Mechanisms of Pain in Sickle Cell Disease

Pain is one of the most common features of sickle cell disease (SCD) lacking effective therapy. Pain in SCD is relatively more complicated than other conditions associated with pain requiring understanding of the pathobiology of pain specific to SCD. The characterization of pain to define the diverse modalities of nociception in SCD is currently under progress via human studies accompanied by transgenic mouse models of SCD. Sickle pathobiology characterized by oxidative stress, inflammation and vascular dysfunction contributes to both peripheral and central nociceptive sensitization via mast cell activation in the periphery, and reactive oxygen species and glial activation and endoplasmic reticulum stress in the spinal cord among other effectors. These effects are mediated via several cellular receptors, which can be targeted to produce positive therapeutic outcomes. In this chapter, we will discuss the present understanding of molecular mechanisms of SCD pain and outline the mechanism‐based translational potential of novel actionable targets to treat SCD pain

Osteosarcomagenesis: Biology, Development, Metastasis, and Mechanisms of Pain

Osteosarcoma is the most common primary cancer of the bone and third most common cancer in children and adolescents with approximately 900 new cases annually in the United States. A major facet of osteosarcoma is its high level of genomic instability, in particular chromosomal instability, which is the result of increased or decreased chromosome number in a cell. Furthermore, pain is the most common symptomatic feature of osteosarcoma that lacks effective therapy. Pain in osteosarcoma is relatively more complicated than many other painful conditions requiring a more thorough understanding of its etiology, pathobiology, and neurobiology to allow the development of better therapies for reducing pain in osteosarcoma patients. Studies are underway to define the diverse modalities of presentation, growth, development, metastases, and nociception in osteosarcoma. New data from human studies in combination with data from studies incorporating transgenic mouse models of osteosarcoma are providing valuable insights into the mechanisms underlying the development of both the tumor and the tumor-induced pain. These new data will undoubtedly lead to improved prognoses, as well as the development of novel therapeutics that will significantly decrease bone cancer pain

Excitatory amino acid binding sites in the trigeminal principal sensory and spinal trigeminal nuclei of the rat

Quantitative autoradiography was used to examine the density and distribution of excitatory amino acid (EAA) binding site subtypes in the principal sensory and spinal trigeminal nuclei of the rat trigeminal complex. The highest densities of (NMDA), [alpha]-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA), kainate and metabotropic receptors were found in the superficial laminae (I and II) of subnucleus caudalis, a region known to be densely innervated by primary afferent nociceptive terminals. Lower densities of EAA binding sites were observed in spinal subnuclei interpolaris and oralis and within the principal sensory nucleus. These results are consistent with the hypothesis that EAAs are involved in primary afferent nociceptive neurotransmission.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29948/1/0000306.pd

Secretion of MCP-1 and other paracrine factors in a novel tumor-bone coculture model

BackgroundThe bone-tumor microenvironment encompasses unique interactions between the normal cells of the bone and marrow cavity and the malignant cells from a primary or metastasized cancer. A multitude of paracrine factors within this microenvironment such as the growth factor, TGF-beta, and the chemokine, MCP-1, are secreted by many of these cell types. These factors can act in concert to modulate normal and malignant cell proliferation, malignant cell migration and invasion and, often, mediate bone cancer pain. Although many valuable in vitro and in vivo models exist, identifying the relevant paracrine factors and deciphering their interactions is still a challenge. The aim of our study is to test an ex vivo coculture model that will allow monitoring of the expression, release and regulation of paracrine factors during interactions of an intact femur explant and tumor cells.MethodsIntact or marrow-depleted neonatal mouse femurs and select murine and human sarcoma or carcinoma cell lines were incubated singly or in coculture in specialized well plates. Viability of the bone and cells was determined by immunohistochemical stains, microscopy and marrow cytopreps. Secretion and mRNA expression of paracrine factors was quantitated by ELISA and real-time RT-PCR.ResultsCompartments of the bone were optimally viable for up to 48 h in culture and tumor cells for up to 4 days. Bone was the major contributor of TGF-beta and MMP2 whereas both bone and sarcoma cells secreted the chemokine MCP-1 in cocultures. Synergistic interaction between the femur and sarcoma resulted in enhanced MCP-1 secretion and expression in cocultures and was dependent on the presence of the hematopoietic component of the bone as well as other bone cells. In contrast, coculturing with breast carcinoma cells resulted in reduction of TGF-beta and MCP-1 secretion from the bone.ConclusionThese studies illustrate the feasibility of this model to examine paracrine interactions between intact bone and tumor cells. Further study of unique regulation of MCP-1 secretion and signaling between these cell types in different types of cancer will be possible using this simulated microenvironment

Targeting putative mu opioid/metabotropic glutamate receptor-5 heteromers produces potent antinociception in a chronic murine bone cancer model

Este proyecto se redacta como definición de la reforma del local mencionado con anterioridad, para su explotación comercial como tienda de conveniencia. El acceso principal se realiza desde la calle Felip II. Se plantea una separación funcional del local. En la planta baja se sitúan la zona de venta con las cajas de cobro, dos aseos aseo para el público y el oficio de panadería con su mostrador correspondiente. La planta baja comunica a través de una escalera y una plataforma montacargas con una entreplanta, denominada “altillo” en los planos. Aquí se ubican los espacios de acceso restringido: los vestuarios y aseos del personal, almacén, cuarto de control del almacén, cuarto de mercancía valiosa, cuarto de informática, cuarto de limpieza y cuarto de basuras. El almacén comunica directamente con la planta baja mediante una plataforma montacargas, situada cerca del acceso al local

