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Riters LV, Stevenson SA. Using seasonality and birdsong to understand mechanisms underlying context-appropriate shifts in social motivation and reward. Horm Behav 2022; 142:105156. [PMID: 35313200 PMCID: PMC9382228 DOI: 10.1016/j.yhbeh.2022.105156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/11/2022] [Accepted: 03/11/2022] [Indexed: 12/29/2022]
Abstract
Social motivation and reward are dynamic and flexible, shifting adaptively across contexts to meet changing social demands. This is exceptionally apparent when seasonal contexts are considered in seasonally breeding songbirds as they cycle from periods of sexual motivation and reward during the breeding season to periods of extreme gregariousness outside the breeding season when non-sexual social interactions gain reward value, motivating birds to form flocks. Here we review evidence demonstrating a key integrative role for the medial preoptic area (mPOA) in the seasonally-appropriate adjustment of behaviors, with seasonal changes in dopamine activity in mPOA adjusting social motivation and changes in opioid activity modifying social reward. Experiments demonstrate that dramatic seasonal fluctuations in steroid hormone concentrations alter patterns of opioid- and dopamine-related protein and gene expression in mPOA to modify social motivation and reward to meet seasonal changes in social demands. These studies of birdsong and seasonality provide new insights into neural and endocrine mechanisms underlying adaptive changes in social motivation and reward and highlight an underappreciated, evolutionarily conserved role for the mPOA in important social behaviors in non-reproductive contexts.
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Affiliation(s)
- Lauren V Riters
- Department of Integrative Biology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Sharon A Stevenson
- Department of Integrative Biology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin-Madison, Madison, WI 53706, USA
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2
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Song learning and plasticity in songbirds. Curr Opin Neurobiol 2021; 67:228-239. [PMID: 33667874 DOI: 10.1016/j.conb.2021.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 02/05/2021] [Accepted: 02/05/2021] [Indexed: 11/20/2022]
Abstract
Birdsong provides a fascinating system to study both behavioral and neural plasticity. Oscine songbirds learn to sing, exhibiting behavioral plasticity both during and after the song-learning process. As a bird learns, its song progresses from a plastic and highly variable vocalization into a more stereotyped, crystallized song. However, even after crystallization, song plasticity can occur: some species' songs become more stereotyped over time, whereas other species can incorporate new song elements. Alongside the changes in song, songbirds' brains are also plastic. Both song and neural connections change with the seasons in many species, and new neurons can be added to the song system throughout life. In this review, we highlight important research on behavioral and neural plasticity at multiple timescales, from song development in juveniles to lifelong modifications of learned song.
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Stevenson SA, Piepenburg A, Spool JA, Angyal CS, Hahn AH, Zhao C, Riters LV. Endogenous opioids facilitate intrinsically-rewarded birdsong. Sci Rep 2020; 10:11083. [PMID: 32632172 PMCID: PMC7338348 DOI: 10.1038/s41598-020-67684-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 06/11/2020] [Indexed: 01/16/2023] Open
Abstract
Many songbirds sing in non-reproductive contexts while in flocks. Singing in such gregarious contexts is critical for maintaining and learning songs; however, song is not directed towards other individuals and has no obvious, immediate social consequences. Studies using conditioned place preference (CPP) tests of reward indicate that song production in gregarious contexts correlates positively with a bird’s intrinsic reward state and with opioid markers in the medial preoptic nucleus (mPOA). However, the causal involvement of opioids in gregarious song is unknown. Here we report that the selective mu opioid receptor (MOR) agonist fentanyl dose-dependently facilitates gregarious song and reduces stress/anxiety-related behavior in male and female European starlings. Furthermore, infusion of siRNA targeting MORs specifically in mPOA both suppresses gregarious song and disrupts the positive association between affective state and singing behavior, as revealed using CPP tests of song-associated reward. Results strongly implicate opioids in gregarious song and suggest that endogenous opioids in the mPOA may facilitate song by influencing an individual’s intrinsic reward state.
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Affiliation(s)
- Sharon A Stevenson
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Alice Piepenburg
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Jeremy A Spool
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA.,Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Caroline S Angyal
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Allison H Hahn
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA.,Department of Psychology, St. Norbert College, De Pere, WI, 54115, USA
| | - Changjiu Zhao
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Lauren V Riters
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA.
