1
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Roberta C, Vera S, Hans A H, Michael H H. Activation patterns of dopaminergic cell populations reflect different learning scenarios in a cichlid fish, Pseudotropheus zebra. J Chem Neuroanat 2023; 133:102342. [PMID: 37722435 DOI: 10.1016/j.jchemneu.2023.102342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 09/13/2023] [Accepted: 09/14/2023] [Indexed: 09/20/2023]
Abstract
Dopamine is present in all vertebrates and the functional roles of the subsystems are assumed to be similar. Whereas the effect of dopaminergic modulation is well investigated in different target systems, less is known about the factors that are causing the modulation of dopaminergic cells. Using the zebra mbuna, Pseudotropheus zebra, a cichlid fish from Lake Malawi as a model system, we investigated the activation of specific dopaminergic cell populations detected by double-labeling with TH and pS6 antibodies while the animals were solving different learning tasks. Specifically, we compared an intense avoidance learning situation, an instrumental learning task, and a non-learning isolated group and found strong activation of different dopaminergic cell populations. Preoptic-hypothalamic cell populations respond to the stress component in the avoidance task, and the forced movement/locomotion may be responsible for activation in the posterior tubercle. The instrumental learning task had little stress component, but the activation of the raphe superior in this group may be correlated with attention or arousal during the training sessions. At the same time, the weaker activation of the nucleus of the posterior commissure may be related to positive reward acting onto tectal circuits. Finally, we examined the co-activation patterns across all dopaminergic cell populations and recovered robust differences across experimental groups, largely driven by hypothalamic, posterior tubercle, and brain stem regions possibly encoding the valence and salience associated with stressful stimuli. Taken together, our results offer some insights into the different functions of the dopaminergic cell populations in the brain of a non-mammalian vertebrate in correlation with different behavioral conditions, extending our knowledge for a more comprehensive view of the mechanisms of dopaminergic modulation in vertebrates.
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Affiliation(s)
- Calvo Roberta
- Institute of Zoology, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, Meckenheimer Allee 169, 53115 Bonn, Germany.
| | - Schluessel Vera
- Institute of Zoology, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, Meckenheimer Allee 169, 53115 Bonn, Germany
| | - Hofmann Hans A
- Department of Integrative Biology, Institute for Neuroscience, University of Texas at Austin, 2415 Speedway, Austin, TX 78712, USA
| | - Hofmann Michael H
- Institute of Zoology, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, Meckenheimer Allee 169, 53115 Bonn, Germany
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2
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Almeida MM, Cabrita E, Fatsini E. The Use of Sand Substrate Modulates Dominance Behaviour and Brain Gene Expression in a Flatfish Species. Animals (Basel) 2023; 13:ani13060978. [PMID: 36978519 PMCID: PMC10044175 DOI: 10.3390/ani13060978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/04/2023] [Accepted: 03/06/2023] [Indexed: 03/11/2023] Open
Abstract
Physical complexity adds physical enrichment to rearing conditions. This enrichment promotes fish welfare and reduces detrimental characteristics that fish develop in captivity. Senegalese sole (Solea senegalensis) is an important species for European aquaculture, where it is reared in intensive conditions using fibreglass tanks. However, reproductive dysfunctions present in this species do not allow it to complete its life cycle in captivity. Recently, dominance behaviour has been studied to try to solve this problem. The present study aimed to assess the effect of sand as environmental enrichment in the dominance behaviour and brain mRNA abundance of Senegalese sole juveniles. Four tanks of sole (n = 48 fish in total) were established in two different environments (with and without sand). Juveniles were subjected to dominance tests of feeding and territoriality. Behaviours analysed by video recordings related to the distance from the food delivered and harassment behaviour towards other individuals (e.g., resting of the head on another individual). In both environments, dominant sole were the first to feed, displayed more head-resting behaviour and dominated the area close to the feeding point, where the events were reduced in fish maintained in the sand. mRNA expression related to differentiation of dopamine neurons (nr4a2) and regulation of maturation (fshra) were significantly upregulated in dominant fish in the sand environment compared to dominants maintained without sand. The use of an enriched environment may affect Senegalese sole dominance, enhance welfare and possibly advance future maturation.
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3
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Rodriguez-Santiago M, Jordan A, Hofmann HA. Neural activity patterns differ between learning contexts in a social fish. Proc Biol Sci 2022; 289:20220135. [PMID: 35506226 PMCID: PMC9065956 DOI: 10.1098/rspb.2022.0135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Learning and decision-making are greatly influenced by context. When navigating a complex social world, individuals must quickly ascertain where to gain important resources and which group members are useful sources of such information. Such dynamic behavioural processes require neural mechanisms that are flexible across contexts. Here we examine how the social context influences the learning response during a cue discrimination task and the neural activity patterns that underlie acquisition of this novel information. Using the cichlid fish, Astatotilapia burtoni, we show that learning of the task is faster in social groups than in a non-social context. We quantify the neural activity patterns by examining the expression of Fos, an immediate-early gene, across brain regions known to play a role in social behaviour and learning (such as the putative teleost homologues of the mammalian hippocampus, basolateral amygdala and medial amygdala/BNST complex). We find that neural activity patterns differ between social and non-social contexts. Taken together, our results suggest that while the same brain regions may be involved in the learning of a cue association, the activity in each region reflects an individual's social context.
