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Social Enhancement of Adult Neurogenesis in Zebrafish is Not Regulated by Cortisol. Neuroscience 2023; 509:51-62. [PMID: 36400322 DOI: 10.1016/j.neuroscience.2022.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 11/04/2022] [Accepted: 11/08/2022] [Indexed: 11/17/2022]
Abstract
In Mammals adult neurogenesis is influenced by environmental conditions, and the glucocorticoid hormones (GC) play a major role in this regulation. In contrast in fish, the study of the effects of cortisol on the regulation of environmental driven adult neurogenesis has produced conflicting results. While in some species elevated cortisol levels impair cell proliferation, in others, it promotes cell proliferation and differentiation. This lack of consistency may be explained by methodological differences across studies, namely in the stimuli and/or cortisol treatments used. Here, we tested the effects of the social environment on adult neurogenesis, considering a positive and a negative social context, and different durations of cortisol exposure. We hypothesise that there is an interaction between the valence of the social environment and cortisol, such that elevated acute cortisol experienced during social interactions only have a detrimental effect on neurogenesis in negative social contexts. Therefore, fish were exposed to a positive (conspecific shoal) or negative (predator) social experience, and the interaction between the valence of the social context and cortisol exposure (acute and chronic) was tested. Our results indicate that adult neurogenesis is modulated by the social environment, with the number of newly generated cells being dependent on the valence of the social information (positive > negative). These effects were independent of cortisol, either for acute or chronic exposure, highlighting the social environment as a key factor in the modulation of cell proliferation in the adult zebrafish brain, and rejecting a role for cortisol in this modulation.
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2
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Mikloska KV, Zrini ZA, Bernier NJ. Severe hypoxia exposure inhibits larval brain development but does not affect the capacity to mount a cortisol stress response in zebrafish. J Exp Biol 2021; 225:274120. [PMID: 34931659 DOI: 10.1242/jeb.243335] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/14/2021] [Indexed: 11/20/2022]
Abstract
Fish nursery habitats are increasingly hypoxic and the brain is recognized as highly hypoxia-sensitive, yet there is a lack of information on the effects of hypoxia on the development and function of the larval fish brain. Here, we tested the hypothesis that by inhibiting brain development, larval exposure to severe hypoxia has persistent functional effects on the cortisol stress response in zebrafish (Danio rerio). Exposing 5 days post-fertilization (dpf) larvae to 10% dissolved O2 (DO) for 16 h only marginally reduced survival, but it decreased forebrain neural proliferation by 55%, and reduced the expression of neurod1, gfap, and mbpa, markers of determined neurons, glia, and oligodendrocytes, respectively. The 5 dpf hypoxic exposure also elicited transient increases in whole body cortisol and in crf, uts1, and hsd20b2 expression, key regulators of the endocrine stress response. Hypoxia exposure at 5 dpf also inhibited the cortisol stress response to hypoxia in 10 dpf larvae and increased hypoxia tolerance. However, 10% DO exposure at 5 dpf for 16h did not affect the cortisol stress response to a novel stressor in 10 dpf larvae or the cortisol stress response to hypoxia in adult fish. Therefore, while larval exposure to severe hypoxia can inhibit brain development, it also increases hypoxia tolerance. These effects may transiently reduce the impact of hypoxia on the cortisol stress response but not its functional capacity to respond to novel stressors. We conclude that the larval cortisol stress response in zebrafish has a high capacity to cope with severe hypoxia-induced neurogenic impairment.
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Affiliation(s)
- Kristina V Mikloska
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Zoe A Zrini
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Nicholas J Bernier
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
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3
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Antioxidant capacity differs across social ranks and with ascension in males of a group-living fish. Comp Biochem Physiol A Mol Integr Physiol 2021; 265:111126. [PMID: 34906630 DOI: 10.1016/j.cbpa.2021.111126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 12/07/2021] [Accepted: 12/07/2021] [Indexed: 01/04/2023]
Abstract
Animals that live in groups often form hierarchies in which an individual's behaviour and physiology varies based on their social rank. Occasionally, a subordinate can ascend into a dominant position and the ascending individual must make rapid behavioural and physiological adjustments to solidify their dominance. These periods of social transition and instability can be stressful and ascending individuals often incur large metabolic costs that could influence their oxidative status. Most previous investigations examining the link between oxidative status and the social environment have done so under stable social conditions and have evaluated oxidative status in a single tissue. Therefore, evaluations of how oxidative status is regulated across multiple tissues during periods of social flux would greatly enhance our understanding of the relationship between oxidative status and the social environment. Here, we assessed how antioxidant capacity in three tissues (brain, gonad, and muscle) varied among dominant, subordinate, and ascending males of the group-living cichlid fish, Neolamprologus pulcher. Antioxidant capacity in the brain and muscle of ascending males was intermediate to that of dominant (highest levels) and subordinate males (lowest levels) and correlated with differences in social and locomotor behaviours, respectively. Gonad antioxidant capacity was lower in ascending males than in dominant males. However, gonad antioxidant capacity was positively correlated with the size of ascending males' gonads suggesting that ascending males may increase gonad antioxidant capacity as they develop their gonads. Overall, our results highlight the widespread physiological consequences of social ascension and emphasize the importance of tissue-specific measures of oxidative status.
