Intestinal inflammation-associated hypersensitivity is attenuated in a DSS model of colitis in Sigma-1 knockout C57BL/6 mice

Altres ajuts: Acord transformatiu CRUE-CSICAjuts: The present work was funded by Laboratories ESTEVE, Barcelona, SpainSigma-1 receptors (σ1R) have been implicated in several pain pathways. We assessed the implication of σ1Rs in the development of intestinal inflammation and inflammation-associated referred hypersensitivity in a model of colitis in σ1R knockout (KO) mice. Colitis was induced with dextran sulfate sodium (DSS) in wild type (WT) and σ1R KO mice. The development of referred mechanical hypersensitivity (von Frey test) was assessed. Colonic and spinal changes in expression of immune- and sensory-related markers were also investigated (RT-qPCR/Western blot). Absence of σ1Rs had little impact in colitis generation and progression, although during the chronic phase a reduction in edema and a down-regulation of iNOS gene expression was observed. In σ1R KO mice, inflammation-associated hypersensitivity was significantly attenuated (paw) or completely prevented (abdomen). During colitis, in WT mice, changes in the colonic expression of nociceptive markers were observed during the acute and chronic phases of inflammation. Although σ1R KO mice showed similar regulation in the acute phase, an attenuated response was observed during the chronic phase of colitis. These differences were especially relevant for CB2 and TRPV1 receptors, which could play an important role in σ1-mediated regulation of sensitivity. No changes were detected on ERK phosphorylation at the level of the lumbosacral spinal cord. In summary, intestinal inflammation-associated referred hyperalgesia was reduced (paw) or absent (abdomen) in σ1R KO mice, thus confirming an important role for σ1R in the development of colitis-associated hypersensitivity. These results identify σ1Rs as a possible therapeutic target for the treatment of hypersensitivity associated to intestinal inflammation

Genetic and Pharmacological Blockade of Sigma-1 Receptors Attenuates Inflammation-Associated Hypersensitivity during Acute Colitis in CD1 Mice

Sigma-1 receptors (σRs) are implicated in nociception, including pain sensitization, and inflammation. We assessed the role of σRs on acute colitis-associated hypersensitivity using both genetic (constitutive knockout) and pharmacological blockade of the receptor. Colitis was induced in CD1 wild-type (WT) and σR KO mice (exposure to dextran sodium sulfate, 3%). A von Frey test was used to assess referred mechanosensitivity (abdominal and plantar withdrawal responses). The effects of the selective σR antagonists BD1063 and E-52862 were also assessed in WT animals. The expression of immune and sensory-related markers (RT-qPCR, Western blot) was assessed in the colon and lumbosacral spinal cord. The genetic ablation or pharmacological blockade of σRs attenuated acute colonic inflammation in a similar manner. Mechanosensitivity was similar in WT and σR KO mice before colitis. In WT mice, but not in σR KO, colitis was associated with the development of referred mechanical hypersensitivity, manifested as a reduction in the withdrawal thresholds to mechanical probing (paw and abdominal wall). In WT mice, BD1063 and E-52862 blocked colitis-associated hypersensitivity. A genotype- and treatment-related differential regulation of sensory-related markers was detected locally (colon) and within the spinal cord. σRs are involved in the development of acute intestinal inflammation and its associated referred mechanical hypersensitivity. The selective modulation of sensory-related pathways within the colon and spinal cord might be part of the underlying mechanisms. These observations support the pharmacological use of σR antagonists for the treatment of intestinal inflammation-induced hypersensitivity

Selective blockade of the sigma-1 receptor for the treatment of pain of different aetiology: Preclinical studies

