¿El licopeno puede eliminar los efectos perjudiciales de la hiperoxia en los cerebros inmaduros? / Can lycopene eliminate the harmful effects of hyperoxia in an immature brain?

Objetivos: Al ser un antioxidante, el licopeno protege a las células contra el daño causado por los radicales libres, fortalece los enlaces intercelulares y mejora el metabolismo celular. Este estudio analiza los efectos del licopeno sobre los trastornos neurodegenerativos por hiperoxia en ratas recién nacidas a término. Métodos: Estas ratas se dividieron en cuatro grupos: grupo 1 de referencia con normoxia, grupo 2 con normoxia + licopeno, grupo 3 de referencia con hiperoxia y grupo 4 con hiperoxia + licopeno. Los grupos 1 y 2 se supervisaron en condiciones de aire ambiental, y los grupos 3 y 4 se supervisaron con un nivel de oxígeno > 85 % O2. Los grupos 2 y 4 recibieron inyecciones intraperitoneales de licopeno de 50 mg/kg/día; los otros grupos recibieron inyecciones intraperitoneales de aceite de maíz con el mismo volumen. Las ratas se sacrificaron en el día 11, después de 10 días con hiperoxia. Se extrajeron los cerebros, y se evaluaron los parámetros del sistema oxidativo. Resultados: Se detectaron lesiones cerebrales por hiperoxia en sustancia blanca, regiones corticales y tálamo. Aumentó la cantidad de células apoptóticas y disminuyó la cantidad de células PCNA positivas en los grupos 3 y 4, comparados con el grupo 1. No se observó una mejora significativa en la cantidad de células apoptóticas y células PCNA positivas en los grupos 3 y 4; además, aumentó la apoptosis. Conclusión: Se halló que el licopeno no mostró efectos terapéuticos para el daño cerebral en ratas recién nacidas. Además, se demostró que el licopeno podría causar efectos tóxicos.

Objectives. In addition to protecting cells against free radical harm thanks to its anti-oxidant nature, lycopene strengthens the bonds among cells and improves cell metabolism. This study focuses on analyzing therapeutic effects of lycopene in hyperoxia-induced neurodegenerative disorders in newborn rats. Methods. Term newborn rats were divided into four groups as the normoxia control group (group-1), normoxia+lycopene group (group-2), hyperoxia control group (group-3) and hyperoxia+lycopene group (group-4). Group-1 and group-2 were monitored in room air while the group-3 and group-4 were monitored at > 85% O2. The group-2 and group-4 were injected with lycopene intrapertioneally (i.p. ) at 50mg/kg/day while the other groups were injected with corn oil i.p. at the same volume. The rats we sacrificed on the 11th day following the 10-day hyperoxia. The brains were removed and oxidant system parameters were assessed. Results. Injury resulting from hyperoxia was detected in the white matter, cortical regions, and thalamus of the brains. It was observed that the number of apoptotic cells increased and the number of proliferating cell nuclear antigen (PCNA) positive cells decreased in the groups-3 and 4 compared to the group-1. No significant improvement in the number of apoptotic cells and PCNA positive cells was observed in the groups-3 and 4, and apoptosis increased as well. Conclusion. This study found that lycopene, did not show any therapeutic effects for brain damage treatment in newborn rats. In addition, this study demonstrated that lycopene might lead to toxic effects.

Ultrastructural morphological alterations during hyperoxia exposure in relation to glutathione peroxidase activity and free radicals productions in the mitochondria of the cortical brain / Alteraciones morfológicas ultraestructurales durante la exposición a la hiperoxia en relación con la actividad de la glutatión peroxidasa y la producción de radicales libres en las mitocondrias de la corteza cerebral

