Review: Implication of redox imbalance in animal health and performance at critical periods,insights from different farm species

The process of oxidative stress occurs all over the production chain of animals and food products. This review summarises insights obtained in different farm species (pigs, ruminants, poultry, and fishes) to underpin the most critical periods for the venue of oxidative stress, namely birth/hatching and weaning/start-feeding phase. Common responses between species are also unravelled in periods of high physiological demands when animals are facing dietary deficiencies in specific nutrients, suggesting that nutritional recommendations must consider the modulation of responses to oxidative stress for optimising production performance and quality of food products. These conditions concern challenges such as heat stress, social stress, and inflammation. The magnitude of the responses is partly dependent on the prior experience of the animals before the challenge, reinforcing the importance of nutrition and other management practices during early periods to promote the development of antioxidant reserves in the animal. When these practices also improved the performance and health of the animal, this further confirms the central role played by oxidative stress in physiologically and environmentally induced perturbations. Difficulties in interpreting responses to oxidative stress arise from the fact that the indicators are only partly shared between studies, and their modulations may also be challenge-specific. A consensus about the best indicators to assess pro-oxidative and antioxidant pathways is of huge demand to propose a synthetic index measurable in a non-invasive way and interpretable along the productive life of the animals.     

The immune response of tilapia Oreochromis mossambicus and its susceptibility to Streptococcus iniae under stress in low and high temperatures

Mozambique tilapia Oreochromis mossambicus acclimated to 27 degrees C were then held at 19, 23, 27 (control), 31 and 35 degrees C, and were examined for non-specific cellular and humoral responses after 12-96 h. Total leucocyte count decreased significantly when fish were transferred to 19 and 23 degrees C after 48 and 96 h, and when transferred to 35 degrees C over 12-96 h, respectively. Respiratory burst decreased significantly when fish were transferred to 19, 31 and 35 degrees C over 24-96 h, whereas phagocytic activity and phagocytic index decreased significantly when fish were transferred to low temperatures (19 and 23 degrees C) and high temperatures (31 and 35 degrees C) over 12-96 h. Lysozyme activity decreased significantly when fish were transferred to 19 degrees C after 12-96 h, but increased significantly when transferred to 31 and 35 degrees C over 48-96 h. Alternative complement pathway (ACH(50)) also decreased significantly when transferred to 19 and 23 degrees C after 12h, but increased significantly when transferred to 31 and 35 degrees C after 24h. In another experiment, tilapia reared at 27 degrees C were injected intraperitoneally with Streptococcus iniae at a dose of 1 x 10(7)colony-forming units (cfu)fish(-1), and then reared onward at water temperatures of 19, 23, 27 (control), 31 and 35 degrees C. Over 48-168 h, the cumulative mortality of S. iniae-injected fish held in 19 and 35 degrees C was significantly higher than that of injected-fish held in 23, 27 and 31 degrees C. It is concluded that transfer of tilapia O. mossambicus from 27 degrees C to low temperatures (19 and 23 degrees C) after 12h, and transfer of fish from 27 degrees C to high temperatures (31 and 35 degrees C) reduced their immune capability. Moreover, tilapia under temperature stress at 19 and 35 degrees C from 27 degrees C decreased its resistance against S. iniae.     

Elevated 11-ketotestosterone during paternal behavior in the Bluebanded goby (Lythrypnus dalli)

The relationship between androgens and paternal behavior is not straightforward, potentially because of the diversity of tasks a male must undertake to maximize reproductive success, notably alternating between courtship, aggression, and offspring care. In some species, these events are separated in time, but in others they are coincident. The endocrine profiles of species that simultaneously court, parent, and defend a nest, such as male bluebanded gobies (Lythrypnus dalli), are not well understood. We sampled a potent fish androgen, 11-ketotestosterone (KT), at different life history stages (experienced parenting males, experienced males not actively parenting, inexperienced males with their first clutch, and females), to examine this relationship. We found that experienced parenting L. dalli males have the highest KT levels of any group, while none of the other groups differed significantly. Males showed elevated KT levels when they had eggs compared to when they did not. Our data suggest that KT facilitates at least some aspects of parental care in L. dalli.     

