Corticosterone Metabolites Research Articles

The Effects of Different Feeding Routines on Welfare in Laboratory Mice.

The accepted norm in most laboratories around the globe is feeding laboratory mice an ad libitum diet, although several health impairments are well-established. In contrast, reducing the animals' body weight by feeding them less food once per day (referred to as 24 h schedule) has been shown to enhance life span and reduce disease susceptibility. Against this background, this study aimed at systematically investigating the effects of different feeding routines. Therefore, three feeding routines were compared to the standard ad libitum feeding and effects on body weight development and welfare were investigated in male C57BL/6J mice. In particular, a 24 h schedule group, an AUTO group, characterized by an automated supply of small pieces of food all over the day, and a 4 h removal group, characterized by daily removal of food for 4 h, were studied. While the removal of food for 4 h per day did not lead to a reduction of body weight, and hence is unlikely to prevent negative effects of overfeeding, both the 24 h schedule group and the AUTO group led to the aspired body weight reduction. In the AUTO group, however, higher levels of corticosterone metabolites and stereotypies were observed, implying a rather negative impact on welfare. By contrast, no distinct negative effects of a 24 h schedule were found. Studies like this underline the general need for evidence-based severity assessments of any procedure involving living animals.

Validation of a noninvasive technique to quantify stress in northern bobwhite (Colinus virginianus).

Examination of the endocrine system through non-invasive fecal sampling may improve population management more than using demographic indicators alone. By addressing the physiological mechanisms that are influencing fitness, management actions can be proactively developed to alleviate stressors. Proactive determination of vulnerable populations is critical for species of concern, such as the Northern Bobwhite (Colinus virginianus), which have suffered decades of population decline. We validated an assay to noninvasively measure the adrenocortical response of captive reared bobwhite through fecal corticosterone metabolites (FCM). All individuals received three sequential 48-hour treatments in which samples were collected every 4 hours, including a reference period, an adrenocorticotropic hormone (ACTH) challenge and a biological stressor (exposure to a hunting dog). Reference FCM values had a mean concentration of 16.75 pg/mg (95% CrI: 13.68, 19.91) with adrenocortical activity increasing by 73% for the duration of the ACTH challenge (29.00 pg/mg; CrI: 25.01, 33.78). FCM concentrations remained similar to that of the reference levels during the biological stressor (16.56 pg/mg; CrI: 13.33, 19.92). Our study validates the use of feces to detect changes in FCM levels in our subject species but also demonstrates the complexity of FCM and the importance of both physiological and biological validation prior to field implementation.

Preliminary evaluation of urinary cytology and running wheel activity to detect oestrus and the effect of daily handling on breeding success of fat-tailed dunnarts Sminthopsis crassicaudata

Eight recently weaned female fat-tailed dunnarts (Sminthopsis crassicaudata) were divided into two experimental groups: those in Group A (n = 4) received limited handling, whereas those in Group B (n = 4) were handled daily for the collection of urine samples to detect changes in cornified epithelial cells (CEC). Daily faecal output, food consumption, running wheel activity and weekly bodyweight changes were recorded. Faecal corticosterone metabolite (FCM) concentrations were determined over two periods, namely after introduction to either a new enclosure or a male for mating. Although changes in faecal output, food consumption, bodyweight and running wheel activity showed no relationship to oestrus, CEC scoring was a suitable means for detecting oestrus. Overall mean FCM concentrations did not differ significantly (P > 0.05) between the Groups A and B, and pouch young were produced in both (Group A, n = 2; Group B, n = 3), suggesting that daily handling is not a significant factor affecting breeding success. However, females that did not produce young during the study period demonstrated higher baseline FCM concentrations than females that did (mean (±s.e.m.) 79.8 ± 4.0 vs 62.3 ± 3.1 ng g−1). Daily handling for urine collection for CEC scoring appears to have little effect on adrenal output or reproductive success, confirming its utility as a reproductive management tool for this species.

Effect of Repeated Exposure to Isoflurane on Nest Building and Burrowing in Mice.

