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Freiler MK, Deckard ML, Proffitt MR, Troy Smith G. Differential expression of steroid-related genes across electrosensory brain regions in two sexually dimorphic species of electric knifefish. Gen Comp Endocrinol 2024; 355:114549. [PMID: 38797340 PMCID: PMC11265523 DOI: 10.1016/j.ygcen.2024.114549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 05/14/2024] [Accepted: 05/15/2024] [Indexed: 05/29/2024]
Abstract
The production of communication signals can be modulated by hormones acting on the brain regions that regulate these signals. However, less is known about how signal perception is regulated by hormones. The electrocommunication signals of weakly electric fishes are sexually dimorphic, sensitive to hormones, and vary across species. The neural circuits that regulate the production and perception of these signals are also well-characterized, and electric fishes are thus an excellent model to examine the neuroendocrine regulation of sensorimotor mechanisms of communication. We investigated (1) whether steroid-related genes are expressed in sensory brain regions that process communication signals; and (2) whether this expression differs across sexes and species that have different patterns of sexual dimorphism in their signals. Apteronotus leptorhynchus and Apteronotus albifrons produce continuous electric organ discharges (EODs) that are used for communication. Two brain regions, the electrosensory lateral line lobe (ELL) and the dorsal torus semicircularis (TSd), process inputs from electroreceptors to allow fish to detect and discriminate electrocommunication signals. We used qPCR to quantify the expression of genes for two androgen receptors (ar1, ar2), two estrogen receptors (esr1, esr2b), and aromatase (cyp19a1b). Four out of five steroid-related genes were expressed in both sensory brain regions, and their expression often varied between sexes and species. These results suggest that expression of steroid-related genes in the brain may differentially influence how EOD signals are encoded across species and sexes, and that gonadal steroids may coordinately regulate central circuits that control both the production and perception of EODs.
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Affiliation(s)
- Megan K Freiler
- Department of Biology, Indiana University, 1001 E 3(rd) St., Bloomington, IN 47405, United States; Center for the Integrative Study of Animal Behavior, Indiana University, 409 N. Park Ave, Bloomington, IN 47405, United States.
| | - Mikayla L Deckard
- Department of Biology, Indiana University, 1001 E 3(rd) St., Bloomington, IN 47405, United States
| | - Melissa R Proffitt
- Department of Biology, Indiana University, 1001 E 3(rd) St., Bloomington, IN 47405, United States; Center for the Integrative Study of Animal Behavior, Indiana University, 409 N. Park Ave, Bloomington, IN 47405, United States
| | - G Troy Smith
- Department of Biology, Indiana University, 1001 E 3(rd) St., Bloomington, IN 47405, United States; Center for the Integrative Study of Animal Behavior, Indiana University, 409 N. Park Ave, Bloomington, IN 47405, United States
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2
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Hasunuma I. Central regulation of reproduction in amphibians. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:219-229. [PMID: 38084833 DOI: 10.1002/jez.2769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 11/22/2023] [Accepted: 11/27/2023] [Indexed: 02/27/2024]
Abstract
This review article includes a literature review of synteny analysis of the amphibian gonadotropin-releasing hormone (GnRH) genes, the distribution of GnRH 1 and GnRH2 neurons in the central nervous system of amphibians, the function and regulation of hypophysiotropic GnRH1, and the function of GnRH1 in amphibian reproductive behaviors. It is generally accepted that GnRH is the key regulator of the hypothalamic-pituitary-gonadal axis. Three independent GnRH genes, GnRH1, GnRH2, and GnRH3, have been identified in vertebrates. Previous genome synteny analyses suggest that there are likely just two genes, gnrh1 and gnrh2, in amphibians. In three groups of amphibians: Anura, Urodela, and Gymnophiona, the distributions of GnRH1 and GnRH2 neurons in the central nervous system have also been previously reported. Moreover, these neuronal networks were determined to be structurally independent in all species examined. The somata of GnRH1 neurons are located in the terminal nerve, medial septum (MS), and preoptic area (POA), and some GnRH1 neurons in the MS and POA project into the median eminence. In contrast, the somata of GnRH2 neurons are located in the midbrain tegmentum. In amphibians, GnRH1 neurons originate from the embryonic olfactory placode, while GnRH2 neurons originate from the midbrain. The characterization and feedback regulation mechanisms of hypophysiotropic GnRH1 neurons in amphibians, the involvement of GnRH1 in amphibian reproductive behavior, and its possible mechanism of action should be elucidated in future.