Behavioral and physiological responses of a wild teleost fish to cortisol and androgen manipulation during parental care

Proximate mediators of reproductive behaviors in vertebrates have a long history of study. In fishes, relatively few studies have focused on hormonal control of parental care, despite a comprehensive background on the general physiology of fishes, and the frequent occurrence of parental care behaviors. Studies on this taxon have repeatedly found that the relationships between androgens and paternal care do not follow the predictions made in the avian and mammalian literature. Glucocorticoids may also have a role in mediating parental behaviors, possibly through their role as regulators of metabolism. As such, we investigated the role of 11-ketotestosterone (11-KT) and cortisol in mediating parental effort of male smallmouth bass (Micropterus dolomieu) by manipulating hormone titers in wild fish. In smallmouth bass, males spawn annually with a single female and defend a single brood for up to 30 days. Treatment of parental fish with cyproterone acetate (CYA; an androgen receptor antagonist) resulted in a decrease in nest defense in response to a simulated brood predator; however, no changes in nest success, nest tending or biochemical indicators of nutritional status were detected. Treatment with exogenous cortisol did not change parental behavior, but did increase the rate of nest failure, possibly owing to the energetic cost of chronically elevated cortisol concentrations. We discuss these findings in the context of resource-driven trade-offs and highlight life history as an important factor controlling parental effort in species with costly parental care behaviors.     

Prenatal maternal programming determines testosterone response during social challenge

The present study investigated in domestic guinea pigs whether the effects of prenatal social stress are pathological consequences of adverse social conditions; or whether mothers adjust their offspring to the environment they experience during pregnancy. As a prenatal stressor social instability was used: we studied male guinea pig offspring whose mothers lived in a stable social environment (SE-sons) or in an unstable social environment (UE-sons) during pregnancy. Eight experimental groups were established, consisting of one SE-son, one UE-son and five females, respectively. All experimental groups remained in a stable group composition for the whole investigation time. We hypothesized that if mothers prenatally adapt their offspring, in a stable social environment SE-sons will be dominant, display agonistic and courtship behavior more frequently, have higher body weights, be less stressed and have higher testosterone concentrations than UE-sons. Our results show no significant differences between SE- and UE-sons concerning behavior, body weight or plasma-cortisol concentrations. Hence no evidence exists that an unstable social environment during pregnancy has pathological consequences for the male offsprings' phenotype. However, SE-sons had significantly higher plasma testosterone concentrations than UE-sons in phases when females were receptive. A higher reactivity of the hypothalamic-pituitary-gonadal axis might enable SE-males to adjust testosterone levels to the present social situation: they are significantly elevated in decisive phases of female receptivity, but remain on a lower level before and after reproductive challenge. Thus, mothers who experienced social stability during pregnancy provide their sons prenatally with a promising reproductive strategy in competitive situations later in life.     

药物安全性评价中豚鼠全身过敏试验方法的研究

目的在新药临床前安全性评价中对药物致敏性的研究日益受到重视。本实验基于我国新药评价指导原则,分析探讨SFDA颁布的指导原则中豚鼠全身过敏实验方案中可能影响实验结果的问题和因素。方法在GLP条件下,以体重为300～400克的豚鼠为实验对象,以牛血清白蛋白、生理盐水等受试物为对照,研究不同致敏剂量、激发剂量、激发时间、激发途径和激发次数等条件下,豚鼠全身过敏的发生情况。结果在一定剂量范围内,豚鼠全身过敏反应的发生率与致敏剂量、激发剂量和激发途径无关,但症状发生的严重程度与致敏剂量、激发剂量和激发途径有关。结论新药过敏性评价研究应参照指导原则,注意试验的剂量设计和给药途径。     

Experimental evaluation of the pathogenicity of Perkinsusolseni in juvenile Manila clams Ruditapes philippinarum