Nest building and burrowing are highly motivated natural behaviors in rodents, and changes in these behaviors can serve as welfare assessment tools. In this study, we investigated: 1) the limits of agreement between 2 observers for a refined scoring method for nest-building behavior; 2) the effect of repeated exposure to 15 min of isoflurane on nest-building behavior; 3) the effect of 24 h of grid-floor housing, repeated exposure to 15 min isoflurane, and daily intraperitoneal injection of 0.2 mL 0.9% isotonic saline for 3 d on burrowing behavior; and 4) the effect of exposure to grid-floor housing, isoflurane, and intraperitoneal injections on fecal corticosterone metabolites, body weight, fur status, and sucrose preference in mice. SPF C57BL/6NTac female mice (n = 27) were included in the study and were assessed first for burrowing behavior, followed by 2 wk of rest and then for nesting behavior. The refined scoring method for nest-building activity had good inter observer agreement. According to this method, a single exposure to anesthesia with isoflurane led to a decrease in nest-building activity and sucrose preference; a second exposure to anesthesia with isoflurane had no effect on nest building. Neither grid-floor housing nor repeated exposure to isoflurane anesthesia had any effect on burrowing behavior in mice. In contrast, intraperitoneal injections increased burrowing behavior. In conclusion, a refined scoring method for nest-building activity test that we developed for this study proved to be objective and sensitive to the effect of an initial exposure to anesthesia with isoflurane.

Habitat urbanization and stress response are primary predictors of personality variation in northern cardinals (Cardinalis cardinalis)

AbstractBehavioral traits that vary consistently among individuals across different contexts are often termed as ‘personality traits,’ while the correlated suite formed by those traits is called a ‘behavioral syndrome’. Both personality trait and behavioral syndrome are potentially responsive to animal ‘states’, defined as strategically relevant individual features affecting the cost-and-benefit trade-offs of behavioral actions. Both extrinsic ‘states’ (e.g. urban versus rural habitats), and intrinsic ‘states’ (e.g. sex), may shape among-individual variation in personality traits, as well as behavioral syndromes. Here, we used northern cardinals sampled from four locations to examine the effect of habitat type (urban versus rural, an extrinsic state), stress hormone corticosterone (CORT) parameters, body weight and sex (intrinsic states) on personality traits and behavioral syndrome variation. We used behavioral trials to measure five personality traits. Using principal component analysis to quantify personality traits first, followed by general linear mixed models, we found that habitat type, CORT at capture and 2-day CORT response affected some personality traits, while body weight and sex did not. Cardinals inhabiting more urbanized areas had lower CORT metabolite levels at capture and were more neophilic, less neophobic and also less aggressive than their rural conspecifics. Using structural equation modeling to construct behavioral syndromes formed by our selected personality traits, we found that urban and rural cardinals varied in the models representing syndrome structure. When utilizing the shared syndrome structural model to examine the effects of states, habitat type and 2-day CORT response appear to affect syndrome variation in a coordinated, not hierarchical, manner.

Substrates and Clearance Products of Fetal Adrenal Glucocorticoid Synthesis in Full-Term Human Umbilical Circulation.

In full-term elective caesarian sections, fetal flow of adrenal substrate steroids to products differs by sex, with males (M) in molar equilibrium whereas females (F) add net molarity and synthesize more cortisol. Using the same sampling design, paired, full-term, arterial, and venous umbilical cord samples and intrapartum chart records were obtained at the time of vaginal delivery (N = 167, 85 male) or emergency C-section (N = 38, 22 male). Eight steroids were quantified by liquid chromatography coupled to tandem mass spectrometry (adrenal glucocorticoids [cortisol, corticosterone], sequential cortisol precursor steroids [17-hydroxyprogesterone, 11-deoxycortisol], cortisol and corticosterone metabolites [cortisone and 11-dehydrocorticosterone], and gonadal steroids [androstenedione, testosterone]). Fetal sex was not significant in any analytic models. Going through both phase 1 and phase 2 labor increased fetal adrenal steroidogenesis and decreased male testosterone relative to emergency C-sections that do not reach stage 2 of labor (ie, head compressions) and elective C-sections with no labor. Sum adrenal steroid molarity arriving in venous serum was almost double the equivalent metric for deliveries without labor. No effects of operative vaginal delivery were noted. Maternal regional anesthetic suppressed venous concentrations, and fetal synthesis replaced that steroid. Approximate molar equivalence between substrate pool depletion and net glucocorticoid synthesis was seen. Paired venous and arterial umbilical cord serum has the potential to identify sex differences that underlie antenatal programming of hypothalamic-pituitary-adrenal axis function in later life. However, stage 2 labor before the collection of serum, and regional anesthetic for the mother, mask those sex differences.

