Sigma-1 receptor agonism exacerbates immune-driven nociception: Role of TRPV1 + nociceptors.

The analgesic effects of sigma-1 antagonists are undisputed, but the effects of sigma-1 agonists on pain are not well studied. Here, we used a mouse model to show that the administration of the sigma-1 agonists dextromethorphan (a widely used antitussive drug), PRE-084 (a standard sigma-1 ligand), and pridopidine (a selective drug being investigated in clinical trials for the treatment of neurodegenerative diseases) enhances PGE2-induced mechanical hyperalgesia. Superficial plantar incision induced transient weight-bearing asymmetry at early time points, but the mice appeared to recover at 24 h, despite noticeable edema and infiltration of neutrophils (a well-known cellular source of PGE2) at the injured site. Sigma-1 agonists induced a relapse of weight bearing asymmetry in a manner dependent on the presence of neutrophils. The effects of sigma-1 agonists were all reversed by administration of the sigma-1 antagonist BD-1063 in wild-type mice, and were absent in sigma-1 knockout mice, supporting the selectivity of the effects observed. The proalgesic effects of sigma-1 agonism were also abolished by the TRP antagonist ruthenium red and by in vivo resiniferatoxin ablation of TRPV1 + peripheral sensory neurons. Therefore, sigma-1 agonism exacerbates pain-like responses in mice with a mild inflammatory state through the action of TRPV1 + nociceptors. We also show that sigma-1 receptors are present in most (if not all) mouse and human DRG neurons. If our findings translate to humans, further studies will be needed to investigate potential proalgesic effects induced by sigma-1 agonism in patients treated with sigma-1 agonists.

Paclitaxel antitumor effect improvement in lung cancer and prevention of the painful neuropathy using large pegylated cationic liposomes.

Paclitaxel (PTX), a drug widely used in lung cancer, has serious limitations including the development of peripheral neurotoxicity, which may lead to treatment discontinuation and therapy failure. The transport of PTX in large cationic liposomes could avoid this undesirable effect, improving the patient's prognosis. PTX was encapsulated in cationic liposomes with two different sizes, MLV (180-200 nm) and SUV (80-100 nm). In both cases, excellent biocompatibility and improved internalization and antitumor effect of PTX were observed in human and mice lung cancer cells in culture, multicellular spheroids and cancer stem cells (CSCs). In addition, both MLV and SUV with a polyethylene glycol (PEG) shell, induced a greater tumor volume reduction than PTX (56.4 % and 57.1 % vs. 36.7 %, respectively) in mice. Interestingly, MLV-PEG-PTX did not induce either mechanical or heat hypersensitivity whereas SUV-PEG-PTX produced a similar response to free PTX. Analysis of PTX distribution showed a very low concentration of the drug in the dorsal root ganglia (DRG) with MLV-PEG-PTX, but not with SUV-PEG-PTX or free PTX. These results support the hypothesis that PTX induces peripheral neuropathy by penetrating the endothelial fenestrations of the DRG (80-100 nm, measured in mice). In conclusion, our larger liposomes (MLV-PEG-PTX) not only showed biocompatibility, antitumor activity against CSCs, and in vitro and in vivo antitumor effect that improved PTX free activity, but also protected from PTX-induced painful peripheral neuropathy. These advantages could be used as a new strategy of lung cancer chemotherapy to increase the PTX activity and reduce its side effects.

Urinary bladder sigma-1 receptors: A new target for cystitis treatment.

