Aging and miR-155 in mice influence survival and neuropathic pain after spinal cord injury.

Spinal cord injury (SCI) elicits chronic pain in 65% of individuals. In addition, SCI afflicts an increasing number of aged individuals, and those with SCI are predisposed to shorter lifespan. Our group previously identified that deletion of the microRNA miR-155 reduced neuroinflammation and locomotor deficits after SCI. Here, we hypothesized that aged mice would be more susceptible to pain symptoms and death soon after SCI, and that miR-155 deletion would reduce pain symptoms in adult and aged mice and improve survival. Adult (2 month-old) and aged (20 month-old) female wildtype (WT) and miR-155 knockout (KO) mice received T9 contusion SCI. Aged WT mice displayed reduced survival and increased autotomy - a symptom of spontaneous pain. In contrast, aged miR-155 KO mice after SCI were less susceptible to death or spontaneous pain. Evoked pain symptoms were tested using heat (Hargreaves test) and mechanical (von Frey) stimuli. At baseline, aged mice showed heightened heat sensitivity. After SCI, adult and aged WT and miR-155 KO mice all exhibited heat and mechanical hypersensitivity at all timepoints. miR-155 deletion in adult (but not aged) mice reduced mechanical hypersensitivity at 7 and 14 d post-SCI. Therefore, aging predisposes mice to SCI-elicited spontaneous pain and expedited mortality. miR-155 deletion in adult mice reduces evoked pain symptoms, and miR-155 deletion in aged mice reduces spontaneous pain and expedited mortality post-SCI. This study highlights the importance of studying geriatric models of SCI, and that inflammatory mediators such as miR-155 are promising targets after SCI for improving pain relief and longevity.

High-fat diet worsens the impact of aging on microglial function and morphology in a region-specific manner.

Hippocampal microglia are vulnerable to the effects of aging, displaying a primed phenotype and hyper-responsiveness to various stimuli. We have previously shown that short-term high-fat diet (HFD) significantly impairs hippocampal- and amygdala-based cognitive function in the aged without affecting it in the young. Here, we assessed if morphological and functional changes in microglia might be responsible for this. We analyzed hippocampus and amygdala from young and aging rats that had been given three days HFD, a treatment sufficient to cause both hippocampal- and amygdala-dependent cognitive and neuroinflammatory differences in the aged. Aging led to the expected priming of hippocampal microglia in that it increased microglial numbers and reduced branching in this region. Aging also increased microglial phagocytosis of microbeads in the hippocampus, but the only effect of HFD in this region was to increase the presence of enlarged synaptophysin boutons in the aged, indicative of neurodegeneration. In the amygdala, HFD exacerbated the effects of aging on microglial priming (morphology) and markedly suppressed phagocytosis without notably affecting synaptophysin. These data reveal that, like the hippocampus, the amygdala displays aging-related microglial priming. However, the microglia in this region are also uniquely vulnerable to the detrimental effects of short-term HFD in aging.

Spinal Cord Injury in Rats Dysregulates Diurnal Rhythms of Fecal Output and Liver Metabolic Indicators.

Spinal cord injury (SCI) dysregulates metabolic homeostasis. Metabolic homeostasis is optimized across the day by the circadian system. Despite the prevalence of metabolic pathologies after SCI, post-SCI circadian regulation of metabolism remains understudied. Here, we hypothesized that SCI in rats would disrupt circadian regulation of key metabolic organs, leading to metabolic dysregulation. Female and male Sprague-Dawley rats received moderate thoracic (T)-9 contusion SCI (or sham surgery). First, SCI disrupted diurnal rhythms in two metabolic behaviors: fecal production and food intake rhythms were ablated acutely. SCI also expedited whole-gut transit time. In parallel, acute SCI increased plasma glucose. Diurnal glucose storage-release cycles regulated by the liver were disrupted by SCI, which also increased liver glucose metabolism messenger RNAs (mRNAs). Further, SCI disrupted liver clock gene expression and suppressed inflammatory gene rhythms. Together, our novel data suggest that SCI disrupts typical metabolic and circadian function. Improving post-SCI metabolic function could enhance recovery of homeostasis.

Neuroinflammatory priming to stress is differentially regulated in male and female rats.

