Effect of S-methyl-l-thiocitrulline dihydrochloride on rat micturition reflex

ABSTRACT Objective: To evaluate the effect of neuronal nitric oxide synthase on the striated urethral sphincter and the urinary bladder. Materials and Methods: A coaxial catheter was implanted in the proximal urethra and another one in the bladder of female rats, which were anesthetized with subcutaneous injection of urethane. The urethral pressure with saline continuous infusion and bladder isovolumetric pressure were simultaneously recorded. Two groups of rats were formed. In group I, an intrathecal catheter was implanted on the day of the experiment at the L6-S1 level of the spinal cord; in group II, an intracerebroventricular cannula was placed 5-6 days before the experiment. Results: It was verified that the group treated with S-methyl-L-thio-citrulline, via intrathecal pathway, showed complete or partial inhibition of the urethral sphincter relaxation and total inhibition of the micturition reflexes. The urethral sphincter and the detrusor functions were recovered after L-Arginine administration. When S-methyl-L-thio-citrulline was administered via intracerebroventricular injection, there was a significant increase of urethral sphincter tonus while preserving the sphincter relaxation and the detrusor contractions, at similar levels as before the use of the drugs. Nevertheless there was normalization of the urethral tonus when L-Arginine was applied. Conclusions: The results indicate that, in female rats anaesthetized with urethane, the nNOS inhibitor administrated through the intrathecal route inhibits urethral sphincter relaxation, while intracerebroventricular injection increases the sphincter tonus, without changing bladder function. These changes were reverted by L-Arginine administration. These findings suggest that the urethral sphincter and detrusor muscle function is modulated by nitric oxide.

Caryocar brasiliense camb protects against genomic and oxidative damage in urethane-induced lung carcinogenesis

The antioxidant effects of Caryocar brasiliense Camb, commonly known as the pequi fruit, have not been evaluated to determine their protective effects against oxidative damage in lung carcinogenesis. In the present study, we evaluated the role of pequi fruit against urethane-induced DNA damage and oxidative stress in forty 8-12 week old male BALB/C mice. An in vivo comet assay was performed to assess DNA damage in lung tissues and changes in lipid peroxidation and redox cycle antioxidants were monitored for oxidative stress. Prior supplementation with pequi oil or its extract (15 µL, 60 days) significantly reduced urethane-induced oxidative stress. A protective effect against DNA damage was associated with the modulation of lipid peroxidation and low protein and gene expression of nitric oxide synthase. These findings suggest that the intake of pequi fruit might protect against in vivo genotoxicity and oxidative stress.

Myeloid-derived suppressor cells and associated events in urethane-induced lung cancer

OBJECTIVES: Myeloid-derived suppressor cells contribute to the immunosuppressive microenvironment during tumor development and limit the efficacy of cancer immunotherapy. Identifying myeloid-derived suppressor cells and associated factors is the first step in creating strategies to reverse the suppressive effects of these cells on the immune system. METHODS: To induce lung cancer, we administered 2 doses of urethane to BALB/c mice and observed these animals for 120 days. After this period, we evaluated the percentage of myeloid-derived suppressor cells in the blood, lung and bone marrow. The expression of alpha-smooth muscle actin, transforming growth factor-β, Toll-like receptor 2, Toll-like receptor 4, and interleukin-6 was also determined in the lung tissue. RESULTS: Myeloid-derived suppressor cells were increased in all evaluated tissues after lung cancer development in association with increased Toll-like receptor 4 expression and decreased interleukin-6 expression in the lung. We observed alpha-smooth muscle actin and transforming growth factor-β expression in lung nodules. CONCLUSIONS: We believe that the early diagnosis of cancer through determining the blood levels of myeloid-derived suppressor cells followed by the depletion of these cells should be further investigated as a possible approach for cancer treatment. .

