Divergent neural nodes are species‐ and hormone‐dependent in the brood parasitic brain

• Published in: Genes, brain and behavior Vol. 23; no. 5; pp. e12907 - n/a
• Main Authors: Duque, Fernanda G., Azam, Asma, Kaur, Amanpreet, Pao, Rachel, Lynch, Kathleen S.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2024; John Wiley & Sons, Inc
• Subjects: Abundance; Animals; bed nucleus stria terminalis; Brain; Brain - metabolism; Brood parasitism; Corticotropin-releasing hormone; Female; Nesting Behavior; Nests; Neuropeptides; Original; Oxytocin; Oxytocin - analogs & derivatives; Oxytocin - genetics; Oxytocin - metabolism; Oxytocin - pharmacology; Paraventricular Hypothalamic Nucleus - metabolism; Paraventricular nucleus; parental care; Preoptic area; Preoptic Area - metabolism; Prolactin; Septal Nuclei - metabolism; Social behavior; social behavior network; social neuropeptides; Songbirds - genetics; Species; Species Specificity; Stria terminalis; parental care; social behavior network; preoptic area; social neuropeptides; bed nucleus stria terminalis; paraventricular nucleus
• DOI: 10.1111/gbb.12907
• ISSN: 1601-1848; 1601-183X

Avian brood parasitism is an evolutionarily derived behavior for which the neurobiological mechanisms are mostly unexplored. We aimed to identify brain regions that have diverged in the brood‐parasitic brain using relative transcript abundance of social neuropeptides and receptors. We compared behavioral responses and transcript abundance in three brain regions in the brown‐headed cowbird (BHCO), a brood parasite, and a closely related parental species, the red‐winged blackbird (RWBL). Females of both species were treated with mesotocin (MT; avian homolog of oxytocin) or saline prior to exposure to nest stimuli. Results reveal that MT promotes approach toward nests with eggs rather than nests with begging nestlings in both species. We also examined relative transcript abundance of the five social neuropeptides and receptors in the brain regions examined: preoptic area (POA), paraventricular nucleus (PVN) and bed nucleus of the stria terminalis (BST). We found that MT‐treated cowbirds but not blackbirds exhibited lower transcript abundance for two receptors, corticotropin‐releasing factor 2 (CRFR2) and prolactin receptor (PRLR) in BST. Additionally, MT‐treated cowbirds had higher PRLR in POA, comparable to those found in blackbirds, regardless of treatment. No other transcripts of interest exhibited significant differences as a result of MT treatment, but we found a significant effect of species in the three regions. Together, these results indicate that POA, PVN, and BST represent neural nodes that have diverged in avian brood parasites and may serve as neural substrates of brood‐parasitic behavior. Mesotocin (MT, homologous to oxytocin in mammals) enhances natural preferences for egg‐related stimuli in brood‐parasitic and parental females alike. In the brain, MT treatment was associated with changes in gene expression in the bed nucleus of the stria terminalis and the preoptic area in brood parasitic females.