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4
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Kumar S, Mohapatra AN, Sharma HP, Singh UA, Kambi NA, Velpandian T, Rajan R, Iyengar S. Altering Opioid Neuromodulation in the Songbird Basal Ganglia Modulates Vocalizations. Front Neurosci 2019; 13:671. [PMID: 31333400 PMCID: PMC6618663 DOI: 10.3389/fnins.2019.00671] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 06/11/2019] [Indexed: 11/16/2022] Open
Abstract
Although the interplay between endogenous opioids and dopamine (DA) in the basal ganglia (BG) is known to underlie diverse motor functions, few studies exist on their role in modulating speech and vocalization. Vocal impairment is a common symptom of Parkinson’s disease (PD), wherein DA depletion affects striosomes rich in μ-opioid receptors (μ-ORs). Symptoms of opioid addiction also include deficiencies in verbal functions and speech. To understand the interplay between the opioid system and BG in vocalization, we used adult male songbirds wherein high levels of μ-ORs are expressed in Area X, a BG region which is part of a circuit similar to the mammalian thalamocortical-basal ganglia loop. Changes in DA, glutamate and GABA levels were analyzed during the infusion of different doses of the μ-OR antagonist naloxone (50 and 100 ng/ml) specifically in Area X. Blocking μ-ORs in Area X with 100 ng/ml naloxone led to increased levels of DA in this region without altering the number of songs directed toward females (FD). Interestingly, this manipulation also led to changes in the spectro-temporal properties of FD songs, suggesting that altered opioid modulation in the thalamocortical-basal ganglia circuit can affect vocalization. Our study suggests that songbirds are excellent model systems to explore how the interplay between μ-ORs and DA modulation in the BG affects speech/vocalization.
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Affiliation(s)
| | | | - Hanuman Prasad Sharma
- Department of Ocular Pharmacology and Pharmacy, Dr. R. P. Centre, All India Institute of Medical Sciences, New Delhi, India
| | | | | | - Thirumurthy Velpandian
- Department of Ocular Pharmacology and Pharmacy, Dr. R. P. Centre, All India Institute of Medical Sciences, New Delhi, India
| | - Raghav Rajan
- Indian Institute of Science Education and Research, Pune, Pune, India
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Spool JA, Merullo DP, Zhao C, Riters LV. Co-localization of mu-opioid and dopamine D1 receptors in the medial preoptic area and bed nucleus of the stria terminalis across seasonal states in male European starlings. Horm Behav 2019; 107:1-10. [PMID: 30423316 PMCID: PMC6348025 DOI: 10.1016/j.yhbeh.2018.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/31/2018] [Accepted: 11/09/2018] [Indexed: 01/06/2023]
Abstract
In seasonally breeding animals, changes in photoperiod and sex-steroid hormones may modify sexual behavior in part by altering the activity of neuromodulators, including opioids and dopamine. In rats and birds, activation of mu-opioid receptors (MOR) and dopamine D1 receptors in the medial preoptic area (mPOA) often have opposing effects on sexual behavior, yet mechanisms by which the mPOA integrates these opposing effects to modulate behavior remain unknown. Here, we used male European starlings (Sturnus vulgaris) to provide insight into the hypothesis that MOR and D1 receptors modify sexual behavior seasonally by altering activity in the same neurons in the mPOA. To do this, using fluorescent immunohistochemistry, we examined the extent to which MOR and D1 receptors co-localize in mPOA neurons and the degree to which photoperiod and the sex-steroid hormone testosterone alter co-localization. We found that MOR and D1 receptors co-localize throughout the mPOA and the bed nucleus of the stria terminalis, a region also implicated in the control of sexual behavior. Numbers of single and co-labeled MOR and D1 receptor labeled cells were higher in the rostral mPOA in photosensitive males (a condition observed just prior to the breeding season) compared to photosensitive males treated with testosterone (breeding season condition). In the caudal mPOA co-localization of MOR and D1 receptors was highest in photosensitive males compared to photorefractory males (a post-breeding season condition). Seasonal shifts in the degree to which neurons in the mPOA integrate signaling from opioids and dopamine may underlie seasonal changes in the production of sexual behavior.
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Affiliation(s)
- Jeremy A Spool
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA.
| | - Devin P Merullo
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA.
| | - Changjiu Zhao
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA.
| | - Lauren V Riters
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA.
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Spool JA, Jay MD, Riters LV. Nest box exploration may stimulate breeding physiology and alter mRNA expression in the medial preoptic area of female European starlings. ACTA ACUST UNITED AC 2018; 221:jeb.174441. [PMID: 29695491 DOI: 10.1242/jeb.174441] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 04/18/2018] [Indexed: 12/22/2022]
Abstract
Environmental resources are proposed to fine-tune the timing of breeding, yet how they may do so remains unclear. In female European starlings (Sturnus vulgaris), nest cavities are limited resources that are necessary for breeding. Females that explore nest cavities, compared with those that do not, readily perform sexually motivated behaviors. We assigned female starlings to aviaries with: (1) no nest boxes, (2) nest boxes, or (3) nest boxes, plants, flowing water, insects and berries to test the hypothesis that environmental resources alter neural systems to stimulate mating behavior. Compared with other females, females that were housed with and explored nest boxes had higher estradiol, higher preproenkephalin (PENK) mRNA and lower levels of D1 and D2 dopamine receptor mRNA in the medial preoptic area (mPOA); a region in which opioids and dopamine modify female sexual behaviors and sexual motivation. Additionally, in the mPOA, PENK and tyrosine hydroxylase mRNA positively predicted, whereas estrogen receptor beta mRNA negatively predicted, nest box exploration. In the ventromedial hypothalamus (a region in which estradiol acts to stimulate sexual behavior), estrogen receptor alpha mRNA was highest in females that had access to but did not explore nest cavities. It is likely that seasonal increases in estradiol modify mRNA in the mPOA to facilitate nest cavity exploration. It is also possible that nest cavity exploration further alters gene expression in the mPOA, functioning to coordinate mating with resource availability. Thus, nest cavity exploration may be a form of self-stimulation that alters neural systems to fine-tune sexual behavior.