Caracterização de resinas para base de prótese e reembasamento: propriedades físico-químicas e mecânicas / Characterization of denture base and reline resins: physical, chemical and mechanical properties

Este estudo avaliou propriedades físico-químicas e mecânicas de resinas para base de prótese, uma fotoativada (Eclipse - E) à base de UDMA e outra termicamente ativada por micro-ondas (Nature Cryl MC - NC) à base de PMMA, e um reembasador quimicamente ativado (Tokuyama Rebase Fast II - TR II) à base de PEMA. Propriedades viscoelásticas (E', tan δ e Tg), contração linear de polimerização (CLP), sorção (Sor) e solubilidade (Sol) em água e em saliva artificial, grau de conversão (GC) e coeficiente de inchamento (CI) foram avaliados para a caracterização dos polímeros. A resistência à flexão dos materiais intactos (E, NC, TR II) e reembasados (E-E, E-TRII, NC-NC- NC-TR II) também foi avaliada. As propriedades viscoelásticas foram avaliadas em corpos-de-prova retangulares (64 x 10 x 3,3 mm), submetidos (n=2) à análise térmica dinâmico-mecânica (DMTA) em dois ciclos de varredura após confecção (controle) e armazenagem em saliva. O módulo de armazenamento (E') e o amortecimento mecânico (tan δ) a 37 ºC e a temperatura de transição vítrea (Tg) foram registrados durante o 1º ciclo da DMTA. A CLP (%) foi avaliada (n=10), em projetor de perfil (Nikon 6C), em corpos-de-prova circulares (50 x 0,5 mm). A Sor e a Sol (µg/mm3) foram mensuradas (n=5) seguindo as recomendações da ISO 1567. O GC (%) foi avaliado (n=5) por espectroscopia de infravermelho por transformadas de Fourier (32 leituras; resolução 4,0 cm-1 ). O coeficiente de inchamento foi realizado (n=5) de acordo com a teoria de Flory-Rhener. Os ensaios mecânicos de flexão (0,5 mm/min) foram realizados (n=10) em corpos-de-prova (64 x 10 x 3,3 mm) intactos ou reembasados e a resistência (MPa) calculada na tensão máxima (RFM) e no limite de proporcionalidade (RFLP). Os dados foram avaliados por ANOVA, seguida por Tukey HSD (α=0,05) ou Dunnett (α=0,05). As resinas E e NC apresentaram similar E', superior a TR II. O tan δ foi ordenado como TR II > NC > E. A Tg não foi alterada após armazenagem em saliva artificial. Os maiores valores de Tg nos grupos controle e armazenados foram apresentados, respectivamente, pelos materiais E e NC. Houve deslocamento dos picos de tan δ após o segundo ciclo de DMTA. Independente do meio de imersão, a Sor (µg/mm3 ) foi ordenada em NC > E > TR II. A armazenagem em saliva reduziu a Sol (µg/mm3 ) dos materiais. A resina E exibiu os menores valores de CLP, CI e o maior GC. NC exibiu a maior CLP e CI. TR II exibiu valores intermediários de CLP, CI e o menor GC. Os maiores valores de RFM e RFLP foram produzidos por E. A RFM e RFLP dos materiais reembasados foi ordenada em E-E > NC-NC > E-TRII> NC-TR II. A armazenagem em saliva não influenciou a resistência à flexão dos materiais intactos ou reembasados. No geral, a resina para base de prótese E apresentou propriedades físico-químicas e mecânicas superiores à NC e TR II

This study evaluated the physical-chemical and mechanical properties of denture base resins, one UDMA light-activated (Eclipse-E) and one PMMA heat-polymerized (Nature Cryl MC - NC). The PEMA autopolymerizing reliner (Tokuyama Rebase Fast II - TR II) was also evaluated. Viscoelastic properties (E', tan δ e Tg), linear shrinkage polymerization (LPS), sorption (Sor) and solubility (Sol) in water and in artificial saliva, degree of conversion (DC) and coefficient of swelling (CS) were employed for polymer characterization. The flexural strength of intact (E, NC, TR II) and relined samples (E-E, E-TRII, NC-NC- NC-TR II) was also made. The viscoelastic properties were evaluated by two cycles of dynamic mechanical thermal analysis (DMTA) on each rectangular (64 x 10 x 3.3 mm) samples (n=2). The storage modulus (E') and loss tangent (tan δ) at 37 ºC and the glass transition temperature (Tg) were recorded from the 1st DMTA cycle. LPS (%) was evaluated (n=10) by a Nikon 6C optical comparator, on circular samples (50 x 0.5 mm). Sor and Sol (µg/mm3 ) were measured (n=6) according to ISO 1567. DC (%) was evaluated (n=5) by FTIR spectroscopy (32 scans; resolution 4.0 cm-1). CS was evaluated (n=5) by Flory-Rhener theory. A three-point flexural tests (0.5 mm/min) was applied (n=10) on rectangular intact and relined samples. The ultimate flexural strength (FSU) and the flexural strength at the proportional limit (FSPl) were recorded in MPa. Data were analyzed with ANOVA, followed by Tukey HSD (α=0.05) ou Dunnett (α=0.05). E and NC had similar E', higher than TR II. Tan δ was arranged as TR II > NC > E. The Tg was not affected after saliva storage. The higher Tg values were obtained for E and NC. Tan δ peaks were shifted after 2 DMTA cycles. Regardless the medium immersion, Sor (µg/mm3 was arranged as NC > E > TR II. Saliva storage reduced Sol (µg/mm3) of the materials. E showed the lowest values of LPS, CS and the highest value of DC. NC showed the highest LPS and CS.TR II showed intermediated values of LPS, CS and the lowest DC. The highest FSU and FSPl values were exhibited by E. The FSU and FSPl of relined samples were arranged as E-E > NC-NC > E-TRII > NC-TR II. Saliva storage did not affect the flexural strength of intact and relined samples. Overall, the denture base resin E showed higher physicochemical and mechanical properties than NC and TR II