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Diving into the streams and waves of constitutive and regenerative olfactory neurogenesis: insights from zebrafish. Cell Tissue Res 2020; 383:227-253. [PMID: 33245413 DOI: 10.1007/s00441-020-03334-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/02/2020] [Indexed: 02/06/2023]
Abstract
The olfactory system is renowned for its functional and structural plasticity, with both peripheral and central structures displaying persistent neurogenesis throughout life and exhibiting remarkable capacity for regenerative neurogenesis after damage. In general, fish are known for their extensive neurogenic ability, and the zebrafish in particular presents an attractive model to study plasticity and adult neurogenesis in the olfactory system because of its conserved structure, relative simplicity, rapid cell turnover, and preponderance of neurogenic niches. In this review, we present an overview of the anatomy of zebrafish olfactory structures, with a focus on the neurogenic niches in the olfactory epithelium, olfactory bulb, and ventral telencephalon. Constitutive and regenerative neurogenesis in both the peripheral olfactory organ and central olfactory bulb of zebrafish is reviewed in detail, and a summary of current knowledge about the cellular origin and molecular signals involved in regulating these processes is presented. While some features of physiologic and injury-induced neurogenic responses are similar, there are differences that indicate that regeneration is not simply a reiteration of the constitutive proliferation process. We provide comparisons to mammalian neurogenesis that reveal similarities and differences between species. Finally, we present a number of open questions that remain to be answered.
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Abstract
Fish welfare is an essential issue that needs to be tackled by the aquaculture industry. In order to address it, studies have been limited to a small number of species and the information is generally scattered. In order to have a consistent overview of the welfare of farmed fishes, we present the FishEthoBase, an open-access database that ultimately aims to provide information on the welfare of all fish species currently farmed worldwide. Presently with 41 species, this database is directed to all stakeholders in the field and targets not only to bridge the gaps between them but also to provide scientific information to improve the welfare of fish. The current text explains the database and presents an analysis of the welfare scores of 41 species, suggesting that (i) the general welfare state of farmed fishes is poor, (ii) there is some potential for improvement and (iii) this potential is related to research on species’ needs, but (iv) there are many remaining knowledge gaps and (v) current fish farming technologies do not seem to fully address welfare issues. The existence of a framework, such as the FishEthoBase, is proposed as fundamental to the design of strategies that improve the welfare of farmed fish.
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6
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Validation of hippocampal biomarkers of cumulative affective experience. Neurosci Biobehav Rev 2019; 101:113-121. [PMID: 30951763 PMCID: PMC6525303 DOI: 10.1016/j.neubiorev.2019.03.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 03/29/2019] [Accepted: 03/31/2019] [Indexed: 12/29/2022]
Abstract
Recent knowledge on hippocampal structural plasticity is reviewed. This knowledge is harnessed to develop biomarkers of cumulative experience. Hippocampal plasticity is shown to have construct, content and criterion validity in mammals. The biomarkers require further validation to be used in birds and fish. We discuss some practical considerations to implement the biomarkers.
Progress in improving the welfare of captive animals has been hindered by a lack of objective indicators to assess the quality of lifetime experience, often called cumulative affective experience. Recent developments in stress biology and psychiatry have shed new light on the role of the mammalian hippocampus in affective processes. Here we review these findings and argue that structural hippocampal biomarkers demonstrate criterion, construct and content validity as indicators of cumulative affective experience in mammals. We also briefly review emerging findings in birds and fish, which have promising implications for applying the hippocampal approach to these taxa, but require further validation. We hope that this review will motivate welfare researchers and neuroscientists to explore the potential of hippocampal biomarkers of cumulative affective experience.