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Affiliation(s)
- Itaru Hasunuma
- Department of Biology, Faculty of Science, Toho University, Funabashi, Chiba, Japan
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3
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Baugh AT. Male Cope's gray treefrogs (Hyla chrysoscelis) in amplexus have elevated and correlated steroid hormones compared to solitary males. Gen Comp Endocrinol 2024; 345:114391. [PMID: 37844651 DOI: 10.1016/j.ygcen.2023.114391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 10/18/2023]
Abstract
Gonadal steroid hormones are typically elevated during the breeding season-a finding known as an associated reproductive pattern. Though less studied, there is also evidence, in both sexes, for elevated adrenal/interrenal steroids, including acute elevations on the day of mating. I investigated gonadal and interrenal steroids in wild male Cope's gray treefrogs at breeding aggregations. I collected blood from males found in amplexus with female mates (amplexed males) and males sampled at the same time and location that were actively advertising vocally and without a mate (solo males). Concentrations of plasma corticosterone, testosterone, and 17β-estradiol (CORT, T and E2, respectively) were validated and measured. These two categories of males differed in four ways: (1) amplexed males exhibited significantly elevated concentrations of all three steroids compared to solo males (CORT: +347 %; T: +60 %; and E2: +43 %); (2) these hormone profiles alone accurately predicted male mating category with ca. 83 % accuracy using a discriminant function analysis; (3) amplexed males exhibited significant between-hormone correlations (T and E2 were positively correlated and CORT and E2 were negatively correlated) whereas no correlations were found in solo males; (4) amplexed males showed a negative correlation with CORT concentration and the time of night, whereas no such pattern was present in solo males. These findings suggest an acute and strong coactivation of the interrenal and gonadal axes that could drive phenotypic integration during this fitness-determining moment. I discuss these findings and suggest experiments to determine causation, including the role of motor behavior driving endocrine states and the role of female selection on endocrine profiles.
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Affiliation(s)
- Alexander T Baugh
- Department of Biology, Swarthmore College, 500 College Avenue, Singer Hall, Swarthmore, PA 19081, USA.
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Capshaw G, Brown AD, Peña JL, Carr CE, Christensen-Dalsgaard J, Tollin DJ, Womack MC, McCullagh EA. The continued importance of comparative auditory research to modern scientific discovery. Hear Res 2023; 433:108766. [PMID: 37084504 PMCID: PMC10321136 DOI: 10.1016/j.heares.2023.108766] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/23/2023] [Accepted: 04/05/2023] [Indexed: 04/23/2023]
Abstract
A rich history of comparative research in the auditory field has afforded a synthetic view of sound information processing by ears and brains. Some organisms have proven to be powerful models for human hearing due to fundamental similarities (e.g., well-matched hearing ranges), while others feature intriguing differences (e.g., atympanic ears) that invite further study. Work across diverse "non-traditional" organisms, from small mammals to avians to amphibians and beyond, continues to propel auditory science forward, netting a variety of biomedical and technological advances along the way. In this brief review, limited primarily to tetrapod vertebrates, we discuss the continued importance of comparative studies in hearing research from the periphery to central nervous system with a focus on outstanding questions such as mechanisms for sound capture, peripheral and central processing of directional/spatial information, and non-canonical auditory processing, including efferent and hormonal effects.
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Affiliation(s)
- Grace Capshaw
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Andrew D Brown
- Department of Speech and Hearing Sciences, University of Washington, Seattle, WA 98105, USA
| | - José L Peña
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Catherine E Carr
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | | | - Daniel J Tollin
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Department of Otolaryngology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Molly C Womack
- Department of Biology, Utah State University, Logan, UT 84322, USA.
| | - Elizabeth A McCullagh
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK 74078, USA.
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Anderson NK, Schuppe ER, Gururaja KV, Mangiamele LA, Martinez JCC, Priti H, May RV, Preininger D, Fuxjager MJ. A Common Endocrine Signature Marks the Convergent Evolution of an Elaborate Dance Display in Frogs. Am Nat 2021; 198:522-539. [PMID: 34559606 DOI: 10.1086/716213] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractUnrelated species often evolve similar phenotypic solutions to the same environmental problem, a phenomenon known as convergent evolution. But how do these common traits arise? We address this question from a physiological perspective by assessing how convergence of an elaborate gestural display in frogs (foot-flagging) is linked to changes in the androgenic hormone systems that underlie it. We show that the emergence of this rare display in unrelated anuran taxa is marked by a robust increase in the expression of androgen receptor (AR) messenger RNA in the musculature that actuates leg and foot movements, but we find no evidence of changes in the abundance of AR expression in these frogs' central nervous systems. Meanwhile, the magnitude of the evolutionary change in muscular AR and its association with the origin of foot-flagging differ among clades, suggesting that these variables evolve together in a mosaic fashion. Finally, while gestural displays do differ between species, variation in the complexity of a foot-flagging routine does not predict differences in muscular AR. Altogether, these findings suggest that androgen-muscle interactions provide a conduit for convergence in sexual display behavior, potentially providing a path of least resistance for the evolution of motor performance.