Análise da ação da Himatanthus drasticus na progressão do câncer de pulmão induzido por uretana em camundongos / Analysis of the action of Himatanthus drasticus in progression of urethane-induced lung cancer in mice

Objective: To evaluate the effect of janaguba in inhibiting the development of lung cancer in an experimental urethane-induced model. Methods: a total of 3 mg/kg urethane was injected in 51 Balb-C mice aged 7-13 weeks of life. Janaguba was administered orally daily in two doses: 0.04 mL (Group 2, G2) and 0.06 mL (Group 3, G3), for 20 weeks. After this period, the mice were sacrificed and the number of lesions counted. Results: The mean weight of Group 2 was lower than that of Group 3, and that of Group 1 (Control, G1) (G1 = 35.533 g; G2 = 33.359 g; G3 = 37.125 g). The number of nodules did not differ between groups (mean G1 = G2 = G3 = 1; p = 0.88). Conclusion: Janaguba had an effect on the growth of mice, but had no influence on the progression of lung cancer in this model.

Objetivo: Avaliar a ação da janaguba na inibição do desenvolvimento de câncer de pulmão em modelo experimental induzido por uretana. Métodos: Foram injetados 3mg/kg de uretana em 51 camundongos Balb-C , com 7 a 13 semanas de vida. Janaguba foi administrada via oral diariamente em duas doses: 0,04 mL (Grupo 2, G2) e 0,06 mL(Grupo 3,G3), por 20 semanas. Após esse período, os camundongos foram sacrificados e o número de lesões, contado. Resultados: A média de peso do Grupo 2 foi menor que a do Grupo 3, e que a do Grupo 1 (Controle, G1) (G1 = 35,533 g; G2 = 33,359 g; G3 = 37,125 g). O número de nódulos não diferiu entre os grupos (média G1 = G2 = G3 = 1; p = 0,88). Conclusão: A janaguba apresentou um efeito no crescimento dos camundongos, mas não apresentou influência na progressão do câncer de pulmão neste modelo.

Urban, traffic- related particles and lung tumors in urethane treated mice

OBJECTIVE: The present study was designed to evaluate the effects of urban, traffic-related, fine particulate matter (PM2.5) on mice lung tumorigenesis under controlled exposure conditions. METHODS: Four groups of female Swiss mice were treated with intraperitonial injections of urethane and saline solution. Urethane was used to start the carcinogenesis process. The animals were housed in two chambers receiving filtered and polluted air. In the polluted air chamber, pollutant levels were low. After two months of exposure, the animals were euthanized and lung tumoral nodules were counted. RESULTS: Saline-treated animals showed no nodules. Urethane-treated animals showed 2.0+2.0 and 4.0+3.0 nodules respectively, in the filtered and non-filtered chambers (p = 0.02), thus showing experimental evidence of increased carcinogenic-induced lung cancer with increasing PM2.5 exposure. CONCLUSION: Our data support the concept that low levels of PM2.5 may increase the risk of developing lung tumors.