Exposure to stressors can enhance neuroinflammatory responses, and both stress and neuroinflammation are predisposing factors in the development of psychiatric disorders. Females suffer disproportionately more from several psychiatric disorders, yet stress-induced changes in neuroinflammation have primarily been studied in males. Here we tested whether exposure to inescapable tail shock sensitizes or 'primes' neuroinflammatory responses in male and female rats. At 24 h post-stress, male and female rats exposed to a peripheral immune challenge enhanced neuroinflammatory responses and exacerbated anxiety- and depressive-like behaviors. These changes are likely glucocorticoid dependent, as administering exogenous CORT, caused a similar primed inflammatory response in the hippocampus of male and female rats. Further, stress disinhibited anti-inflammatory signaling mechanisms (such as CD200R) in the hippocampus of male and female rats. In males, microglia are considered the likely cellular source mediating neuroinflammatory priming; stress increased cytokine expression in ex vivo male microglia. Conversely, microglia isolated from stressed or CORT treated females did not exhibit elevated cytokine responses. Microglia isolated from both stressed male and female rats reduced phagocytic activity; however, suggesting that microglia from both sexes experience stress-induced functional impairments. Finally, an immune challenge following either stress or CORT in females, but not males, increased peripheral inflammation (serum IL-1ß). These novel data suggest that although males and females both enhance stress-induced neuroinflammatory and behavioral responses to an immune challenge, this priming may occur through distinct, sex-specific mechanisms.

Spatiotemporal magnetic fields enhance cytosolic Ca2+ levels and induce actin polymerization via activation of voltage-gated sodium channels in skeletal muscle cells.

Cellular function is modulated by the electric membrane potential controlling intracellular physiology and signal propagation from a motor neuron to a muscle fiber resulting in muscle contraction. Unlike electric fields, magnetic fields are not attenuated by biological materials and penetrate deep into the tissue. We used complex spatiotemporal magnetic fields (17-70 mT) to control intracellular signaling in skeletal muscle cells. By changing different parameters of the alternating magnetic field (amplitude, inversion time, rotation frequency), we induced transient depolarization of cellular membranes leading to i) Na+ influx through voltage-gated sodium channels (VGSC), ii) cytosolic calcium increase, and iii) VGSC- and ryanodine receptor-dependent increase of actin polymerization. The ion fluxes occurred only, when the field was applied and returned to baseline after the field was turned off. The 30-s-activation-cycle could be repeated without any loss of signal intensity. By contrast, static magnetic fields of the same strength exhibited no effect on myotube Ca2+ levels. Mathematical modeling suggested a role for the alternating magnetic field-induced eddy current, which mediates a local change in the membrane potential triggering the activation of VGSC. These findings might pave the way for the use of complex magnetic fields to improve function of skeletal muscles in myopathies.

Spinal Cord Injury in Rats Disrupts the Circadian System.

Spinal cord injury (SCI) perturbs many physiological systems. The circadian system helps maintain homeostasis throughout the body by synchronizing physiological and behavioral functions to predictable daily events. Whether disruption of these coordinated daily rhythms contributes to SCI-associated pathology remains understudied. Here, we hypothesized that SCI in rats would dysregulate several prominent circadian outputs including glucocorticoids, core temperature, activity, neuroinflammation, and circadian gene networks. Female and male Sprague Dawley rats were subjected to clinically relevant thoracic 9 moderate contusion SCI (or laminectomy sham surgery). Diurnal measures-including rhythms of plasma corticosterone (CORT), body temperature, and activity (using small implanted transmitters), and intraspinal circadian and inflammatory gene expression-were studied prior to and after surgery. SCI caused overall increases and disrupted rhythms of the major rodent glucocorticoid, CORT. Presurgery and sham rats displayed expected rhythms in body temperature and activity, whereas rats with SCI had blunted daily rhythms in body temperature and activity. In parallel, SCI disrupted intraspinal rhythms of circadian clock gene expression. Circadian clock genes can act as transcriptional regulators of inflammatory pathways. Indeed, SCI rats also showed dysregulated rhythms in inflammatory gene expression in both the epicenter and distal spinal cord. Our data show that moderate SCI in rats causes wide-ranging diurnal rhythm dysfunction, which is severe at acute time points and gradually recovers over time. Normalizing post-SCI diurnal rhythms could enhance the recovery of homeostasis and quality of life.

Exploring acute-to-chronic neuropathic pain in rats after contusion spinal cord injury.