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Gall MD, Baugh AT, Lucas JR, Bee MA. Social Communication across Reproductive Boundaries: Hormones and the Auditory Periphery of Songbirds and Frogs. Integr Comp Biol 2021; 61:292-301. [PMID: 33988694 DOI: 10.1093/icb/icab075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Most animals experience reproductive transitions in their lives; for example, reaching reproductive maturity or cycling in and out of breeding condition. Some reproductive transitions are abrupt, while others are more gradual. In most cases, changes in communication between the sexes follow the time course of these reproductive transitions and are typically thought to be coordinated by steroid hormones. We know a great deal about hormonal control of communication behaviors in birds and frogs, as well as the central neural control of these behaviors. There has also been significant interest in the effects of steroid hormones on central nervous system structures that control both the production and reception of communication signals associated with reproductive behaviors. However, peripheral sensory structures have typically received less attention, although there has been growing interest in recent years. It is becoming clear that peripheral sensory systems play an important role in reproductive communication, are plastic across reproductive conditions, and, in some cases, this plasticity may be mediated by steroid hormones. In this article, we discuss recent evidence for the role of peripheral auditory structures in reproductive communication in birds and frogs, the plasticity of the peripheral auditory system, and the role of steroid hormones in mediating the effects of the peripheral auditory system on reproductive communication. We focus on both seasonal and acute reproductive transitions, introduce new data on the role of hormones in modulating seasonal patterns, and make recommendations for future work.
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Affiliation(s)
- Megan D Gall
- Department of Biology, Vassar College, 124 Raymond Avenue, Poughkeepsie, NY 12604, USA
| | - Alexander T Baugh
- Department of Biology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA
| | - Jeffrey R Lucas
- Department of Biological Sciences, Purdue University, West Lafayette, IN 65203, USA
| | - Mark A Bee
- Department of Ecology, Evolution, and Behavior, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN 55108, USA.,Graduate Program in Neuroscience, University of Minnesota, 321 Church Street SE, Minneapolis, MN 55455, USA
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7
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Baugh AT, Gray-Gaillard SL. Excreted testosterone and male sexual proceptivity: A hormone validation and proof-of-concept experiment in túngara frogs. Gen Comp Endocrinol 2021; 300:113638. [PMID: 33017582 DOI: 10.1016/j.ygcen.2020.113638] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/09/2020] [Accepted: 09/28/2020] [Indexed: 12/14/2022]
Abstract
Conventional methods for sampling hormones often preclude strong inference experimental designs, including repeated measures of both hormones and behavior and balanced or simultaneous designs for hormone-behavior sampling. In amphibians there is an opportunity to non-invasively and repeatedly sample excreted steroids in the water. We examined testosterone (T) in túngara frogs (Physalaemus (=Engystomops) pustulosus) using minimally invasive water-borne methods. First, we validated procedures for the collection, extraction and measurement of T in adult males and females using pharmacological challenges coupled with estimates of parallelism and recovery determination. Next, we extended the timeline of sampling over 9 days in order to evaluate the kinetics of excretion (baseline phase, challenge phase, recovery phase), including the estimation of individual differences during baseline sampling. We also estimated concentrations of creatinine (Cr) in each water sample and evaluated whether correcting for this proxy of urine concentration significantly decreased error variance in T estimates. Lastly, we incorporated a standardized and repeated measures assay of male sexual proceptivity (phonotaxis) during the predicted peak T and recovery T timepoints. We found strong evidence supporting the utility of these methods for precise, biologically informative estimates of T in both sexes. Males had higher T than females and responded to pharmacological challenges by elevating T substantially within 48 h of challenge (hCG, GnRH). Males exhibited repeatability in baseline T and phonotaxis frequencies were positively associated with higher T. Adjusting T levels for the simultaneous measure of Cr significantly improved model fit, which in conjunction with marked variation in urine concentration, suggests that urine likely serves as the major source of excreted T. In summary, this proof-of-concept and methods study demonstrates the utility and accuracy of measuring water-borne T and behavior in amphibians.
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Affiliation(s)
- Alexander T Baugh
- Department of Biology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, United States.
| | - Sophie L Gray-Gaillard
- Department of Biology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, United States
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8
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Burmeister SS, Rodriguez Moncalvo VG, Pfennig KS. Differential encoding of signals and preferences by noradrenaline in the anuran brain. J Exp Biol 2020; 223:jeb214148. [PMID: 32647019 PMCID: PMC7522018 DOI: 10.1242/jeb.214148] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 07/07/2020] [Indexed: 11/20/2022]
Abstract
Social preferences enable animals to selectively interact with some individuals over others. One influential idea for the evolution of social preferences is that preferred signals evolve because they elicit greater neural responses from sensory systems. However, in juvenile plains spadefoot toad (Spea bombifrons), a species with condition-dependent mating preferences, responses of the preoptic area, but not of the auditory midbrain, mirror adult social preferences. To examine whether this separation of signal representation from signal valuation generalizes to other anurans, we compared the relative contributions of noradrenergic signalling in the preoptic area and auditory midbrain of S. bombifrons and its close relative Spea multiplicata We manipulated body condition in juvenile toads by controlling diet and used high pressure liquid chromatography to compare call-induced levels of noradrenaline and its metabolite MHPG in the auditory midbrain and preoptic area of the two species. We found that calls from the two species induced different levels of noradrenaline and MHPG in the auditory system, with higher levels measured in both species for the more energetic S. bombifrons call. In contrast, noradrenaline levels in the preoptic area mirrored patterns of social preferences in both S. bombifrons and S. multiplicata That is, noradrenaline levels were higher in response to the preferred calls within each species and were modified by diet in S. bombifrons (with condition-dependent preferences) but not S. multiplicata (with condition-independent preferences). Our results are consistent with a potentially important role for preoptic noradrenaline in the development of social preferences and indicate that it could be a target of selection in the evolution of condition-dependent social preferences.