Association between decreases in type V collagen and apoptosis in mouse lung chemical carcinogenesis: a preliminary model to study cancer cell behavior

OBJECTIVE: The importance of type V collagen and its relationships with other types of collagen and with vascular and epithelial apoptosis were studied in a model of chemical carcinogenesis in the mouse lung. METHODS: Two groups of male Balb/c mice were studied: a) animals that received two intraperitoneal doses of 3 g/kg urethane carcinogen (urethane group = 24); and b) animals submitted to a sham procedure, comparable to the test group (control group = 7). Both groups were sacrificed after 120 days. In situ detection of apoptosis, immunohistochemistry, immunofluorescence and histomorphometry were used to evaluate the fraction occupied by the tumor, vascular and epithelial apoptosis, and type V, III and I collagen fibers in the lung parenchyma from both groups. RESULTS: The lung parenchyma from the urethane group showed low fractions of vascular and epithelial apoptosis as well as reduced type V collagen fibers when compared to the control group. A significant direct association was found between type V and III collagen fibers and epithelial apoptosis, type V collagen fibers and vascular apoptosis, and type V and type I collagen fibers. CONCLUSION: The results show that a direct link between low amounts of type V collagen and decreased cell apoptosis may favor cancer cell growth in the mouse lung after chemical carcinogenesis, suggesting that strategies aimed at preventing decreased type V collagen synthesis or local responses to reduced apoptosis may have a greater impact in lung cancer control.

Actividad antifúngica de quitosano carbamato de etilo en Candida albicans / Antifungal activity of chitosano ethil carbamate on Candida albicans

El incremento de las infecciones producidas en seres humanos y/o animales por hongos y el aumento de la resistencia de estos últimos a algunos farmacos, han conducido a la búsqueda de nuevos productos con actividad antifúngica. Producto de la síntesis química se ha obtenido la sustancia de origen natural, llamada Quitosano Carbamato de etilo (QCE) que ha demostrado acción antifúngica, particularmente a Candida albicans. Los objetivos de este trabajo fueron determinar ¶in vitro la Concentración Mínima Inhibitoria (CIM), Concentración Letal Media (CLM) y Letal (CL) de QCE para cultivos de C. albicans en CM al 2 por ciento. Establecer para esta misma levadura su curva de crecimiento, el tiempo de inicio de acción del QCE y los cambios morfoló-gicos de las celulas levaduriformes en CM al 2 por ciento con adición de QCE (0.89 mg/mL). Ademßs, determinar la acción del QCE (0.89 mg/mL) para las levaduras Criptococcus albus, Saccharomyces cerevisiae, Sporobolomyces roseus y 5 cepas de C. albicans aisladas de casos clínicos en el Hospital Clínico Regional Valdivia (H.C.R.V.). La CIM fue 0.25 mg/mL, la CLM fue 0.45 mg/mL y la CL 0,89 mg/mL. La curva de crecimiento elaborada para los cultivos de C. albicans sin adición de QCE fue la típica de una levadura y, por el contrario, la elaborada para los cultivos adicionados con QCE sólo registró la etapa de latencia. El tiempo de inicio de la acción del QCE para la cepa control de C. albicans comienza a las 12 horas de incubación. Las celulas de C. albicans obtenidas de cultivos tratados con QCE se mostraron colapsadas, de menor tamaño, no forman tubo germinativo y tampoco pseudomicelio. El QCE inhibió el desarrollo de cultivos de C. albus, S. cerevisiae, S. roseus y para tres de cinco cepas ensayadas de C. albicans obtenidas desde casos clínicos.

Cardiovascular responses to microinjections of GABA or anesthetics into the rostral ventrolateral medulla of conscious and anesthetized rats

