids (LCT). Reexposure to LCT and exposure to MCT (medium chain fatty acids) solutions of slightly different composition – no soybean lecithin used as an emulsifier – were well tolerated. These data suggest that traces of soybean proteins are the allergenic agents. Therefore, hypersensitivity to concomitant medications, including parenteral nutrition, has to be considered in oncologic patients demonstrating severe systemic reactions to intravenous therapy.