What Factors Drive Prolactin and Corticosterone Responses to Stress in a Long‐Lived Bird Species (Snow PetrelPagodroma nivea)?

Abstract

Life-history theory predicts that individuals should adapt their parental investment to the costs and benefits of the current reproductive effort. This could be achieved by modulating the hormonal stress response, which may shift energy investment away from reproduction and redirect it toward survival. In birds, this stress response consists of a release of corticosterone that may be accompanied by a decrease in circulating prolactin, a hormone involved in the regulation of parental care. We lack data on the modulation of the prolactin stress response. In this study, we tested the hypothesis that individuals should modulate their prolactin stress response according to the fitness value of the current reproductive effort relative to the fitness value of future reproduction. Specifically, we examined the influence of breeding status (failed breeders vs. incubating birds) and body condition on prolactin and corticosterone stress responses in a long-lived species, the snow petrel Pagodroma nivea. When facing stressors, incubating birds had higher prolactin levels than failed breeders. However, we found no effect of body condition on the prolactin stress response. The corticosterone stress response was modulated according to body condition but was not affected by breeding status. We also performed an experiment using injections of adrenocorticotropic hormone (ACTH) and found that the modulation of the corticosterone stress response was probably associated with a reduction in ACTH release by the pituitary and a decrease in adrenal sensitivity to ACTH. In addition, we examined whether prolactin and corticosterone secretion were functionally linked. We found that these two hormonal stress responses were not correlated. Moreover, injection of ACTH did not affect prolactin levels, demonstrating that short-term variations in prolactin levels are not governed directly or indirectly by ACTH release. Thus, we suggest that the corticosterone and prolactin responses to short-term stressors are independent and may therefore mediate some specific components of parental investment in breeding birds. With mounting evidence, we suggest that examining both corticosterone and prolactin stress responses could be relevant to parental investment in vertebrates.

Does prolactin mediate parental and life-history decisions in response to environmental conditions in birds? A review

“…This finding was then confirmed in a few other species (Criscuolo et al, 2002;Groscolas et al, 2008;Spée et al, 2010). Supporting the idea of a non-linear relationship between prolactin levels and the energetic status, the negative relationship between prolactin levels and body condition becomes more apparent as individuals are more energetically constrained (O'Dwyer et al, 2006;Angelier et al, 2009b;Riechert et al, 2014b).…”

“…To our knowledge, a single study has examined this question in domestic birds and it did not report any correlation between prolactin levels and the energetic status of chicken hens (Zadworny et al, 1988). Although this result was confirmed in several studies on wild birds (Hector and Goldsmith, 1985;Cherel et al, 1994;Angelier et al, 2009bAngelier et al, , 2015Heidinger et al, 2010;Kosztolanyi et al, 2012;Crossin et al, 2012), others found that parent birds have lower prolactin levels when in poor body condition (Criscuolo et al, 2006;Jonsson et al, 2006;O'Dwyer et al, 2006;Angelier et al, 2007bAngelier et al, , 2009bGroscolas et al, 2008;Spée et al, 2010;Schmid et al, 2011;Riechert et al, 2014b). The negative impact of nutritional conditions on circulating prolactin levels seems to only appear when individuals reach a lower threshold of body condition.…”

“…Thus, it has been shown that the corticosterone stress response varies among individuals (Lendvai et al, 2007;Goutte et al, 2010), populations (Silverin et al, 1997;Breuner et al, 2003) and species (Bokony et al, 2009;Hau et al, 2010) and these differences can be related to specific parental decisions and life-history strategies (Wingfield and Sapolsky, 2003;. Although the corticosterone and the prolactin stress responses have rarely been examined together, they often provide complementary information on parental investment in parent birds Angelier et al, 2007aAngelier et al, , 2009bAngelier et al, , 2015Heidinger et al, 2006Heidinger et al, , 2010Schmid et al, 2011Schmid et al, , 2013. For instance, the corticosterone stress response was not related to parental decisions in a recent study of incubating snow petrels, but it was tightly correlated to the energetic status of the parents.…”

Organism–environment interactions in a changing world: a mechanistic approach

“…Interestingly, older birds do appear to be better at raising young (Angelier et al 2007;Berman et al 2009) and this agespecific pattern can be related to a higher sensitivity to stress in young birds than in old birds. Thus, young Snow Petrels show an important increase in corticosterone levels in response to acute stress (tending to deter onset of breeding or promote abandonment of a nest) and a large decrease in prolactin levels (which tends to inhibit parental care thus promoting abandonment of the nest; Angelier et al 2007Angelier et al , 2009Goutte et al 2010). These data suggest that despite breeding in a severe environment, acute stress has the potential to disrupt breeding in this species, especially in sensitive young individuals.…”

The Effect of Prolactin in Response to Academic Stress during Examination Condition in Healthy Male and Female University Students

“…In the academic institutions, stress has been categorized to have both positive and negative consequences if not managed well [6]. Despite the increase in technological development and the rapid growth of information, competition among all group of people has become on the increase, as a result people become more occupied and tensed up with stress [1][2]. Although appropriate stress is a stage for self-growth and it gives people motivation for advancement in life.…”