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Affiliation(s)
- Mariana Rodriguez-Santiago
- Institute for Neuroscience, The University of Texas at Austin, Austin, TX, USA.,Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA.,Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Alex Jordan
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA.,Max Planck Institute of Animal Behavior, Konstanz, Germany
| | - Hans A Hofmann
- Institute for Neuroscience, The University of Texas at Austin, Austin, TX, USA.,Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA.,Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
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4
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Maruska KP, Anselmo CM, King T, Mobley RB, Ray EJ, Wayne R. Endocrine and neuroendocrine regulation of social status in cichlid fishes. Horm Behav 2022; 139:105110. [PMID: 35065406 DOI: 10.1016/j.yhbeh.2022.105110] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 12/28/2021] [Accepted: 01/04/2022] [Indexed: 01/07/2023]
Abstract
Position in a dominance hierarchy profoundly impacts group members' survival, health, and reproductive success. Thus, understanding the mechanisms that regulate or are associated with an individuals' social position is important. Across taxa, various endocrine and neuroendocrine signaling systems are implicated in the control of social rank. Cichlid fishes, with their often-limited resources of food, shelter, and mates that leads to competition, have provided important insights on the proximate and ultimate mechanisms related to establishment and maintenance of dominance hierarchies. Here we review the existing information on the relationships between endocrine (e.g., circulating hormones, gonadal and other tissue measures) and neuroendocrine (e.g., central neuropeptides, biogenic amines, steroids) systems and dominant and subordinate social rank in male cichlids. Much of the current literature is focused on only a few representative cichlids, particularly the African Astatotilapia burtoni, and several other African and Neotropical species. Many hormonal regulators show distinct differences at multiple biological levels between dominant and subordinate males, but generalizations are complicated by variations in experimental paradigms, methodological approaches, and in the reproductive and parental care strategies of the study species. Future studies that capitalize on the diversity of hierarchical structures among cichlids should provide insights towards better understanding the endocrine and neuroendocrine mechanisms contributing to social rank. Further, examination of this topic in cichlids will help reveal the selective pressures driving the evolution of endocrine-related phenotypic traits that may facilitate an individual's ability to acquire and maintain a specific social rank to improve survival and reproductive success.
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Affiliation(s)
- Karen P Maruska
- Department of Biological Sciences, 202 Life Sciences Bldg., Louisiana State University, Baton Rouge, LA 70803, United States of America.
| | - Chase M Anselmo
- Department of Biological Sciences, 202 Life Sciences Bldg., Louisiana State University, Baton Rouge, LA 70803, United States of America
| | - Teisha King
- Department of Biological Sciences, 202 Life Sciences Bldg., Louisiana State University, Baton Rouge, LA 70803, United States of America
| | - Robert B Mobley
- Department of Biological Sciences, 202 Life Sciences Bldg., Louisiana State University, Baton Rouge, LA 70803, United States of America
| | - Emily J Ray
- Department of Biological Sciences, 202 Life Sciences Bldg., Louisiana State University, Baton Rouge, LA 70803, United States of America
| | - Rose Wayne
- Department of Biological Sciences, 202 Life Sciences Bldg., Louisiana State University, Baton Rouge, LA 70803, United States of America
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5
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Ogawa S, Parhar IS. Role of Habenula in Social and Reproductive Behaviors in Fish: Comparison With Mammals. Front Behav Neurosci 2022; 15:818782. [PMID: 35221943 PMCID: PMC8867168 DOI: 10.3389/fnbeh.2021.818782] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 12/27/2021] [Indexed: 02/05/2023] Open
Abstract
Social behaviors such as mating, parenting, fighting, and avoiding are essential functions as a communication tool in social animals, and are critical for the survival of individuals and species. Social behaviors are controlled by a complex circuitry that comprises several key social brain regions, which is called the social behavior network (SBN). The SBN further integrates social information with external and internal factors to select appropriate behavioral responses to social circumstances, called social decision-making. The social decision-making network (SDMN) and SBN are structurally, neurochemically and functionally conserved in vertebrates. The social decision-making process is also closely influenced by emotional assessment. The habenula has recently been recognized as a crucial center for emotion-associated adaptation behaviors. Here we review the potential role of the habenula in social function with a special emphasis on fish studies. Further, based on evolutional, molecular, morphological, and behavioral perspectives, we discuss the crucial role of the habenula in the vertebrate SDMN.
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6
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Butler JM, Maruska KP. Expression of tachykinin3 and related reproductive markers in the brain of the African cichlid fish Astatotilapia burtoni. J Comp Neurol 2019; 527:1210-1227. [PMID: 30644550 DOI: 10.1002/cne.24622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 12/05/2018] [Accepted: 12/17/2018] [Indexed: 11/06/2022]
Abstract
Neurokinin B, encoded by the tachykinin3 gene, plays a crucial role in regulating reproduction in mammals via KNDy neurons and interaction with GnRH. Previous work in teleost fishes has focused on hypothalamic tac3 expression for its role in reproduction, but detailed studies on extra-hypothalamic tac3 expression are limited. Here, we identified two tac3 genes in the social African cichlid fish Astatotilapia burtoni, only one of which produces a functional protein containing the signature tachykinin motif. In situ hybridization for tac3a mRNA identified cell populations throughout the brain. Numerous tac3a cells lie in several thalamic and hypothalamic nuclei, including periventricular nucleus of posterior tuberculum, lateral tuberal nucleus (NLT), and nucleus of the lateral recess (NRL). Scattered tac3-expressing cells are also present in telencephalic parts, such as ventral (Vv) and supracomissural (Vs) part of ventral telencephalon. In contrast to other teleosts, tac3 expression was absent from the pituitary. Using double-fluorescent staining, we localized tac3a-expressing cells in relation to GnRH and kisspeptin cells. Although no GnRH-tac3a colabeled cells were observed, dense GnRH fibers surround and potentially synapse with tac3a cells in the preoptic area. Only minimal (<5%) colabeling of tac3a was observed in kiss2 cells. Despite tac3a expression in many nodes of the mesolimbic reward system, it was absent from tyrosine hydroxylase (TH)-expressing cells, but tac3a cells were located in areas with dense TH fibers. The presence of tac3a-expressing cells throughout the brain, including in socially relevant brain regions, suggest more diverse functions beyond regulation of reproductive physiology that may be conserved across vertebrates.