When food access is challenging: evidence of wood mice ability to balance energy budget under predation risk and physiological stress reactions

Prey species must balance the energetic cost of locomotion, foraging effort, and predation risk. In our work, we assessed how the wood mice (Apodemus sylvaticus) balance these costs by manipulating food access difficulty and predation risk. Live trapping was conducted in Madrid (Spain) where 80 Sherman traps were set in four different plots. To assess how wood mice manage their energy budget, all traps were first subjected to a control period followed by four treatments of 3-day duration in which food access was experimentally manipulated (free access, straw balls, straw balls wrapped in metal wire, opened plastic bottles, closed bottles). Predation risk was simulated by exposing half of the traps to fox feces. To quantify food intake, we weighed the remnants of food left by each captured mouse. Furthermore, we collected mouse fecal samples from traps to evaluate the physiological stress response by quantifying fecal corticosterone metabolites (FCM). Results showed that despite mice generally avoiding traps treated with fox feces, predation risk did not modulate food intake or FCM levels. By contrast, the experimental manipulation of food access determined the amount eaten and increased FCM levels, probably owing to the different degrees of difficulty and the energy required to obtain the food. Moreover, recaptured individuals ate more, indicating that experience critically determines mice ability to reduce the costs of accessing food. By analyzing the joint variation between mice intake and FCM levels depending on food restriction treatments, we found that mice were able to modulate their energetic expenditure depending on food access difficulty probably in order to achieve a positive marginal value of energy. For wild animals, to optimally balance the energetic budget is critical to maximize fitness. However, foraging decisions are influenced by numerous internal and external factors which are poorly understood. We studied free-ranging mice behavioral and physiological stress response to different food restriction treatments, testing also the influence of predation risk and experience. We found that predation risk modulated mice capturability but not the feeding behavior or the stress response. We also discovered that mice seem to be able to adjust energy allocation when a novel resource appear, and that energy budget optimization may be mediated via glucocorticoid release and individuals experience.

The effect of cage size on stress levels in captive green anole (Anolis carolinensis)

Abstract Reptiles are often used as model species in scientific research and are popular in the pet trade, yet how they cope with captive conditions has not been well studied. Stress caused by captivity could affect the endocrinology, physiology and behaviour of animals, resulting in a general decrease in welfare and could confound the results of scientific experiments. One of the factors that could influence stress in a captive environment is the size of the cage. However, the effect of cage size on stress has rarely been investigated in reptiles. In this study, the effect of cage size on the behaviour, morphology and physiology of the green anole (Anolis carolinensis) was quantified. We were unable to find an effect of cage dimensions (range 0.05 to 0.2 m3) on body mass, tail-base width, heterophil to lymphocyte ratios (H/L ratios), behaviour and faecal corticosterone metabolite (FCM) levels.

Systematic analysis of severity in a widely used cognitive depression model for mice.

Animal models in psychiatric research are indispensable for insights into mechanisms of behaviour and mental disorders. Distress is an important aetiological factor in psychiatric diseases, especially depression, and is often used to mimic the human condition. Modern bioethics requires balancing scientific progress with animal welfare concerns. Therefore, scientifically based severity assessment of procedures is a prerequisite for choosing the least compromising paradigm according to the 3Rs principle. Evidence-based severity assessment in psychiatric animal models is scarce, particularly in depression research. Here, we assessed severity in a cognitive depression model by analysing indicators of stress and well-being, including physiological (body weight and corticosterone metabolite concentrations) and behavioural (nesting and burrowing behaviour) parameters. Additionally, a novel approach for objective individualised severity grading was employed using clustering of voluntary wheel running (VWR) behaviour. Exposure to the paradigm evoked a transient elevation of corticosterone, but neither affected body weight, nesting or burrowing behaviour. However, the performance in VWR was impaired after recurrent stress exposure, and the individual severity level increased, indicating that this method is more sensitive in detecting compromised welfare. Interestingly, the direct comparison to a somatic, chemically induced colitis model indicates less distress in the depression model. Further objective severity assessment studies are needed to classify the severity of psychiatric animal models in order to balance validity and welfare, reduce the stress load and thus promote refinement.