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Depression-like state behavioural outputs may confer beneficial outcomes in risky environments. Sci Rep 2019; 9:3792. [PMID: 30846817 PMCID: PMC6405905 DOI: 10.1038/s41598-019-40390-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/14/2019] [Indexed: 12/30/2022] Open
Abstract
Recent theories in evolutionary medicine have suggested that behavioural outputs associated with depression-like states (DLS) could be an adaptation to unpredictable and precarious situations. In animal models, DLS are often linked to diverse and unpredictable stressors or adverse experiences. Theoretically, there are a range of potential fitness benefits associated with behavioural inhibition (typical to DLS), as opposed to more active/aggressive responses to adverse or uncontrollable events. This stance of evolutionary medicine has to our knowledge not been tested empirically. Here we address a possible key benefit of behavioural inhibition in a comparative model for social stress (territorial rainbow trout). By treating fish with the fast-acting antidepressant ketamine, we reversed the behavioural inhibition (i.e. stimulated an increase in activity level) in subordinate fish. During confrontation with a previously unfamiliar larger, aggressive and dominant individual, this increase in activity led to higher amounts of received aggression compared to sham-treated subordinates. This suggests that the behavioural inhibition characterizing animal models of DLS is indeed an effective coping strategy that reduces the risk of injuries in vulnerable social situations.
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Tea J, Alderman SL, Gilmour KM. Social stress increases plasma cortisol and reduces forebrain cell proliferation in subordinate male zebrafish ( Danio rerio). ACTA ACUST UNITED AC 2019; 222:jeb.194894. [PMID: 30530837 DOI: 10.1242/jeb.194894] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/03/2018] [Indexed: 12/11/2022]
Abstract
Many animals, including zebrafish (Danio rerio), form social hierarchies through competition for limited resources. Socially subordinate fish may experience chronic stress, leading to prolonged elevation of the glucocorticoid stress hormone cortisol. As elevated cortisol levels can impair neurogenesis, the present study tested the hypothesis that social stress suppresses cell proliferation in the telencephalon of subordinate zebrafish via a cortisol-mediated mechanism. Cell proliferation was assessed using incorporation of the thymidine analogue 5-bromo-2'-deoxyuridine (BrdU). After 48 and 96 h of social interaction, subordinate male zebrafish exhibited elevated plasma cortisol concentrations and significantly lower numbers of BrdU+ cells in the dorsal but not ventral regions of the telencephalon compared with dominant or group-housed control male fish. After a 2 week recovery in a familiar group of conspecifics, the number of BrdU+ cells that co-labelled with a neuronal marker (NeuN) was modestly reduced in previously subordinate male fish, suggesting that the reduction of cell proliferation during social stress may result in fewer cells recruited into the neuronal population. In contrast to male social hierarchies, subordinate female zebrafish did not experience elevated plasma cortisol, and the number of BrdU+ cells in the dorsal telencephalic area was comparable among dominant, subordinate and group-housed control female fish. Treating male zebrafish with metyrapone, a cortisol synthesis inhibitor, blocked the cortisol response to social subordination and attenuated the suppression of brain cell proliferation in the dorsal telencephalic area of subordinate fish. Collectively, these data support a role for cortisol in regulating adult neurogenesis in the telencephalon of male zebrafish during social stress.
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Affiliation(s)
- Jonathan Tea
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada K1N 6N5
| | - Sarah L Alderman
- Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G 2W1
| | - Kathleen M Gilmour
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada K1N 6N5
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Maruska K, Soares MC, Lima-Maximino M, Henrique de Siqueira-Silva D, Maximino C. Social plasticity in the fish brain: Neuroscientific and ethological aspects. Brain Res 2019; 1711:156-172. [PMID: 30684457 DOI: 10.1016/j.brainres.2019.01.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 01/16/2019] [Accepted: 01/22/2019] [Indexed: 12/17/2022]
Abstract
Social plasticity, defined as the ability to adaptively change the expression of social behavior according to previous experience and to social context, is a key ecological performance trait that should be viewed as crucial for Darwinian fitness. The neural mechanisms for social plasticity are poorly understood, in part due to skewed reliance on rodent models. Fish model organisms are relevant in the field of social plasticity for at least two reasons: first, the diversity of social organization among fish species is staggering, increasing the breadth of evolutionary relevant questions that can be asked. Second, that diversity also suggests translational relevance, since it is more likely that "core" mechanisms of social plasticity are discovered by analyzing a wider variety of social arrangements than relying on a single species. We analyze examples of social plasticity across fish species with different social organizations, concluding that a "core" mechanism is the initiation of behavioral shifts through the modulation of a conserved "social decision-making network", along with other relevant brain regions, by monoamines, neuropeptides, and steroid hormones. The consolidation of these shifts may be mediated via neurogenomic adjustments and regulation of the expression of plasticity-related molecules (transcription factors, cell cycle regulators, and plasticity products).