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Affiliation(s)
- Julie M Butler
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Karen P Maruska
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana
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7
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Riaño-Quintero C, Gómez-Ramírez E, Hurtado-Giraldo H. Glyphosate commercial formulation effects on preoptic area and hypothalamus of Cardinal Neon Paracheirodon axelrodi (Characiformes: Characidae). NEOTROPICAL ICHTHYOLOGY 2019. [DOI: 10.1590/1982-0224-20190025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ABSTRACT In Colombia the use of glyphosate commercial formulations (Roundup™) for spraying have left deleterious effects on animals and humans. Much of this spraying takes place at the Orinoco basin, habitat of one of the most exported ornamental fish in Colombia, Cardinal neon. To evaluate the effect of Roundup Activo™ four experimental treatments were carried out with 0 mg/L (T1), 0.1 mg/L (T2), 1 mg/L (T3) and 5 mg/L (T4) during 30 days of exposure. The fishes were processed for high-resolution optical microscopy. The main finding of Roundup Activo™ exposure was an increase in mast cells number in brain blood vessels and some neuronal nuclei of the preoptic and posterior diencephalic areas, including hypothalamus. A correlation between concentrations and mast cells number was observed, with the largest mast cells number in T4 treatment. Mast cells presence is a stress benchmark, suggesting the beginning of allergic, inflammatory and apoptotic events. Presence of mast cells in these brain areas may lead to alterations on reproduction, visual and olfactory information integration among other processes. These alterations may result in diminished survival, affecting the conservation of this species in its natural habitat.
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8
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Maruska KP, Fernald RD. Astatotilapia burtoni: A Model System for Analyzing the Neurobiology of Behavior. ACS Chem Neurosci 2018. [PMID: 29522313 DOI: 10.1021/acschemneuro.7b00496] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Most biomedical research is performed using a very limited number of "model" species. In part, this has resulted from a combination of full genomes, manipulation of genes, and short generation times in these species. However, the advent of low-cost sequencing and gene editing in any organism has increased the use of nontraditional organisms. Many scientists have paraphrased the adage by Krogh [ Krogh , A. ( 2018 ) Science 70 , 200 - 204 ] that for many biological problems some species will prove to be most convenient and useful to study. In particular, using organisms most suited to the specific research question can lead to novel insights about fundamental physiological, neurobiological, immunological, and neuroendocrine systems that can advance our understanding of the well-being and health of humans. In addition, such studies have led to new ideas about the evolution and mechanisms that control social behavior. Fishes constitute about 50% of all vertebrate species and are the most diverse vertebrate radiation. Here we review behavioral and neurobiological discoveries of plasticity in social behavior resulting from analysis of an African cichlid fish, showing how its unique behavioral system has facilitated a broad range of discoveries. For many future questions, Astatotilapia burtoni and other cichlid fishes may be ideally suited to study as we advance our understanding of the neural basis of social decisions.
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Affiliation(s)
- Karen P. Maruska
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Russell D. Fernald
- Biology Department, Stanford University, Stanford, California 94305, United States
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9
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Fatsini E, Rey S, Ibarra-Zatarain Z, Mackenzie S, Duncan NJ. Dominance behaviour in a non-aggressive flatfish, Senegalese sole (Solea senegalensis) and brain mRNA abundance of selected transcripts. PLoS One 2017; 12:e0184283. [PMID: 28877259 PMCID: PMC5587333 DOI: 10.1371/journal.pone.0184283] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 08/21/2017] [Indexed: 11/18/2022] Open
Abstract
Dominance is defined as the preferential access to limited resources. The present study aimed to characterise dominance in a non-aggressive flatfish species, the Senegalese sole (Solea senegalensis) by 1) identifying dominance categories and associated behaviours and 2) linking dominance categories (dominant and subordinate) with the abundance of selected mRNA transcripts in the brain. Early juveniles (n = 74, 37 pairs) were subjected to a dyadic dominance test, related to feeding, and once behavioural phenotypes had been described the abundance of ten selected mRNAs related to dominance and aggressiveness was measured in the brain. Late juveniles were subjected to two dyadic dominance tests (n = 34, 17 pairs), related to feeding and territoriality and one group test (n = 24, 4 groups of 6 fish). Sole feeding first were categorized as dominant and sole feeding second or not feeding as subordinate. Three social behaviours (i. "Resting the head" on another fish, ii. "Approaching" another fish, iii. "Swimming above another" fish) were associated with dominance of feeding. Two other variables (i. Total time occupying the preferred area during the last 2 hours of the 24 h test, ii. Organisms occupying the preferred area when the test ended) were representative of dominance in the place preference test. In all tests, dominant fish compared to subordinate fish displayed a significantly higher number of the behaviours "Rest the head" and "Approaches". Moreover, dominant sole dominated the sand at the end of the test, and in the group test dominated the area close to the feed delivery point before feed was delivered. The mRNA abundance of the selected mRNAs related to neurogenesis (nrd2) and neuroplasticity (c-fos) in dominant sole compared to subordinate were significantly different. This is the first study to characterise dominance categories with associated behaviours and mRNA abundance in Senegalese sole and provides tools to study dominance related problems in feeding and reproduction in aquaculture.