A novel multi-parametric analysis of non-invasive methods to assess animal distress during chronic pancreatitis

Ethical responsibility, legal requirements and the need to improve the quality of research create a growing interest in the welfare of laboratory animals. Judging the welfare of animals requires readout parameters, which are valid and sensitive as well as specific to assess distress after different interventions. In the present study, we evaluated the sensitivity and specificity of different non-invasive parameters (body weight change, faecal corticosterone metabolites concentration, burrowing and nesting activity) by receiver operating characteristic curves and judged the merit of a multi-parametric analysis by logistic regression. Chronic pancreatitis as well as laparotomy caused significant changes in all parameters. However, the accuracy of these parameters was different between the two animal models. In both animal models, the multi-parametric analysis relying on all the readout parameters had the highest accuracy when predicting distress. This multi-parametric analysis revealed that C57BL/6 mice during the course of chronic pancreatitis often experienced less distress than mice after laparotomy. Interestingly these data also suggest that distress does not steadily increase during chronic pancreatitis. In conclusion, combining these non-invasive methods for severity assessment represents a reliable approach to evaluate animal distress in models such as chronic pancreatitis.

Analytic and Interpretational Pitfalls to Measuring Fecal Corticosterone Metabolites in Laboratory Rats and Mice.

Minimization and alleviation of stress are generally viewed as desirable aspects of laboratory animal management and use. However, achieving that goal requires an unambiguous and valid measure of stress. Glucocorticoid concentrations are commonly used as a physiologic index of stress. Measurement of glucocorticoids in blood, serum or plasma clearly reflects many types of both acute and chronic stress. However, the rapid rise in concentrations of circulating glucocorticoids that occurs even with relatively simple manipulations such as handling has led to the increased use of fecal glucocorticoid metabolite (FCM) assays, which provide a temporally integrated measure that may allow a more accurate interpretation of chronic stressors. In this review, we consider 3 aspects of glucocorticoids as a measure of stress. First, we discuss the analytic and interpretational pitfalls of using FCM concentrations as an index of stress in mice and rats. Second, we consider evidence that some degree of stress may benefit animals by priming physiologic and behavioral adaptations that render the animals more resilient in the face of stress. Finally, we use 2 situations-social housing and food restriction-to illustrate the concept of hormesis-a biologic phenomenon in which a low dose or intensity of a challenge has a beneficial effect, whereas exposure to high doses or intensities is detrimental.

Coping with style: individual differences in responses to environmental variation

Between-individual differences in coping with stress encompass neurophysiological, cognitive and behavioural reactions. The coping style model proposes two alternative response patterns to challenges that integrate these types of reactions. The “proactive strategy” combines a general fight-or-flight response and inflexibility in learning with a relatively low HPA (hypothalamic–pituitary–adrenal) response. The “reactive strategy” includes risk aversion, flexibility in learning and an enhanced HPA response. Although numerous studies have investigated the possible covariance of cognitive, behavioural and physiological responses, findings are still mixed. In the present study, we tested the predictions of the coping style model in an unselected population of bank voles (Myodes glareolus) (N = 70). We measured the voles’ boldness, activity, speed and flexibility in learning and faecal corticosterone metabolite levels under three conditions (holding in indoor cages, in outdoor enclosures and during open field test). Individuals were moderately consistent in their HPA response across situations. Proactive voles had significantly lower corticosterone levels than reactive conspecifics in indoor and outdoor conditions. However, we could not find any co-variation between cognitive and behavioural traits and corticosterone levels in the open field test. Our results partially support the original coping style model but suggest a more complex relationship between cognitive, behavioural and endocrine responses than was initially proposed. Understanding the proximate mechanisms regulating the individual variation in responses to environmental challenges and changes is fundamental in ecological and evolutionary research. Theory predicts correlations between behavioural, cognitive and physiological traits to form alternative strategies named coping styles but recent studies report contrasting and mixed findings. We examined the relationship between a measure of endocrine state (concentrations of faecal glucocorticoid metabolites), two behavioural traits (boldness and activity) and two cognitive traits (speed and flexibility of learning) in 70 unselected bank voles (Myodes glareolus) under three different conditions. The findings partially support the original coping style model’s hypothesis and predictions. We found individual consistency of all traits. However, correlations between behavioural and cognitive aspects and endocrine state were found only in two of the three tested conditions, highlighting the need for further investigations and testing of theory.