Exposure to normobaric hyperoxia (NH) is known to increase the production of reactive oxygen species (ROS) by mitochondria. The present study was designed to examine mitochondrial ultrastructure morphological changes in the cortical brainin relation to glutathione peroxidase (GPX) activity and free radicals (FR) productions in brain tissue during hyperoxia exposure. The experimental groups were exposed to NH for 24 and 48 h continuously. Following the exposure periods, animals were sacrificed and cortical tissues were divided randomly into two parts; the first part was processed for the ultrastructural examination and the second was homogenized for GPX and FR determinations. Analysis of variance (ANOVA) showed that the main effects of O2 exposure periods were significant (p<0.05) for GPX and FR. Pair-wise means comparisons showed that NH elevated the average (+SE) GPX activity significantly (p<0.05) from the baseline control value of 5670.99+556.34 to13748.42+283.04 and 15134.19+1529.26 U/L with increasing length of NH exposure period from 24 to 48 h, respectively. Similarly, FR production was increased significantly (p<0.05) to 169.73+10.31 and 185.33+21.87, above baseline control of 105.27+5.25 Unit. Ultrastructure examination showed that O2 breathing for 48 h resulted in giant and swelled mitochondria associated with diluted inner membrane and damaged cristae. These mitochondria pathological alterations were associated with damages of myelin, axonal and cellular organelles. Normobaric-hyperoxia inducts mitochondria oxidative stress (MOS) and the subsequent rise of ROS causes variety of ultrastructure morphological pathological alterations in the organelles of cortical brain cells.

Se sabe que la exposición a la hiperoxia normobárica (HN) aumenta la producción de especies reactivas de oxígeno (ERO) por parte de las mitocondrias. El estudio se diseñó para examinar los cambios morfológicos de la ultraestructura mitocondrial en la corteza cerebral con la actividad de la glutatión peroxidasa (GPX) y la producción de radicales libres (RL) en el tejido cerebral durante la exposición a la hiperoxia. Los grupos experimentales fueron expuestos a HN durante 24 y 48 h continuamente. Tras los períodos de exposición, los animales se sacrificaron y los tejidos corticales se dividieron aleatoriamente en dos partes; la primera parte se procesó para el examen ultraestructural y la segunda se homogeneizó para las determinaciones de GPX y RL. El análisis de varianza (ANOVA) mostró que los efectos principales de los períodos de exposición al O2 fueron significativos (p <0,05) para GPX y RL. Las comparaciones de medias por pares mostraron que la HN elevó la actividad promedio de GPX (+ SE) significativamente (p <0,05) desde el valor de control de línea base de 5670,99 + 556,34 a 13748,42 + 283,04 y 15134,19 + 1529,26 U / L con una mayor duración del período de exposición a HN de 24 a 48 h, respectivamente. De manera similar, la producción de RL se incrementó significativamente (p <0,05) a 169,73 + 10,31 y 185,33 + 21,87, por encima del control de referencia de 105,27 + 5,25 unidades. El examen de la ultraestructura mostró que la respiración de O2 durante 48 h dio lugar a mitocondrias gigantes e hinchadas asociadas con la membrana interna diluida y las crestas dañadas. Estas alteraciones patológicas de las mitocondrias se asociaron con daños de mielina, axones y organelos celulares. La hiperoxia normobárica induce el estrés oxidativo mitocondrial (MOS) y el posterior aumento de las ERO provoca una variedad de alteraciones patológicas y morfológicas en los organelos de las células cerebrales corticales.

Effects of erythromycin on γ-glutamyl cysteine synthetase and interleukin-1β in hyperoxia-exposed lung tissue of premature newborn rats / Efeitos da eritromicina sobre a γ-glutamil-cisteína-sintetase e a interleucina-1β no tecido pulmonar exposto à hiperóxia de ratos recém-nascidos prematuros

Objective: To explore the effect of erythromycin on hyperoxia-induced lung injury. Methods: One-day-old preterm offspring Sprague-Dawley (SD) rats were randomly divided into four groups: group 1, air + sodium chloride; group 2, air + erythromycin;group 3, hyperoxia + sodium chloride; and group 4, hyperoxia + erythromycin. At one, seven, and 14 days of exposure, glutathione (GSH) and interleukin-1 beta (IL-1 beta) were detected by double-antibody sandwich enzyme-linked immunosorbent assay (ELISA), and bicinchoninic acid (BCA) was used to detect GSH protein. γ-glutamine-cysteine synthetase (γ-GCS) mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). Results: Compared with group 1, expressions of GSH and γ-GCS mRNA in group 3 were significantly increased at one and seven days of exposure (p < 0.05), but expression of γ-GCS mRNA was significantly reduced at 14 days; expression of IL-1 beta in group 3 was significantly increased at seven days of exposure (p < 0.05), and was significantly reduced at 14 days. Compared with group 3, expressions of GSH and γ-GCS mRNA in group 4 were significantly increased at one, seven, and 14 days of exposure (p < 0.05), but expressions of GSH showed a downward trend at 14 days; expression of IL-1 beta in group 4 was significantly reduced at one and seven days of exposure (p < 0.05). Conclusions: Changes in oxidant-mediated IL-1 beta and GSH are involved in the development of hyperoxia-induced lung injury. Erythromycin may up-regulate the activity of γ-GCS, increasing the expression of GSH, inhibiting the levels of oxidant-mediated IL-1 beta and alleviating hyperoxia-induced lung injury via an antioxidant effect. .