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Affiliation(s)
| | | | - Karin S Pfennig
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
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9
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Boyd SK. Effects of intracerebroventricular arginine vasotocin on a female amphibian proceptive behavior. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:505-513. [DOI: 10.1007/s00359-019-01340-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/29/2019] [Accepted: 05/02/2019] [Indexed: 10/26/2022]
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10
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Baugh AT, Bastien B, Still MB, Stowell N. Validation of water-borne steroid hormones in a tropical frog (Physalaemus pustulosus). Gen Comp Endocrinol 2018; 261:67-80. [PMID: 29397994 DOI: 10.1016/j.ygcen.2018.01.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 12/18/2022]
Abstract
Minimally invasive methods for estimating hormone concentrations in wild vertebrates offer the opportunity to repeatedly measure behavior and hormone concentrations within individuals while minimizing experimenter interference during sample collection. We examined three steroid hormones (corticosterone, CORT; 17-β estradiol, E2; progesterone, PROG) in túngara frogs (Physalaemus pustulosus) using non-invasive water-borne methods. Using solid-phase extraction of water samples and liquid extraction of plasma and homogenate samples, coupled with enzyme immunoassays, we complimented the conventional validation approaches (parallelism, recovery determination) with dose-response assays that incorporated pharmacological challenges with adrenocorticotropic hormone (ACTH) and human chorionic gonadotropin (HCG). We also compared steroid concentrations in water to those observed in plasma and whole body homogenates. Lastly, we identified the constituent steroids in each sample type with a panel targeting 30 steroid species using high performance liquid chromatography-mass spectrometry (HPLC-MS). We found that a 60-min water-bath captures physiologically relevant changes in concentrations of CORT, E2 and PROG. Peak levels of water-borne CORT were found at approximately 2 h after ACTH injection. Water-borne CORT and E2 concentrations were positively correlated with their plasma and homogenate equivalents, while water-borne PROG was uncorrelated with homogenate PROG concentrations but negatively correlated with homogenate E2 concentrations. Together, our findings indicate that sampling water-borne hormones presents a non-invasive and biologically informative approach that will be useful for behavioral endocrinologists and conservation physiologists.
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Affiliation(s)
- Alexander T Baugh
- Department of Biology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA.
| | - Brandon Bastien
- Department of Biology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA
| | - Meghan B Still
- Department of Integrative Biology, The University of Texas at Austin, 1 University Station, C0930, Austin, TX 78712, USA
| | - Nicole Stowell
- Department of Biology, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA
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11
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Burmeister SS. Neurobiology of Female Mate Choice in Frogs: Auditory Filtering and Valuation. Integr Comp Biol 2018; 57:857-864. [PMID: 29048536 DOI: 10.1093/icb/icx098] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mate choice is a decision making process with profound implication for the reproductive success of both the sender and the chooser. Preferences for conspecific over heterospecific males and for some conspecifics over others are typically mediated by a female's response to signals produced by males. And although one can experimentally describe a female's preference function, there is relatively little understood about the neural mechanisms mediating these preferences. In anurans, mating preferences have often been explained in terms of sensory biases. Indeed, in the túngara frog (Physalaemus pustulosus), the auditory system appears to act as a filter for conspecific calls. However, auditory responses are not good predictors of intraspecific mating preferences in túngara frogs. Rather, neural activity in the preoptic area, which can be gated by estradiol, is a better predictor of mating preferences. A similar pattern holds in spadefoot toads (Spea bombifrons): the preoptic area, but not the auditory midbrain, integrates physiological cues in its response to mating calls in a pattern that predicts preferences. Neuroanatomically, the anuran preoptic area is poised to mediate forebrain influences on auditory response of the midbrain and it has descending projections to the medulla and spinal cord that could directly influence motor responses. Indeed, lesions of the preoptic area abolish phonotaxis. A role for the preoptic area in mating preferences is supported by studies in mammals that show the preoptic area is required for the expression of preferences. Further, activity of the preoptic area correlates with mating preference in fish. This leads to a model for the neurobiological mechanisms of mate choice, in which sensory systems filter relevant signals from irrelevant ones, but the preoptic area assigns value to the range of relevant signals.