Benefits of non-invasive methods compared to telemetry for distress analysis in a murine model of pancreatic cancer

Prospective severity assessment is legally required in many countries to ensure high-quality research along with high welfare standards for laboratory animals. Mice and rats, the most common laboratory species, are prey animals that usually suppress signs of pain and suffering. Therefore, highly sensitive readout parameters are necessary to adequately quantify distress. The present study compared the performance of different non-invasive methods in determining animal distress, such as measuring body weight, distress score, faecal corticosterone metabolites, burrowing, and nesting behaviour, with continuous monitoring of heart rate, body temperature and activity by telemetry. The distress caused by two surgical interventions was compared and the burden caused by tumour growth was described. Transmitter implantation caused higher distress than laparotomy plus carcinoma cell injection into the pancreas. Surprisingly, no significant increase in distress was observed during tumour growth. The receiver operating characteristic curve analysis revealed that some non-invasive distress-parameters, i.e., distress-score and burrowing activity, exhibited slightly better performance to quantify distress than the most suitable parameters measured by telemetry. Due to the high burden caused by the implantation of the telemetric device, the use of non-invasive methods to assess distress in laboratory animals after surgical interventions should be favoured in future studies.

Costs and benefits of social connectivity in juvenile Greylag geese

Living in groups has various advantages and disadvantages for group members. We investigated the fitness consequences of early social connectivity (normalized Freeman degrees based on nearest neighbour data), physiology (levels of excreted corticosterone metabolites assayed from droppings), and agonistic interactions in a group of free-ranging greylag geese (Anseranser). Forty-four greylag geese below 3 years of age were observed in three different seasonal phases: during the re-aggregation of the flock in autumn, at the end of the winter and during the forthcoming breeding season. We show that corticosterone metabolite levels and initiated and received aggression increased with increasing social connectivity. Individuals had higher connectivity scores in the winter flock than during the mating and breeding seasons. One-year old juveniles were more connected than 2- and 3-year old individuals. In addition, we examined the link between social connectivity during early development and reproductive success several years later. We found that birds with greater connectivity early in life attempted to breed at a younger age. Furthermore, successful breeders with higher early connectivity scores had higher numbers of fledged goslings. Our results show that social context in early life stages may have long-term effects on individual fitness.

Toward evidence‐based severity assessment in rat models with repeated seizures: II. Chemical post–status epilepticus model

Considering the complexity of neuronal circuits and their epilepsy-associated alterations, epilepsy models cannot be completely replaced by in vitro experimental approaches. Decisions about ethical approval of in vivo studies require a thorough weighing of the animal's burden and the benefit regarding the expected gain in knowledge. Based on combined behavioral, biochemical, and physiological analyses, we assessed the impact on animal well-being and condition in different phases of the pilocarpine post-status epilepticus (SE) model in rats. As a consequence of SE, increased levels of impairment were evident in the early postinsult phase and late chronic phase, whereas only mild impairment was observed in the interim phase. Parameters that stood out as sensitive indicators of animal distress include burrowing, which proved to be affected throughout all experimental phases, saccharin preference, fecal corticosterone metabolites, heart rate, and heart rate variability. The cumulative burden with temporary but not long-lasting phases of more pronounced impairment suggests a classification of severe as a basis for laboratory-specific prospective and retrospective evaluation. Among the parameters analyzed, burrowing behavior and saccharin preference stand out as candidate parameters that seem to be well suited to obtain information about animal distress in epileptogenesis models.