Objetivo: Explorar o efeito da eritromicina sobre lesões pulmonares induzidas por hiperóxia. Métodos: Uma prole de ratos Sprague-Dawley (SD) prematuros com um dia de vida foi dividida aleatoriamente em quatro grupos: grupo 1 ar + cloreto de sódio, grupo 2 ar + eritromicina, grupo 3 hiperóxia + cloreto de sódio e grupo 4 hiperóxia + eritromicina. Com um, sete e 14 dias de exposição, foram detectadas Glutationa (GSH) e Interleucina-1 beta (IL-1 beta) pelo ensaio imunossorvente ligado à enzima (ELISA), e o ácido bicinconinico (BCA) foi utilizado para detectar a proteína GSH. O mRNA da γ-glutamil-cisteina-sintetase (γ-GCS) foi detectado por reação em cadeia da polimerase via transcriptase reversa (RT-PCR). Resultados: Comparadas ao grupo 1, as expressões do mRNA da GSH e da γ-GCS no grupo 3 aumentaram significativamente com um e sete dias de exposição (p < 0,05), porém a expressão de mRNA da γ-GCS diminuiu significativamente aos 14 dias; a expressão de IL-1 beta no grupo 3 aumentou significativamente aos 7 dias de exposição (p < 0,05) e diminuiu significativamente aos 14 dias. Comparadas ao grupo 3, as expressões do mRNA da GSH e da γ-GCS no grupo 4 aumentaram significativamente com um, sete e 14 dias de exposição (p < 0,05), porém as expressões de GSH mostraram uma tendência de queda aos 14 dias; a expressão de IL-1 beta no grupo 4 foi reduzida significativamente com um e sete dias de exposição (p < 0,05). Conclusões: As variações de IL-1 beta e GSH mediadas por oxidantes estão envolvidas no desenvolvimento de lesão pulmonar induzida por hiperóxia. A eritromicina poderá regular positivamente a atividade da γ-GCS, aumentando a expressão de GSH, inibindo os níveis de interleucina-1beta mediada por ...

Hiperoxia por dos horas produce daño morfológico cerebral luego de asfixia neonatal experimental / Two-hour hyperoxia following experimental neonatal asphyxia produces morphological brain damage

Objetivos: Determinar el efecto de una exposición de dos horas de hiperoxia al 21%, 40% y 100% sobre la morfología cerebral, en un modelo experimental de asfixia neonatal. Diseño: Estudio experimental. Institución: Instituto Nacional de Salud del Niño, Lima, Perú. Material biológico: Ratas albinas Holtzmann. Intervenciones: Ciento veinte ratas albinas Holtzmann de una semana de nacidas (a excepción del grupo control) fueron sometidas a asfixia experimental por ligadura de la arteria carótida izquierda y luego expuestas a hipoxia (oxígeno al 8%). Después fueron asignadas aleatoriamente a uno de los siguientes grupos: exposición por dos horas a O2 al 100%, a O2 al 40%, a O2 al 21% y un grupo control (no expuesto a asfixia experimental). El daño cerebral fue evaluado mediante la medición del peso cerebral y el porcentaje del área cerebral con daño microscópico. Principales medidas de resultados: Daño cerebral. Resultados: El peso cerebral promedio fue menor en los animales de los grupos sometidos a hiperoxia experimental (ANOVA; p<0,001). Se presentó daño cerebral microscópico con mayor frecuencia en el grupo sometido a hipoxia experimental que recibió O2 100% por dos horas y con menor frecuencia en el que recibió O2 al 40% (60% versus 43,3%), diferencia que fue estadísticamente significativa (prueba χ²; p<0,001). El grupo sometido a hipoxia experimental que recibió O2 100% tuvo un mayor porcentaje promedio de área cerebral con daño microscópico (18,3%), en comparación con los otros grupos de hipoxia experimental, aunque la diferencia no fue estadísticamente significativa (ANOVA; p=0,123). Conclusiones: La hiperoxia al 100% por dos horas se asoció con menor peso cerebral y mayor daño cerebral en animales de experimentación sometidos a asfixia neonatal experimental.