No adequate treatment is available for painful urinary bladder disorders such as interstitial cystitis/bladder pain syndrome, and the identification of new urological therapeutic targets is an unmet need. The sigma-1 receptor (σ1-R) modulates somatic pain, but its role in painful urological disorders is unexplored. The urothelium expresses many receptors typical of primary sensory neurons (e.g. TRPV1, TRPA1 and P2X3) and high levels of σ1-R have been found in these neurons; we therefore hypothesized that σ1-R may also be expressed in the urothelium and may have functional relevance in this tissue. With western blotting and immunohistochemical methods, we detected σ1-R in the urinary bladder in wild-type (WT) but not in σ1-R-knockout (σ1-KO) mice. Interestingly, σ1-R was located in the bladder urothelium not only in mouse, but also in human bladder sections. The severity of histopathological (edema, hemorrhage and urothelial desquamation) and biochemical alterations (enhanced myeloperoxidase activity and phosphorylation of extracellular regulated kinases 1/2 [pERK1/2]) that characterize cyclophosphamide-induced cystitis was lower in σ1-KO than in WT mice. Moreover, cyclophosphamide-induced pain behaviors and referred mechanical hyperalgesia were dose-dependently reduced by σ1-R antagonists (BD-1063, NE-100 and S1RA) in WT but not in σ1-KO mice. In contrast, the analgesic effect of morphine was greater in σ1-KO than in WT mice. Together these findings suggest that σ1-R plays a functional role in the mechanisms underlying cyclophosphamide-induced cystitis, and modulates morphine analgesia against urological pain. Therefore, σ1-R may represent a new drug target for urinary bladder disorders.

Intracolonic Mustard Oil Induces Visceral Pain in Mice by TRPA1-Dependent and -Independent Mechanisms: Role of Tissue Injury and P2X Receptors.

Both TRPA1 and purinergic P2X receptors have been proposed as potential targets for the treatment of visceral pain. We found that the intracolonic administration of a low dose mustard oil (0.5%), a well-known TRPA1 agonist, produced nociceptive responses and abdominal wall referred mechanical hyperalgesia, without inducing apparent tissue damage. Both nociceptive responses and referred hyperalgesia were abolished by the ablation of TRPV1-expressing neurons (and the consequent ablation of TRPA1+ nociceptors) by resiniferatoxin (RTX) treatment, and by the TRPA1 antagonist AP18. However, a higher dose of mustard oil (2.5%) damaged the colonic epithelium and induced pERK activation in the spinal cord, and these processes were clearly independent of TRPV1-expressing neurons ablated by RTX. This higher dose of mustard oil induced nociceptive responses and referred mechanical hyperalgesia which were insensitive or only slightly sensitive to resiniferatoxin or AP18, but were markedly reduced by the P2X antagonist TNP-ATP, which is known to inhibit nociceptive actions induced by ATP released from injured tissues. In conclusion, whereas a low dose of intracolonic mustard oil induces visceral pain in a manner fully dependent on TRPA1 actions, when a high dose of this chemical irritant is used, visceral pain becomes mostly independent of TRPA1 activation but clearly enhanced by ATP purportedly released by the damaged colonic epithelium. Therefore, TRPA1 inhibition is not sufficient to substantially decrease visceral pain during tissue injury, whereas purinergic antagonism appears to be a more effective strategy.

Grip strength in mice with joint inflammation: A rheumatology function test sensitive to pain and analgesia.

Grip strength deficit is a measure of pain-induced functional disability in rheumatic disease. We tested whether this parameter and tactile allodynia, the standard pain measure in preclinical studies, show parallels in their response to analgesics and basic mechanisms. Mice with periarticular injections of complete Freund's adjuvant (CFA) in the ankles showed periarticular immune infiltration and synovial membrane alterations, together with pronounced grip strength deficits and tactile allodynia measured with von Frey hairs. However, inflammation-induced tactile allodynia lasted longer than grip strength alterations, and therefore did not drive the functional deficits. Oral administration of the opioid drugs oxycodone (1-8 mg/kg) and tramadol (10-80 mg/kg) induced a better recovery of grip strength than acetaminophen (40-320 mg/kg) or the nonsteroidal antiinflammatory drugs ibuprofen (10-80 mg/kg) or celecoxib (40-160 mg/kg); these results are consistent with their analgesic efficacy in humans. Functional impairment was generally a more sensitive indicator of drug-induced analgesia than tactile allodynia, as drug doses that attenuated grip strength deficits showed little or no effect on von Frey thresholds. Finally, ruthenium red (a nonselective TRP antagonist) or the in vivo ablation of TRPV1-expressing neurons with resiniferatoxin abolished tactile allodynia without altering grip strength deficits, indicating that the neurobiology of tactile allodynia and grip strength deficits differ. In conclusion, grip strength deficits are due to a distinct type of pain that reflects an important aspect of the human pain experience, and therefore merits further exploration in preclinical studies to improve the translation of new analgesics from bench to bedside.