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Affiliation(s)
| | - Sonia Rey
- Institute of Aquaculture, Pathfoot Building, University of Stirling, Stirling, Scotland, United Kingdom
| | - Zohar Ibarra-Zatarain
- IRTA, Sant Carles de la Ràpita, Tarragona, Spain.,CONACYT-UAN-CENIT, Calle 3 S/N, Ciudad industrial, Tepic, Mexico
| | - Simon Mackenzie
- Institute of Aquaculture, Pathfoot Building, University of Stirling, Stirling, Scotland, United Kingdom
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10
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Socially induced plasticity in sensorimotor gating in the African cichlid fish Astatotilapia burtoni. Behav Brain Res 2017; 332:32-39. [DOI: 10.1016/j.bbr.2017.05.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/18/2017] [Accepted: 05/22/2017] [Indexed: 01/01/2023]
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11
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Weitekamp CA, Nguyen J, Hofmann HA. Social context affects behavior, preoptic area gene expression, and response to
D2
receptor manipulation during territorial defense in a cichlid fish. GENES BRAIN AND BEHAVIOR 2017; 16:601-611. [DOI: 10.1111/gbb.12389] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 03/31/2017] [Accepted: 04/27/2017] [Indexed: 11/27/2022]
Affiliation(s)
- C. A. Weitekamp
- Department of Integrative Biology University of Texas at Austin Austin TX USA
| | - J. Nguyen
- Department of Integrative Biology University of Texas at Austin Austin TX USA
| | - H. A. Hofmann
- Department of Integrative Biology University of Texas at Austin Austin TX USA
- Institute for Cell and Molecular Biology University of Texas at Austin Austin TX USA
- Institute for Neuroscience University of Texas at Austin Austin TX USA
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12
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Bridges K, Venables B, Roberts A. Effects of dietary methylmercury on the dopaminergic system of adult fathead minnows and their offspring. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:1077-1084. [PMID: 27677528 DOI: 10.1002/etc.3630] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 09/04/2016] [Accepted: 09/27/2016] [Indexed: 06/06/2023]
Abstract
Mercury (Hg) is a ubiquitous environmental contaminant and potent neurotoxin, which may be transformed by bacteria in aquatic ecosystems to methylmercury (MeHg), an organic form which bioaccumulates and biomagnifies. Consequently, long-lived organisms at the top of the food web are at risk of dietary MeHg exposure, which can be actively transferred from mother to offspring. Exposure during neurodevelopment can lead to serious, irreversible neurological dysfunction, associated with a variety of cognitive and motor abnormalities. At low dietary concentrations, MeHg exposure has been associated with deficits in attention and hyperactivity in multiple species. Pathways associated with cognitive function and motor activity are primarily associated with the dopaminergic system. The present study used a model fish species, Pimephales promelas, to examine the effects of MeHg exposure on dopamine concentrations and monoamine oxidase activity in embryos and adult brains. Adult fatheads were exposed for 30 d to either a control or a treated diet (0.72 ppm Hg). Embryonic and larval exposures were a result of maternal transfer of dietary MeHg. The authors confirmed hyperactive behaviors in embryos and detected significant changes in embryonic dopamine concentrations. Similar effects on dopamine concentrations were seen in the telencephalon of adult brains. Exposure to MeHg also corresponded with a significant decrease in monoamine oxidase activity in both embryos and brain tissue. Collectively, these results suggest that current exposure scenarios in North America are sufficient to induce alterations to this highly conserved neurochemical pathway in offspring, which may have adverse effects on fish behavior and cognition. Environ Toxicol Chem 2017;36:1077-1084. © 2016 SETAC.
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Affiliation(s)
- Kristin Bridges
- Department of Biological Sciences and Institute of Applied Sciences, University of North Texas, Denton, Texas, USA
| | - Barney Venables
- Department of Biological Sciences and Institute of Applied Sciences, University of North Texas, Denton, Texas, USA
| | - Aaron Roberts
- Department of Biological Sciences and Institute of Applied Sciences, University of North Texas, Denton, Texas, USA
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13
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Weitekamp CA, Hofmann HA. Neuromolecular correlates of cooperation and conflict during territory defense in a cichlid fish. Horm Behav 2017; 89:145-156. [PMID: 28108326 DOI: 10.1016/j.yhbeh.2017.01.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 01/07/2023]
Abstract
Cooperative behavior is widespread among animals, yet the neural mechanisms have not been studied in detail. We examined cooperative territory defense behavior and associated neural activity in candidate forebrain regions in the cichlid fish, Astatotilapia burtoni. We find that a territorial male neighbor will engage in territory defense dependent on the perceived threat of the intruder. The resident male, on the other hand, engages in defense based on the size and behavior of his partner, the neighbor. In the neighbor, we find that an index of engagement correlates with neural activity in the putative homolog of the mammalian basolateral amygdala and in the preoptic area, as well as in preoptic dopaminergic neurons. In the resident, neighbor behavior is correlated with neural activity in the homolog of the mammalian hippocampus. Overall, we find distinct neural activity patterns between the neighbor and the resident, suggesting that an individual perceives and processes an intruder challenge differently during cooperative territory defense depending on its own behavioral role.