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Affiliation(s)
- Jeremy A Spool
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA
| | - Melannie D Jay
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA
| | - Lauren V Riters
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA
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7
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Messina S, Eens M, Casasole G, AbdElgawad H, Asard H, Pinxten R, Costantini D. Experimental inhibition of a key cellular antioxidant affects vocal communication. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Simone Messina
- Behavioural Ecology & Ecophysiology Group Department of Biology University of Antwerp Universiteitsplein 1 2610 Wilrijk Belgium
| | - Marcel Eens
- Behavioural Ecology & Ecophysiology Group Department of Biology University of Antwerp Universiteitsplein 1 2610 Wilrijk Belgium
| | - Giulia Casasole
- Behavioural Ecology & Ecophysiology Group Department of Biology University of Antwerp Universiteitsplein 1 2610 Wilrijk Belgium
| | - Hamada AbdElgawad
- Integrated Molecular Plant Physiology Research Department of Biology University of Antwerp Antwerp Belgium
- Department of Botany Faculty of Science University of Beni‐Suef Beni‐Suef62511 Egypt
| | - Han Asard
- Integrated Molecular Plant Physiology Research Department of Biology University of Antwerp Antwerp Belgium
| | - Rianne Pinxten
- Behavioural Ecology & Ecophysiology Group Department of Biology University of Antwerp Universiteitsplein 1 2610 Wilrijk Belgium
- Faculty of Social Sciences Antwerp School of Education University of Antwerp Antwerp Belgium
| | - David Costantini
- Behavioural Ecology & Ecophysiology Group Department of Biology University of Antwerp Universiteitsplein 1 2610 Wilrijk Belgium
- UMR 7221 Muséum National d'Histoire Naturelle 7 rue Cuvier 75231 Paris Cedex 05 France
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Riters LV, Cordes MA, Stevenson SA. Prodynorphin and kappa opioid receptor mRNA expression in the brain relates to social status and behavior in male European starlings. Behav Brain Res 2016; 320:37-47. [PMID: 27913257 DOI: 10.1016/j.bbr.2016.11.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 11/21/2016] [Accepted: 11/28/2016] [Indexed: 12/18/2022]
Abstract
Numerous animal species display behavioral changes in response to changes in social status or territory possession. For example, in male European starlings only males that acquire nesting sites display high rates of sexual and agonistic behavior. Past studies show that mu and delta opioid receptors regulate behaviors associated with social ascension or defeat. Opioids also act at kappa receptors, with dynorphin binding with the highest affinity; however, the role of these opioids in social behavior has not been well studied. We observed flocks of male starlings during the breeding season and ran quantitative real-time polymerase chain reaction (qPCR) to measure expression of kappa opioid receptors (OPRK1) and prodynorphin (PDYN) in brain regions involved in social behavior and motivation (ventral tegmental area [VTA], medial preoptic nucleus [mPOA]) and vocal behavior (Area X). Males with nesting territories displayed more sexual/agonistic behavior than males without nesting territories. They also had lower OPRK1 expression in VTA and mPOA. OPRK1 expression in VTA correlated negatively with sexual/agonistic behaviors, consistent with past studies showing kappa receptors in VTA to inhibit sociosexual behaviors. PDYN in mPOA correlated negatively with a measure of nesting behavior that may also reflect sexual motivation. PDYN in Area X related positively to song. Distinct patterns of OPRK1 and PDYN expression in VTA, mPOA, and Area X related to gonad volume, suggesting that breeding condition may modify (or be modified by) OPRK1 and PDYN expression. Studies are now needed to further characterize the role of OPRK1 and PDYN in status-appropriate social behaviors.