Vocalisation and its association with androgens and corticosterone in a night frog (Nyctibatrachus humayuni) with unique breeding behaviour

AbstractIn anurans, vocalisation is used to communicate within and between the sexes during reproduction. Knowledge of vocal repertoire and its diversity is essential in understanding its significance in sexual selection. In this context, we studied the vocal behaviour of Nyctibatrachus humayuni and quantified the urinary metabolites of androgens and corticosterone to understand the associations among hormones, body condition index and vocalisation. Our results show that males of N. humayuni produce an amplitude‐modulated call consisting of a train of pulses. Interestingly, a high degree of inter‐individual variation was observed in the call parameters. The dominant frequency and pulse interval were negatively correlated with male body size, whereas pulse duration and pulse duty cycle were positively correlated with it. Dominant frequency was negatively correlated with androgens and corticosterone, whereas pulse interval was negatively correlated with corticosterone. Further, pulse duty cycle, pulse duration and pulses per call were positively associated with corticosterone. Surprisingly, none of the acoustic parameters was associated with male body temperature and body condition. A significant variation was evident in the vocal effort, dominant frequency and amplitude of advertisement calls produced under different social situations. Calls produced during territory establishment had lower dominant frequency but higher vocal effort, whereas those produced during courtship had higher amplitude and vocal effort than the calls produced in the absence of a competitor/female. Our results suggest that greater inter‐male variability in the advertisement call of N. humayuni could be important in female choice as it may help females to assess the quality of a male. Further, androgens and corticosterone could be important in modulating crucial parameters of the advertisement call.

Potential Impact of Construction Noise on Selected Zoo Animals.

Simple SummaryAnimals in zoos can adapt to many noises they hear on a regular basis. However, construction noise that is intense or occurs unpredictably may negatively impact the welfare state of some animals and induce a chronic stress response. This study aimed to understand the behavioral response to construction noise of selected species in an urban zoo in order to guide mitigating actions in advance of, and during, a planned construction project. The behavior of elephants, giraffes, emus and alligators was recorded during 90-min exposures to different sound environments including ambient sound, and four construction sound treatments. A non-invasive measure of physiological stress response was also measured in emus. All species appeared to respond to the recorded noise, with giraffes, elephants and emu, demonstrating behavioral changes potentially indicative of agitation or stress. This study has implications for the trade-offs that occur when zoos seek to improve long-term animal welfare through enclosure refurbishment and short-term impacts on animals exposed to construction noise.In anticipation of a major construction project in an urban New Zealand zoo, a study was initiated to assess the response to construction noise of selected animal species (elephant, giraffe, emu and alligator) previously observed to be sensitive to this kind of noise. The overall aim was to detect any signs of aversive responses to this noise to enable keepers to recognize these and take any necessary mitigating actions during the construction period. The experimental approach involved the creation of acoustic maps of each focal animal enclosure, a series of 90-min video recordings of the animals’ behavior in response to ambient noise (control) and amplified broadcast of pre-recorded continuous and intermittent construction noise. Concentration of fecal corticosterone metabolites was also measured for the emus. Key findings were that giraffes, elephants and emus appeared to show an increase in behaviors that could indicate stress or agitation including vigilance and locomotion and may prefer quieter regions of their enclosure during sound exposure. Giraffes also increased close contact with conspecifics when exposed to construction noise. While alligators did not show clear evidence of noise-related stress, our findings indicated that all focal species showed some behavioral responses to recorded construction noise.

