Article

Juveniles exposed to embryonic corticosterone have enhanced flight performance.

Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada K9J 7B8.
Proceedings of the Royal Society B: Biological Sciences (Impact Factor: 5.68). 11/2008; 276(1656):499-505. DOI: 10.1098/rspb.2008.1294
Source: PubMed

ABSTRACT Exposure to maternally derived glucocorticoids during embryonic development impacts offspring phenotype. Although many of these effects appear to be transiently 'negative', embryonic exposure to maternally derived stress hormones is hypothesized to induce preparative responses that increase survival prospects for offspring in low-quality environments; however, little is known about how maternal stress influences longer-term survival-related performance traits in free-living individuals. Using an experimental elevation of yolk corticosterone (embryonic signal of low maternal quality), we examined potential impacts of embryonic exposure to maternally derived stress on flight performance, wing loading, muscle morphology and muscle physiology in juvenile European starlings (Sturnus vulgaris). Here we report that fledglings exposed to experimentally increased corticosterone in ovo performed better during flight performance trials than control fledglings. Consistent with differences in performance, individuals exposed to elevated embryonic corticosterone fledged with lower wing loading and had heavier and more functionally mature flight muscles compared with control fledglings. Our results indicate that the positive effects on a survival-related trait in response to embryonic exposure to maternally derived stress hormones may balance some of the associated negative developmental costs that have recently been reported. Moreover, if embryonic experience is a good predictor of the quality or risk of future environments, a preparative phenotype associated with exposure to apparently negative stimuli during development may be adaptive.

0 Bookmarks
 · 
83 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Exposure to excess glucocorticoids during embryonic development affects offspring reproduction and suppresses the hypothalamic-pituitary-gonadal (HPG) axis in mammals. However, whether corticosterone (CORT) causes similar effects in the chicken remains unclear. In the present study, we injected low (0.2 μg) and high (1 μg) doses of CORT in ovo before incubation and detected changes in aggressive behavior, tonic immobility (TI), reproductive performances, and HPG axis gene expression in posthatch chickens of different ages. High dose of CORT suppressed growth rate from 3 weeks of age, increased the frequency of aggressive behaviors, which was associated with elevated plasma CORT concentration. High-dose CORT significantly (P < 0.05) down-regulated arginine vasotocin (AVT), corticotropin-releasing hormone (CRH), 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) and gonadotropin-releasing hormone 1 (GnRH1), while significantly (P < 0.05) up-regulated gonadotropin-inhibitory hormone (GnIH) and 11β-HSD1 mRNA expression in the hypothalamus. Glucocorticoid receptor (GR) and 20-hydroxysteroid dehydrogenase (20-HSD) mRNA levels were not affected by CORT treatment. High-dose CORT significantly (P < 0.05) reduced egg production and egg quality, which was associated with decreased ovary and oviduct weight. Moreover, CORT exposure significantly decreased (P < 0.05) luteinizing hormone (LH) receptor and follicle-stimulating hormone (FSH) receptor mRNA abundance in theca cells of ovarian follicles 1 (F1), F2 and F3. In addition, yolk CORT concentration was significantly higher in eggs laid by hens prenatally exposed to high-dose CORT. Our findings suggest that in ovo administration of CORT programs the aggressive behaviors and reproductive functions in the chicken through alterations of HPG axis.
    Animal reproduction science 01/2014; · 1.56 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 1. Glucocorticoid hormones are an integral part of the vertebrate stress response, and theoretical models argue for a link between glucocorticoid levels and individual fitness. The cort-fitness hypothesis posits that elevated levels of baseline glucocorticoids are reflective of an individual in poor condition and with a reduced likelihood of survival. Surprisingly, this hypothesis remains virtually untested for the juvenile life-history stage, a period that is often characterized by high mortality rates. 2. To address this issue, we explored whether glucocorticoid levels just prior to fledging were related to survival during the juvenile period in the Swainson's thrush (Catharus ustulatus), a short-lived, temperate-breeding passerine bird. Over 2 years, we blood-sampled nestling thrushes to quantify glucocorticoid levels and then used radio telemetry to assess whether individuals died or survived to emigrate from the study area. Finally, we measured vegetation characteristics at the nest and at locations used by individuals during the juvenile period to quantify the relative importance of habitat features and glucocorticoid levels on survival. 3. Predation was the leading cause of death, and overall juvenile survival rate was 34·6%. We found that survival was positively associated with baseline corticosterone and, to a lesser extent, size-corrected body mass and date of fledging. Contrary to expectations, we found no evidence that the amount of vegetative cover at the nest site or at locations used during the juvenile period was associated with survival. 5. Although we cannot completely rule out the cort-fitness hypothesis, our data appear to support the cort-activity hypothesis and suggest that elevated baseline corticosterone levels in juvenile thrushes may be linked to enhanced post-fledging survival via increased locomotor activity that promotes foraging, more effective escape from predators or both.
    Functional Ecology 10/2012; 26(5):1127-1134. · 4.86 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Abstract 1. The objective of this study was to evaluate the effect of maternal stress induced by supplementing the hen's diet with 2 mg/hen/d dietary corticosterone (CORT) on embryonic development, biochemical blood parameters and hatching performance of broiler chicks. 2. A total of 200 Ross broiler breeder hens at 42 weeks of age were randomly divided into two groups: maternal stress (MS) or control. Hens in the MS were fed 2 mg /hen/d CORT for 14 d. Eggs (648 and 635 eggs for MS and control, respectively) were collected from d 3 to 14 of dietary CORT supplementation and incubated. Weights of embryo, chicks and organs and body composition were determined during incubation and at hatch. Biochemical blood parameters were measured at internal pipping stage and d of hatch. Hatching performance and embryonic mortalities were recorded. 3. Hens fed a diet supplemented with CORT had lighter body weight and produced less eggs at the end of the 14 d treatment period. Although MS embryos were heavier than control from 12 to 18 d of incubation, chick weight was similar at d of hatch. Lower relative weights for yolk sac and bursa were observed at 12 d of incubation for MS chicks compared to control. Chicks from both groups had similar body content in spite of higher fat content of MS embryos on d 18 of incubation. 4. MS had no effect on the duration of incubation or hatching performance but increased mortality at the pipping stage. 5. The results suggest that hormone-mediated maternal stress might affect embryonic development during incubation without adverse effect on chick weight and body composition.
    British Poultry Science 01/2014; · 1.15 Impact Factor

Full-text (2 Sources)

Download
27 Downloads
Available from
Jun 4, 2014