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Affiliation(s)
- Lauren V Riters
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706, USA.
| | - Melissa A Cordes
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706, USA
| | - Sharon A Stevenson
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706, USA
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9
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Spool JA, Stevenson SA, Angyal CS, Riters LV. Contributions of testosterone and territory ownership to sexually-motivated behaviors and mRNA expression in the medial preoptic area of male European starlings. Horm Behav 2016; 86:36-44. [PMID: 27633459 PMCID: PMC5159298 DOI: 10.1016/j.yhbeh.2016.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 09/07/2016] [Accepted: 09/10/2016] [Indexed: 12/16/2022]
Abstract
Animals integrate social information with their internal endocrine state to control the timing of behavior, but how these signals are integrated in the brain is not understood. The medial preoptic area (mPOA) may play an integrative role in the control of courtship behavior, as it receives projections from multiple sensory systems, and is central to the hormonal control of courtship behavior across vertebrates. Additionally, data from many species implicate opioid and dopaminergic systems in the mPOA in the control of male courtship behavior. We used European starlings to test the hypothesis that testosterone (T) and social status (in the form of territory possession) interact to control the timing of courtship behavior by modulating steroid hormone-, opioid- and dopaminergic-related gene expression in the mPOA. We found that only males given both T and a nesting territory produced high rates of courtship behavior in response to a female. T treatment altered patterns of gene expression in the mPOA by increasing androgen receptor, aromatase, mu-opioid receptor and preproenkephalin mRNA and decreasing tyrosine hydroxylase mRNA expression. Territory possession did not alter mRNA expression in the mPOA, despite the finding that only birds with both T and a nesting territory produced courtship behavior. We propose that T prepares the mPOA to respond to the presence of a female with high rates of courtship song by altering gene expression, but that activity in the mPOA is under a continuous (i.e. tonic) inhibition until a male starling obtains a nesting territory.
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MESH Headings
- Animals
- Courtship
- Dopamine/genetics
- Dopamine/metabolism
- Female
- Gene Expression Regulation
- Male
- Motivation/physiology
- Preoptic Area/metabolism
- RNA, Messenger/metabolism
- Receptors, Androgen/genetics
- Receptors, Androgen/metabolism
- Receptors, Dopamine/genetics
- Receptors, Dopamine/metabolism
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Sexual Behavior, Animal/physiology
- Starlings/blood
- Starlings/genetics
- Starlings/physiology
- Territoriality
- Testosterone/blood
- Testosterone/physiology
- Vocalization, Animal/physiology
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Affiliation(s)
- Jeremy A Spool
- Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706, USA.
| | - Sharon A Stevenson
- Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706, USA.
| | - Caroline S Angyal
- Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706, USA.
| | - Lauren V Riters
- Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706, USA.
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10
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Johnston RA, Paxton KL, Moore FR, Wayne RK, Smith TB. Seasonal gene expression in a migratory songbird. Mol Ecol 2016; 25:5680-5691. [DOI: 10.1111/mec.13879] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 09/17/2016] [Accepted: 09/21/2016] [Indexed: 12/23/2022]
Affiliation(s)
- Rachel A. Johnston
- Department of Ecology and Evolutionary Biology University of California, Los Angeles 610 Charles E Young Dr. South Rm. 4162 Los Angeles CA 90095 USA
| | - Kristina L. Paxton
- Department of Biological Sciences University of Southern Mississippi Hattiesburg MS 39406 USA
- Department of Biology University of Hawaii Hilo Hilo HI 96720 USA
| | - Frank R. Moore
- Department of Biological Sciences University of Southern Mississippi Hattiesburg MS 39406 USA
| | - Robert K. Wayne
- Department of Ecology and Evolutionary Biology University of California, Los Angeles 610 Charles E Young Dr. South Rm. 4162 Los Angeles CA 90095 USA
| | - Thomas B. Smith
- Department of Ecology and Evolutionary Biology University of California, Los Angeles 610 Charles E Young Dr. South Rm. 4162 Los Angeles CA 90095 USA
- Center for Tropical Research Institute of the Environment and Sustainability University of California, Los Angeles Los Angeles CA 90095 USA
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11
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DeVries MS, Cordes MA, Rodriguez JD, Stevenson SA, Riters LV. Neural endocannabinoid CB1 receptor expression, social status, and behavior in male European starlings. Brain Res 2016; 1644:240-8. [PMID: 27206544 DOI: 10.1016/j.brainres.2016.05.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/11/2016] [Accepted: 05/17/2016] [Indexed: 12/22/2022]
Abstract
Many species modify behavior in response to changes in resource availability or social status; however, the neural mechanisms underlying these modifications are not well understood. Prior work in male starlings demonstrates that status-appropriate changes in behavior involve brain regions that regulate social behavior and vocal production. Endocannabinoids are ubiquitously distributed neuromodulators that are proposed to play a role in adjusting behavior to match social status. As an initial step to provide insight into this hypothesis we observed flocks of male starlings in outdoor aviaries during the breeding season. We used quantitative real-time PCR to measure expression of endocannabinoid CB1 receptors in brain regions involved in social behavior and motivation (lateral septum [LS], ventral tegmental area [VTA], medial preoptic nucleus [POM]) and vocal behavior (Area X and robust nucleus of the arcopallium; RA). Males with nesting sites sang to females and displaced other males more than males without nesting sites. They also had higher levels of CB1 receptor expression in LS and RA. CB1 expression in LS correlated positively with agonistic behaviors. CB1 expression in RA correlated positively with singing behavior. CB1 in VTA also correlated positively with singing when only singing birds were considered. These correlations nicely map onto the well-established role of LS in agonistic behavior and the known role of RA in song production and VTA in motivation and song production. Studies are now needed to precisely characterize the role of CB1 receptors in these regions in the production of status-appropriate social behaviors.