Objectives: To determine the effect of 2-hour exposure to 21% O2, 40% O2 and 100% O2 on cerebral morphology in an experimental model of neonatal asphyxia. Design: Experimental study. Setting: Instituto Nacional de Salud del Niño, Lima, Peru. Biologic material: Holtzman albino rats. Interventions: A sample of 120 one week-old Holtzman albino rats (with the exception of the control group) underwent experimental asphyxia by left carotid artery ligation and then exposition to hypoxia (8% O2); thereafter rats were randomly assigned to one of the following groups: exposition for two hours to 100% O2, to 40% O2, to 21% O2, and a control group (not exposed to experimental asphyxia). Brain damage was determined by brain weight and percentage of microscopic brain area damage. Main outcome measures: Brain damage. Results: Brain weight was lower in animals with experimental hyperoxia (ANOVA, p<0.001). Microscopic damage was more frequent in the group receiving 100% O2 for two hours and with less frequency in the group receiving 40% O2 (60% versus 43.3%). The difference was statistically significant (χ2 test: p<0.001). The group receiving 100% O2 had more microscopic brain damage (18.3 %) in comparison with the other groups of experimental hypoxia, but the difference was not statistically significant (ANOVA, p=0.123). Conclusions: Following neonatal asphyxia 100% two-hour hyperoxia was associated with less brain weight and more damage in experimental animals.

Alterações da histoarquitetura pulmonar de camundongos neonatos expostos à hiperóxia / Alterations in the pulmonary histoarchitecture of neonatal mice exposed to hyperoxia

OBJETIVOS: Analisar os efeitos da exposição à hiperóxia (100% de oxigênio) sobre a histoarquitetura pulmonar de camundongos neonatos. MÉTODOS: Camundongos neonatos da linhagem Balb/c foram expostos à hiperóxia (GH) (100% de oxigênio) (n = 10) em uma câmara (15 x 20 x 30 cm) por 24 horas, com fluxo de 2 L/min. O grupo controle (GC) (n = 10) foi exposto a normóxia em um mesmo tipo de câmara e pelo mesmo tempo. Após a exposição, os animais foram sacrificados por decapitação, os pulmões foram removidos para análise histológica e processados de acordo com a rotina do laboratório. Cortes de 3 µm de espessura foram corados com hematoxilina e eosina (H&E). A análise morfométrica foi realizada com o objetivo de analisar macrófagos presentes na luz alveolar, densidade de superfície (Sv) de trocas gasosas, densidade de volume (Vv) de parênquima pulmonar e áreas de atelectasias. RESULTADOS: Foi verificada diminuição do número de macrófagos alveolares (MØ) no GH (GH = 0,08±0,01 MØ/mm²; GC = 0,18±0,03 MØ/mm²; p = 0,0475), Sv de troca gasosa no GH (GH = 8,08 ± 0,12 mm² /mm³; GC = 8,65 ± 0,20 mm² /mm³; p = 0,0233), Vv de parênquima pulmonar no GH (GH = 54,7/33,5/83,5 %/mm²; GC = 75/56,7/107,9 %/mm²; p < 0.0001) quando comparado com o GC. Entretanto, houve aumento de áreas de atelectasias no GH (GH = 17,5/11,3/38,4 atelectasia/mm²; GC = 14/6,1/24,4 atelectasia/mm²; p = 0,0166) quando comparado com o GC. CONCLUSÃO: Nossos resultados indicam que a hiperóxia promoveu alterações na histoarquitetura pulmonar, aumentando áreas de atelectasia e hemorragia alveolar difusa.

