Laura L Carruth

Georgia State University, Atlanta, Georgia, United States

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Publications (7)31.12 Total impact

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    ABSTRACT: Early developmental stress can have long-term physiological and behavioral effects on an animal. Developmental stress and early corticosterone (Cort) exposure affect song quality in many songbirds. Early housing condition can act as a stressor and affect the growth of nestlings and adult song, and improvements in housing condition can reverse adverse effects of early stress exposure in rodents. However, little is known about this effect in songbirds. Therefore, we took a novel approach to investigate if housing condition can modify the effects of early Cort exposure on adult song in male zebra finches. We manipulated early housing conditions to include breeding in large communal flight cages (FC; standard housing condition; with mixed-sex and mix-aged birds) versus individual breeding cages (IBC, one male–female pair with small, IBC-S, or large clutches, IBC-L) in post-hatch Cort treated male birds. We found that Cort treated birds from IBC-S have higher overall song learning scores (between tutor and pupil) than from FC but there is no difference between these groups in the No-Cort treated birds. When examining the effects of Cort within each housing condition, overall song learning scores decreased in Cort treated birds from flight cages but increased in birds from IBC-S compared to controls. Likewise, the total number of syllables and syllable types increased significantly in Cort treated birds from IBC-S, but decreased in FC-reared birds though this effect was not statistically significant. These findings suggest that the effects of early Cort treatment on learned features of song depend on housing condition.
    Hormones and Behavior 01/2014; · 3.74 Impact Factor
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    ABSTRACT: Male rat copulation is mediated by estrogen-sensitive neurons in the medial preoptic area (MPO) and medial amygdala (MEA); however, the mechanisms through which estradiol (E(2)) acts are not fully understood. We hypothesized that E(2) acts through estrogen receptor α (ERα) in the MPO and MEA to promote male mating behavior. Antisense oligodeoxynucleotides (AS-ODN) complementary to ERα mRNA were bilaterally infused via minipumps into either brain area to block the synthesis of ERα, which we predicted would reduce mating. Western blot analysis and immunocytochemistry revealed a knockdown of ERα expression in each brain region; however, compared to saline controls, males receiving AS-ODN to the MPO showed significant reductions in all components of mating, whereas males receiving AS-ODN to the MEA continued to mate normally. These results suggest that E(2) acts differently in these brain regions to promote the expression of male rat sexual behavior and that ERα in the MPO, but not in the MEA, promotes mating.
    Hormones and Behavior 05/2012; 62(1):50-7. · 3.74 Impact Factor
  • Mahin Shahbazi, Manfred Schmidt, Laura L Carruth
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    ABSTRACT: Stress has long lasting effects on physiology, development, behavior, reproductive success and the survival of an individual. These effects are mediated by glucocorticoids, such as corticosterone, via glucocorticoid receptors (GR), however the exact mechanisms underlying these effects are unknown. GR have been widely studied in mammals but little is known about GR in other vertebrate groups, especially songbirds. We investigated the distribution, quantity, and subcellular-localization of GR-immunoreactive (GRir) neurons in the brains of male zebra finches on P10 (post-hatch day 10, song nuclei formed), and in adulthood (post-hatch day 90 or older) using immunohistochemistry. GRir neurons were widely distributed in the brains of male zebra finches including two song nuclei HVC (acronym is a proper name) and RA (nucleus robustus arcopallii) and brain regions including HP (hippocampal formation), BSTl (lateral part of the bed nucleus of the stria terminalis), POM (nucleus preopticus medialis), PVN (nucleus paraventricularis magnocellularis), TeO (optic tectum), S (nucleus of the solitary tract), LoC (Locus coeruleus). Distribution did not vary at the two age points examined, however there were significant differences in staining intensity. Subcellular GR-immunoreactivity patterns were classified as cytoplasmic, nuclear, or both (cytoplasmic and nuclear) and there were significant differences in the overall number of GRir neurons and neurons with both nuclear and cytoplasmic staining in P10 and adult brains. However, there were no significant differences in the percentage of subcellular GR immunoreactivity patterns between P10 and adults. Our study of GRir neuronal distribution in the zebra finch brain may contribute towards understanding of the complex and adverse effects of stress on brain during two different stages of life history.
    General and Comparative Endocrinology 12/2011; 174(3):354-61. · 2.82 Impact Factor
  • Kelli A Duncan, Laura L Carruth
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    ABSTRACT: The majority of songbird species have sexually dimorphic neuronal circuits for song learning and production and these differences are paralleled by sex differences in behavior, with only males singing or singing at a higher rate than females. Therefore songbirds serve as an excellent model for studying the mechanisms that influence the sexually dimorphic development of the brain and behavior. Past research focused on the actions of steroid hormones or their receptors in the development of these sex differences. This review examines the distribution and action of steroid receptor coactivators in the songbird brain; more specifically the actions of RPL7, SRC-1, and CBP on the song control system. Coactivators enhance the transcriptional activity of the nuclear steroid receptors with which they associate, and therefore may play a role in modulating the development of sex differences in the brain and behavior. The actions of these proteins may help elucidate the hormonal mechanisms that underlie song nuclei development and steroid activated singing behavior in adulthood.
