Neurotranscriptomic changes associated with chick-directed parental care in adult non-reproductive Japanese quail

Patricia C Lopes,Robert De Bruijn

doi:10.1038/s41598-021-94927-6

Abstract

For many species, parental care critically affects offspring survival. But what drives animals to display parental behaviours towards young? In mammals, pregnancy-induced physiological transformations seem key in preparing the neural circuits that lead towards attraction (and reduced-aggression) to young. Beyond mammalian maternal behaviour, knowledge of the neural mechanisms that underlie young-directed parental care is severely lacking. We took advantage of a domesticated bird species, the Japanese quail, for which parental behaviour towards chicks can be induced in virgin non-reproductive adults through a sensitization procedure, a process that is not effective in all animals. We used the variation in parental responses to study neural transcriptomic changes associated with the sensitization procedure itself and with the outcome of the procedure (i.e., presence of parental behaviours). We found differences in gene expression in the hypothalamus and bed nucleus of the stria terminalis, but not the nucleus taeniae. Two genes identified are of particular interest. One is neurotensin, previously only demonstrated to be causally associated with maternal care in mammals. The other one is urocortin 3, causally demonstrated to affect young-directed neglect and aggression in mammals. Because our studies were conducted in animals that were reproductively quiescent, our results reflect core neural changes that may be associated with avian young-directed care independently of extensive hormonal stimulation. Our work opens new avenues of research into understanding the neural basis of parental care in non-placental species.

Highlights

IntroductionParental care critically affects offspring survival. But what drives animals to display parental behaviours towards young? In mammals, pregnancy-induced physiological transformations seem key in preparing the neural circuits that lead towards attraction (and reduced-aggression) to young
For many species, parental care critically affects offspring survival
Pregnancy-induced physiological transformations seem key in preparing the neural circuits that lead towards attraction to an infant[1]

Summary

Introduction

Parental care critically affects offspring survival. But what drives animals to display parental behaviours towards young? In mammals, pregnancy-induced physiological transformations seem key in preparing the neural circuits that lead towards attraction (and reduced-aggression) to young. Because the sensitization is capable of eliciting young-directed parental care under short-days (when quails have regressed gonads and are reproductively quiescent), we are afforded the additional opportunity to study young-directed care in the absence of major changes to gonadal steroids, and in the absence of egg-laying or egg incubation experience and, in the absence of the main hormonal changes generally associated with avian parental behaviours[10]. This gives us insights into the core neural changes that promote young-directed parental care in birds independently of extensive hormonal stimulation. Our experiments highlight the importance of using intra-species variation in parental responses to elucidate neural mechanisms of parental behaviour and to discover new molecular pathways involved in avian parental care, several of which are likely conserved across other vertebrate taxa

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Conclusion