OBJECTIVES: To analyze the effects of exposure to hyperoxia (100% oxygen) on the lung histoarchitecture of neonatal mice. METHODS: Neonatal Balb/c mice were exposed to hyperoxia (HG) (100% oxygen) (n = 10) in a chamber (15 x 20 x 30 cm) for 24 horas ours with a flow of 2 L/min. The control group (CG) (n = 10) was exposed to normoxia in the same type of chamber and for the same time. After exposure, the animals were euthanized by decapitation; the lungs were removed and processed for histological examination according to the laboratory routine. Three-mm thick sections were stained with hematoxylin and eosin (H&E). The morphometric analysis was performed with in order to analyze the macrophages present in the alveolar lumen, surface density (Sv) of gas exchange, volume density (Vv) of lung parenchyma, and areas of atelectasis. RESULTS: A decrease in the number of alveolar macrophages (MØ) was observed in the HG (HG = 0.08±0.01 MØ/mm², CG = 0.18±0.03 MØ/mm², p = 0.0475), Sv of gas exchange in HG (HG = 8.08±0.12 mm² /mm³, CG = 8.65±0.20 mm² /mm³, p = 0.0233), Vv of lung parenchyma in HG (HG = 54.7/33.5/83.5%/ mm²; CG = 75/56.7/107.9%/mm², p < 0.0001) when compared with the CG. However, there was an increase in areas of atelectasis in HG (HG = 17.5/11.3/38.4 atelectasis/mm², CG = 14/6.1/24.4 atelectasis/mm², p = 0.0166) when compared with the CG. CONCLUSION: The present results indicate that hyperoxia caused alterations in lung histoarchitecture, increasing areas of atelectasis and diffuse alveolar hemorrhage.

Neuroproteccióndel extracto hidroalcohólico de las hojas de Satureja brevicalyx ‘wayra muña’ en un modelo animal de hiperoxia e hipoxia-isquemia / Satureja brevicalyx ‘wayra muna’ leaves hydroalcoholic extract neuroprotection in a hyperoxia and ischemia-hypoxia animal model

Objetivos: Evaluar el efecto neuroprotector del extracto hidroalcohólico de hojas de Satureja brevicalyx ‘wayra muña’ en ratas sometidas a hiperoxia, y su progenie sometidas a hipoxia isquemia. Diseño: Experimental. Lugar: Área de Cirugía Experimental, Instituto Nacional de Salud del Niño, y Laboratorios del Centro de Investigación de Bioquímica y Nutrición, Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú. Material biológico: Rattus novegicus de la cepa Holtzman, hojas secas de Satureja brevicalyx ‘wayra muña’. Intervenciones: Tratamiento con el extracto en dos modelos: hiperoxia en ratas hembras adultas, e hipoxia en la progenie de ratas madre tratadas. Se realiza ANOVA y prueba de Tukey. Principales medidas de resultados: Actividad de superóxido dismutasa (SOD), niveles de glutatión (GSH) total y niveles de sustancias reactivas al ácido tiobarbitúrico (TBARS). Resultados: En las ratas tratadas con el extracto se observó disminución significativa de TBARS y participación de GSH y SOD. Conclusiones: Nuestros resultados sugieren que el extracto hidroalcólico de Satureja brevicalyx ejerce efecto neuroprotector en condición de hiperoxia e hipoxia experimental, mediante la mitigación de la lipoperoxidación como parámetro de daño oxidativo, con participación del GSH y la actividad de SOD como mecanismos de defensa antioxidante.

Objectives: To determine Satureja brevicalyx ‘wayra muna’ leaves hydroalcoholic extract neuroprotective effect in rats subjected to hyperoxia and its progeny to hypoxia ischemia. Design: Experimental. Setting: Department of Experimental Surgery, National Institute of Child Health, and Biochemistry and Nutrition Research Center Laboratory, Faculty of Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru. Biological material: Rattus novegicus Holtzman strain, Satureja brevicalyx ‘wayra muna’ dry leaves. Interventions: Treatment with the extract had two models: hyperoxia in adult female rats and hypoxia in the offspring of rats treated. Both ANOVA and Tukey test were performed. Main outcome measures: Superoxide dismutase (SOD) activity, total glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) levels. Results: Rats treated with the extract showed significant decrease in TBARS and participation of GSH and SOD. Conclusions: Our results suggest that Satureja brevicalyx hydroalcoholic extract exerts neuroprotective effect in hyperoxia and hypoxia conditions by alleviating experimental lipid peroxidation, an oxidative damage parameter, with participation of GSH and SOD activity as antioxidant defense mechanisms.