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Affiliation(s)
- M Susan DeVries
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706 USA
| | - Melissa A Cordes
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706 USA
| | - Jonathan D Rodriguez
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706 USA
| | - Sharon A Stevenson
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706 USA
| | - Lauren V Riters
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706 USA.
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12
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DeVries MS, Cordes MA, Stevenson SA, Riters LV. Differential relationships between D1 and D2 dopamine receptor expression in the medial preoptic nucleus and sexually-motivated song in male European starlings (Sturnus vulgaris). Neuroscience 2015; 301:289-97. [PMID: 26079111 DOI: 10.1016/j.neuroscience.2015.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 05/19/2015] [Accepted: 06/06/2015] [Indexed: 12/13/2022]
Abstract
Converging data in songbirds support a central role for the medial preoptic nucleus (POM) in motivational aspects of vocal production. Recent data suggest that dopamine in the POM plays a complex modulatory role in the production of sexually-motivated song and that an optimal level of dopamine D1 receptor stimulation is required to facilitate singing behavior. To further explore this possibility, we used quantitative real-time PCR to examine relationships between mRNA expression of D1 as well as D2 receptors in the POM (and also the lateral septum and Area X) and sexually-motivated singing behavior in male European starlings. Results showed that both males with the highest and lowest D1 expression in the POM sang significantly less than males with intermediate levels of expression. Furthermore, singing behavior rose linearly in association with increasing levels of D1 expression in POM but dropped abruptly, such that individuals with D1 expression values higher than the mean sang very little. Analysis of birds with low and intermediate levels of D1 expression in POM revealed strong positive correlations between D1 expression and song but negative relationships between D2 receptor expression and song. These findings support prior work suggesting an optimal level of POM D1 receptor stimulation best facilitates sexually-motivated singing behavior. Results also suggest that D2 receptors may work in opposition to D1 receptors in POM to modify vocal production.
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Affiliation(s)
- M S DeVries
- Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, Madison, WI 53706, USA.
| | - M A Cordes
- Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, Madison, WI 53706, USA.
| | - S A Stevenson
- Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, Madison, WI 53706, USA.
| | - L V Riters
- Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, Madison, WI 53706, USA.
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13
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Amorin N, Calisi RM. Measurements of Neuronal Soma Size and Estimated Peptide Concentrations in Addition to Cell Abundance Offer a Higher Resolution of Seasonal and Reproductive Influences of GnRH-I and GnIH in European Starlings. Integr Comp Biol 2015; 55:332-42. [DOI: 10.1093/icb/icv063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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14
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Cordes MA, Stevenson SA, Driessen TM, Eisinger BE, Riters LV. Sexually-motivated song is predicted by androgen-and opioid-related gene expression in the medial preoptic nucleus of male European starlings (Sturnus vulgaris). Behav Brain Res 2015; 278:12-20. [PMID: 25264575 PMCID: PMC4559756 DOI: 10.1016/j.bbr.2014.09.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 09/08/2014] [Accepted: 09/15/2014] [Indexed: 12/15/2022]
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.
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Affiliation(s)
- M A Cordes
- University of Wisconsin, Madison Department of Zoology, 430 Lincoln Ave., Madison, WI, USA.