Blockade of Adrenal Medulla-Derived Epinephrine Potentiates Bee Venom-Induced Antinociception in the Mouse Formalin Test: Involvement of Peripheral β-Adrenoceptors

The injection of diluted bee venom (DBV) into an acupoint has been used traditionally in eastern medicine to treat a variety of inflammatory chronic pain conditions. We have previously shown that DBV had a potent antinociceptive efficacy in several rodent pain models. However, the peripheral mechanisms underlying DBV-induced antinociception remain unclear. The present study was designed to investigate the role of peripheral epinephrine on the DBV-induced antinociceptive effect in the mouse formalin assay. Adrenalectomy significantly enhanced the antinociceptive effect of DBV during the late phase of the formalin test, while chemical sympathectomy had no effect. Intraperitoneal injection of epinephrine blocked this adrenalectomy-induced enhancement of the DBV-induced antinociceptive effect. Moreover, injection of a phenylethanolamine N-methyltransferase (PNMT) inhibitor enhanced the DBV-induced antinociceptive effect. Administration of nonselective β-adrenergic antagonists also significantly potentiated this DBV-induced antinociception, in a manner similar to adrenalectomy. These results demonstrate that the antinociceptive effect of DBV treatment can be significantly enhanced by modulation of adrenal medulla-derived epinephrine and this effect is mediated by peripheral β-adrenoceptors. Thus, DBV acupoint stimulation in combination with inhibition of peripheral β-adrenoceptors could be a potentially novel strategy for the management of inflammatory pain

The Effect of Electroacupuncture on Osteosarcoma Tumor Growth and Metastasis: Analysis of Different Treatment Regimens

Osteosarcoma is the most common malignant bone tumor found in children and adolescents and is associated with many complications including cancer pain and metastasis. While cancer patients often seek complementary and alternative medicine (CAM) approaches to treat cancer pain and fatigue or the side effects of chemotherapy and treatment, there is little known about the effect of acupuncture treatment on tumor growth and metastasis. Here we evaluate the effects of six different electroacupuncture (EA) regimens on osteosarcoma tumor growth and metastasis in both male and female mice. The most significant positive effects were observed when EA was applied to the ST-36 acupoint twice weekly (EA-2X/3) beginning at postimplantation day 3 (PID 3). Twice weekly treatment produced robust reductions in tumor growth. Conversely, when EA was applied twice weekly (EA-2X/7), starting at PID 7, there was a significant increase in tumor growth. We further demonstrate that EA-2X/3 treatment elicits significant reductions in tumor lymphatics, vasculature, and innervation. Lastly, EA-2X/3 treatment produced a marked reduction in pulmonary metastasis, thus providing evidence for EA’s potential antimetastatic capabilities. Collectively, EA-2X/3 treatment was found to reduce both bone tumor growth and lung metastasis, which may be mediated in part through reductions in tumor-associated vasculature, lymphatics, and innervation

Intrathecal Clonidine Suppresses Phosphorylation of the N-Methyl-D-Aspartate Receptor NR1 Subunit in Spinal Dorsal Horn Neurons of Rats with Neuropathic Pain

BACKGROUND: Intrathecal (IT) administration of the -2 adrenoceptor agonist, clonidine, produces significant analgesic effects. Although several mechanisms underlying clonidine-induced analgesia have been proposed, the possible interaction with N-methyl-D-aspartate (NMDA) receptors as a major antinociceptive mechanism has not been addressed. We designed the present study to determine whether clonidine or other analgesics can affect spinal NMDA receptor activation in rats with chronic constriction injury (CCI)-induced neuropathy. METHODS: Rats underwent unilateral CCI, and received IT clonidine (1, 5, 20 µg/rat), [d-Ala2, NMe-Phe4, Gly-ol5]-enkephalin (DAMGO, µ opioid receptor agonist, 1 µg/rat), gabapentin (anticonvulsant, 100 µg/rat) or vehicle 2 wks later. After drug injection, we measured the pain response to thermal or mechanical stimuli and used immunohistochemistry to evaluate spinal cord phosphorylated NMDA-receptor subunit 1 (pNR1) expression. RESULTS: Two weeks after CCI surgery, rats displayed significant mechanical allodynia and thermal hyperalgesia, and the spinal cord dorsal horn showed a significant increase in the number of pNR1 immunoreactive neurons. IT injection of clonidine (20 µg/rat), DAMGO and gabapentin potently reduced mechanical allodynia and thermal hyperalgesia. Importantly, IT clonidine, but not IT DAMGO or gabapentin, dose-dependently reduced CCI-induced pNR1 expression in all lamina of the spinal cord dorsal horn by 30 min after injection. In addition, IT injection of the -2 adrenoceptor antagonist, idazoxan (40 µg/rat) 10 min before clonidine injection completely reversed clonidines antihyperalgesic and antiallodynic effects, as well as clonidines suppressive effect on CCI-induced NR1 phosphorylation in the spinal cord dorsal horn. CONCLUSIONS: Our data indicate that IT clonidines antihyperalgesic/antiallodynic effect on neuropathic pain is associated with a significant reduction in spinal NMDA receptor phosphorylation and suggests a potentially novel mechanism of clonidines action.Supported by a grant (M103KV010015 06K2201 01510) from the Brain Research Center of the 21st Century Frontier Research Program funded by the Ministry of Science and Technology of the Republic of Korea and a grant (R01–2005-000–10580–0) from the Basic Research Program of the Korea Science & Engineering Foundation