Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes

Abstract Background Some breeds of sheep are highly seasonal in terms of reproductive capability, and these changes are regulated by photoperiod and melatonin secretion. These changes affect the reproductive performance of rams, impairing semen quality and modifying hormonal profiles. Also, the antioxidant defence systems seem to be modulated by melatonin secretion, and shows seasonal variations. The aim of this study was to investigate the presence of melatonin and testosterone in ram seminal plasma and their variations between the breeding and non-breeding seasons. In addition, we analyzed the possible correlations between these hormones and the antioxidant enzyme defence system activity. Methods Seminal plasma from nine Rasa Aragonesa rams were collected for one year, and their levels of melatonin, testosterone, superoxide dismutase (SOD), glutathione reductase (GRD), glutathione peroxidase (GPX) and catalase (CAT) were measured. Results All samples presented measurable quantities of hormones and antioxidant enzymes. Both hormones showed monthly variations, with a decrease after the winter solstice and a rise after the summer solstice that reached the maximum levels in October-November, and a marked seasonal variation (P < 0.01) with higher levels in the breeding season. The yearly pattern of GRD and catalase was close to that of melatonin, and GRD showed a significant seasonal variation (P < 0.01) with a higher activity during the breeding season. Linear regression analysis between the studied hormones and antioxidant enzymes showed a significant correlation between melatonin and testosterone, GRD, SOD and catalase. Conclusions These results show the presence of melatonin and testosterone in ram seminal plasma, and that both hormones have seasonal variations, and support the idea that seasonal variations of fertility in the ram involve interplay between melatonin and the antioxidant defence system.

Atividade da catalase e da lactato desidrogenase em tilápias submetidas a estresse de confinamento: efeito da cor do ambiente

Avaliaram-se os efeitos da cor do ambiente sobre o crescimento e a atividade da enzima antioxidante catalase (CAT) e da lactato desidrogenase (LDH) em tilápias do Nilo (n=24; 36,2±3,6g). Oito exemplares foram mortos para determinação da atividade basal das enzimas e os demais permaneceram isolados durante 14 dias sob espectro de luz branca ou azul (n=8 peixes/tratamento). A seguir os peixes foram submetidos a um estresse diário de confinamento de 90 minutos (15° ao 28° dia) e pesados semanalmente para cálculo da taxa de crescimento específico (TCE). A TCE negativa confirmou que o confinamento provocou estresse nos peixes, independentemente da cor do ambiente. O aumento da atividade da LDH no músculo vermelho dos peixes mantidos sob luz branca ou azul indicou mudança do metabolismo aeróbio para anaeróbio. O estresse reduziu a atividade da CAT no músculo branco dos peixes mantidos sob a luz branca ou azul. Na musculatura vermelha, esta redução ocorreu apenas nos animais mantidos sob a luz branca. O confinamento aumenta os processos metabólicos anaeróbios e é adequado para estudos sobre os efeitos do estresse. O espectro de luz azul não evita a redução do crescimento e a demanda energética anaeróbia em situações de estresse, mas preserva a atividade da CAT, contribuindo para o bem-estar da tilápia.

Biochemical dissection of diageotropica and Never ripe tomato mutants to Cd-stressful conditions

In order to further address the modulation of signaling pathways of stress responses and their relation to hormones, we used the ethylene-insensitive Never ripe (Nr) and the auxin-insensitive diageotropica (dgt) tomato mutants. The two mutants and the control Micro-Tom (MT) cultivar were grown over a 40-day period in the presence of Cd (0.2 mM CdCl2 and 1 mM CdCl2). Lipid peroxidation, leaf chlorophyll, praline content, Cd content and antioxidant enzyme activities in roots, leaves and fruits were determined. The overall results indicated that the MT genotype had the most pronounced Cd damage effects while Nr and dgt genotypes might withstand or avoid stress imposed by Cd. This fact may be attributed, at least in part, to the fact that the known auxin-stimulated ethylene production is comprised in dgt plants. Conversely, the Nr genotype was more affected by the Cd imposed stress than dgt, which may be explained by the fact that Nr retains a partial sensitivity to ethylene. These results add further information that should help unraveling the relative importance of ethylene in regulating the cell responses to stressful conditions. (C) 2012 Elsevier Masson SAS. All rights reserved.