Improvement of the antioxidant and hypolipidaemic effects of cowpea flours (Vigna unguiculata) by fermentation: results of in vitro and in vivo experiments.

BACKGROUND: The antioxidant capacity and hypolipidaemic effects of Vigna unguiculata, as well as their potential improvement by different fermentation and thermal processes were studied using in vitro and in vivo methods. RESULTS: Phenolic content and reducing capacity of legume acetone extract were significantly increased by different fermentation processes, and by the thermal treatment of fermented legume flours. TBARS inhibiting capacity was increased by fermentation but not by thermal treatment. A higher ability to decrease Cu(2+)/H2O2-induced electrophoretic mobility of LDL was found in fermented when compared to raw legume extracts, and a higher protective effect on short term metabolic status of HT-29 cells was found for raw and lactobacillus-fermented Vigna followed by naturally fermented Vigna extracts. Significant improvements in plasma antioxidant capacity and hepatic activity of antioxidant enzymes were observed in rats that consumed fermented legume flours when compared to the untreated legume or a casein-methionine control diet. In addition, liver weight and plasma levels of cholesterol and triglycerides were also positively affected by untreated or naturally fermented Vigna. CONCLUSION: V. unguiculata has demonstrated its potential as a functional food with interesting antioxidant and lipid lowering properties, which can be further augmented by fermentation processes associated or not to thermal processing.

Genetic inactivation and pharmacological blockade of sigma-1 receptors prevent paclitaxel-induced sensory-nerve mitochondrial abnormalities and neuropathic pain in mice.

BACKGROUND: Paclitaxel, a widely-used antineoplastic drug, produces a painful peripheral neuropathy that in rodents is associated with peripheral-nerve mitochondrial alterations. The sigma-1 receptor (σ1R) is a ligand-regulated molecular chaperone involved in mitochondrial calcium homeostasis and pain hypersensitivity. This receptor plays a key role in paclitaxel-induced neuropathic pain, but it is not known whether it also modulates mitochondrial abnormalities.In this study, we used a mouse model of paclitaxel-induced neuropathic pain to test the involvement of the σ1R in the mitochondrial abnormalities associated with paclitaxel, by using genetic (σ1R knockout mice) and pharmacological (σ1R antagonist) approaches. RESULTS: Paclitaxel administration to wild-type (WT) mice produced cold- and mechanical-allodynia, and an increase in the frequency of swollen and vacuolated mitochondria in myelinated A-fibers, but not in C-fibers, of the saphenous nerve. Behavioral and mitochondrial alterations were marked at 10 days after paclitaxel-administration and had resolved at day 28. In contrast, paclitaxel treatment did not induce allodynia or mitochondrial abnormalities in σ1R knockout mice. Moreover, the prophylactic treatment of WT mice with BD-1063 also prevented the neuropathic pain and mitochondrial abnormalities induced by paclitaxel. CONCLUSIONS: These results suggest that activation of the σ1R is necessary for development of the sensory nerve mitochondrial damage and neuropathic pain produced by paclitaxel. Therefore, σ1R antagonists might have therapeutic value for the prevention of paclitaxel-induced neuropathy.