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Affiliation(s)
- Chelsea A Weitekamp
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78705, USA
| | - Hans A Hofmann
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78705, USA; Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78705, USA; Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78705, USA.
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14
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Williams MJ, Klockars A, Eriksson A, Voisin S, Dnyansagar R, Wiemerslage L, Kasagiannis A, Akram M, Kheder S, Ambrosi V, Hallqvist E, Fredriksson R, Schiöth HB. The Drosophila ETV5 Homologue Ets96B: Molecular Link between Obesity and Bipolar Disorder. PLoS Genet 2016; 12:e1006104. [PMID: 27280443 PMCID: PMC4900636 DOI: 10.1371/journal.pgen.1006104] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 05/13/2016] [Indexed: 12/24/2022] Open
Abstract
Several reports suggest obesity and bipolar disorder (BD) share some physiological and behavioural similarities. For instance, obese individuals are more impulsive and have heightened reward responsiveness, phenotypes associated with BD, while bipolar patients become obese at a higher rate and earlier age than people without BD; however, the molecular mechanisms of such an association remain obscure. Here we demonstrate, using whole transcriptome analysis, that Drosophila Ets96B, homologue of obesity-linked gene ETV5, regulates cellular systems associated with obesity and BD. Consistent with a role in obesity and BD, loss of nervous system Ets96B during development increases triacylglyceride concentration, while inducing a heightened startle-response, as well as increasing hyperactivity and reducing sleep. Of notable interest, mouse Etv5 and Drosophila Ets96B are expressed in dopaminergic-rich regions, and loss of Ets96B specifically in dopaminergic neurons recapitulates the metabolic and behavioural phenotypes. Moreover, our data indicate Ets96B inhibits dopaminergic-specific neuroprotective systems. Additionally, we reveal that multiple SNPs in human ETV5 link to body mass index (BMI) and BD, providing further evidence for ETV5 as an important and novel molecular intermediate between obesity and BD. We identify a novel molecular link between obesity and bipolar disorder. The Drosophila ETV5 homologue Ets96B regulates the expression of cellular systems with links to obesity and behaviour, including the expression of a conserved endoplasmic reticulum molecular chaperone complex known to be neuroprotective. Finally, a connection between the obesity-linked gene ETV5 and bipolar disorder emphasizes a functional relationship between obesity and BD at the molecular level. The World Health Organization suggests obesity is a major cause of poor health and is becoming the leading public health concern. Likewise, mood-based disorders, such as bipolar disorder, are one of the top ten causes of disability worldwide. There is evidence that obesity and bipolar disorder may be linked and that obesity may exacerbate bipolar disorder symptoms. For the first time, our work evidences a molecular-link between obesity and bipolar disorder. In humans the obesity-linked gene ETV5 was also associated with bipolar disorder. Using the model organism Drosophila melanogaster (the fruit fly) we show that the ETV5 homologue Ets96B regulates a series of genes known to be neuroprotective and inhibiting the expression of Ets96 in dopaminergic neurons induces phenotypes linked to obesity and bipolar disorder, including increased lipid storage, increased anxiety and reduced sleep. Our work will help to further the understanding of how these to disorders may interact.
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Affiliation(s)
- Michael J. Williams
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
- * E-mail:
| | - Anica Klockars
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Anders Eriksson
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Sarah Voisin
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Rohit Dnyansagar
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Lyle Wiemerslage
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Anna Kasagiannis
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Mehwish Akram
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Sania Kheder
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Valerie Ambrosi
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Emilie Hallqvist
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Robert Fredriksson
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Helgi B. Schiöth
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
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15
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Social Regulation of Gene Expression in Threespine Sticklebacks. PLoS One 2015; 10:e0137726. [PMID: 26367311 PMCID: PMC4569571 DOI: 10.1371/journal.pone.0137726] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 08/20/2015] [Indexed: 11/25/2022] Open
Abstract
Identifying genes that are differentially expressed in response to social interactions is informative for understanding the molecular basis of social behavior. To address this question, we described changes in gene expression as a result of differences in the extent of social interactions. We housed threespine stickleback (Gasterosteus aculeatus) females in either group conditions or individually for one week, then measured levels of gene expression in three brain regions using RNA-sequencing. We found that numerous genes in the hindbrain/cerebellum had altered expression in response to group or individual housing. However, relatively few genes were differentially expressed in either the diencephalon or telencephalon. The list of genes upregulated in fish from social groups included many genes related to neural development and cell adhesion as well as genes with functions in sensory signaling, stress, and social and reproductive behavior. The list of genes expressed at higher levels in individually-housed fish included several genes previously identified as regulated by social interactions in other animals. The identified genes are interesting targets for future research on the molecular mechanisms of normal social interactions.