Spinal cord injury (SCI) causes chronic pain in 65% of individuals. Unfortunately, current pain management is inadequate for many SCI patients. Rodent models could help identify how SCI pain develops, explore new treatment strategies, and reveal whether acute post-SCI morphine worsens chronic pain. However, few studies explore or compare SCI-elicited neuropathic pain in rats. Here, we sought to determine how different clinically relevant contusion SCIs in male and female rats affect neuropathic pain, and whether acute morphine worsens later chronic SCI pain. First, female rats received sham surgery, or 150kDyn or 200kDyn midline T9 contusion SCI. These rats displayed modest mechanical allodynia and long-lasting thermal hyperalgesia. Next, a 150kDyn (1s dwell) midline contusion SCI was performed in male and female rats. Interestingly, males, but not females showed SCI-elicited mechanical allodynia; rats of both sexes had thermal hyperalgesia. In this model, acute morphine treatment had no significant effect on chronic neuropathic pain symptoms. Unilateral SCIs can also elicit neuropathic pain that could be exacerbated by morphine, so male rats received unilateral T13 contusion SCI (100kDyn). These rats exhibited significant, transient mechanical allodynia, but not thermal hyperalgesia. Acute morphine did not exacerbate chronic pain. Our data show that specific rat contusion SCI models cause neuropathic pain. Further, chronic neuropathic pain elicited by these contusion SCIs was not amplified by our course of early post-trauma morphine. Using clinically relevant rat models of SCI could help identify novel pain management strategies.

Morphine amplifies mechanical allodynia via TLR4 in a rat model of spinal cord injury.

Central neuropathic pain (CNP) is a pervasive, debilitating problem that impacts thousands of people living with central nervous system disorders, including spinal cord injury (SCI). Current therapies for treating this type of pain are ineffective and often have dose-limiting side effects. Although opioids are one of the most commonly used CNP treatments, recent animal literature has indicated that administering opioids shortly after a traumatic injury can actually have deleterious effects on long-term health and recovery. In order to study the deleterious effects of administering morphine shortly after trauma, we employed our low thoracic (T13) dorsal root avulsion model (Spinal Neuropathic Avulsion Pain, SNAP). Administering a weeklong course of 10mg/kg/day morphine beginning 24h after SNAP resulted in amplified mechanical allodynia. Co-administering the non-opioid toll-like receptor 4 (TLR4) antagonist (+)-naltrexone throughout the morphine regimen prevented morphine-induced amplification of SNAP. Exploration of changes induced by early post-trauma morphine revealed that this elevated gene expression of TLR4, TNF, IL-1ß, and NLRP3, as well as IL-1ß protein at the site of spinal cord injury. These data suggest that a short course of morphine administered early after spinal trauma can exacerbate CNP in the long term. TLR4 initiates this phenomenon and, as such, may be potential therapeutic targets for preventing the deleterious effects of administering opioids after traumatic injury.

Anti-inflammatory and antiatherogenic effects of the NLRP3 inflammasome inhibitor arglabin in ApoE2.Ki mice fed a high-fat diet.

BACKGROUND: This study was designed to evaluate the effect of arglabin on the NLRP3 inflammasome inhibition and atherosclerotic lesion in ApoE2Ki mice fed a high-fat Western-type diet. METHODS AND RESULTS: Arglabin was purified, and its chemical identity was confirmed by mass spectrometry. It inhibited, in a concentration-dependent manner, interleukin (IL)-1ß and IL-18, but not IL-6 and IL-12, production in lipopolysaccharide and cholesterol crystal-activated cultured mouse peritoneal macrophages, with a maximum effect at ≈50 nmol/L and EC50 values for both cytokines of ≈ 10 nmol/L. Lipopolysaccharide and cholesterol crystals did not induce IL-1ß and IL-18 production in Nlrp3(-/-) macrophages. In addition, arglabin activated autophagy as evidenced by the increase in LC3-II protein. Intraperitoneal injection of arglabin (2.5 ng/g body weight twice daily for 13 weeks) into female ApoE2.Ki mice fed a high-fat diet resulted in a decreased IL-1ß plasma level compared with vehicle-treated mice (5.2±1.0 versus 11.7±1.1 pg/mL). Surprisingly, arglabin also reduced plasma levels of total cholesterol and triglycerides to 41% and 42%, respectively. Moreover, arglabin oriented the proinflammatory M1 macrophages into the anti-inflammatory M2 phenotype in spleen and arterial lesions. Finally, arglabin treatment markedly reduced the median lesion areas in the sinus and whole aorta to 54% (P=0.02) and 41% (P=0.02), respectively. CONCLUSIONS: Arglabin reduces inflammation and plasma lipids, increases autophagy, and orients tissue macrophages into an anti-inflammatory phenotype in ApoE2.Ki mice fed a high-fat diet. Consequently, a marked reduction in atherosclerotic lesions was observed. Thus, arglabin may represent a promising new drug to treat inflammation and atherosclerosis.