We evaluated the pathogenicity of Perkinsus olseni towards the Manila clam, Ruditapes philippinarum, by an experimental challenge. For production of prezoosporangia of P. olseni, we injected uninfected Manila clams with cells of a pure strain of P. olseni and reared them for 7 d. Prezoosporangia were isolated from the soft tissue of the injected clams after culturing in Ray’s fluid thioglycollate medium. Hatchery-reared, uninfected juvenile clams (3-10 mm shell length) were challenged by immersion in one of two concentrations of a prezoosporangial suspension of P. olseni for 6 d. The challenged clams had significantly higher mortality at both the concentrations than the unchallenged clams. The mortality due to infection dose-dependently began approximately 4 weeks and 7 weeks after challenge in the higher and lower concentrations, respectively. This is the first experimental evidence that P. olseni causes direct mortality in Manila clams. The lethal level of infection was estimated at approximately 10⁷ pathogen cells/g soft tissue weight.     

The effect of challenge and trickle Trichuris muris infections on the polarisation of the immune response

In the field, determination of mechanisms of immunity to geohelminths are problematic due to the variation in infection exposure, host genetics, nutrition and co-infection. This study uses a well defined laboratory model, Trichuris muris in the mouse to study immune responses to challenge and trickle infections. The rationale is thus to study parasite acquisition under more natural antigen dose exposure. Antigen dose has previously been shown in this system to affect the outcome of infection with low antigen doses favouring type 1 responses (and susceptibility) and high antigen doses favouring type 2 responses (and resistance). A high level challenge infection could be established in a normally resistant host but only following priming of the immune response by a low level infection. Once type 2 responses were initiated it was impossible to switch an ongoing type 2 response even using IL-12 which is a potent stimulus of type 1 responses. Trickle infections resulted in no clear polarisation of the immune response. It was possible to build up the level of infection to a threshold level beyond which type 2 responses and expulsion were initiated. This threshold level was dependent upon host genetic background. Our results reveal a complex spectrum of responses and demonstrate that resistance and type 2 responses can be built up with increasing parasite exposure. The data provide compelling evidence to support a role for acquisition of acquired immunity to gastro-intestinal nematodes under complex infection patterns such as those found in the field.     

Testosterone reactivity to facial display of emotions in men and women

Previous studies have examined testosterone's role in regulating the processing of facial displays of emotions (FDEs). However, the reciprocal process – the influence of FDEs, an evolutionarily ancient and potent class of social signals, on the secretion of testosterone – has not yet been studied. To address this gap, we examined the effects of emotional content and sex of facial stimuli in modulating endogenous testosterone fluctuations, as well as sex differences in the endocrine responses to faces. One hundred and sixty-four young healthy men and women were exposed, in a between-subjects design, to happy or angry same-sex or opposite-sex facial expressions. Results showed that in both men (n = 85) and women (n = 79), extended exposure to faces of the opposite sex, regardless of their apparent emotional content, was accompanied by an accumulation in salivary testosterone when compared to exposure to faces of the same sex. Furthermore, testosterone change in women exposed to angry expressions was greater than testosterone change in women exposed to happy expressions. These results add emotional facial stimuli to the collection of social signals that modulate endocrine status, and are discussed with regard to the evolutionary roles of testosterone.     

Testosterone levels and their associations with lifetime number of opposite sex partners and remarriage in a large sample of American elderly men and women

Testosterone (T) has been argued to modulate mating and parenting behavior in many species, including humans. The role of T for these behaviors has been framed as the challenge hypothesis. Following this hypothesis, T should be positively associated with the number of opposite sex partners a male has. Indeed research in humans has shown that T is positively related to the number of opposite sex partners a young man has had. Here we test, in both men and women, whether this relationship extends to the lifetime number of sex partners. We also explored whether or not T was associated with current marital status, partnership status and whether or not the participant remarried. Using a large sample of elderly men and women (each sample n > 700), we show that T is positively and sizably associated with the number of opposite sex partners in men. When controlling for potential confounding variables such as educational attainment, age, BMI, ethnicity, specific use of a medication and time of sampling this effect remained. For women, the relationship between T and number of opposite sex partners was positive but did not prove to be robust. In both men and women there was no evidence for an association between T and current marital status and partnership status (being in a relationship or not). However, remarriage was positively associated with T, but only in males. Results are discussed with reference to the literature on T and sex partners, remarriage and more broadly the challenge hypothesis.