[Homocysteine and cognitive impairment in Parkinson's disease]. / Homocisteína y deterioro cognitivo en la enfermedad de Parkinson.

INTRODUCTION: The relationship between homocysteine (Hc) and vascular diseases has been known for more than 30 years. Lately, Hc has also been related to cognitive and motor impairment. In Parkinson's disease (PD), chronic treatment with levodopa could induce higher levels of Hc, and thus may increase risk of cognitive impairment. AIMS: To confirm that PD patients treated with levodopa have higher levels of Hc and to establish a relationship between Hc, folic acid and vitamin B12 levels. Also, we studied a possible link between those variables and cognitive function. PATIENTS AND METHODS: 58 patients with diagnosis of PD were included (45 under treatment with levodopa). Basal levels of Hc, vitamin B12 and folic acid were determined. Forty five patients underwent neuropsychological evaluation. RESULTS: Hc levels were significantly higher in patients taking levodopa and were not related to levodopa dosage or treatment duration. There was a negative correlation between Hc levels and those of vitamin B12 and folic acid in men but we found no such correlation in women. Entacapone was not found to reduce Hc levels. Hc levels were significantly higher in patients with cognitive impairment (9 out of 45 patients). CONCLUSIONS: Our study confirms presence of high levels of Hc in PD patients under treatment with levodopa, more evident in patients with cognitive impairment.

Homocisteína y deterioro cognitivo en la enfermedad de Parkinson / Homocysteine and cognitive impairment in Parkinson’s disease

Introducción. La relación entre homocisteína (Hc) y enfermedades vasculares se conoce desde hace más de 30 años. En los últimos años se ha relacionado también con deterioro cognitivo y motor. En la enfermedad de Parkinson (EP), el tratamiento crónico con levodopa puede inducir un incremento en los niveles de Hc, implicando un riesgo añadido para el deterioro cognitivo. Objetivos. Confirmar la elevación de los niveles de Hc en pacientes con EP tratados con levodopa, su relación con los niveles de vitamina B12 y folato, y si podía existir una relación entre dichas variables y la función cognitiva. Pacientes y métodos. Se incluyeron 58 pacientes diagnosticados de EP (45 en tratamiento con levodopa), se determinaron los niveles basales de Hc, vitamina B12 y folato, y se realizó una evaluación neuropsicológica en 45 de los pacientes. Resultados. El nivel de Hc estaba significativamente más elevado en los pacientes en tratamiento con levodopa, sin relación con la dosis ni el tiempo en tratamiento. Existía una correlación negativa entre los valores de Hc y vitamina B12 y folato en los hombres, que no se observó en las mujeres. Tomar entacapona no redujo los niveles de Hc. El nivel de Hc estaba significativamente más elevado en los pacientes con deterioro cognitivo (9 de los 45 evaluados).Conclusiones. Nuestro estudio confirma la elevación de los niveles de Hc en pacientes con EP en tratamiento con levodopa, y de forma más evidente en los pacientes con deterioro cognitivo (AU)

Introduction. The relationship between homocysteine (Hc) and vascular diseases has been known for more than 30 years. Lately, Hc has also been related to cognitive and motor impairment. In Parkinson’s disease (PD), chronic treatment with levodopa could induce higher levels of Hc, and thus may increase risk of cognitive impairment. Aims. To confirm that PD patients treated with levodopa have higher levels of Hc and to establish a relationship between Hc, folic acid and vitamin B12 levels. Also, we studied a possible link between those variables and cognitive function. Patients and methods. 58 patients with diagnosis of PD were included (45 under treatment with levodopa). Basal levels of Hc, vitamin B12 and folic acid were determined. Forty five patients underwent neuropsychological evaluation. Results. Hc levels were significantly higher in patients taking levodopa and were not related to levodopa dosage or treatment duration. There was a negative correlation between Hc levels and those of vitamin B12 and folic acid in men but we found no such correlation in women. Entacapone was not found to reduce Hc levels. Hc levels were significantly higher in patients with cognitive impairment (9 out of 45 patients). Conclusions. Our study confirms presence of high levels of Hc in PD patients under treatment with levodopa, more evidentin patients with cognitive impairment (AU)

Changes in intracellular sodium, chlorine, and potassium concentrations in staurosporine-induced apoptosis.