[spa] La presente Tesis Doctoral se centra en el estudio del receptor sigma-1 (σ1) en el campo del dolor. Esta investigación ha sido parte de un proyecto de la empresa farmacéutica ESTEVE centrado en el descubrimiento de fármacos con afinidad por el receptor σ1 para el tratamiento de dolor de diferente etiología. El objetivo principal de esta Tesis fue explorar el interés terapéutico del bloqueo del receptor σ1 para el manejo farmacológico del dolor neuropático, inflamatorio y postoperatorio. Se evaluó la potencia y eficacia del antagonista selectivo del receptor σ1, S1RA (E-52862) en estos diferentes tipos de dolor, y se comparó con otros fármacos analgésicos comercializados. Con este fin, se emplearon dos especies (rata y ratón), diferentes evaluaciones comportamentales relacionadas con el dolor (respuesta de retirada de la pata trasera a la estimulación térmica y mecánica), y diferentes estrategias farmacológicas (administración sistémica aguda y repetida del antagonista E-52862). También se utilizaron ratones knockout por el receptor σ1 para estudiar la especificidad in vivo del E-52862 y la participación del receptor σ1 en la modulación espinal de varios marcadores moleculares relacionados con el dolor con el fin de determinar el mecanismo de acción del receptor. En resumen, los resultados de esta Tesis Doctoral proporcionan nuevos conocimientos sobre el receptor σ1 y apoyan el desarrollo clínico de antagonistas selectivos por este receptor como una intervención terapéutica adecuada para lograr analgesia en condiciones de dolor de diferente etiología.[eng] The present Doctoral Thesis focuses on the study of the Sigma-1 receptor (σ1R) in the field of pain. This research has been a part of the preclinical σ1R project focusing on drug discovery of σ1R ligands for the treatment of pain of different aetiologies at the pharmaceutical company ESTEVE. The main goal of this Doctoral Thesis was to explore the therapeutic interest of σ1R blockade in the pharmacological management of neuropathic, inflammatory and postoperative pain. Neuropathic pain was the main indication at the beginning of this Doctoral Thesis, but inflammatory and postoperative pain had never been explored. The efficacy of the selective σ1R antagonist S1RA (E-58262) in these different types of pain was evaluated, and its potency and efficacy was compared to other marketed analgesic drugs. To this end, two species (rat and mouse), different pain-related behavioural endpoints (hind paw withdrawal response to thermal and mechanical stimulation), and different pharmacological strategies (systemic acute and repeated E-52862 administration), were evaluated. σ1R knockout mice were also used to study the in vivo specificity of E-52862 and the involvement of σ1R in the spinal modulation of several pain-related molecular markers in order to ascertain the mechanism of action of σ1R. Taken together, the results of this Doctoral Thesis provide new knowledge about σ1R and support the clinical development of selective σ1R antagonists as a suitable therapeutic intervention to achieve analgesia in pain conditions of different aetiology

The selective sigma-1 receptor antagonist E-52862 attenuates neuropathic pain of different aetiology in rats

E-52862 is a selective σ(1)R antagonist currently undergoing phase II clinical trials for neuropathic pain and represents a potential first-in-class analgesic. Here, we investigated the effect of single and repeated administration of E-52862 on different pain-related behaviours in several neuropathic pain models in rats: mechanical allodynia in cephalic (trigeminal) neuropathic pain following chronic constriction injury of the infraorbital nerve (IoN), mechanical hyperalgesia in streptozotocin (STZ)-induced diabetic polyneuropathy, and cold allodynia in oxaliplatin (OX)-induced polyneuropathy. Mechanical hypersensitivity induced after IoN surgery or STZ administration was reduced by acute treatment with E-52862 and morphine, but not by pregabalin. In the OX model, single administration of E-52862 reversed the hypersensitivity to cold stimuli similarly to 100 mg/kg of gabapentin. Interestingly, repeated E-52862 administration twice daily over 7 days did not induce pharmacodynamic tolerance but an increased antinociceptive effect in all three models. Additionally, as shown in the STZ and OX models, repeated daily treatment with E-52862 attenuated baseline pain behaviours, which supports a sustained modifying effect on underlying pain-generating mechanisms. These preclinical findings support a role for σ(1)R in neuropathic pain and extend the potential for the use of selective σ(1)R antagonists (e.g., E-52862) to the chronic treatment of cephalic and extra-cephalic neuropathic pain