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Affiliation(s)
- Sabrina S Burmeister
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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12
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Santillo A, Falvo S, Di Fiore MM, Chieffi Baccari G. Seasonal changes and sexual dimorphism in gene expression of StAR protein, steroidogenic enzymes and sex hormone receptors in the frog brain. Gen Comp Endocrinol 2017; 246:226-232. [PMID: 28027903 DOI: 10.1016/j.ygcen.2016.12.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 12/20/2016] [Accepted: 12/21/2016] [Indexed: 01/08/2023]
Abstract
The brain of amphibians contains all the key enzymes of steroidogenesis and has a high steroidogenic activity. In seasonally-breeding amphibian species brain steroid levels fluctuate synchronously with the reproductive cycle. Here we report a study of gene expression of StAR protein, key steroidogenic enzymes and sex hormone receptors in the telencephalon (T) and diencephalon-mesencephalon (D-M) of male and female reproductive and post-reproductive Pelophylax esculentus, a seasonally breeding anuran amphibian. Significant differences in gene expression were observed between (a) the reproductive and post-reproductive phase, (b) the two brain regions and (c) male and female frogs. During the reproductive phase, star gene expression increased in the male (both T and D-M) but not in the female brain. Seasonal fluctuations in expression levels of hsd3b1, hsd17b1, srd5a1 and cyp19a1 genes for neurosteroidogenic enzymes occurred in D-M region of both sexes, with the higher levels in reproductive period. Moreover, the D-M region generally showed higher levels of gene expression than the T region in both sexes. Gene expression was higher in females than males for most genes, suggesting higher neurosteroid production in female brain. Seasonal and sex-linked changes were also observed in gene expression for androgen (ar) and estrogen (esr1, esr2) receptors, with the males showing the highest ar levels in reproductive phase and the highest esr1 and esr2 levels in post-reproductive phase; in contrast, females showed the maximum expression for all three genes in reproductive phase. The results are the first evidence for seasonal changes and sexual dimorphism of gene expression of the neurosteroidogenic pathway in amphibians.
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Affiliation(s)
- Alessandra Santillo
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania Luigi Vanvitelli, via Vivaldi, 43, 81100 Caserta, Italy.
| | - Sara Falvo
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania Luigi Vanvitelli, via Vivaldi, 43, 81100 Caserta, Italy
| | - Maria Maddalena Di Fiore
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania Luigi Vanvitelli, via Vivaldi, 43, 81100 Caserta, Italy
| | - Gabriella Chieffi Baccari
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania Luigi Vanvitelli, via Vivaldi, 43, 81100 Caserta, Italy
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14
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Chakraborty M, Burmeister SS. Effects of estradiol on neural responses to social signals in female túngara frogs. ACTA ACUST UNITED AC 2015; 218:3671-7. [PMID: 26449971 DOI: 10.1242/jeb.127738] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/21/2015] [Indexed: 11/20/2022]
Abstract
Estradiol plays an important role in mediating changes in female sexual behavior across reproductive cycles. In the túngara frog [Physalaemus (=Engystomops) pustulosus], the relationship between gonadal activity and female sexual behavior, as expressed by phonotaxis, is mediated primarily by estradiol. Estradiol receptors are expressed in auditory and motivational brain areas and the hormone could serve as an important modulator of neural responses to conspecific calls. To better understand how estradiol modifies neural responses to conspecific social signals, we manipulated estradiol levels and measured expression of the immediate early gene egr-1 in the auditory midbrain, thalamus and limbic forebrain in response to conspecific or heterospecific calls. We found that estradiol and conspecific calls increased egr-1 expression in the auditory midbrain and limbic forebrain, but in the thalamus, only conspecific calls were effective. In the preoptic area, estradiol enhanced the effect of the conspecific call on egr-1 expression, suggesting that the preoptic area could act as a hormonal gatekeeper to phonotaxis. Overall, the results suggest that estradiol has broad influences on the neural circuit involved in female reproduction, particularly those implicated in phonotaxis.
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Affiliation(s)
- Mukta Chakraborty
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Sabrina S Burmeister
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA Curriculum in Neurobiology, University of North Carolina, Chapel Hill, NC 27599, USA
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15
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Coumailleau P, Kah O. Expression of the cyp19a1 gene in the adult brain of Xenopus is neuronal and not sexually dimorphic. Gen Comp Endocrinol 2015; 221:203-12. [PMID: 26255686 DOI: 10.1016/j.ygcen.2015.08.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 07/16/2015] [Accepted: 08/04/2015] [Indexed: 01/07/2023]
Abstract
The last step of oestrogen biosynthesis is catalyzed by the enzyme aromatase, the product of the cyp19a1 gene. In vertebrates, cyp19a1 is expressed in the brain resulting in a local oestrogen production that seems important not only for the control of reproduction-related circuits and sexual behaviour, but also for the regulation of neural development, synaptic plasticity and cell survival. In adult amphibians, the precise sites of expression of cyp19a1 in the brain have not been investigated which prevents proper understanding of its potential physiological functions. The present study aimed at examining the precise neuroanatomical distribution of cyp19a1 transcripts in adult brains of both male and female Xenopus. We found that cyp19a1 expression is highly regionalized in the brains of both sexes. The highest expression was found in the anterior part of the preoptic area and in the caudal hypothalamus, but significant levels of cyp19a1 transcripts were also found in the supraoptic paraventricular and suprachiasmatic areas, and in brain regions corresponding to the septum, bed nucleus of the stria terminalis and amygdala. Importantly, no obvious difference between male and female Xenopus was detected at the level of cyp19a1 transcripts. Additionally, in the brain of adult Xenopus, cyp19a1 transcripts were detected in neurons, and not in glial cells. These data and those available in other vertebrates on cyp19a1/aromatase expression suggest that, with the intriguing exception of teleost fishes, cyp19a1 was under strong evolutionary conservation with respect to its sites of expression and the nature of the cells in which it is expressed.