Ion gradients across the plasma membrane, fundamentally K(+), play a pivotal role in the execution phase of apoptosis. However, little is known about other monovalent anions (Cl(-)) or cations (Na(+)) in apoptosis. In addition, the relationship between changes in total ion composition and morphological and biochemical events are poorly understood. We investigated simultaneous changes in sodium (Na), chlorine (Cl), and potassium (K) concentrations in stauroporine-induced apoptosis by quantitative electron probe X-ray microanalysis (EPXMA) in single cells. Apoptotic cells identified unequivocally from the presence of chromatin condensation in backscattered electron images were characterized by an increase in intracellular Na, a decrease in intracellular Cl and K concentrations, and a decrease in K/Na ratio. The ouabain-sensitive Rb-uptake assay demonstrated a net decrease in Na(+)/K(+)-ATPase activity, suggesting that increases in Na and decreases in K and the K/Na ratio in apoptotic cells were related with inhibition of the Na(+)/K(+)-ATPase pump. These changes in diffusible elements were associated with externalization of phosphatidyl serine and oligonucleosomal fragmentation of DNA. This alteration in ion homeostasis and morphological hallmarks of apoptosis occur in cells that have lost their inner mitochondrial transmembrane potential and before the plasma membrane becomes permeable.

Dependencia temporal del valor pronóstico de los receptores esteroides en el cáncer de mama / Temporary dependency of steroid-receptor prognostic value in breast cancer

FUNDAMENTO: La influencia de los factores pronósticos en el cáncer de mama presenta variaciones temporales a lo largo de su seguimiento. Nuestro objetivo fue valorar los cambios acontecidos en el riesgo relativo de recurrencia aportado por los receptores esteroides. PACIENTES Y MÉTODO: Estudiamos a 455 pacientes con cáncer de mama primario operable de las que se determinaron parámetros clínicos, histopatológicos y los receptores de estrógeno (RE) y progesterona (RPg), con un seguimiento medio de 72 meses (intervalo, 42-130 meses), valorando su significación pronóstica en la supervivencia libre de enfermedad (SLE) y supervivencia global (SG) mediante un análisis multivariante proporcional y modelo de regresión no proporcional de Cox (dependiente del tiempo). RESULTADOS: El 66,8 por ciento de las pacientes resultaron RE+ y un 54,7 por ciento RPg+. Encontramos una alta asociación de ambos receptores con el grado histológico, permeación linfática-venosa, estado menopáusico e índice de mitosis. No observamos tal asociación con el tamaño, invasión ganglionar axilar y estadio del tumor. En el análisis univariable, el fenotipo RE-/RPg- frente a RE+/RPg+ presentó un riesgo relativo de 2,15 (IC del 95 por ciento, 1,59-2,99) en SLE (p = 0,001) y 1,95 (IC del 95 por ciento, 1,38-2,59) en SG (p = 0,0043). En el análisis multivariante, el fenotipo RE-/RPg- frente a RE+/RPg+ fue un factor pronóstico independiente junto con el grado de invasión ganglionar axilar y el índice de mitosis, tanto para la SLE como la SG. En el modelo dependiente del tiempo, las pacientes RE-/RPg- presentaron un riesgo relativo de recidiva 5,6 veces superior a las pacientes RE+/RPg+ al iniciar el seguimiento, que decreció durante los 4 primeros años hasta converger. CONCLUSIONES: En pacientes con cáncer de mama el fenotipo del receptor esteroide tiene un valor pronóstico relativo, cuya significación disminuye con el tiempo (AU)