Carotenoid supplementation and GnRH challenges influence female endocrine physiology, immune function, and egg-yolk characteristics in Japanese quail (Coturnix japonica)

Abstract

Androgens and carotenoids circulating in plasma affect the physiology and behavior of vertebrates. Much is known about control mechanisms and functions of each of these substances, yet their interactive effects are not well understood. Here we examine possible additive, multiplicative, and interactive effects of testosterone and carotenoids on female endocrine physiology, immunocompetence, and investment in eggs by simultaneously manipulating levels of testosterone [via gonadotropin releasing hormone (GnRH) challenges] and carotenoids (via diet supplementation) in captive female Japanese quail (Coturnix japonica). Females were randomly assigned to one of four treatments: carotenoid supplementation, GnRH challenge, GnRH challenge + carotenoid supplementation, or control. Carotenoid supplementation significantly increased circulating plasma carotenoid levels and acquired immune system performance, but not innate immunity. GnRH challenges elevated circulating testosterone and carotenoid levels, and induced immunosuppression in females. However, females in the GnRH challenge + carotenoid supplementation treatment had higher cell-mediated immune responses than control females and similar responses to those of carotenoid-supplemented females. Hence, availability of carotenoids in female quail seemed to counteract immunosuppressive effects of GnRH challenges. Our results provide further evidence for synergistic effects of carotenoids and testosterone on endocrine physiology and immune function in female birds. Elevated plasma testosterone or carotenoids levels resulted in increased deposition of those compounds to eggs, respectively. Furthermore, because we found that concentrations of testosterone and carotenoids in yolks were correlated within each treatment group, differential deposition of hormones and carotenoids in eggs may not only respond to surrounding social and environmental conditions, but also to other components of the egg.

Maternally Derived Egg Hormones, Antibodies and Antimicrobial Proteins: Common and Different Pathways of Maternal Effects in Japanese Quail

“…The pattern of the correlative response in yolk T in females selected for contrasting fearfulness and social motivation showed similar features as the direct response to selection for egg T concentrations. We recorded a limited potential for a decrease of yolk T levels as compared to the population mean in non-selected lines of Japanese quail in the present study (7.34±0.66 ng/g yolk) as well as in other studies [4], [25], [43], [44]. Moreover, a narrower range of inter-female variability in yolk T deposition was found in lines exhibiting low egg hormone levels (LTI, LSR and LET) as compared to lines with high hormone levels (STI, HSR and HET).…”

Carotenoids increase immunity and sex specifically affect color and redox homeostasis in a monochromatic seabird

“…Despite zeaxanthin supplementation, no increase in zeaxanthin levels in plasma was detected. This result is in line with studies in common lizards (Lacerta vivipara; San-Jose et al 2012), common tern (Sterna hirundo) chicks (Benito et al 2011), and blue tit (Cyanistes caeruleus) nestlings (Larcombe et al 2010) but contrasts with studies in some other birds Peluc et al 2012). This lack of effect may stem from the low amount of zeaxanthin supplied to the birds, the low sample size or preferential absorption of lutein over zeaxanthin when both carotenoids are in competition.…”

“…In kittiwakes, as in numerous bird species (Blount et al 2003;Alonso-Alvarez et al 2004;Baeta et al 2008;Thorogood et al 2008;Benito et al 2011;Peluc et al 2012), dietary lutein supplementation increased lutein levels in plasma. Despite zeaxanthin supplementation, no increase in zeaxanthin levels in plasma was detected.…”

Long-term effect of yolk carotenoid levels on testis size in a precocial bird

“…Finally, while we acknowledge the possibility that prenatal carotenoid exposure may have detrimental consequences for testes maturation and thus sperm production in our study, we believe that it is inconsistent with the accumulating evidence that carotenoid supplementation improves sperm quality ( [26,28], but see [30]). In addition, the injected carotenoid dose was well within the natural range [17] and yolk carotenoid levels after injection were not unnaturally high since females were fed with a low-carotenoid diet during the whole experiment.…”