The rostral ventrolateral medulla (RVLM) contains neurons involved in tonic and reflex control of arterial pressure. We describe the effects of gamma-aminobutyric acid (GABA) and anesthetics injected into the RVLM of conscious and urethane (1.2 g/kg, iv) anesthetized Wistar rats (300-350 g). In conscious rats, bilateral microinjection of GABA (50 nmol/200 nl) induced a small but significant decrease in blood pressure (from 130 ± 3.6 to 110 ± 5.6 mmHg, N = 7). A similar response was observed with sodium pentobarbital microinjection (24 nmol/200 nl). However, in the same animals, the fall in blood pressure induced by GABA (from 121 ± 8.9 to 76 ± 8.8 mmHg, N = 7) or pentobarbital (from 118 ± 4.5 to 57 ± 11.3 mmHg, N = 6) was significantly increased after urethane anesthesia. In contrast, there was no difference between conscious (from 117 ± 4.1 to 92 ± 5.9 mmHg, N = 7) and anesthetized rats (from 123 ± 6.9 to 87 ± 8.7 mmHg, N = 7) when lidocaine (34 nmol/200 nl) was microinjected into the RVLM. The heart rate variations were not consistent and only eventually reached significance in conscious or anesthetized rats. The right position of pipettes was confirmed by histology and glutamate microinjection into the RVLM. These findings suggest that in conscious animals the RVLM, in association with the other sympathetic premotor neurons, is responsible for the maintenance of sympathetic vasomotor tone during bilateral RVLM inhibition. Activity of one or more of these premotor neurons outside the RVLM can compensate for the effects of RVLM inhibition. In addition, the effects of lidocaine suggest that fibers passing through the RVLM are involved in the maintenance of blood pressure in conscious animals during RVLM inhibition

Estudo das alterações morfológicas causadas pela uretana em modelo de carcinogênese bucal DMBA-induzida / The study of morphologic changes induced by urethana in an oral chemical carcinogenesis DMBA-induced model

A proposta desse trabalho resultou da necessidade de reavaliar o potencial carcinogênico da uretana, em concentrações mais baixas, a partir do modelo experimental de carcinogênese bucal DMBA-induzida. Cem hamsters sírios dourados foram separados em cinco grupos experimentais. O grupo 1 recebeu aplicações tópicas de uretana 0,5 por cento na borda lateral da língua; grupo 2, uretana 6 por cento; grupo 3 uretana 0,5 por cento + DMBA, e o grupo 5- DMBA (controle positivo). Os dados obtidos mostraram que a uretana a 0,5 por cento e 6 por cento não induziu alterações histolíticas nos grupos 1 e 2. A formação de carcinomas nos animais tratados com uretana e DMBA ocorreu em proporções menores quando comparado com o grupo controle positivo (DMBA). A uretana a 0,5 por cento e 6 por cento reduziu a carcinogenicidade do DMBA, e não apresentou potencial carcinogênico de iniciação, promoção e/ou progressão

Efeito protetor do chá de cogumelo do sol (Agaricus blazei Murill) contra a ação genetóxica do uretano em células somáticas de Drosophila melanogaster / Protective effect of the tea of sun mushroom (Agaricus blazei Murill) against genetoxic action of urethane on somatic cells of Drosophila to melanogaster

O Agaricus blazei vem sendo utilizado popularmente no tratamento de uma série de doenças: diabetes, redução do colesterol, stress físico e até mesmo câncer. Sua possível ação tumoricida está associada à ativação de células Natural Killer. Para avaliar os possíveis efeitos protetores do chá de A. blazei (62,5 g.L-1) contra a ação genotóxica do uretano (10mM), utilizou-se o Teste para Detecção de Mutação e Recombinação Somática (Somatic Mutation And Recombination Test-SMAT). Foram utilizadas larvas de 72 ± 4h, resultantes dos cruzamentos padrão e alta bioativação metabólica. Os resultados obtidos demonstraram que não houve aumento, estatisticamente significativo, nas freqüências de manchas mutantes, em larvas expostas ao chá de A. blazei. Quando A. blazei foi associado ao uretano, foi observada uma redução estatisticamente significativa nas freqüências das manchas mutantes. Os resultados sugerem que o A. blazei não é genotóxico e exerce um efeito protetor contra a ação genotóxica do uretano.