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16
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Jalabert C, Quintana L, Pessina P, Silva A. Extra-gonadal steroids modulate non-breeding territorial aggression in weakly electric fish. Horm Behav 2015; 72:60-7. [PMID: 25989595 DOI: 10.1016/j.yhbeh.2015.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 05/04/2015] [Accepted: 05/11/2015] [Indexed: 01/03/2023]
Abstract
The neuroendocrine control of intraspecific aggression is a matter of current debate. Although aggression in a reproductive context has been associated with high levels of circulating androgens in a broad range of species, it has also been shown to occur during the non-breeding season when gonads are regressed and plasma steroid hormone levels are low. In mammals and birds the aromatization of androgens into estrogens plays a key role in the regulation of aggression in both the breeding and non-breeding seasons. This is the first study in a teleost fish to explore the role of steroids in the modulation of non-breeding aggression. Gymnotus omarorum is a highly aggressive teleost fish that exhibits aggression all year-round. We analyzed male-male non-breeding agonistic behavior, compared circulating 11-Ketotestosterone (11-KT) levels between dominants and isolated males, assessed the regulatory role of aromatization of androgens into estrogens, and evaluated the gonads as a source of these sex steroids. We found that high levels of aggression occurred in the non-breeding season despite low plasma 11-KT levels, and that there was no difference in 11-KT levels between dominant and isolated males. We demonstrated that acute aromatase inhibition decreased aggression, distorted contest dynamics, and affected expected outcome. We also found that castrated individuals displayed aggressive behavior indistinguishable from non-castrated males. Our results show, for the first time in teleost fish, that territorial aggression of G. omarorum during the non-breeding season depends on a non-gonadal estrogenic pathway.
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Affiliation(s)
- Cecilia Jalabert
- Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo 11600, Uruguay
| | - Laura Quintana
- Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo 11600, Uruguay
| | - Paula Pessina
- Laboratorio de Técnicas Nucleares, Facultad de Veterinaria, Universidad de la Republica, Montevideo 11600, Uruguay
| | - Ana Silva
- Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo 11600, Uruguay; Laboratorio de Neurociencias, Facultad de Ciencias, Universidad de la Republica, Montevideo 11400, Uruguay.
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17
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Chabbi A, Ganesh CB. Evidence for the involvement of dopamine in stress-induced suppression of reproduction in the cichlid fish Oreochromis mossambicus. J Neuroendocrinol 2015; 27:343-56. [PMID: 25712855 DOI: 10.1111/jne.12269] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 02/02/2015] [Accepted: 02/19/2015] [Indexed: 01/23/2023]
Abstract
In the present study, we examined whether stress-induced suppression of reproduction is mediated through the catecholaminergic neurotransmitter dopamine (DA) in the female cichlid fish Oreochromis mossambicus. In the first experiment, application of antibody against tyrosine hydroxylase (TH; a marker for DA) in brain sections revealed the presence of intensely stained TH immunoreactive cells in the preoptic area (POA) and nucleus preopticus (NPO) during the previtellogenic phase. These cells showed weak immunoreactivity during the vitellogenic and prespawning phases concomitant with darkly stained luteinising hormone (LH) immunoreactive content in the proximal pars distalis (PPD) of the pituitary gland and fully ripened follicles (stage V) in the ovary of control fish. However, in fish exposed to aquacultural stressors, TH secreting cells remained intensely stained in POA and NPO regions during the prespawning phase, indicating increased synthetic and secretory activity, which was reflected by a significantly higher DA content compared to controls. Increased DA activity as a result of stress was associated with a decrease in the LH immunoreactive content in the PPD and an absence of stage V follicles in the ovary. In the second experiment, administration of DA caused effects similar to those in stressed fish, whereas DA receptor antagonist domperidone (DOM) treatment significantly increased the LH content in the PPD and the number of stage V follicles in unstressed fish. On the other hand, treatment of stressed fish with DOM resulted in dark accumulations of LH immunoreactive content in the PPD accompanied by the presence of stage V follicles in the ovary. Taken together, these results suggest an additional pathway for the inhibitory effects of stress through dopaminergic neurones along the reproductive axis.
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Affiliation(s)
- A Chabbi
- Neuroendocrinology Research Lab, Department of Studies in Zoology, Karnatak University, Dharwad, Karnataka, India
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18
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Vaccaro R, Toni M, Casini A, Vivacqua G, Yu S, D'este L, Cioni C. Localization of α-synuclein in teleost central nervous system: immunohistochemical and Western blot evidence by 3D5 monoclonal antibody in the common carp, Cyprinus carpio. J Comp Neurol 2015; 523:1095-124. [PMID: 25488013 DOI: 10.1002/cne.23722] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 12/03/2014] [Accepted: 12/03/2014] [Indexed: 01/26/2023]
Abstract
Alpha synuclein (α-syn) is a 140 amino acid vertebrate-specific protein, highly expressed in the human nervous system and abnormally accumulated in Parkinson's disease and other neurodegenerative disorders, known as synucleinopathies. The common occurrence of α-syn aggregates suggested a role for α-syn in these disorders, although its biological activity remains poorly understood. Given the high degree of sequence similarity between vertebrate α-syns, we investigated this proteins in the central nervous system (CNS) of the common carp, Cyprinus carpio, with the aim of comparing its anatomical and cellular distribution with that of mammalian α-syn. The distribution of α-syn was analyzed by semiquantitative western blot, immunohistochemistry, and immunofluorescence by a novel monoclonal antibody (3D5) against a fully conserved epitope between carp and human α-syn. The distribution of 3D5 immunoreactivity was also compared with that of choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), and serotonin (5HT) by double immunolabelings. The results showed that a α-syn-like protein of about 17 kDa is expressed to different levels in several brain regions and in the spinal cord. Immunoreactive materials were localized in neuronal perikarya and varicose fibers but not in the nucleus. The present findings indicate that α-syn-like proteins may be expressed in a few subpopulations of catecholaminergic and serotoninergic neurons in the carp brain. However, evidence of cellular colocalization 3D5/TH or 3D5/5HT was rare. Differently, the same proteins appear to be coexpressed with ChAT by cholinergic neurons in several motor and reticular nuclei. These results sustain the functional conservation of the α-syn expression in cholinergic systems and suggest that α-syn modulates similar molecular pathways in phylogenetically distant vertebrates.