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Affiliation(s)
- Karen Maruska
- Department of Biological Sciences, Louisiana State University, Baton Rouge, USA
| | - Marta C Soares
- Centro de Investigação em Biodiversidade e Recursos Genéticos - CIBIO, Universidade do Porto, Vairão, Portugal
| | - Monica Lima-Maximino
- Laboratório de Biofísica e Neurofarmacologia, Universidade do Estado do Pará, Campus VIII, Marabá, Brazil; Grupo de Pesquisas em Neuropsicofarmacologia e Psicopatologia Experimental, Brazil
| | - Diógenes Henrique de Siqueira-Silva
- Laboratório de Neurociências e Comportamento "Frederico Guilherme Graeff", Universidade Federal do Sul e Sudeste do Pará, Marabá, Brazil; Grupo de Estudos em Reprodução de Peixes Amazônicos, Universidade Federal do Sul e Sudeste do Pará, Marabá, Brazil
| | - Caio Maximino
- Grupo de Pesquisas em Neuropsicofarmacologia e Psicopatologia Experimental, Brazil; Laboratório de Neurociências e Comportamento "Frederico Guilherme Graeff", Universidade Federal do Sul e Sudeste do Pará, Marabá, Brazil.
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10
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Social isolation impairs active avoidance performance and decreases neurogenesis in the dorsomedial telencephalon of rainbow trout. Physiol Behav 2019; 198:1-10. [DOI: 10.1016/j.physbeh.2018.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 10/04/2018] [Accepted: 10/04/2018] [Indexed: 11/22/2022]
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Øverli Ø, Sørensen C. On the Role of Neurogenesis and Neural Plasticity in the Evolution of Animal Personalities and Stress Coping Styles. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:167-174. [DOI: 10.1159/000447085] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Individual variation in how animals react to stress and environmental change has become a central topic in a wide range of biological disciplines, from evolutionary ecology to biomedicine. Such variation manifests phenotypically as correlated trait-clusters (referred to as coping styles, behavioral syndromes, shyness-boldness, or personality traits). Thresholds for switching from active coping (fight-flight) to inhibition and passive behavior when exposed to stress depend on experience and genetic factors. Comparative research has revealed a range of neuroendocrine-behavioral associations which are conserved throughout the vertebrate subphylum, including factors affecting perception, learning, and memory of stimuli and events. Here we review conserved aspects of the contribution of neurogenesis and other aspects of neural plasticity to stress coping. In teleost fish, brain cell proliferation and neurogenesis have received recent attention. This work reveals that brain cell proliferation and neurogenesis are associated with heritable variation in stress coping style, and they are also differentially affected by short- and long-term stress in a biphasic manner. Routine-dependent and inflexible behavior in proactive individuals is associated with limited neural plasticity. These evolutionarily conserved relationships hold the potential to illuminate the biological background for stress-related neurobiological disorders.
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Dunlap KD. Fish Neurogenesis in Context: Assessing Environmental Influences on Brain Plasticity within a Highly Labile Physiology and Morphology. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:156-166. [DOI: 10.1159/000446907] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Fish have unusually high rates of brain cell proliferation and neurogenesis during adulthood, and the rates of these processes are greatly influenced by the environment. This high level of cell proliferation and its responsiveness to environmental change indicate that such plasticity might be a particularly important mechanism underlying behavioral plasticity in fish. However, as part of their highly labile physiology and morphology, fish also respond to the environment through processes that affect cell proliferation but that are not specific to behavioral change. For example, the environment has nonspecific influences on cell proliferation all over the body via its effect on body temperature and growth rate. In addition, some fish species also have an unusual capacity for sex change and somatic regeneration, and both of these processes likely involve widespread changes in cell proliferation. Thus, in evaluating the possible behavioral role of adult brain cell proliferation, it is important to distinguish regionally specific responses in behaviorally relevant brain nuclei from global proliferative changes across the whole brain or body. In this review, I first highlight how fish differ from other vertebrates, particularly birds and mammals, in ways that have a bearing on the interpretation of brain plasticity. I then summarize the known effects of the physical and social environment, sex change, and predators on brain cell proliferation and neurogenesis, with a particular emphasis on whether the effects are regionally specific. Finally, I review evidence that environmentally induced changes in brain cell proliferation and neurogenesis in fish are mediated by hormones and play a role in behavioral responses to the environment.
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13
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A novel role for pigment genes in the stress response in rainbow trout (Oncorhynchus mykiss). Sci Rep 2016; 6:28969. [PMID: 27373344 PMCID: PMC4931468 DOI: 10.1038/srep28969] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/13/2016] [Indexed: 12/14/2022] Open
Abstract
In many vertebrate species visible melanin-based pigmentation patterns correlate with high stress- and disease-resistance, but proximate mechanisms for this trait association remain enigmatic. Here we show that a missense mutation in a classical pigmentation gene, melanocyte stimulating hormone receptor (MC1R), is strongly associated with distinct differences in steroidogenic melanocortin 2 receptor (MC2R) mRNA expression between high- (HR) and low-responsive (LR) rainbow trout (Oncorhynchus mykiss). We also show experimentally that cortisol implants increase the expression of agouti signaling protein (ASIP) mRNA in skin, likely explaining the association between HR-traits and reduced skin melanin patterning. Molecular dynamics simulations predict that melanocortin 2 receptor accessory protein (MRAP), needed for MC2R function, binds differently to the two MC1R variants. Considering that mRNA for MC2R and the MC1R variants are present in head kidney cells, we hypothesized that MC2R activity is modulated in part by different binding affinities of the MC1R variants for MRAP. Experiments in mammalian cells confirmed that trout MRAP interacts with the two trout MC1R variants and MC2R, but failed to detect regulation of MC2R signaling, possibly due to high constitutive MC1R activity.