| | - S A Stevenson
- University of Wisconsin, Madison Department of Zoology, 430 Lincoln Ave., Madison, WI, USA
| | - T M Driessen
- 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
| | - B E Eisinger
- 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
| | - L V Riters
- University of Wisconsin, Madison Department of Zoology, 430 Lincoln Ave., Madison, WI, USA
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15
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Paredes R. Opioids and sexual reward. Pharmacol Biochem Behav 2014; 121:124-31. [DOI: 10.1016/j.pbb.2013.11.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 10/16/2013] [Accepted: 11/07/2013] [Indexed: 10/26/2022]
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16
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Cordes MA, Stevenson SA, Riters LV. Status-appropriate singing behavior, testosterone and androgen receptor immunolabeling in male European starlings (Sturnus vulgaris). Horm Behav 2014; 65:329-39. [PMID: 24594286 PMCID: PMC4010097 DOI: 10.1016/j.yhbeh.2014.02.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 02/22/2014] [Accepted: 02/24/2014] [Indexed: 12/27/2022]
Abstract
Vocalizations convey information about an individual's motivational, internal, and social status. As circumstances change, individuals respond by adjusting vocal behavior accordingly. In European starlings, a male that acquires a nest site socially dominates other males and dramatically increases courtship song. Although circulating testosterone is associated with social status and vocal production it is possible that steroid receptors fine-tune status-appropriate changes in behavior. Here we explored a possible role for androgen receptors. Male starlings that acquired nest sites produced high rates of courtship song. For a subset of males this occurred even in the absence of elevated circulating testosterone. Immunolabeling for androgen receptors (ARir) was highest in the medial preoptic nucleus (POM) in males with both a nest site and elevated testosterone. For HVC, ARir was higher in dominant males with high testosterone (males that sang longer songs) than dominant males with low testosterone (males that sang shorter songs). ARir in the dorsal medial portion of the nucleus intercollicularis (DM) was elevated in males with high testosterone irrespective of dominance status. Song bout length related positively to ARir in POM, HVC and DM, and testosterone concentrations related positively to ARir in POM and DM. Results suggest that the role of testosterone in vocal behavior differs across brain regions and support the hypothesis that testosterone in POM underlies motivation, testosterone in HVC relates to song quality, and testosterone in DM stimulates vocalizations. Our data also suggest that singing may influence AR independent of testosterone and that alternative androgen-independent pathways regulate status-appropriate singing behavior.
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Affiliation(s)
- M A Cordes
- Department of Zoology, University of Wisconsin, Madison 53706, USA.
| | - S A Stevenson
- Department of Zoology, University of Wisconsin, Madison 53706, USA
| | - L V Riters
- Department of Zoology, University of Wisconsin, Madison 53706, USA
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17
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Riters LV, Pawlisch BA, Kelm-Nelson CA, Stevenson SA. Inverted-U shaped effects of D1 dopamine receptor stimulation in the medial preoptic nucleus on sexually motivated song in male European starlings. Eur J Neurosci 2013; 39:650-62. [PMID: 24528137 DOI: 10.1111/ejn.12429] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 10/23/2013] [Indexed: 01/10/2023]
Abstract
Past studies in songbirds have highlighted a central role for the medial preoptic nucleus (mPOA) in context-appropriate vocal communication. During the breeding season, male songbirds sing primarily to attract females (sexually motivated song) and to repel competitors (agonistically motivated song). Past data have linked dopamine and D1 dopamine receptors in the mPOA to sexually motivated but not agonistically motivated song; however, direct effects of dopamine receptor manipulations in the mPOA on song have not been experimentally tested. Here, we tested the hypothesis that D1 receptor stimulation in the mPOA selectively influences sexually motivated male song, and the possibility that the effects of D1 receptor agonism differ at low and high doses. In a first study, breeding-condition male European starlings received infusions of saline or a single dose of the D1 receptor agonist SKF 38393 on separate test days into the mPOA or hypothalamic control areas. Stimulation of D1 receptors in the mPOA triggered sexually motivated but not agonistically motivated song. A second study showed inverted-U shaped dose-response effects of the agonist, such that low levels of sexually motivated song were observed at low and high levels of D1 receptor activation. A third study showed that the effects of the D1 receptor agonist were blocked by the D1 receptor antagonist SCH 23390. These findings suggest that an optimal level of D1 receptor stimulation in the mPOA is needed to facilitate sexually motivated vocal production. The results support a central, context-specific role for the mPOA in vocal communication, and more broadly demonstrate a complex, modulatory influence of D1 receptors in the mPOA on sexually motivated behavior.
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Affiliation(s)
- Lauren V Riters
- Department of Zoology, University of Wisconsin - Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI 53706, USA
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18
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Kelm-Nelson CA, Riters LV. Curvilinear relationships between mu-opioid receptor labeling and undirected song in male European starlings (Sturnus vulgaris). Brain Res 2013; 1527:29-39. [PMID: 23774651 DOI: 10.1016/j.brainres.2013.06.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 05/22/2013] [Accepted: 06/06/2013] [Indexed: 01/08/2023]
Abstract
Female-directed communication in male songbirds has been reasonably well studied; yet, relatively little is known about communication in other social contexts. Songbirds also produce song that is not clearly directed towards another individual (undirected song) when alone or in flocks. Although the precise functions of undirected song may differ across species, this type of song is considered important for flock maintenance, song learning or practice. Past studies show that undirected song is tightly coupled to analgesia and positive affective state, which are both mediated by opioid activity. Furthermore, labeling for the opioid met-enkephalin in the medial preoptic nucleus (POM) correlates positively with undirected song production. We propose that undirected song is facilitated and maintained by opioid receptor activity in the POM and other brain regions involved in affective state, analgesia, and social behavior. To provide insight into this hypothesis, we used immunohistochemistry to examine relationships between undirected song and mu-opioid receptors in male starlings. Polynomial regression analyses revealed significant inverted-U shaped relationships between measures of undirected song and mu-opioid receptor labeling in the POM, medial bed nucleus of the stria terminalis (BSTm), and periaqueductal gray (PAG). These results suggest that low rates of undirected song may stimulate and/or be maintained by mu-opioid receptor activity; however, it may be that sustained levels of mu-opioid receptor activity associated with high rates of undirected song cause mu-opioid receptor down-regulation. The results indicate that mu-opioid receptor activity in POM, BSTm, and PAG may underlie previous links identified between undirected song, analgesia, and affective state.
