title: Sexually-motivated song is predicted by androgen-and opioid-related gene expression in the medial preoptic nucleus of male European starlings (Sturnus vulgaris).
abstract: Across vertebrates, communication conveys information about an individual's motivational state, yet little is known about the neuroendocrine regulation of motivational aspects of communication. For seasonally breeding songbirds, increases in testosterone in spring stimulate high rates of sexually-motivated courtship song, though not all birds sing at high rates. It is generally assumed that testosterone or its metabolites act within the medial preoptic nucleus (POM) to stimulate the motivation to sing. In addition to androgen receptors (ARs) and testosterone, opioid neuropeptides in the POM influence sexually-motivated song production, and it has been proposed that testosterone may in part regulate song by modifying opioid systems. To gain insight into a possible role for androgen-opioid interactions in the regulation of communication we examined associations between sexually-motivated song and relative expression of ARs, mu opioid receptors (muORs), and preproenkephalin (PENK) in the POM (and other regions) of male European starlings using qPCR. Both AR and PENK expression in POM correlated positively with singing behavior, whereas muOR in POM correlated negatively with song. Furthermore, the ratio of PENK/muOR expression correlated negatively with AR expression in POM. Finally, in the ventral tegmental area (VTA), PENK expression correlated negatively with singing behavior. Results support the hypothesis that ARs may alter opioid gene expression in POM to fine-tune singing to reflect a male's motivational state. Data also suggest that bidirectional relationships may exist between opioids and ARs in POM and song, and additionally support a role for opioids in the VTA, independent of AR activity in this region.
authors.affiliation: University of Wisconsin, Madison Department of Zoology, 430 Lincoln Ave., Madison, WI, USA. Electronic address: macordes@wisc.edu.
authors.forename: M A
authors.initials: MA
authors.lastname: Cordes
authors.affiliation: University of Wisconsin, Madison Department of Zoology, 430 Lincoln Ave., Madison, WI, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Stevenson
authors.affiliation: University of Wisconsin, Madison Department of Zoology, 430 Lincoln Ave., Madison, WI, USA; Washington State University, Integrated Physiology and Neuroscience Department, 1815 Ferdinand's Lane, Pullman, WA, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Driessen
authors.affiliation: University of Wisconsin, Madison Department of Zoology, 430 Lincoln Ave., Madison, WI, USA; University of Wisconsin-Madison School of Medicine and Public Health, Waisman Center and Department of Neuroscience, 1500 Highland Ave., Madison, WI 53705, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Eisinger
authors.affiliation: University of Wisconsin, Madison Department of Zoology, 430 Lincoln Ave., Madison, WI, USA.
authors.forename: L V
authors.initials: LV
authors.lastname: Riters
mesh_terms: D000728:Androgens / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D005260:Female; D015870:Gene Expression; D016014:Linear Models; D008297:Male; D009042:Motivation; D011301:Preoptic Area / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000378:metabolism*; D012726:Sexual Behavior, Animal / Q000502:physiology*; D046749:Starlings; D013739:Testosterone / Q000235:genetics / Q000378:metabolism
chemical_list: D000728:Androgens; D012333:RNA, Messenger; D011944:Receptors, Androgen; D017450:Receptors, Opioid, mu; D013739:Testosterone
keywords: Androgens; Communication; Courtship; Motivation; Opioids; Songbird