Cardiovascular and respiratory responses to microinjection of L-glutamate into the caudal pressor area in conscious and anesthetized rats

The role of the caudal pressor area (CPA) in the maintenance of vasomotor tonus in anesthetized and decerebrate animals has been clearly established. In conscious animals, however, the participation of CPA in the cardiovascular control remains to be fully elucidated. In the present study, unilateral L-glutamate (L-Glu) (10 and/or 20 nmol/70 nl) microinjection into CPA, in conscious male Wistar rats (250-280 g) caused a significant increase in mean arterial blood pressure (MAP; control: 112 + or - 1.9 mmHg; after 20 nmol L-Glu: 139 + or - 4.5 mmHg, N = 12, P<0.05) and respiratory rate (control: 81 + or - 3.5 breaths/min; after 10 nmol L-Glu: 92 + or - 3 breaths/min, P<0.05; after 20 nmol L-Glu: 104 + or - 5 breaths/min, N = 6, P<0.05). The subsequent anesthesia with urethane caused a significant increase in basal respiratory frequency (conscious: 81 + or - 3.5 breaths/min; under urethane: 107 + or - 1.3 breaths/min, N = 6, P<0.05). Anesthesia also significantly attenuated L-Glu-evoked pressor (conscious: deltaMAP = +27 mmHg; anesthetized: deltaMAP = +18 mmHg, P<0.05) and respiratory responses. These results suggest that glutamatergic receptors in the CPA are involved in cardiovascular and respiratory modulation in conscious rats

Consideraçöes sobre a presença de carbamato de etila em alimentos e bebidas alcoólicas: uma revisäo / Considerations about the presence of ethyl carbamate in foods and alcoholic beverages: a review

A contaminação de alimentos e bebidas alcoólicas por carbamato de etila (CE), bem como seu mecanismo de formação são discutidos neste artigo de revisão. O CE induz efeitos mutagênicos, teratogênicos e carcinogênicos em animais de experimentação, sendo considerado substância potencialmente carcinogênica para o homem. Com o propósito de alertar para os riscos à saúde decorrentes da exposição ao CE, este artigo trata da ocorrência deste contaminante em alimentos e bebidas, bem como de suas propriedades físico-químicas e aspectos analíticos e toxicológicos.

Mecánica respiratoria del conejo bajo la acción del uretano, el pentobarbital o la mezcla cloralosa-uretano / Respiratory mechanics of the rabbit under the action of urethane, pentobarbital or chloralose-urethane mixture

Se caracterizó el patrón respiratorio dle conejo bajo la acción de 3 anestésicos. Se registraron el flujo y el volumen respiratorios mediante un neumotacógrafo, la presión intraesofágica y el electrocardiograma, en animales que respiraban espontáneamente en condiciones basales, agrupados y anestesiados como sigue: grupo 1: pentobarbital EV, 30 mg/kg; grupo 2: mezcla de uretano EV, 400 mg/kg y cloralosa EV, 60-80 mg/kg y grupo 3: uretano IP, 1,5 g/kg. Se analizaron las variables frecuencia respiratoria, volumen corriente, volumen minuto, flujo inspiratorio medio, relación entre tiempo de inspiración y tiempo total de la respiración (tiempo útil), resistencia pulmonar, complianza dinámica y frecuencia cardíaca. En el grupo 3 las variables indicadoras de la ventilación difirieron significativamente respecto a los grupos 1 y 2, que no mostraron diferencias entre sí. El tiempo útil fue diferente en los 3 grupos. En las demás variables no hubo diferencias significativas. Se valora que el uretano pueda ejercer una acción estimulante sobre la respiración

Cortical facilitatory action on centralis lateralis thalamic activity during the development of carrageenin-produced inflammation

In order to understand the neuronal mechanisms involved in acute and chronic pain, we studied the thalamic and cortical control action, which allows the suppression of the neuronal responses to noxious stimulation. As an experimental pain model we used carrageenin injected in the paw of male Wistar rats. The tonic facilitatory cortical control on centralis lateralis thalamic nuclei (CL) activity is described at different times after carrgeenin-produced inflammation. Simultaneous extracellular unit recordings were carried out at CL and medial prefrontal cortex (PCx) cells in anesthetized male Wistar rats. The PCx control was tested by blocking in a transient and reversible manner, using the cortical spreading depression (CSD). Carrageenin injection (1 percent; 0.2 ml) into the plantar surface of the right hind paw, and the influence of Lidocaine (2 percent; 0.2 ml) applied in the inflamed paw, was tested on unit activity in PCx and CL cells. Thalamic cells recorded in acute and subacute stages (24-72 h aftercarrageenin administration) were activated by tactile, light pressure and joint movement stimulation yielded before the injection. After carrageenin, the thalamic cells displayed spontaneous high frequency burst discharges, also presenting a progressive and significant increase (p < 0.001, ANOVA test) of their spontaneous firing when rate when compared with control cell activity. Lidocaine reduced the enhanced activity induced by carrageenin in thalamic neurones (p < 0.001, Student t test). In PCx neurones were also recorded in acute and subacute stages. Cortical cells from acute and subacute group were activated by nociceptive and non-nociceptives stimulation. In acute stage, cortical cells increased their firing rate after carrageenin and we could not observe modifications upon their firing rate due to Lidocaine. The CSD blocked all cortical activity in acute subacute stages. During the CSDs, overall thalamic activity was suppressed in neurones from acute (91 percent) and subacute (87 percent) stages. The blockage was observed when the propagated weve produced by CSD arrived into the medial prefrontal cortex. the CSD also suppressed the PCx and the CL noxious responses evoked by pressure in the receptive field. This study show the tonic facilitatory control of the PCx upon intralaminar thalamic noxious responses, during acute and subsacute stages of carrageenin produced inflammation. In the literature, it has been proposed that the CL thalamic...