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14
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Abstract
Teleost fish have a remarkable neurogenic and regenerative capacity in the adult throughout the rostrocaudal axis of the brain. The distribution of proliferation zones shows a remarkable conservation, even in distantly related teleost species, suggesting a common teleost ground plan of proliferation zones. There are different progenitor populations in the neurogenic niches-progenitors positive for radial glial markers (dorsal telencephalon, hypothalamus) and progenitors with neuroepithelial-like characteristics (ventral telencephalon, optic tectum, cerebellum). Definition of these progenitors has allowed studying their role in normal growth of the adult brain, but also when challenged following a lesion. From these studies, important roles have emerged for intrinsic mechanisms and extrinsic signals controlling the activation of adult neurogenesis that enable regeneration of the adult brain to occur, opening up new perspectives on rekindling regeneration also in the context of the mammalian brain.
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Affiliation(s)
- Julia Ganz
- Institute of Neuroscience, 1254 University of Oregon, Eugene, Oregon 97403
| | - Michael Brand
- Biotechnology Center, and DFG-Research Center for Regenerative Therapies Dresden, Technische Universität Dresden, 01307 Dresden, Germany
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McNeil PL, Nebot C, Sloman KA. Physiological and Behavioral Effects of Exposure to Environmentally Relevant Concentrations of Prednisolone During Zebrafish (Danio rerio) Embryogenesis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:5294-304. [PMID: 27120978 DOI: 10.1021/acs.est.6b00276] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The presence of synthetic glucocorticoids within the aquatic environment has been highlighted as a potential environmental concern as they may mimic the role of endogenous glucocorticoids during vertebrate ontogeny. Prednisolone is a commonly prescribed synthetic glucocorticoid which has been repeatedly detected in the environment. This study investigated the impact of environmentally relevant concentrations of prednisolone (0.1, 1, and 10 μg/L) during zebrafish embryogenesis using physiological and behavioral end points which are known to be mediated by endogenous glucocorticoids. The frequency of spontaneous muscle contractions (24 hpf) was significantly reduced by prednisolone and 0.1 μg/L increased the distance embryos swam in response to a mechanosensory stimulus (48 hpf). The percentage of embryos hatched significantly increased following prednisolone treatment (1 and 10 μg/L), while growth and mortality were unaffected. The onset of heart contraction was differentially affected by prednisolone while heart rate and oxygen consumption both increased significantly throughout embryogenesis. No substantial effect on the axial musculature was observed. Morphological changes to the lower jaw were detected at 96 hpf in response to 1 μg/L of prednisolone. Several parameters of swim behavior were also significantly affected. Environmentally relevant concentrations of prednisolone therefore alter early zebrafish ontogeny and significantly affect embryo behavior.
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Affiliation(s)
- Paul L McNeil
- Institute of Biomedical and Environmental Health Research, School of Science and Sport, University of the West of Scotland , Paisley, U.K
| | - Carolina Nebot
- Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Veterinary Medicine, University of Santiago de Compostela , Lugo, Spain
| | - Katherine A Sloman
- Institute of Biomedical and Environmental Health Research, School of Science and Sport, University of the West of Scotland , Paisley, U.K
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Holmes MM. Social regulation of adult neurogenesis: A comparative approach. Front Neuroendocrinol 2016; 41:59-70. [PMID: 26877107 DOI: 10.1016/j.yfrne.2016.02.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 02/07/2016] [Accepted: 02/09/2016] [Indexed: 01/25/2023]
Abstract
The social environment sculpts the mammalian brain throughout life. Adult neurogenesis, the birth of new neurons in the mature brain, can be up- or down-regulated by various social manipulations. These include social isolation, social conflict, social status, socio-sexual interactions, and parent/offspring interactions. However, socially-mediated changes in neuron production are often species-, sex-, and/or region-specific. In order to reconcile the variability of social effects on neurogenesis, we need to consider species-specific social adaptations and other contextual variables (e.g. age, social status, reproductive status, etc.) that shift the valence of social stimuli. Using a comparative approach to understand how adult-generated neurons in turn influence social behaviors will shed light on how adult neurogenesis contributes to survival and reproduction in diverse species.