    Frontiers in Neuroendocrinology 01/2011; 32(1):84-94. · 7.99 Impact Factor
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    Kelli A Duncan, Pedro Jimenez, Laura L Carruth
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    ABSTRACT: Coactivator proteins, such as steroid receptor coactivator-1 (SRC-1) greatly enhance gene expression by amplifying steroid-induced transcription regulated by receptors such as estrogen receptor. These proteins may also play a role in the development of sex differences in central nervous system as well the maintenance of the sexually dimorphic behaviors in adulthood. One well-studied sexually dimorphic behavior is singing in songbirds such as the Australian zebra finch (Taeniopygia guttata). Song learning and production is controlled by the song control system, a collection of sexually dimorphic nuclei found in the avian telencephalon. While the actions of steroid hormones on song nuclei development has been under debate, steroids, such as testosterone, influence singing behavior in adulthood. We hypothesize that the differential expression of coactivators in male and female brains aid in organizing the song nuclei during development and function in adulthood to aid in activating the song control nuclei to induce singing behavior. The distribution of SRC-1-immunoreactive neurons was localized in the brains of male and female zebra finches on the day of hatch (P1) and in adults. In adults SRC-1 immunoreactive cells are found in the four main song control nuclei as well as other steroid sensitive brain regions. We found that SRC-1 is sexually dimorphic in the adult zebra finch telencephalon, suggesting that coactivators may play a role in the maintenance of sexually dimorphic behaviors including singing.
    General and Comparative Endocrinology 11/2010; 170(2):408-14. · 2.82 Impact Factor
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    Kelli A Duncan, Pedro Jimenez, Laura L Carruth
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    ABSTRACT: The brain and behavior of the Australian zebra finch (Taeniopygia guttata) are sexually dimorphic. Only males sing courtship songs and the regions of the brain involved in the learning and production of song are significantly larger in males than females. Therefore the zebra finch serves as an excellent model for studying the mechanisms that influence brain sexual differentiation, and the majority of past research on this system has focused on the actions of steroid hormones in the development of these sex differences. Coregulators, such as coactivators and corepressors, are proteins and RNA activators that work by enhancing or depressing the transcriptional activity of the nuclear steroid receptor with which they associate, and thereby modulating the development of sex-specific brain morphologies and behaviors. The actions of these proteins may help elucidate the hormonal mechanisms that underlie song nuclei development. Research described in this review focus on the role of estrogen receptor coactivators in the avian brain; more specifically we will focus on the role of RPL7 (ribosomal protein L7; also known as L7/SPA) on sexual differentiation of the zebra finch song system. Collectively, these studies provide information about the role of steroid receptor coactivators on development of the zebra finch song system as well as on sexual differentiation of brain.
    Psychoneuroendocrinology 07/2009; 34 Suppl 1:S30-8. · 5.59 Impact Factor
  • Source
    Kelli A Duncan, Laura L Carruth
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    ABSTRACT: Sex differences in the zebra finch (Taeniopygia guttata) brain are robust and include differences in morphology (song control nuclei in males are significantly larger) and behavior (only males sing courtship songs). In zebra finches, hormonal manipulations during development fail to reverse sex differences in song nuclei size and suggest that the classical model of sexual differentiation is incomplete for birds. Coactivators act to initiate transcriptional activity of steroid receptors, and may help explain why hormonal manipulations alone are not sufficient to demasculinize the male zebra finch brain. The present study investigated the expression and localization of L7/SPA (an estrogen receptor coactivator) mRNA and protein expression across the development of zebra finch song nuclei from males and females collected on P1 (song nuclei not yet formed), P10 (posthatch day 10, song nuclei formed), P30 (30 days posthatch, sexually immature but song nuclei formed and birds learning to sing), and adult birds (older than 65 days and sexually mature). Northern blot analysis showed a significant sex difference in P1 and adult L7/SPA mRNA expression while Western blot analysis also showed enhanced expression in the male brain at all age points. Both in situ hybridization and immunohistochemistry demonstrated that L7/SPA mRNA and protein were located in the song nuclei as well as expressed globally. Elevated coactivator expression may be a possible mechanism controlling the development of male song control nuclei, and coactivators such as L7/SPA may be important regulators of the masculinizing effects of estradiol on brain sexual differentiation.
    Developmental Neurobiology 01/2008; 67(14):1852-66. · 4.42 Impact Factor

Publication Stats

52 Citations
31.12 Total Impact Points


  • 2008–2014
    • Georgia State University
      • • Center for Behavioral Neuroscience
      • • Neuroscience Institute
      • • Department of Biology
      Atlanta, Georgia, United States
  • 2009–2011
    • Lehigh University
      • Department of Biological Sciences
      Bethlehem, PA, United States