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Affiliation(s)
- Cynthia A Kelm-Nelson
- Department of Zoology, University of Wisconsin-Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI 53706, USA.
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Kelm-Nelson CA, Stevenson SA, Cordes MA, Riters LV. Modulation of male song by naloxone in the medial preoptic nucleus. Behav Neurosci 2013; 127:451-7. [PMID: 23544595 DOI: 10.1037/a0032329] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Studies in songbirds implicate opioid neuropeptides in singing behavior; however, past results are contradictory. In starlings, the effect of opioid manipulations on sexually motivated courtship song differed in birds naturally singing at low compared to high rates, and mu-opioid receptors were denser in several regions, including the medial preoptic nucleus (POM) in low singing males. In the present study, we found that low singing male starlings also had significantly higher enkephalin (ENK) immunolabeling densities in the POM than high singers. We blocked opioid receptor activity in the POM with naloxone injections and found that this increased both song rate and song bout length in low singers, suggesting that high densities of mu receptors and ENK in the POM actively suppress song in these males. In contrast to its effects on low singers, naloxone in the POM of high singers dose dependently decreased song rate and tended to reduce song bout length. This suggests that at least some level of opioid activity in POM is necessary for song production. Our results are the first to demonstrate that direct administration of naloxone into the POM influences sexually motivated song, and that effects differ depending on an individual's initial rate of song and associated density of ENK. We suggest that differential effects seen in past studies of opioids and song may in part be explained by differences in the natural song rate of subjects and accompanying differences in ENK activity and neural substrate sensitivity to opioids in POM.
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20
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Riters LV, Ellis JMS, Angyal CS, Borkowski VJ, Cordes MA, Stevenson SA. Links between breeding readiness, opioid immunolabeling, and the affective state induced by hearing male courtship song in female European starlings (Sturnus vulgaris). Behav Brain Res 2013; 247:117-24. [PMID: 23473880 DOI: 10.1016/j.bbr.2013.02.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 02/10/2013] [Accepted: 02/26/2013] [Indexed: 12/19/2022]
Abstract
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.
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Affiliation(s)
- Lauren V Riters
- Department of Zoology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Abstract
This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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Kelm-Nelson CA, Stevenson SA, Riters LV. Context-dependent links between song production and opioid-mediated analgesia in male European starlings (Sturnus vulgaris). PLoS One 2012; 7:e46721. [PMID: 23056422 PMCID: PMC3462760 DOI: 10.1371/journal.pone.0046721] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 09/05/2012] [Indexed: 01/07/2023] Open
Abstract
Little is known about the neural mechanisms that ensure appropriate vocal behaviors within specific social contexts. Male songbirds produce spontaneous (undirected) songs as well as female-directed courtship songs. Opioid neuropeptide activity in specific brain regions is rewarding, at least in mammals, and past studies suggest that the opioid met-enkephalin in such areas is more tightly linked to undirected than female-directed song. Recent data using a song-associated place preference paradigm further suggest that production of undirected but not directed song is tightly linked to intrinsic reward. Opioids have analgesic properties. Therefore, if production of undirected song is closely linked to opioid-mediated reward, the production of undirected but not directed song should be associated with analgesia. Consistent with this prediction, in male starlings we identified a positive correlation between analgesia (decreased reactivity to a hot water bath) and undirected song (in non-breeding season condition males in affiliative flocks) but not female-directed song (in breeding season condition males presented with females). When breeding condition males were divided according to social status, a negative correlation was found in subordinate males (i.e. males that failed to acquire a nest box). These data are consistent with the hypotheses 1) that the production of undirected song is facilitated or maintained by opioids (and/or other neuromodulators that also induce analgesia) and 2) that production of female-directed song is not linked in the same way to release of the same neuromodulators. Results also demonstrate a link between analgesia and song in subordinate individuals lacking a nesting territory within the breeding season. Overall, the findings indicate that distinct neural mechanisms regulate communication in different social contexts and support the working hypothesis that undirected but not directed song is tightly linked to opioid release.