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Affiliation(s)
- Melissa M Holmes
- Department of Psychology, University of Toronto, Canada; Department of Cell & Systems Biology, University of Toronto, Canada; Department of Ecology & Evolutionary Biology, University of Toronto, Canada.
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17
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Shams S, Chatterjee D, Gerlai R. Chronic social isolation affects thigmotaxis and whole-brain serotonin levels in adult zebrafish. Behav Brain Res 2015; 292:283-7. [DOI: 10.1016/j.bbr.2015.05.061] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 05/24/2015] [Accepted: 05/29/2015] [Indexed: 12/16/2022]
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18
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Fraser TWK, Vindas MA, Fjelldal PG, Winberg S, Thörnqvist PO, Øverli Ø, Skjæraasen JE, Hansen TJ, Mayer I. Increased reactivity and monoamine dysregulation following stress in triploid Atlantic salmon (Salmo salar). Comp Biochem Physiol A Mol Integr Physiol 2015; 185:125-31. [PMID: 25882085 DOI: 10.1016/j.cbpa.2015.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 04/03/2015] [Accepted: 04/05/2015] [Indexed: 10/23/2022]
Abstract
Artificial triploid salmonids are sterile and therefore commercially bred to prevent genetic interactions between wild and domestic fish strains. The full biological effects of having an extra chromosome set are largely unknown, but triploids are considered to be more sensitive to sub-optimal environmental conditions and to be stressed by the presence of diploid conspecifics. Brain serotonergic and dopaminergic activity are known to regulate the stress response in vertebrates, but monoamine systems in diploid and triploid fish have yet to be compared. Here we study monoamine neurochemistry in the telencephalon and brain stem of juvenile diploid and triploid Atlantic salmon (Salmo salar) in response to stress (unstressed vs stressed individuals) and holding (separate- vs mixed-ploidy) conditions. Both diploids and triploids showed an increase in serotonergic activity following stress, but the increase was significantly greater in the telencephalon of triploids compared to diploids. Furthermore, while telencephalic dopaminergic activity was significantly increased in diploids following stress, there was no response in triploids. Holding conditions had a significant effect on dopaminergic activity in the brain stem of diploids only, with lower values in mixed- compared to separate-ploidy conditions. These results suggest artificially produced triploids experience increased reactivity and monoaminergic dysregulation following stress that may impede their welfare and performance.
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Affiliation(s)
| | | | - Per Gunnar Fjelldal
- Institute of Marine Research (IMR), Matre Research Station, Matredal, Norway
| | - Svante Winberg
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | | | - Øyvind Øverli
- Department of Biosciences, University of Oslo, Oslo, Norway
| | | | - Tom Jonny Hansen
- Institute of Marine Research (IMR), Matre Research Station, Matredal, Norway
| | - Ian Mayer
- Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway
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19
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Nardocci G, Navarro C, Cortés PP, Imarai M, Montoya M, Valenzuela B, Jara P, Acuña-Castillo C, Fernández R. Neuroendocrine mechanisms for immune system regulation during stress in fish. FISH & SHELLFISH IMMUNOLOGY 2014; 40:531-538. [PMID: 25123831 DOI: 10.1016/j.fsi.2014.08.001] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 07/10/2014] [Accepted: 08/03/2014] [Indexed: 06/03/2023]
Abstract
In the last years, the aquaculture crops have experienced an explosive and intensive growth, because of the high demand for protein. This growth has increased fish susceptibility to diseases and subsequent death. The constant biotic and abiotic changes experienced by fish species in culture are challenges that induce physiological, endocrine and immunological responses. These changes mitigate stress effects at the cellular level to maintain homeostasis. The effects of stress on the immune system have been studied for many years. While acute stress can have beneficial effects, chronic stress inhibits the immune response in mammals and teleost fish. In response to stress, a signaling cascade is triggered by the activation of neural circuits in the central nervous system because the hypothalamus is the central modulator of stress. This leads to the production of catecholamines, corticosteroid-releasing hormone, adrenocorticotropic hormone and glucocorticoids, which are the essential neuroendocrine mediators for this activation. Because stress situations are energetically demanding, the neuroendocrine signals are involved in metabolic support and will suppress the "less important" immune function. Understanding the cellular mechanisms of the neuroendocrine regulation of immunity in fish will allow the development of new pharmaceutical strategies and therapeutics for the prevention and treatment of diseases triggered by stress at all stages of fish cultures for commercial production.