[Proximal pancreatectomy in a case of nesidioblastosis]. / Pancreatectomía proximal en nesidioblastosis.

A 19 moth-old child who presented seizures secondary to intractable hypoglycemia, fulfilling the clinical and biochemical criteria for hyperinsulinism was studied. Histopathological findings of the pancreas showed the presence of small clusters of b cell islets throughout acinar tissue near ducts, in both the head and the proximal third of the body. Proximal pancreatectomy (60%) and distal pancreatic-jejunostomy (Roux-in-Y) were performed. This procedure was effective in reverting hypoglycemia and constitutes the first successful alternative treatment.

Pancreatectomía proximal en nesidioblastosis / Proximal pancreatectomy in case of nesidioblastosis

En 1938 Laidiaw acuñó el término de nesidioblastosis refiriéndose a una neodiferenciación de los islotes de Langerhans, originada del epitelio de los conductos pancreáticos. Se presenta un caso clínico de un niño de 19 meses de edad, con convulsiones secundarias a hipoglucemia intratable. Se diagnosticó hiperinsulinismo con base en criterios clínicos y bioquímicos. Los hallazgos histopatológicos del páncreas mostraron la presencia de racimos de islotes de células P por todo el tejido acinar localizados en cabeza y un tercio proximal del cuerpo. Se realizó el diagnóstico de nesidioblastosis y para su tratamiento se practicó pancreatectomía proximal (60%), con una pancreático yeyunostomía distal (Y en Roux). Después del tratamiento, el paciente tuvo normalización de los niveles séricos de glucosa y de insulina. Se concluye que este procedimiento resultó efectivo al revertir la hipoglucemia, por lo que constituye el primer tratamiento alternativo al método convencional.

A 19 month old child who presented seizures secondary to intractable hypoglycemia, fulfilling the clinical and biochemical criteria for hyperinsulinism was studied. Histopathological findings of the pancreas showed the presence of small clusters of b cell islets throughout acinar tissue near ducts, in both the head and the proximal third of the body. Proximal pancreatectomy (60%) and distal pancreatic jejunostomy (Roux in Y) were performed. This procedure was effective in reverting hypoglycemia and constitutes the first successful alternative treatment.

[Effect of ramipril on the glucose/insulin coefficient and the ventricular mass index in patients with light to moderate arterial hypertension]. / Efecto del ramipril sobre el cociente glucosa/insulina y el índice de masa ventricular izquierda en pacientes con hipertensión arterial leve a moderada.

This longitudinal prospective study was designed to assess the effects of the angiotensin converting enzyme inhibitor (ACEI) ramipril on ventricular mass, left ventricle (LV) diastolic function and blood pressure in patients with mild to moderate essential hypertension and hyperinsulinemia. LV diastolic dysfunction is the first target organ alteration occurring in hypertensive patients, while ventricular hypertrophy is the most relevant predictive factor for cardiovascular morbility and mortality in systemic hypertension. Because several studies have demonstrated that there is no direct correlation between blood pressure values and the severity of LV hypertrophy or diastolic dysfunction, it is assumed that other factors are involved in the genesis of these functional alterations. Moreover, the hypertensive effect of insulin is caused by sympathetic stimulation, sodium and water renal retention and protooncogene stimulation leading to myocardial and vascular fibrosis and hypertrophy. We studied 24 hypertensive patients with hyperinsulinemia. All patients underwent an overall and cardiologic clinical evaluation, and electrocardiographic and ecocardiographic studies were performed at baseline and 6 months after being treated with 2.5 to 5 mg/day ramipril. Ramipril treatment significantly reduced systolic (12 mmHg) and diastolic (12 mmHg) pressure levels, basal insulin serum levels (23.62 pmol/dL vs 10.42 pmol/dL), and left ventricle mass index values (143.8 g/m2 vs 118.2 g/m2). Among the variables assessing LV diastolic function, only the transmitral flow E/A wave ratio showed significant differences in women. Ramipril was well tolerated and no significant adverse events were reported.