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Affiliation(s)
- Pascal Coumailleau
- Research Institute in Health, Environment and Occupation, INSERM U1085, SFR Biosite, Université de Rennes 1, Campus de Beaulieu, 35 042 Rennes cedex, France.
| | - Olivier Kah
- Research Institute in Health, Environment and Occupation, INSERM U1085, SFR Biosite, Université de Rennes 1, Campus de Beaulieu, 35 042 Rennes cedex, France
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16
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Bhandari RK, Deem SL, Holliday DK, Jandegian CM, Kassotis CD, Nagel SC, Tillitt DE, Vom Saal FS, Rosenfeld CS. Effects of the environmental estrogenic contaminants bisphenol A and 17α-ethinyl estradiol on sexual development and adult behaviors in aquatic wildlife species. Gen Comp Endocrinol 2015; 214:195-219. [PMID: 25277515 DOI: 10.1016/j.ygcen.2014.09.014] [Citation(s) in RCA: 180] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 08/08/2014] [Accepted: 09/20/2014] [Indexed: 12/12/2022]
Abstract
Endocrine disrupting chemicals (EDCs), including the mass-produced component of plastics, bisphenol A (BPA) are widely prevalent in aquatic and terrestrial habitats. Many aquatic species, such as fish, amphibians, aquatic reptiles and mammals, are exposed daily to high concentrations of BPA and ethinyl estradiol (EE2), estrogen in birth control pills. In this review, we will predominantly focus on BPA and EE2, well-described estrogenic EDCs. First, the evidence that BPA and EE2 are detectable in almost all bodies of water will be discussed. We will consider how BPA affects sexual and neural development in these species, as these effects have been the best characterized across taxa. For instance, such chemicals have been in many cases reported to cause sex-reversal of males to females. Even if these chemicals do not overtly alter the gonadal sex, there are indications that several EDCs might demasculinize male-specific behaviors that are essential for attracting a mate. In so doing, these chemicals may reduce the likelihood that these males reproduce. If exposed males do reproduce, the concern is that they will then be passing on compromised genetic fitness to their offspring and transmitting potential transgenerational effects through their sperm epigenome. We will thus consider how diverse epigenetic changes might be a unifying mechanism of how BPA and EE2 disrupt several processes across species. Such changes might also serve as universal species diagnostic biomarkers of BPA and other EDCs exposure. Lastly, the evidence that estrogenic EDCs-induced effects in aquatic species might translate to humans will be considered.
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Affiliation(s)
- Ramji K Bhandari
- Biological Sciences, University of Missouri, Columbia, MO 65211, USA; Columbia Environmental Research Center, U.S. Geological Survey, Columbia, MO 65201, USA
| | - Sharon L Deem
- Institute for Conservation Medicine, Saint Louis Zoo, Saint Louis, MO 63110, USA; Veterinary Clinical Medicine, University of Missouri, Columbia, MO 65211, USA
| | - Dawn K Holliday
- Department of Biology and Environmental Science, Westminster College, Fulton, MO 65251, USA; Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Caitlin M Jandegian
- Columbia Environmental Research Center, U.S. Geological Survey, Columbia, MO 65201, USA; Institute for Conservation Medicine, Saint Louis Zoo, Saint Louis, MO 63110, USA; Masters in Public Health Program, University of Missouri, Columbia, MO 65211, USA
| | | | - Susan C Nagel
- Biological Sciences, University of Missouri, Columbia, MO 65211, USA; Obstetrics, Gynecology, & Women's Health, University of Missouri, Columbia, MO 65211, USA
| | - Donald E Tillitt
- Columbia Environmental Research Center, U.S. Geological Survey, Columbia, MO 65201, USA
| | | | - Cheryl S Rosenfeld
- Biomedical Sciences, University of Missouri, Columbia, MO 65211, USA; Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Genetics Area Program Faculty Member, University of Missouri, Columbia, MO 65211, USA.