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Affiliation(s)
- Gino Nardocci
- Facultad de Ciencias Biológicas y Facultad de Medicina, Universidad Andrés Bello, Santiago, Chile. Av. República 252, 8370134 Santiago, Chile
| | - Cristina Navarro
- Facultad de Ciencias Biológicas y Facultad de Medicina, Universidad Andrés Bello, Santiago, Chile. Av. República 252, 8370134 Santiago, Chile
| | - Paula P Cortés
- Facultad de Ciencias Biológicas y Facultad de Medicina, Universidad Andrés Bello, Santiago, Chile. Av. República 252, 8370134 Santiago, Chile
| | - Mónica Imarai
- Centro de Biotecnología Acuícola (CBA), Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile. Av. Libertador Bernardo O'Higgins 3363, Estación Central, 9170022 Santiago, Chile
| | - Margarita Montoya
- Centro de Biotecnología Acuícola (CBA), Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile. Av. Libertador Bernardo O'Higgins 3363, Estación Central, 9170022 Santiago, Chile
| | - Beatriz Valenzuela
- Centro de Biotecnología Acuícola (CBA), Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile. Av. Libertador Bernardo O'Higgins 3363, Estación Central, 9170022 Santiago, Chile
| | - Pablo Jara
- Centro de Biotecnología Acuícola (CBA), Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile. Av. Libertador Bernardo O'Higgins 3363, Estación Central, 9170022 Santiago, Chile
| | - Claudio Acuña-Castillo
- Centro de Biotecnología Acuícola (CBA), Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile. Av. Libertador Bernardo O'Higgins 3363, Estación Central, 9170022 Santiago, Chile.
| | - Ricardo Fernández
- Facultad de Ciencias Biológicas y Facultad de Medicina, Universidad Andrés Bello, Santiago, Chile. Av. República 252, 8370134 Santiago, Chile.
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20
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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: 21] [Impact Index Per Article: 2.1] [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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21
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Morandini L, Honji RM, Ramallo MR, Moreira RG, Pandolfi M. The interrenal gland in males of the cichlid fish Cichlasoma dimerus: relationship with stress and the establishment of social hierarchies. Gen Comp Endocrinol 2014; 195:88-98. [PMID: 24184109 DOI: 10.1016/j.ygcen.2013.10.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 09/09/2013] [Accepted: 10/19/2013] [Indexed: 11/29/2022]
Abstract
In teleosts, cortisol is the primary glucocorticoid secreted by the steroidogenic cells of the interrenal gland and an increase in its plasma concentration is a frequent indicator of stress. Cortisol has been postulated as an endogenous mediator involved in the regulation of reproduction and aggression related to social dynamics. The cichlid fish Cichlasoma dimerus, is a monogamous species that exhibits complex social hierarchies; males appear in one of two basic alternative phenotypes: non-territorial and territorial males. In this work, we postulated as a general hypothesis that the morphometry of the interrenal gland cells and the plasma levels of cortisol and 11-ketotestosterone (11-KT) are related to the social rank in adult males of C. dimerus. First, the location and distribution of the interrenal gland with respect to its context - the kidney - was studied. Plasma levels of cortisol and 11-KT in territorial and non-territorial males were established by ELISA. Finally, a morphometric analysis of steroidogenic and chromaffin cells of the interrenal gland was performed. Results showed that the interrenal gland was exclusively located in the posterior portion of the cephalic kidney. Non-territorial males presented a greater nuclear area of their steroidogenic cells. Additionally, plasma cortisol and 11-KT levels were lower and higher, respectively, in territorial males. Finally, plasma cortisol levels positively correlated with the nuclear area of interrenal steroidogenic cells. Thus, the interrenal gland, by means of one of its products, cortisol, may be fulfilling an important role in the establishment of social hierarchies and their stability.
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Affiliation(s)
- Leonel Morandini
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, (C1428EHA) Buenos Aires, Argentina
| | - Renato Massaaki Honji
- Departamento de Fisiologia, Instituto de Biociências-USP, Rua do Matão, travessa 14, n.321, sala 220 Cidade Universitária, São Paulo, SP, Brazil
| | - Martín Roberto Ramallo
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, (C1428EHA) Buenos Aires, Argentina
| | - Renata Guimarães Moreira
- Departamento de Fisiologia, Instituto de Biociências-USP, Rua do Matão, travessa 14, n.321, sala 220 Cidade Universitária, São Paulo, SP, Brazil
| | - Matías Pandolfi
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, (C1428EHA) Buenos Aires, Argentina.