Burnt sugarcane harvesting: Particulate matter exposure and the effects on lung function, oxidative stress, and urinary 1-hydroxypyrene

Non-mechanised sugarcane harvesting preceded by burning exposes workers and the people of neighbouring towns to high concentrations of pollutants. This study was aimed to evaluate the respiratory symptoms, lung function and oxidative stress markers in sugarcane workers and the residents of Mendonca, an agricultural town in Brazil, during the non-harvesting and harvesting periods and to assess the population and individual exposures to fine particulate matter (PM2.5). Sugarcane workers and healthy volunteers were evaluated with two respiratory symptom questionnaires, spirometry, urinary 1-hydroxypyrene levels, and the measurement of antioxidant enzymes and plasma malonaldehyde during the non-harvesting and harvesting periods. The environmental assessment was determined from PM2.5 concentration. PM2.5 level increased from 8 mu g/m(3) during the non-harvesting period to 23.5 mu g/m(3) in the town and 61 mu g/m(3) on the plantations during the harvesting period. Wheezing, coughing, sneezing, and breathlessness increased significantly in both groups during the harvesting period, but more markedly in workers. A decrease in lung function and antioxidant enzyme activity was observed in both populations during harvesting; this decrease was greater among the sugarcane workers. The urinary 1-hydroxypyrene levels only increased in the sugarcane workers during the harvesting period. The malonaldehyde levels were elevated in both groups, with a higher increase observed in the workers. This research demonstrates the exposure of sugarcane workers and the inhabitants of a neighbouring town to high PM2.5 concentrations during the sugarcane harvest period. This exposure was higher among the sugarcane workers, as illustrated by both higher PM2.5 concentrations in the sugarcane fields and higher urinary 1-hydroxypyrene levels in the volunteers in this group. The higher incidence of respiratory symptoms, greater decrease in lung function and more marked elevation of oxidative stress markers among the sugarcane workers during the harvest confirms the greater effect magnitude in this population and a dose-dependent relationship between pollution and the observed effects. (C) 2012 Elsevier B.V. All rights reserved.

ENVIRONMENTAL TOBACCO SMOKE INDUCES OXIDATIVE STRESS IN DISTINCT BRAIN REGIONS OF INFANT MICE

Environmental tobacco smoke (ETS) leads to the death of 600,000 nonsmokers annually and is associated with disturbances in antioxidant enzyme capacity in the adult rodent brain. However, little is known regarding the influence of ETS on brain development. The aim of this study was to determine levels of malonaldehyde (MDA) and 3-nitrotyrosine (3-NT), as well as enzymatic antioxidant activities of glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), and superoxide dismutase (SOD), in distinct brain structures. BALB/c mice were exposed to ETS twice daily for 1 h from postnatal day 5 through postnatal day 18. Acute exposure was performed for 1 h on postnatal day 18. Mice were euthanized either immediately (0) or 3 h after the last exposure. Immediately after an acute exposure there were higher GR and GST activities and MDA levels in the hippocampus, higher GPx and SOD activities in the prefrontal cortex, and higher GST activity and MDA levels in the striatum and cerebellum. Three hours later there was an increase in SOD activity and MDA levels in the hippocampus and a decrease in the activity of all enzymes in the prefrontal cortex. Immediately after final repeated exposure there were elevated levels of GST and GR activity and decreased GPx activity in the hippocampus. Moreover, a rise was found in GPx and GST activities in the prefrontal cortex and increased GST and GPx activity in the striatum and cerebellum, respectively. After 3 h the prefrontal cortex showed elevated GR and GST activities, and the striatum displayed enhanced GST activity. Data showed that enzymatic antioxidant system in the central nervous system responds to ETS differently in different regions of the brain and that a form of adaptation occurs after several days of exposure.

Antioxidant and inflammatory aspects of lipoprotein-associated phospholipase A2 (Lp-PLA2 ): a review

The association of cardiovascular events with Lp-PLA2 has been studied continuously today. The enzyme has been strongly associated with several cardiovascular risk markers and events. Its discovery was directly related to the hydrolysis of the platelet-activating factor and oxidized phospholipids, which are considered protective functions. However, the hydrolysis of bioactive lipids generates lysophospholipids, compounds that have a pro-inflammatory function. Therefore, the evaluation of the distribution of Lp-PLA2 in the lipid fractions emphasized the dual role of the enzyme in the inflammatory process, since the HDL-Lp-PLA2 enzyme contributes to the reduction of atherosclerosis, while LDL-Lp-PLA2 stimulates this process. Recently, it has been verified that diet components and drugs can influence the enzyme activity and concentration. Thus, the effects of these treatments on Lp-PLA2 may represent a new kind of prevention of cardiovascular disease. Therefore, the association of the enzyme with the traditional assessment of cardiovascular risk may help to predict more accurately these diseases.