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17
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Aromatase, estrogen receptors and brain development in fish and amphibians. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:152-62. [PMID: 25038582 DOI: 10.1016/j.bbagrm.2014.07.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 06/19/2014] [Accepted: 07/07/2014] [Indexed: 12/20/2022]
Abstract
Estrogens affect brain development of vertebrates, not only by impacting activity and morphology of existing circuits, but also by modulating embryonic and adult neurogenesis. The issue is complex as estrogens can not only originate from peripheral tissues, but also be locally produced within the brain itself due to local aromatization of androgens. In this respect, teleost fishes are quite unique because aromatase is expressed exclusively in radial glial cells, which represent pluripotent cells in the brain of all vertebrates. Expression of aromatase in the brain of fish is also strongly stimulated by estrogens and some androgens. This creates a very intriguing positive auto-regulatory loop leading to dramatic aromatase expression in sexually mature fish with elevated levels of circulating steroids. Looking at the effects of estrogens or anti-estrogens in the brain of adult zebrafish showed that estrogens inhibit rather than stimulate cell proliferation and newborn cell migration. The functional meaning of these observations is still unclear, but these data suggest that the brain of fish is experiencing constant remodeling under the influence of circulating steroids and brain-derived neurosteroids, possibly permitting a diversification of sexual strategies, notably hermaphroditism. Recent data in frogs indicate that aromatase expression is limited to neurons and do not concern radial glial cells. Thus, until now, there is no other example of vertebrates in which radial progenitors express aromatase. This raises the question of when and why these new features were gained and what are their adaptive benefits. This article is part of a Special Issue entitled: Nuclear receptors in animal development.
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Senejani AG, Gaupale TC, Unniappan S, Bhargava S. Nesfatin-1/nucleobindin-2 like immunoreactivity in the olfactory system, brain and pituitary of frog, Microhyla ornata. Gen Comp Endocrinol 2014; 202:8-14. [PMID: 24768694 DOI: 10.1016/j.ygcen.2014.04.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 03/24/2014] [Accepted: 04/06/2014] [Indexed: 11/27/2022]
Abstract
Nesfatin-1 is a recently discovered anorectic protein derived from the precursor nucleobindin-2 (NUCB2). While nesfatin-1 has been widely studied in mammals, and goldfish, there are no reports of nesfatin-1 in amphibians. Using immunohistochemistry and Western blot analysis, this study assessed the distribution of NUCB2/nesfatin-1 in the brain of frog Microhyla ornata. NUCB2/nesfatin-1 like immunoreactivity was found in the olfactory receptor neurons, Bowman's glands and in the olfactory epithelium of medial diverticulum. In the brain, immunoreactive perikarya were seen in the anterior preoptic area, magnocellular nucleus, suprachiasmatic nucleus, ventromedial thalamic nucleus, posterior thalamic nucleus, nucleus infundibularis ventralis and dorsalis, and the cerebellar nucleus. NUCB2/nesfatin-1like immunoreactivity was also detected in the pineal and pituitary glands of frog. The presence of NUCB2/nesfatin-1 in the key brain regions suggest possible roles for this protein in the regulation of physiological processes in frogs.
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Affiliation(s)
- A G Senejani
- Department of Zoology, University of Pune, Ganeshkhind Road, Pune 411007, India
| | - Tekchand C Gaupale
- Department of Zoology, University of Pune, Ganeshkhind Road, Pune 411007, India
| | - Suraj Unniappan
- Laboratory of Integrative Neuroendocrinology, Department of Veterinary Biomedical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada
| | - Shobha Bhargava
- Department of Zoology, University of Pune, Ganeshkhind Road, Pune 411007, India.
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Caras ML. Estrogenic modulation of auditory processing: a vertebrate comparison. Front Neuroendocrinol 2013; 34:285-99. [PMID: 23911849 PMCID: PMC3788044 DOI: 10.1016/j.yfrne.2013.07.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 07/18/2013] [Accepted: 07/21/2013] [Indexed: 11/30/2022]
Abstract
Sex-steroid hormones are well-known regulators of vocal motor behavior in several organisms. A large body of evidence now indicates that these same hormones modulate processing at multiple levels of the ascending auditory pathway. The goal of this review is to provide a comparative analysis of the role of estrogens in vertebrate auditory function. Four major conclusions can be drawn from the literature: First, estrogens may influence the development of the mammalian auditory system. Second, estrogenic signaling protects the mammalian auditory system from noise- and age-related damage. Third, estrogens optimize auditory processing during periods of reproductive readiness in multiple vertebrate lineages. Finally, brain-derived estrogens can act locally to enhance auditory response properties in at least one avian species. This comparative examination may lead to a better appreciation of the role of estrogens in the processing of natural vocalizations and mayprovide useful insights toward alleviating auditory dysfunctions emanating from hormonal imbalances.
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Affiliation(s)
- Melissa L Caras
- Neurobiology and Behavior Graduate Program, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA; Virginia Merrill Bloedel Hearing Research Center, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA.
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20
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Abstract
Animals evaluate and respond to their social environment with adaptive decisions. Revealing the neural mechanisms of such decisions is a major goal in biology. We analyzed expression profiles for 10 neurochemical genes across 12 brain regions important for decision-making in 88 species representing five vertebrate lineages. We found that behaviorally relevant brain regions are remarkably conserved over 450 million years of evolution. We also find evidence that different brain regions have experienced different selection pressures, because spatial distribution of neuroendocrine ligands are more flexible than their receptors across vertebrates. Our analysis suggests that the diversity of social behavior in vertebrates can be explained, in part, by variations on a theme of conserved neural and gene expression networks.