Synergistic effects of predation and parasites on the overwinter survival of root voles

Predators and parasites have been important extrinsic factors influencing the fluctuation of small mammal populations. They can have non-additive effects on a shared group of preys or hosts, which can have important consequences for population dynamics. However, experimental studies incorporating the interactions between predation and parasites are scarce in small mammal populations. Here we systematically examined the synergistic effects of predators and coccidian parasites interaction on overwinter survival and likely mechanisms underlying the synergistic effects in the root vole (Microtus oeconomus). Our aim was to test the general hypothesis that predators and coccidia interact synergistically to decrease overwinter survival of root voles through mediating vole's physiological traits and body conditions. We carried out a factorial experimental design, by which we manipulated the predator exclusion in combination with the parasitic removal in enclosures, and then measured fecal corticosterone metabolite (FCM) levels, immunocompetence, and body conditions in captured animals via repeated live trapping. We found a strong negative synergistic effect of predators and coccidia on survival. Importantly, we found that predators increased both the prevalence and intensity of coccidian infection in voles through immune suppression induced by predation stress, while increased coccidian infection reduced plasma protein and hematocrit level of voles, which may impair anti-predator ability of voles and lead to an increase in predation. Our finding showed when voles are exposed to both predation risk and infection, their synergistic effects greatly reduce overwinter survival and population density. This may be an important mechanism influencing population dynamics in small mammals.

Sex differences in substrates and clearance products of cortisol and corticosterone synthesis in full-term human umbilical circulation without labor: Substrate depletion matches synthesis in males, but not females

BackgroundAntenatal impacts on the hypothalamus- pituitary-adrenal axis affect health throughout later life and the impacts on developing males and females often differ. The female fetus at full-term (sampled as scheduled Caesarian section without antecedent labor) both receives more cortisol in umbilical venous blood and adds more cortisol to umbilical arterial circulation than the male. The current study was designed to expand our knowledge of sex-specific, fetal, adrenal steroid synthesis and clearance pathways. MethodsPaired, full-term, arterial and venous umbilical cord samples were taken at the time of scheduled Caesarian delivery (N = 53, 33 male). Adrenal glucocorticoids (cortisol, corticosterone), cortisol precursor steroids (17-hydroxyprogesterone, 11-deoxycortisol), and cortisol and corticosterone metabolites (cortisone and 11-dehydrocorticosterone), as well as gonadal steroids (testosterone and androstenedione), were quantified by liquid chromatography coupled to tandem mass spectrometry. ResultsBoth sexes preferentially added corticosterone. Males added more testosterone than females. The female fetus had higher umbilical cord (arterial and venous) concentrations of cortisol, as well as higher total steroid molarity summed across the six adrenal steroids, than males. Depletion of substrate pools of 17-hydroxyprogesterone, 11-deoxycortisol, and cortisone could account for only 20% of net female cortisol synthesis. In contrast, increased fetal synthesis of cortisol was balanced by equivalent molar depletion of substrate pools when the fetus was male. ConclusionsPreferential fetal corticosterone synthesis in both sexes, and higher concentrations of cortisol in females were confirmed. Differences in adrenal steroidogenesis pathway function in full-term males and females might underlie antenatal programming of hypothalamic-pituitary-adrenal axis function in later life.

Roads and urban areas as physiological stressors of spiny-tailed lizards, Uromastyx acanthinura

Disturbances caused by roads or urbanization can have a significant impact on wildlife populations. However, it remains unclear whether these human activities can be stressors for wild populations of reptiles. We analyzed and compared plasma corticosterone and fecal corticosterone metabolites in male and female spiny tailed lizards (Uromastyx acanthinura) that were found at different distances from roads and urban areas in Tunisia (N. Africa). Levels of plasma corticosterone and fecal corticosterone metabolites of the same individuals measured with an enzyme immunoassay kit were highly and significantly correlated. This indicated that non-invasive measures of stress levels are equally useful for these types of studies. Males had higher plasma corticosterone than females, and these levels were higher in autumn than in summer and spring in both sexes. Moreover, levels of corticosterone in plasma and corticosterone metabolites in feces were significantly higher when the capture site was closer to roads or urban areas. These results suggest that the alteration of the natural habitat and the disruption caused by road traffic increase stress hormone levels in U. acanthinura lizards. Understanding how free-living animals are influenced by human perturbations could help direction and involvement of conservation strategies for endangered species.