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Affiliation(s)
- Rosa Vaccaro
- Department of Anatomical, Histological, Forensic Medicine and Orthopedics Sciences, Sapienza University, Rome, Italy
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19
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Godinho RM, Pereira P, Raimundo J, Pacheco M, Pinheiro T. Elemental mapping inventory of the fish Liza aurata brain: a biomarker of metal pollution vulnerability. Metallomics 2015; 7:277-82. [PMID: 25561394 DOI: 10.1039/c4mt00281d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The elemental distributions in optic tectum of brains of wild Liza aurata a teleost fish captured in polluted and reference coastal areas were assessed quantitatively by nuclear microscopy providing insights into brain vulnerability to metal pollution. Elemental maps enabled us to visualize optic tectum layers and identify cellular arrangements. Whereas Cl, K and Ca contents identify meninges, the Ca, Fe and Zn concentrations distinguish the underneath grey matter, white matter and inner cellular layers. Exposed animals showed significantly decreased P concentrations and increased contents of Cu, Zn and Ni in all brain structures. These changes highlight homeostasis modification, altered permeability of the blood-brain barrier and suggest risk for neurological toxicity. Our study initiated for the first time an inventory of physiological measures containing images and elemental compositions of brain regions of fish exposed to different environmental conditions. This will help defining total and local brain vulnerability to metals and pollution levels.
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Affiliation(s)
- Rita M Godinho
- Instituto Superior Técnico, Universidade de Lisboa, EN 10, 2686-953 Sacavém, Portugal.
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20
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Hall ZJ, De Serrano AR, Rodd FH, Tropepe V. Casting a wider fish net on animal models in neuropsychiatric research. Prog Neuropsychopharmacol Biol Psychiatry 2014; 55:7-15. [PMID: 24726811 DOI: 10.1016/j.pnpbp.2014.04.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 03/28/2014] [Accepted: 04/01/2014] [Indexed: 01/11/2023]
Abstract
Neuropsychiatric disorders, such as schizophrenia, are associated with abnormal brain development. In this review, we discuss how studying dimensional components of these disorders, or endophenotypes, in a wider range of animal models will deepen our understanding of how interactions between biological and environmental factors alter the trajectory of neurodevelopment leading to aberrant behavior. In particular, we discuss some of the advantages of incorporating studies of brain and behavior using a range of teleost fish species into current neuropsychiatric research. From the perspective of comparative neurobiology, teleosts share a fundamental pattern of neurodevelopment and functional brain organization with other vertebrates, including humans. These shared features provide a basis for experimentally probing the mechanisms of disease-associated brain abnormalities. Moreover, incorporating information about how behaviors have been shaped by evolution will allow us to better understand the relevance of behavioral variation to determine their physiological underpinnings. We believe that exploiting the conservation in brain development across vertebrate species, and the rich diversity of fish behavior in lab and natural populations will lead to significant new insights and a holistic understanding of the neurobiological systems implicated in neuropsychiatric disorders.
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Affiliation(s)
- Zachary J Hall
- Department of Cell & Systems Biology, University of Toronto, Canada
| | - Alex R De Serrano
- Department of Ecology & Evolutionary Biology, University of Toronto, Canada
| | - F Helen Rodd
- Department of Ecology & Evolutionary Biology, University of Toronto, Canada.
| | - Vincent Tropepe
- Department of Cell & Systems Biology, University of Toronto, Canada.