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Affiliation(s)
- Lauren A O'Connell
- Institute for Cellular and Molecular Biology and Section of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
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Hoke KL, Pitts NL. Modulation of sensory-motor integration as a general mechanism for context dependence of behavior. Gen Comp Endocrinol 2012; 176:465-71. [PMID: 22405704 DOI: 10.1016/j.ygcen.2012.02.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 02/18/2012] [Accepted: 02/18/2012] [Indexed: 11/30/2022]
Abstract
Social communication is context-dependent, with both the production of signals and the responses of receivers tailored to each animal's internal needs and external environmental conditions. We propose that this context dependence arises because of neural modulation of the sensory-motor transformation that underlies the social behavior. Neural systems that are restricted to individual behaviors may be modulated at early stages of the sensory or motor pathways for optimal energy expenditure. However, when neural systems contribute to multiple important behaviors, we argue that the sensory-motor relay is the likely site of modulation. Plasticity in the sensory-motor relay enables subtle context dependence of the social behavior while preserving other functions of the sensory and motor systems. We review evidence that the robust responses of anurans to conspecific signals are dependent on reproductive state, sex, prior experience, and current context. A well-characterized midbrain sensory-motor relay establishes signal selectivity and gates locomotive responses to sound. The social decision-making network may modulate this auditory-motor transformation to confer context dependence of anuran reproductive responses to sound. We argue that similar modulation may be a general mechanism by which vertebrates prioritize their behaviors.
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Affiliation(s)
- Kim Lisa Hoke
- Department of Biology, Colorado State University, 1878 Campus Delivery, Fort Collins, CO 80523, USA.
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22
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O'Connell LA, Hofmann HA. The vertebrate mesolimbic reward system and social behavior network: a comparative synthesis. J Comp Neurol 2012; 519:3599-639. [PMID: 21800319 DOI: 10.1002/cne.22735] [Citation(s) in RCA: 691] [Impact Index Per Article: 57.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
All animals evaluate the salience of external stimuli and integrate them with internal physiological information into adaptive behavior. Natural and sexual selection impinge on these processes, yet our understanding of behavioral decision-making mechanisms and their evolution is still very limited. Insights from mammals indicate that two neural circuits are of crucial importance in this context: the social behavior network and the mesolimbic reward system. Here we review evidence from neurochemical, tract-tracing, developmental, and functional lesion/stimulation studies that delineates homology relationships for most of the nodes of these two circuits across the five major vertebrate lineages: mammals, birds, reptiles, amphibians, and teleost fish. We provide for the first time a comprehensive comparative analysis of the two neural circuits and conclude that they were already present in early vertebrates. We also propose that these circuits form a larger social decision-making (SDM) network that regulates adaptive behavior. Our synthesis thus provides an important foundation for understanding the evolution of the neural mechanisms underlying reward processing and behavioral regulation.
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Affiliation(s)
- Lauren A O'Connell
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA
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23
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The distribution of estrogen receptor β mRNA in male and female green anole lizards. Brain Res 2012; 1430:43-51. [DOI: 10.1016/j.brainres.2011.10.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/24/2011] [Accepted: 10/27/2011] [Indexed: 12/30/2022]
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Duarte-Guterman P, Ryan MJ, Hogan NS, Trudeau VL. Developmental Profiles and Thyroid Hormone Regulation of Brain Transcripts in Frogs: A Species Comparison with Emphasis on Physalaemus pustulosus. BRAIN, BEHAVIOR AND EVOLUTION 2011; 79:98-112. [DOI: 10.1159/000331265] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 07/20/2011] [Indexed: 01/18/2023]
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Abstract
Rather than being a static, species specific trait, reproductive behavior in female amphibians is variable within an individual during the breeding season when females are capable of reproductive activity. Changes in receptivity coincide with changes in circulating estrogen. Estrogen is highest at the point when females are ready to choose a male and lay eggs. At this time female receptivity (her probability of responding to a male vocal signal) is highest and her selectivity among conspecific calls (measured by her probability of responding to a degraded or otherwise usually unattractive male signal) is lowest. These changes occur even though females retain the ability to discriminate different acoustic characteristics of various conspecific calls. After releasing her eggs, female amphibians quickly become less receptive and more choosy in terms of their responses to male sexual advertisement signals. Male vocal signals stimulate both behavior and estrogen changes in amphibian females making mating more probable. The changes in female reproductive behavior are the same as those generally accepted as indicative of a change in female sexual arousal leading to copulation. They are situationally triggered, gated by interactions with males, and decline with the consummation of sexual reproduction with a chosen male. The changes can be triggered by either internal physiological state or by the presence of stimuli presented by males, and the same stimuli change both behavior and physiological (endocrine) state in such a way as to make acceptance of a male more likely. Thus amphibian females demonstrate many of the same general characteristics of changing female sexual state that in mammals indicate sexual arousal.
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Affiliation(s)
- Walter Wilczynski
- Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA 30302-5030, USA.
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