Tabaquismo: alteraciones producidas por el uretano en los receptores de macrófagos y el sistema del complemento / Smoking: alterations by urethano in macrophages, complement system

Se comunican los resultados de un análisis de la acción del uretano sobre las células inmunocompetentes (macrófagos), el sistema del complemento y también en los enterocitos. El estudio de los receptores de macrófagos por medio de la formación de rosetas puso de manifiesto que concentraciones altas de uretano destruyen a los macrófagos y disminuyen la unión con IgG y el tercer componente del complemento. Los resultados obtenidos experimentalmente in vitro sugieren que de acuerdo con el grado y tiempo de la exposición al humo de tabaco se puede romper el equilibrio del sistema inmunitario y de otras poblaciones celulares que desembocan en los procesos patológicos que se relacionan con tabaquismo

A comparison of the effects of eserine sulfate on the activity of medullary raphe neurons in the anesthetized rabbit and rat

1. Medullary raphe neurons are involved in the control of sympathetic activity during desynchronized sleep (DS). Eserine sulfate induces a state with the somatic and visceral signs of DS in decerebrate animals. The rabbit and rat display diverse hemodynamic patterns during DS. 2. To determine whether eserine sulfate provokes different responses in the medullary raphe neuron population of these different species, the drug (100 mg/kg, i.v.) was administered to urethane-anesthetized (1.2 g/kg, i.v.) rabbits (1.5-3.0 kg) and rats (Wistar, 260-310 g). 3. Extracellular activity was recorded from 66 neurons in 30 rats. Cholinergic stimulation provoked an increase in discharge rate (DR) in 45 neurons (68), a decrease in 8 neurons (12) and no change in 13 neurons (20). Recordings were obtained from 30 neurons in 11 rabbits. Stimulation of these cells provoked an increase in DR in 17 neurons (57), a decrease in DR in 7 neurons (23) and no change in 6 neurons (20). Interspike interval and auto-correlation analysis was performed on 28 rat and rabbit neurons. No significant difference was found between the rat and the rabbit with respect to the number of the neurons which were either inhibited or excited by cholinergic stimulation (P > 0.05). Similarly, unit response to eserine was not related to whether the unit displayed regular or irregular DR. 4. Therefore, we suggest that the diverse hemodynamic patterns during DS and the distinct cardiovascular responses to raphe nuclei stimulation are not due to differences in the organization of the raphe nuclei themselves but to differences in their axonal projections or in the postsynaptic receptors activated in the intermediolateral cell column or other postsynaptic targets.

Effects of anesthetics on the incidence and duration of reperfusion arrhythmias in isolated rat heart

The present study was carried out to evaluate the effect of anesthetics on reperfusion arrhythmias. Male Wistar rats (200-300 g) were injected ip with heparin (200 IU), followed by anesthesia with thiopental (40 mg/kg), pentobarbital (30 mg/kg), urethane (1.2 g/kg), either, or halothane and sacrificed by decapitation. The isolated heart (5 to 8 per group) was perfused with Locke solution by the Langendorff method and the left coronary artery was ligated for 10 min. The incidence of reperfusion arrhythmias (100 per cent ) was similar in hearts of control and previously anesthetized rats, but the duration of the arrhythmias was significantly increased by anesthesia (5-fold with thiopental, 15-fold with pentobarbital, ether and halothane, and 30-fold with urethane). In hearts taken from unanesthetized rats and perfused with Locke solution containing anesthetics (5-7 per group), the duration of reperfusion arrhythmias decreased with thiopental (0.23 +/- 0.15 min), did not change with pentobarbital (1.14 +/- 0.26 min) and increased with urethane (16.10 +/- 5.60 min). Our results show that anesthetics alter the duration of reperfusion arrhythmias in the isolated rat heart