Efeitos agudos da ventilação mecânica com hiperoxia na morfometria do diafragma de ratos / Acute effects of mechanical ventilation with hyperoxia on the morphometry of the rat diaphragm

CONTEXTUALIZAÇÃO: A asssistência ventilória mecânica (AVM) prolongada associada a altas frações de oxigênio produz impacto negativo na função diafragmática. No entanto, não são claros os efeitos agudos da AVM associada a altas frações de oxigênio em pulmões aparentemente sadios. OBJETIVO: Analisar os efeitos agudos da ventilação mecânica com hiperóxia na morfometria do diafragma de ratos. Métodos: Estudo experimental prospectivo, com nove ratos Wistar, com peso de 400±20 g, randomizados em dois grupos: controle (n=4), anestesiados, traqueostomizados e mantidos em respiração espontânea em ar ambiente por 90 minutos e experimental (n=5), também anestesiados, curarizados, traqueostomizados e mantidos em ventilação mecânica controlada pelo mesmo tempo. Foram submetidos à toracotomia mediana para coleta da amostra das fibras costais do diafragma que foram seccionadas a cada 5 μm e coradas pela hematoxilina e eosina para o estudo morfométrico. Para a análise estatística, foi utilizado o teste t de Student não pareado, com nível de significância de p<0,05. RESULTADOS: Não foram encontrados sinais indicativos de lesão muscular aguda, porém observou-se dilatação dos capilares sanguíneos no grupo experimental. Os dados morfométricos do diâmetro transverso máximo da fibra muscular costal foram em média de 61,78±17,79 µm e de 70,75±9,93 µm (p=0,045) nos grupos controle e experimental respectivamente. CONCLUSÃO: A ventilação mecânica de curta duração com elevada concentração de O2 produziu marcantes alterações microvasculares e musculares, podendo refletir o início do processo inflamatório.

BACKGROUND: Prolonged mechanical ventilatory support (MVS) combined with high oxygen concentrations has a negative impact on diaphragm function. However, the acute effects of MVS with hyperoxia have not been elucidated. Objective: To analyze the acute effects of mechanical ventilation with hyperoxia on the morphometry of the rat diaphragm. METHODS: An experimental, prospective study was conducted with Wistar rats (weight: 400±20 g), which were randomly allocated to two groups. The control group (n=4) was anesthetized, tracheostomized and kept spontaneously breathing room air for 90 minutes. The experimental group (n=5) was also anesthetized, curarized, tracheostomized and kept in controlled mechanical ventilation for the same amount of time. Both groups were submitted to median thoracotomy for sample collection of costal fibers from the diaphragm muscle, which were sectioned every 5 μm and stained with hematoxylin and eosin for the morphometric study. Independent Student's t tests were employed to investigate differences between groups, with a significance level of p<0.05. RESULTS: There were no signs of acute muscle lesions, however the blood capillaries became dilated in the experimental group. The mean morphometric data related to the maximum cross-sectional diameter of the diaphragm costal fibers were 61.78 ±17.79 µm and 70.75±9.93 µm (p=0.045) for the control and experimental groups, respectively. CONCLUSIONS: Short-term mechanical ventilation with hyperoxia led to significant microvascular and muscle changes, which may reflect the onset of an inflammatory process.

Efeitos da hiperóxia sobre o pulmão de ratos Wistar / Effects of hyperoxia on Wistar rat lungs

OBJETIVO: Avaliar a repercussão da elevada concentração de oxigênio (hiperóxia) em um curto período de tempo no pulmão de ratos Wistar. MÉTODOS: Os animais foram divididos em grupos O10', O30', O90', ou seja, ratos expostos à hiperóxia por 10', 30' e 90', respectivamente, e no grupo controle (GC), exposto ao ar ambiente. Os animais foram sacrificados 24 h após a exposição. O lavado broncoalveolar foi realizado e os pulmões foram retirados para análise histológica e estereológica. RESULTADOS: Observamos um aumento do número de macrófagos (2169,9 ± 118,0, 1560,5 ± 107,0 e 1467,6 ± 39,0) e neutrófilos (396,3 ± 35,4, 338,4 ± 17,3 e 388,7 ± 11,7), concomitante a um aumento do dano oxidativo (143,0 ± 7,8 por cento, 180,4 ± 5,6 por cento e 235,0 ± 13,7 por cento) nos grupos O10', O30' e O90', respectivamente, quando comparados ao GC (781,3 ± 78,3 por cento, 61,6 ± 4,2 por cento e 100,6 ± 1,7 por cento). Na análise histológica e estereológica foram observados alvéolos e septos normais no GC (83,51 ± 1,20 por cento e 15 ± 1,21 por cento), no grupo O10' (81,32 ± 0,51 por cento e 16,64 ± 0,70 por cento) e no grupo O30' (78,75 ± 0,54 por cento e 17,73 ± 0,26 por cento). Entretanto, no grupo O90' foi notado um influxo de células inflamatórias nos alvéolos e nos septos alveolares. Hemácias extravasaram do capilar para o alvéolo (59,06 ± 1,22 por cento), com evidências de congestão, hemorragia e edema de septo (35,15 ± 0,69 por cento). CONCLUSÃO: Os resultados indicam que a hiperóxia induziu uma ação lesiva no grupo O90' sobre o parênquima pulmonar, com repercussões de dano oxidativo e infiltrado inflamatório.

