Links between breeding readiness, opioid immunolabeling, and the affective state induced by hearing male courtship song in female European starlings (Sturnus vulgaris)

• Published in: Behavioural brain research 2013-06, Vol.247, p.117-124
• Main Authors: Riters, Lauren V., Ellis, Jesse M.S., Angyal, Caroline S., Borkowski, Vincent J., Cordes, Melissa A., Stevenson, Sharon A.
• Format: Article
• Language: English
• Subjects: Affect - physiology; Animals; Behavioral psychophysiology; Biological and medical sciences; Birdsong; Brain - metabolism; Communication; Courtship; Enkephalin, Methionine - metabolism; Female; Fundamental and applied biological sciences. Psychology; Male; Mate choice; Motivation; Motivation - physiology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reinforcement; Sexual Behavior, Animal - physiology; Social Behavior; Starlings; Vocalization, Animal - physiology
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/j.bbr.2013.02.041

•Behavioral responses to male courtship song differ among female starlings.•Breeding-ready females preferred a chamber in which they previously heard male song.•Non-breeding-ready females did not develop a similar place preference for song.•In breeding-ready females mENK label was highest in VMH, mPOA, Ac, and PAG.•The reward value of male song is linked to motivational state and opioid label. Male courtship vocalizations represent a potent signal designed to attract females; however, not all females find male signals equally attractive. We explored the possibility that the affective state induced by hearing courtship vocalizations depends on the motivational state of a receiver. We used a conditioned place preference test of reward to determine the extent to which the rewarding properties of hearing male courtship song differed in female European starlings categorized as nest box owners (a sign of breeding readiness) or non-owners. Nest box owners developed a preference for a chamber in which they previously heard male courtship song. Non-owners displayed no preference for a chamber in which they previously heard song. Positive correlations were identified between the preference a female developed for the song-paired chamber and female nesting and dominance behaviors observed prior to conditioning (indices of the motivation to breed). Immunolabeling for met-enkephalin (an opioid neuropeptide involved in reward) in the medial preoptic nucleus, ventromedial nucleus of the hypothalamus, nucleus accumbens, and periaqueductal gray was higher in females with compared to those without nest boxes. Both nest box entries and song-induced place preference also correlated positively with met-enkephalin labeling in the ventromedial nucleus of the hypothalamus. These findings indicate that the reward value of vocal signals is linked to individual differences in motivational state; and that differences in enkephalin activity may play a role in modifying an individual's motivational state and/or the reward value of song.