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21
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Vindas MA, Sørensen C, Johansen IB, Folkedal O, Höglund E, Khan UW, Stien LH, Kristiansen TS, Braastad BO, Øverli Ø. Coping with unpredictability: dopaminergic and neurotrophic responses to omission of expected reward in Atlantic salmon (Salmo salar L.). PLoS One 2014; 9:e85543. [PMID: 24465595 PMCID: PMC3894970 DOI: 10.1371/journal.pone.0085543] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 12/04/2013] [Indexed: 01/13/2023] Open
Abstract
Comparative studies are imperative for understanding the evolution of adaptive neurobiological processes such as neural plasticity, cognition, and emotion. Previously we have reported that prolonged omission of expected rewards (OER, or 'frustrative nonreward') causes increased aggression in Atlantic salmon (Salmo salar). Here we report changes in brain monoaminergic activity and relative abundance of brain derived neurotrophic factor (BDNF) and dopamine receptor mRNA transcripts in the same paradigm. Groups of fish were initially conditioned to associate a flashing light with feeding. Subsequently, the expected food reward was delayed for 30 minutes during two out of three meals per day in the OER treatment, while the previously established routine was maintained in control groups. After 8 days there was no effect of OER on baseline brain stem serotonin (5-HT) or dopamine (DA) activity. Subsequent exposure to acute confinement stress led to increased plasma cortisol and elevated turnover of brain stem DA and 5-HT in all animals. The DA response was potentiated and DA receptor 1 (D1) mRNA abundance was reduced in the OER-exposed fish, indicating a sensitization of the DA system. In addition OER suppressed abundance of BDNF in the telencephalon of non-stressed fish. Regardless of OER treatment, a strong positive correlation between BDNF and D1 mRNA abundance was seen in non-stressed fish. This correlation was disrupted by acute stress, and replaced by a negative correlation between BDNF abundance and plasma cortisol concentration. These observations indicate a conserved link between DA, neurotrophin regulation, and corticosteroid-signaling pathways. The results also emphasize how fish models can be important tools in the study of neural plasticity and responsiveness to environmental unpredictability.
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MESH Headings
- Adaptation, Psychological
- Analysis of Variance
- Animals
- Behavior, Animal
- Biogenic Monoamines/metabolism
- Brain/metabolism
- Brain-Derived Neurotrophic Factor/genetics
- Brain-Derived Neurotrophic Factor/metabolism
- Conditioning, Psychological
- Dopaminergic Neurons/metabolism
- Gene Expression Regulation
- Hydrocortisone/blood
- Nerve Growth Factors/metabolism
- Proliferating Cell Nuclear Antigen/genetics
- Proliferating Cell Nuclear Antigen/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Dopamine D1/genetics
- Receptors, Dopamine D1/metabolism
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Reward
- Salmo salar/blood
- Salmo salar/genetics
- Salmo salar/growth & development
- Salmo salar/metabolism
- Stress, Physiological/genetics
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Affiliation(s)
- Marco A. Vindas
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway
- * E-mail:
| | | | | | - Ole Folkedal
- Department of Animal Welfare, Institute of Marine Research, Matredal, Norway
| | - Erik Höglund
- Department of Marine Ecology and Aquaculture, Danish Institute for Fisheries Research, Hirtshals, Denmark
| | - Uniza W. Khan
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Lars H. Stien
- Department of Animal Welfare, Institute of Marine Research, Matredal, Norway
| | - Tore S. Kristiansen
- Department of Animal Welfare, Institute of Marine Research, Matredal, Norway
| | - Bjarne O. Braastad
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Øyvind Øverli
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway
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22
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O'Connell LA, Ding JH, Hofmann HA. Sex differences and similarities in the neuroendocrine regulation of social behavior in an African cichlid fish. Horm Behav 2013; 64:468-76. [PMID: 23899762 DOI: 10.1016/j.yhbeh.2013.07.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Accepted: 07/21/2013] [Indexed: 01/13/2023]
Abstract
An individual's position in a social hierarchy profoundly affects behavior and physiology through interactions with community members, yet little is known about how the brain contributes to status differences between and within the social states or sexes. We aimed to determine sex-specific attributes of social status by comparing circulating sex steroid hormones and neural gene expression of sex steroid receptors in dominant and subordinate male and female Astatotilapia burtoni, a highly social African cichlid fish. We found that testosterone and 17β-estradiol levels are higher in males regardless of status and dominant individuals regardless of sex. Progesterone was found to be higher in dominant individuals regardless of sex. Based on pharmacological manipulations in males and females, progesterone appears to be a common mechanism for promoting courtship in dominant individuals. We also examined expression of androgen receptors, estrogen receptor α, and the progesterone receptor in five brain regions that are important for social behavior. Most of the differences in brain sex steroid receptor expression were due to sex rather than status. Our results suggest that the parvocellular preoptic area is a core region for mediating sex differences through androgen and estrogen receptor expression, whereas the progesterone receptor may mediate sex and status behaviors in the putative homologs of the nucleus accumbens and ventromedial hypothalamus. Overall our results suggest sex differences and similarities in the regulation of social dominance by gonadal hormones and their receptors in the brain.
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Affiliation(s)
- Lauren A O'Connell
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78705, USA; Section of Integrative Biology, University of Texas at Austin, Austin, TX 78705, USA
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23
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Abstract
The emerging field of "neuro-evo-devo" is beginning to reveal how the molecular and neural substrates that underlie brain function are based on variations in evolutionarily ancient and conserved neurochemical and neural circuit themes. Comparative work across bilaterians is reviewed to highlight how early neural patterning specifies modularity of the embryonic brain, which lays a foundation on which manipulation of neurogenesis creates adjustments in brain size. Small variation within these developmental mechanisms contributes to the evolution of brain diversity. Comparing the specification and spatial distribution of neural phenotypes across bilaterians has also suggested some major brain evolution trends, although much more work on profiling neural connections with neurochemical specificity across a wide diversity of organisms is needed. These comparative approaches investigating the evolution of brain form and function hold great promise for facilitating a mechanistic understanding of how variation in brain morphology, neural phenotypes, and neural networks influences brain function and behavioral diversity across organisms.
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Affiliation(s)
- Lauren A O'Connell
- Faculty of Arts and Sciences (FAS) Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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