OBJECTIVE: To study the effects of short-term exposure to high oxygen concentrations (hyperoxia) on Wistar rat lungs. METHODS: Animals were divided into three groups exposed to hyperoxia for 10', 30' and 90' (O10', O30', O90', respectively), together with a control group (exposed to room air). The animals were sacrificed 24 h after exposure. Bronchoalveolar lavage was performed, and the lungs were removed for histological and stereological analysis. RESULTS: In the O10', O30', and O90' groups, respectively and in comparison with the controls, we observed an increase in the numbers of macrophages (2169.9 ± 118.0, 1560.5 ± 107.0, and 1467.6 ± 39.0 vs. 781.3 ± 78.3) and neutrophils (396.3 ± 35.4, 338.4 ± 17.3, and 388.7 ± 11.7 vs. 61.6 ± 4.2), concomitant with an increase in oxidative damage (143.0 ± 7.8 percent, 180.4 ± 5.6 percent, and 235.0 ± 13.7 vs. 100.6 ± 1.7 percent). The histological and stereological analyses revealed normal alveoli and alveolar septa in the controls (83.51 ± 1.20 percent and 15 ± 1.21 percent), in the O10' group (81.32 ± 0.51 percent and 16.64 ± 0.70 percent), and in the O30' group (78.75 ± 0.54 percent and 17.73 ± 0.26 percent). However, in the O90' group, inflammatory cell infiltration was observed in the alveoli and alveolar septa. Red blood cells extravasated from capillaries to the alveoli (59.06 ± 1.22 percent), with evidence of congestion, hemorrhage, and septal edema (35.15 ± 0.69 percent). CONCLUSION: Hyperoxia for 90' caused injury of the lung parenchyma, resulting in oxidative damage and inflammatory cell infiltration.

Ultraestructura de la retinopatía causada por la hiperoxia en ratas en desarrollo / Ultra structure of retinopathy induced by hyperoxia in developing rats

In order to evaluate the effect of postnatal hyperoxia on retinal structure, newborn rats were exposed to different oxygenation intervals (80 ± 1%) with three interruptions of 21% (30 min each). Four groups of rats were exposed from birth to the 6th, 9th, 12th and 14th postnatal day, respectively and another group was placed under normoxia. After this period all oxygenated groups and the controls remained under normoxia until they were 30 days old for the structural analysis of retina. Retinal histology was carried out using conventional techniques for transmission electron microscopy (TEM). In the ganglion cell layer of the retina from rats exposed for 9 days to hyperoxia, capillaries with large projections toward the lumen, were observed as a possible consequence of cellular edema of endothelium. The most severe damage was observed in rats exposed to hyperoxia during 12 and 14 days, showing mitochondrias swollen up and without crests in the areas surrounding the capillaries, necrosis and apoptosis processes, dense bodies, cells with swollen cytoplasms and rupture of the plasmatic membrane. The results suggest that postnatal hyperoxia causes severe damages to the retina in developing rats with a direct relationship between the time exposed to oxygen and ultra structural damages.

Con el propósito de evaluar el efecto de la hiperoxia posnatal sobre la estructura retiniana se analizaron retinas de ratas recién nacidas expuestas a diferentes periodos de oxigenación (80 ±1%), con tres interrupciones de 21% (30 min c/u). Cuatro grupos de ratas fueron expuestas desde su nacimiento hasta el 6to, 9no, 12mo y 14to días de vida y otro grupo fue mantenido en normoxia. Después de este periodo tanto los grupos expuestos a la hiperoxia como los controles permanecieron en normoxia hasta una edad de 30 días para el análisis estructural de la retina. La histología se hizo usando técnicas convencionales para microscopía electrónica de transmisión (MET). En la capa de células ganglionares de la retina de ratas expuestas a nueve días de hiperoxia, se observaron capilares con notables proyecciones hacia la luz, posiblemente como consecuencia de edema celular del endotelio. El daño más intenso fue observado en las ratas expuestas a hiperoxia durante 12 y 14 días, mostrando mitocondrias hinchadas y sin crestas en las áreas circundantes a los capilares, procesos de necrosis y apoptosis, cuerpos densos, células con citoplasmas hinchados y con ruptura de la membrana plasmática. Los resultados sugieren que la hiperoxia posnatal causa graves daños a la retina en las ratas en desarrollo, con una relación directa entre el tiempo de exposición al oxígeno y los daños ultraestructurales.

