Behavioural Biology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, 6747AG Groningen, the Netherlands; Department of Animal Sciences, Wageningen University and Research, 6708WD Wageningen, the Netherlands.
Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372, CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France.
Horm Behav. 2024 Jul;163:105549. doi: 10.1016/j.yhbeh.2024.105549. Epub 2024 Apr 24.
The peptide hormone prolactin plays an important role in the expression of parental care behaviours across bird and mammal taxa. While a great deal is known about how plasma prolactin concentrations vary across the reproductive cycle, the few studies that investigate how prolactin relates to individual-level variation in parental care have reported mixed results. We argue that, since parental care is also affected by social interactions and environmental constraints, prolactin may better reflect behaviours that are indirectly related to parenting than the absolute level of care that is eventually expressed. In this study, we tested for associations between plasma prolactin and the expression of both parental care and proximity to the partner in incubating black-headed gulls, Chroicocephalus ridibundus. Baseline prolactin levels increased with calendar date but were unrelated to incubation behaviours. However, parents who showed a weaker decrease in prolactin to an acute stressor spent more time in close proximity to their incubating partner while not on the nest themselves, suggesting that individual variation in stress-induced prolactin changes reflect differences in parents' tendency to be closely associated with their partner and the joint nesting attempt. Baseline and stress-induced levels of the stress hormone corticosterone were unrelated to both prolactin levels and parental behaviours, suggesting that this hormone is not a strong moderator of parental care in black-headed gulls. One potential explanation for the link between prolactin dynamics and partner proximity is that prolactin reflects parental motivation to provide parental care or retain contact with the breeding partner, but further work is needed to directly test this hypothesis.
肽激素催乳素在鸟类和哺乳动物的亲代照料行为表达中起着重要作用。虽然人们已经了解了血浆催乳素浓度在生殖周期中如何变化，但少数研究催乳素与亲代照料个体水平变化之间关系的研究报告结果不一。我们认为，由于亲代照料也受到社会互动和环境限制的影响，催乳素可能更能反映与育儿间接相关的行为，而不是最终表现出的护理绝对水平。在这项研究中，我们测试了血浆催乳素与亲代照料表达和与伴侣在孵卵黑嘴鸥（Chroicocephalus ridibundus）中的接近程度之间的关联。基础催乳素水平随日历日期而增加，但与孵化行为无关。然而，对急性应激源催乳素下降幅度较小的亲代在不孵卵时与孵卵伴侣的接近程度增加，这表明应激诱导的催乳素变化个体差异反映了父母与伴侣密切相关的倾向以及共同筑巢尝试的差异。基础和应激诱导的应激激素皮质醇水平与催乳素水平和亲代行为均无关，这表明这种激素不是黑嘴鸥亲代照料的一个强有力的调节因素。催乳素动态与伴侣接近度之间联系的一个潜在解释是，催乳素反映了父母提供亲代照料或与繁殖伴侣保持联系的动机，但需要进一步的工作来直接检验这一假设。
