Transepithelial potential difference of the intestine and gallbladder of Hoplias malabaricus, a freshwater teleost. effect of urotensins I and II

This study analyzed the effect of the injection of urotensin I (UI) and urotensis II (UII) on the stabilization of the transepithelial potential difference (TPD) of the medium intestine, rectum, and gallbladder of Hoplias malabaricus to investigate if the transport of ions in these organs is affected "in vivo" by these neurohormones. The TPD of the medium intestine, rectum and gallbladder was serosa positive, and remained constant since the first measurement. The injection of both urotensins did not alter the stabilization of the TPD of the medium intestine and rectum when compared with saline-injected group. The injection of UI increased the TPD of the gallbladder in the beginning (0-10 min) of the stabilization period and in the interval of 20-30 min of the stabilization period when fishes were killed 2h and 4h after the injection, respectively, in relation to saline-injected group. The UII injection increased the TPD of the gallbladder only in the beginning (time 0) of the stabilization period in relation to saline when fishes were killed 2h after the injection. No changes in the TPD of the studied organs were detected when fishes were killed 4h after the injection of UII. This study confirms the hypothesis that UI and UII can participate in the regulation of the composition of the bile of fishes, since the injection of both hormones altered the TPD of the gallbladder of H. malabaricus.Este trabalho analisou o efeito da injeção da urotensina I (UI) e da urotensina 11 (UII) na estabilização da diferença de potencial transepitelial (DPT) do intestino médio, reto e vesícula biliar de Hoplias malabaricus, para verificar se o transporte de íons nestes órgãos é afetado "in vivo" por estes neuro-hormônios. A DPT do intestino médio, reto e vesícula biliar é serosa positiva, e seu valor permaneceu estável desde a primeira medida. A injeção de ambas urotensinas não modificou a estabilização da DPT do intestino médio e reto quando comparada com o grupo injetado com salina. A injeção de UI aumentou a DPT da vesícula biliar no início (0-10 min) do período de estabilização e no intervalo de 20-30 min do período de estabilização quando os peixes foram sacrificados 2 h e 4 h após a injeção, respectivamente, em relação ao grupo injetado com salina. A injeção de UII aumentou a DPT da vesícula biliar somente no início (tempo O) do período de estabilização em relação ao grupo tratado com salina sacrificado 2h após a injeção. Não houve alterações na DPT dos órgãos estudados quando os peixes foram sacrificados 4 h após a injeção da UII. Este estudo confirma a hipótese de que a UI e a UII poderiam participar na regulação da composição da bile dos peixes, uma vez que a injeção de ambos neuro-hormônios alterou a DPT da vesícula biliar de H. malabaricus

THE EFFECT OF INTERMITTENT HYPOXIC TRAINING UNDER OXIDATIVE STRESS PARAMETERS IN WISTAR RATS FED ON STANDARD AND HIGH FAT DIET

Considerando-se que dietas ricas em gordura levam ao estresse oxidativo, causando lesões nas células e que o treinamento hipóxico intermitente (THI) aumenta as defesas antioxidantes endógenas em diversas situações, o objetivo deste estudo foi avaliar o efeito do THI em parâmetros de estresse oxidativo e defesas antioxidantes em fígado de ratos Wistar alimentados com dieta rica em gordura e/ou dieta padrão. Ratos Wistar foram divididos em grupos alimentados com dieta padrão ou rica em gordura. Os grupos foram submetidos a hipóxia intermitente (HI), 15 minutos HI (14-11% O2) intercalados com cinco minutos de re-oxigenação ou sessões de normóxia (N) (21% O2), por um período de duas horas diárias durante 30 dias. Os ratos Wistar alimentados com dieta padrão, e submetidas a HI, apresentaram uma redução de 37,7% na concentração de substâncias reativas ao ácido tiobarbitúrico (TBARS) e aumento de 34,66% e 39,8% no conteúdo de superóxido dismutase (SOD) e catalase (CAT), respectivamente, em comparação com o seu controlo (normoxia). No grupo com dieta rica em gordura, não houve diferença estatística entre os subgrupos HI e N. Nossos dados, que demonstram que o THI possui efeito antioxidante no fígado de ratos Wistar, argumentam em favor do uso alternativo de protocolos de hipoxia intermitente no tratamento de determinadas patologias

Effect of the essential oil of Lippia alba on oxidative stress parameters in silver catfish (Rhamdia quelen) subjected to transport

Juvenile silver fish (Rhamdia quelen)were exposed to the essential oil of Lippia alba and transported in plastic bags (10 specimens per bag, load density of 140–200 g.L−1) for different periods (5, 6 and 7 h) yielding final different oxygen levels. The biomarkers of oxidative stress, lipoperoxidation (LPO), catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST) were measured in the liver, gills and brain of the fish. The juveniles were assigned to 6 different treatment groups according to the presence or not of the essential oil of L. alba inwater (10 μL L−1) and the length of transportation,which determined the final concentration of dissolved oxygen inside the bags: Five hours: hyperoxia (13.25±0.35 mg L−1 O2); hyperoxia with L. alba (11.27±0.22 mg L−1 O2); Six hours: normoxia (7.35±0.35 mg L−1 O2); normoxia with L. alba (7.29±0.40 mg L−1 O2); Seven hours: hypoxia (2.29±0.36 mg L−1 O2); hypoxia with L. alba (3.82±0.7 mg L−1 O2). The presence of essential oil of L. alba causes an increase of LPO in the brain of fish transported for 5 h and a decrease of GST in the fish transported for 5 and 7 h as compared to those transported for 6 h. In the liver, this essential oil of L. alba decreased LPO as well the three antioxidants enzymes measured in fish transported for 5 h whilst in the gills there was a decrease of LPO in fish transported for 5 and 7 h. These results suggest that the presence of the essential oil of L. alba improves the redox state in the evaluated tissues, both under hyperoxia and under hypoxia

Oxidative stress parameters in silver catfish (Rhamdia quelen) juveniles infected with Ichthyophthirius multifiliis and maintained at different levels of water pH

The aim of this study was to determine oxidative stress parameters in the liver, gill and muscle of silver catfish juveniles infected with Ichthyophthirius multifiliis and maintained at pH 5.0 or 7.0 for three days. Juveniles were infected by adding one I. multifiliis-infected juvenile and water containing theronts to tanks. After the appearance of white spots on the skin, infected juveniles exposed to pH 5.0 and 7.0 showed significantly higher thiobarbituric acid reactive substances (TBARS) levels in the liver and gills compared to uninfected juveniles. Liver of infected juveniles exposed to pH 7.0 showed higher catalase (CAT) and lower glutathione-S-transferase (GST) activities, but those maintained at pH 5.0 showed significantly higher GST activity than uninfected juveniles. The gills of infected juveniles showed significantly higher CAT (day two) and GST activity at both pH 5.0 and 7.0 compared to uninfected juveniles. Muscle of infected juveniles showed significantly lower CAT and GST activity and TBARS levels (at day three) when maintained at both pH 5.0 and 7.0 compared to uninfected juveniles. In conclusion, I. multifiliis infection induces liver and gill damage via lipid peroxidation products in silver catfish, but higher antioxidant enzyme activity could indicate a greater degree of protection against this parasite. © 2011 Elsevier B.V