Influence of the pontomencephalic region upon PGO activity regulation at the aducens nucleus in cats

Se ha propuesto que en el tegmento pontomesencefálico, específicamente en la región denominada "área X" (AX) y en el núcleo parabraquial lateral (Pbl), se localizan las células generadoras de la actividad ponto-geniculo-occipital (PGO) que ocurre durante el sueño paradójico. Las evidencias se basan en el análisis de la actividad PGO registrada a nivel tálamico (en el núcleo geniculado lateral; NGL). Sin embargo, la actividad PGO también puede ser registrada en el núcleo abducens (VI par). Con el fin de determinar si la región pontomesencefálica también participa en la regulación de la actividad PGO que se registra a nivel pontino, realizamos pequeñas lesiones electroliticas en el Pbl en el AX, registrado simultáneamente la actividad PGO en el NGL y en el VI par. Se utilizaron gatos anestesiados, curarizados y pretratados con reserpina. La lesión del AX suprimió la actividad PGO registrada en el NGL pero no afectó las espigas registradas a nivel pontino. La lesión del Pbl no modificó la actividad PGO registrada en el NGL ni en el VI par. Estos datos no apoyan la influencia del AX del Pbl sobre la actividad PGO registrada a nivel pontino y sugieren que la región pontomesencefálica sólo juega un papel en la transmisión de las espigas PGO desde el puente al NGL.

Rapidly recurring cortical seizures induce changes in neuronal responsiveness to acetylcholine

La mayoría de los mecanismos propuestos para explicar la descarga epiléptica sugieren un excesivo influjo sináptico o posibles cambios en la excitabilidad celular que resultan en una disminución del umbral conculsivo y en la presencia de actividad autosostenida. Es probable que estos cambios sean causados por modificaciones en la sensibilidad de los receptores de membrana a un neurotransmisor específico. En vista de lo anterior, el objetivo del presente estudio ha sido evaluar la sensibilidad del receptor postsináptico por medio de la aplicación microiontoforética de sustancias cuyo efecto farmacológico es bien conocido, para determinar su posible participación en el proceso epiléptico. Se provocaron cambios en la excitabilidad cortical por estimulación eléctrica en la corteza sensoriomotora de ratas anestesiadas con uretano (1 g/kg intraperitoneal), inmovilizadas con bromuro de pancuronio y mantenidas con respiración mecánica. Los estímulos eléctricos consistieron en trenes de pulsos bifásicos, cada uno con duración de un milisegundo con frecuencia de 100 pps y con duración del tren de 1 segundo. La respuesta de la neurona a la acetilcolina fue evaluada antes y después que se establecieron las descargas. La dosis se midió en monoampres de corriente microiontoforética. Los potenciales del campo extracelular se registraron con el barril central de micropipetas. Los barriles periféricos fueron usados para aplicaciones iontoforéticas de acetilcolina (Ach .1, 1M), atropina (25 mM). Uno de estos barriles conteniendo NaCl (2M) se empleó para el paso automático de corriente de balance; para 613 de estas células las descargas ya estaban establecidas; en las restantes 532 células, la corteza fue normal (sin descargas). Un aumento en la frecuencia promedio de descarga celular se obsevó después de la aplicación iontoforética de Ach. Intensidades de 2 a 50 nA de corriente se emplearon en la corteza con descargas establecidas. En la corteza con descargas no establecidad la respuesta celular a la aplicación de Ach fue menor cuando fueron aplicadas corrientes de igual intensidad. En ambas cortezas, las células respondieron con mucha menor intensidad a la aplicación de NaCl con corriente de magnitud similar a la usada para movilizar la Ach. Estos hallazgos muestran un cambio en la excitabilidad celualr que se refleja en un nivel más elevado de respuesta celular cuando la acetilcolina está presente, y sugieren que este neurotransmisor participa en el mecanismo de la epilep