Estrés oxidativo como posible causante de retinopatía en ratas en desarrollo sometidas a hiperoxia / The effect of oxidative stress on retinal and choroidal cytoarchitecture was evaluated, and the levels of reduced glutathione (GSH) analyzed, in rats subjected to hyperoxygenation (80 ±1% O2). Groups of rats were oxygenated from birth (day 0) to days 6, 9, 12 or 14 of life, while others were kept under normal O2 (controls). GSH blood concentration was determined in each period. Retinal and choroidal histology was studied in 30 day-old rats. GSH concentration was significantly lower in rats oxygenated on days 0-6 and 0-9 than in controls. However, rats kept under high O2 on days 0-12 and 0-14 showed similar values to the controls, possibly due to an adaptive process. In the retina and choroid of rats exposed to O2 on days 0-9, 0-12 and 0-14, capillary vasoconstriction was observed, as well as tight junction weakening in choroidal capillaries leading to hemorrhage. The retina from rats subjected to hyperoxigenation from 0-12 days showed vacuolized horizontal cells with damaged mitochondria and swollen nuclear envelopes. The results show severe structural damage in the retina and choroid when animals are subjected to high O2 levels. / Avaliou-se o efeito do estresse oxidativo sobre a citoarquitetura retiniana e coroidal e analisou-se os níveis de glutation reduzido (GSH) em eritrócitos de ratos submetidos a hiperóxia (80 ±1% O2). Grupos destas foram oxigenados desde o dia do seu nascimento (0) até o dia 6, 9, 12 o 14 de vida, e outras se colocaram em normoxia (controles). Em cada um de estes períodos se determinou a concentração do GSH. A histologia da retina e a coróides se realizou em ratos de 30 dias. As concentrações de GSH em ratos oxigenados de 0-6 e 0-9 dias, foram significativamente mais baixas que nos controles. No entanto, nos grupos de 0-12 e 0-14 dias de hiperóxia mostraram valores similares aos controles, possivelmente como um processo adaptativo. Na retina e coróides de ratos expostos de 0-9, 0-12 e 0-14 dias, se evidenciaram processos de vasoconstrição capilar, assim como debilitação das uniões estreitas dos endotélios capilares coróides, conduzindo a hemorragia. A retina dos ratos submetidos a hiperóxia de 0-12 dias, apresentou células horizontais vacuolizadas, com mitocôndrias alteradas e as envolturas nucleares dilatadas. Os resultados evidenciam os severos danos estruturais que sofrem a retina e a coróides quando os animais são submetidas a altos níveis de oxigenação.

Se evaluó el efecto del estrés oxidativo sobre la citoarquitectura retiniana y coroidal y se analizó los niveles de glutatión reducido (GSH) en eritrocitos de ratas sometidas a hiperoxia (80 ±1% O2). Grupos de éstas fueron oxigenados desde el día de su nacimiento (0) hasta el día 6, 9, 12 o 14 de vida, y otras se colocaron en normoxia (controles). En cada uno de estos períodos se determinó la concentración del GSH. La histología de la retina y la coroides se realizó en ratas de 30 días. Las concentraciones de GSH en ratas oxigenadas de 0-6 y 0-9 días, fueron significativamente más bajas que en los controles. No obstante, en los grupos de 0-12 y 0-14 días de hiperoxia mostraron valores similares a los controles, posiblemente como un proceso adaptativo. En la retina y coroides de ratas expuestas de 0-9, 0-12 y 0-14 días, se evidenciaron procesos de vasoconstricción en capilares retinianos y coroideos, así como debilitamiento de las uniones estrechas de los endotelios capilares coroideos, conduciendo a hemorragia. La retina de las ratas sometidas a hiperoxia de 0-12 días, presentó células horizontales vacuolizadas, con mitocondrias alteradas y las envolturas nucleares dilatadas. Estos resultados evidencian los severos daños estructurales que sufren la retina y la coroides cuando son sometidas a altos niveles de hiperoxia.