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Affiliation(s)
- Cynthia A Kelm-Nelson
- Department of Zoology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
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Riters LV, Stevenson SA. Reward and vocal production: song-associated place preference in songbirds. Physiol Behav 2012; 106:87-94. [PMID: 22285212 PMCID: PMC3314114 DOI: 10.1016/j.physbeh.2012.01.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 09/22/2011] [Accepted: 01/16/2012] [Indexed: 11/18/2022]
Abstract
Vocal production is crucial for successful social interactions in multiple species. Reward can strongly influence behavior; however, the extent to which reward systems influence vocal behavior is unknown. In songbirds, singing occurs in different contexts. It can be spontaneous and undirected (e.g., song produced alone or as part of a large flock) or directed towards a conspecific (e.g., song used to attract a mate or influence a competitor). In this study, we developed a conditioned place preference paradigm to measure reward associated with different types of singing behavior in two songbird species. Both male zebra finches and European starlings developed a preference for a chamber associated with production of undirected song, suggesting that the production of undirected song is tightly coupled to intrinsic reward. In contrast, neither starlings nor zebra finches developed a place preference in association with directed song; however, male starlings singing directed song that failed to attract a female developed a place aversion. Unsuccessful contact calling behavior was also associated with a place aversion. These findings suggest that directed vocal behavior is not tightly linked to intrinsic reward but may be externally reinforced by social interactions. Data across two species thus support the hypothesis that the production of undirected but not directed song is tightly coupled to intrinsic reward. This study is the first to identify song-associated reward and suggests that reward associated with vocal production differs depending upon the context in which communication occurs. The findings have implications for understanding what motivates animals to engage in social behaviors and ways in which distinct reward mechanisms function to direct socially appropriate behaviors.
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Affiliation(s)
- Lauren V. Riters
- Department of Zoology, 428 Birge Hall, 430 Lincoln Avenue, University of Wisconsin – Madison, Madison, WI 53706 USA
| | - Sharon A. Stevenson
- Department of Zoology, 428 Birge Hall, 430 Lincoln Avenue, University of Wisconsin – Madison, Madison, WI 53706 USA
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Riters LV. The role of motivation and reward neural systems in vocal communication in songbirds. Front Neuroendocrinol 2012; 33:194-209. [PMID: 22569510 PMCID: PMC3377815 DOI: 10.1016/j.yfrne.2012.04.002] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 04/17/2012] [Accepted: 04/22/2012] [Indexed: 12/17/2022]
Abstract
Many vertebrates are highly motivated to communicate, suggesting that the consequences of communication may be rewarding. Past studies show that dopamine and opioids in the medial preoptic nucleus (mPOA) and ventral tegmental area (VTA) play distinct roles in motivation and reward. In songbirds, multiple lines of recent evidence indicate that the roles of dopamine and opioid activity in mPOA and VTA in male birdsong differ depending upon whether song is used to attract females (sexually-motivated) or is produced spontaneously (undirected). Evidence is reviewed supporting the hypotheses that (1) mPOA and VTA interact to influence the context in which a male sings, (2) distinct patterns of dopamine activity underlie the motivation to produce sexually-motivated and undirected song, (3) sexually-motivated communication is externally reinforced by opioids released as part of social interactions, and (4) undirected communication is facilitated and rewarded by immediate opioid release linked to the act of singing.
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Affiliation(s)
- Lauren V Riters
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Heimovics SA, Cornil CA, Ellis JMS, Ball GF, Riters LV. Seasonal and individual variation in singing behavior correlates with α2-noradrenergic receptor density in brain regions implicated in song, sexual, and social behavior. Neuroscience 2011; 182:133-43. [PMID: 21397668 DOI: 10.1016/j.neuroscience.2011.03.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/01/2011] [Accepted: 03/04/2011] [Indexed: 12/19/2022]
Abstract
In seasonally breeding male songbirds, both the function of song and the stimuli that elicit singing behavior change seasonally. The catecholamine norepinephrine (NE) modulates attention and arousal across behavioral states, yet the role of NE in seasonally-appropriate vocal communication has not been well-studied. The present study explored the possibility that seasonal changes in alpha 2-noradrenergic receptors (α(2)-R) within song control regions and brain regions implicated in sexual arousal and social behavior contribute to seasonal changes in song behavior in male European starlings (Sturnus vulgaris). We quantified singing behavior in aviary housed males under spring breeding season conditions and fall conditions. α(2)-R were identified with the selective ligand [(3)H]RX821002 using autoradiographic methods. The densities of α(2)-R in song control regions (HVC and the robust nucleus of the arcopallium [RA]) and the lateral septum (LS) were lower in Spring Condition males. α(2)-R densities in the caudal portion of the medial preoptic nucleus (POM) related negatively to singing behavior. Testosterone concentrations were highest in Spring Condition males and correlated with α(2)-R in LS and POM. Results link persistent seasonal alterations in the structure or function of male song to seasonal changes in NE α(2)-Rs in HVC, RA, and LS. Individual differences in α(2)-R in the POM may in part explain individual differences in song production irrespective of the context in which a male is singing, perhaps through NE modification of male sexual arousal.
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Affiliation(s)
- S A Heimovics
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA
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