Efecto del ramipril sobre el cociente glucosa/insulina y el índice de masa ventricular izquierda en pacientes con hipertensión arterial leve a moderada / Effect of ramipril on the glucose/insulin coefficient and the ventricular mass index in patients with light to moderate arterial hypertension

Este estudio longitudinal, prospectivo se diseñó para evaluar el efecto del ramipril, un inhibidor de la enzima convertidora de angiotensina (IECA) sobre la masa ventricular, la función diastólica del ventrículo izquierdo (VI) y los valores de tensión arterial en pacientes con hipertensión arterial sistémica esencial (HAS) leve a moderada con hiperinsulinemia. La primera alteración del paciente hipertenso es la disfunción diastólica del VI y el dato de mayor peso como factor predictor de morbimortalidad cardiovascular en la HAS es la hipertrofia ventricular. Existen múltiples estudios que demuestran que no existe una correlación directa entre los valores de tensión arterial y el grado de hipertrofia o disfunción diastólica del ventrículo izquierdo, motivo por el cual se asume la participación de otros factores en la génesis de estas alteraciones funcionales. Por otra parte, está descrito que la insulina posee efectos hipertensores por estimulación simpática, por retener sodio y agua a nivel renal y por estimular la expresión de protooncogenes con el subsecuente desarrollo de fibrosis e hipertrofia miocárdica y vascular. A pesar de que existe en el mercado una gran cantidad de fármacos antihipertensivos, algunos de ellos producen efectos metabólicos adversos, mientras que otros como los inhibidores de la enzima convertidora de angiotensina (IECAS), los ARAII y los bloqueadores del calcio además de controlar los niveles de presión arterial tienen un efecto neutro o benéfico sobre dichos parámetros. Considerando el efecto de los IECAS sobre el perfil metabólico, se realizó un estudio con 24 pacientes hipertensos esenciales con hiperinsulinemia, a los cuales se les realizó evaluación clínica cardiológica y general, electrocardiograma y ecocardiograma en condiciones basales y después de 6 meses de tratamiento con ramipril a dosis de 2.5 a 5 mg/día. Los resultados muestran una reducción significativa de la tensión arterial sistólica (12 mmHg) y diastólica (12 mmHg), de los niveles séricos de insulina basal (23.62 pmol/dL vs 10.42 pmol/dL), y del índice de masa ventricular izquierda (143.8 g/m² vs 118.2 g/m²). En las variables que evalúan la función diastólica del VI no hubo diferencias estadísticamente significativas a excepción de la relación onda E/onda A del flujo transmitral en el grupo de mujeres. Ramipril fue bien tolerado y no se reportaron eventos adversos significativos.

This longitudinal prospective study was designed to assess the effects of the angiotensin converting enzyme inhibitor (ACEI) ramipril on ventricular mass, left ventricle (LV) diastolic function and blood pressure in patients with mild to moderate essential hypertension and hyperinsulinemia. LV diastolic dysfunction is the first target organ alteration occurring in hypertensive patients, while ventricular hypertrophy is the most relevant predictive factor for cardiovascular morbility and mortality in systemic hypertension. Because several studies have demonstrated that there is no direct correlation between blood pressure values and the severity of LV hypertrophy or diastolic dysfunction, it is assumed that other factors are involved in the genesis of these functional alterations. Moreover, the hypertensive effect of insulin is caused by sympathetic stimulation, sodium and water renal retention and protooncogene stimulation leading to myocardial and vascular fibrosis and hypertrophy. We studied 24 hypertensive patients with hyperinsulinemia. All patients underwent an overall and cardiologic clinical evaluation, and electrocardiographic and ecocardiographic studies were performed at baseline and 6 months after being treated with 2.5 to 5 mg/day ramipril. Ramipril treatment significantly reduced systolic (12 mmHg) and diastolic (12 mmHg) pressure levels, basal insulin serum levels (23.62 pmol/dL vs 10.42 pmol/dL), and left ventricle mass index values (143.8 g/m² vs 118.2 g/m²). Among the variables assessing LV diastolic function, only the transmitral flow E/ A wave ratio showed significant differences in women. Ramipril was well tolerated and no significant adverse events were reported. (Arch Cardiol Mex 2003; 73:24-30).

Arteritis temporal. Informe de un caso originario de San Luis Potosí, México / Temporal arteritis. A case report

La arteritis temporal o de células gigantes, en una vasculitis generalizada que afecta característicamente las arterias craneanas, de etiología desconocida, con cierta predilección racial y geográfica, cuya ocurrencia en nativos mexicanos no ha sido descrita. Informamos una paciente de 85 años, del centro del país y con ascendencia genética también local. Su historia de 3 meses de evolución con dolor, aumento de volumen y tortuosidad de arterias extracraneanas, manifestaciones de polimialgia reumática y amaurosis bilateral; cursó con eritrosedimentación elevada y en la biopsia de arteria temporal se evidenció el infiltrado inflamatorio y de células gigantes características. Con esteroides mejoró sólo parcialmente la agudeza visual. Destacamos la importancia de considerar esta patología, dado que el retraso en el diagnóstico y tratamiento puede resultar en secuelas permanentes