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22
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Sorteni C, Clavenzani P, De Giorgio R, Portnoy O, Sirri R, Mordenti O, Di Biase A, Parmeggiani A, Menconi V, Chiocchetti R. Enteric neuroplasticity in seawater-adapted European eel (Anguilla anguilla). J Anat 2013; 224:180-91. [PMID: 24433383 DOI: 10.1111/joa.12131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2013] [Indexed: 12/01/2022] Open
Abstract
European eels live most of their lives in freshwater until spawning migration to the Sargasso Sea. During seawater adaptation, eels modify their physiology, and their digestive system adapts to the new environment, drinking salt water to compensate for the continuous water loss. In that period, eels stop feeding until spawning. Thus, the eel represents a unique model to understand the adaptive changes of the enteric nervous system (ENS) to modified salinity and starvation. To this purpose, we assessed and compared the enteric neuronal density in the cranial portion of the intestine of freshwater eels (control), lagoon eels captured in brackish water before their migration to the Sargasso Sea (T0), and starved seawater eels hormonally induced to sexual maturity (T18; 18 weeks of starvation and treatment with standardized carp pituitary extract). Furthermore, we analyzed the modification of intestinal neuronal density of hormonally untreated eels during prolonged starvation (10 weeks) in seawater and freshwater. The density of myenteric (MP) and submucosal plexus (SMP) HuC/D-immunoreactive (Hu-IR) neurons was assessed in wholemount preparations and cryosections. The number of MP and SMP HuC/D-IR neurons progressively increased from the freshwater to the salty water habitat (control > T0 > T18; P < 0.05). Compared with freshwater eels, the number of MP and SMP HuC/D-IR neurons significantly increased (P < 0.05) in the intestine of starved untreated salt water eels. In conclusion, high salinity evokes enteric neuroplasticity as indicated by the increasing number of HuC/D-IR MP and SMP neurons, a mechanism likely contributing to maintaining the body homeostasis of this fish in extreme conditions.
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Affiliation(s)
- C Sorteni
- Department of Veterinary Medical Science (UNI EN ISO 9001:2008), University of Bologna, Bologna, Italy; Centro interdipartimentale di ricerca sull'alimentazione umana, University of Bologna, Bologna, Italy
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23
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Maruska KP, Carpenter RE, Fernald RD. Characterization of cell proliferation throughout the brain of the African cichlid fish Astatotilapia burtoni and its regulation by social status. J Comp Neurol 2013; 520:3471-91. [PMID: 22431175 DOI: 10.1002/cne.23100] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
New cells are added in the brains of all adult vertebrates, but fishes have some of the greatest potential for neurogenesis and gliogenesis among all taxa, partly due to their indeterminate growth. Little is known, however, about how social interactions influence cell proliferation in the brain of these fishes that comprise the largest group of vertebrates. We used 5-bromo-2'-deoxyuridine (BrdU) to identify and localize proliferation zones in the telencephalon, diencephalon, mesencephalon, and rhombencephalon that were primarily associated with ventricular surfaces in the brain of the African cichlid fish Astatotilapia burtoni. Cell migration was evident in some regions by 1 day post injection, and many newborn cells coexpressed the neuronal marker HuC/D at 30 days, suggesting they had differentiated into neurons. To test the hypothesis that social status and perception of an opportunity to rise in rank influenced cell proliferation, we compared numbers of BrdU-labeled cells in multiple brain nuclei among fish of different social status. Socially suppressed subordinate males had the lowest numbers of proliferating cells in all brain regions examined, but males that were given an opportunity to rise in status had higher cell proliferation rates within 1 day, suggesting rapid upregulation of brain mitotic activity associated with this social transition. Furthermore, socially isolated dominant males had similar numbers of BrdU-labeled cells compared with dominant males that were housed in a socially rich environment, suggesting that isolation has little effect on proliferation and that reduced proliferation in subordinates is a result of the social subordination. These results suggest that A. burtoni will be a useful model to analyze the mechanisms of socially induced neurogenesis in vertebrates.
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Affiliation(s)
- Karen P Maruska
- Department of Biology, Stanford University, Stanford, California 94305, USA.
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24
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Sørensen C, Johansen IB, Øverli Ø. Neural plasticity and stress coping in teleost fishes. Gen Comp Endocrinol 2013; 181:25-34. [PMID: 23274407 DOI: 10.1016/j.ygcen.2012.12.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 11/28/2012] [Accepted: 12/03/2012] [Indexed: 12/25/2022]
Abstract
Physiological and behavioural responses to environmental change are individually variable traits, which manifest phenotypically and are subject to natural selection as correlated trait-clusters (coping styles, behavioural syndromes, or personality traits). Comparative research has revealed a range of neuroendocrine-behavioural associations which are conserved throughout the vertebrate subphylum. Regulatory mechanisms universally mediate a switch between proactive (e.g. active/aggressive) and reactive (e.g. conservation/withdrawal) behaviour in response to unpredictable and uncontrollable events. Thresholds for switching from active coping to behavioural inhibition are individually variable, and depend on experience and genetic factors. Such factors affect physiological stress responses as well as perception, learning, and memory. Here we review the role of an important contributor to neural processing, the set of biochemical, molecular, and structural processes collectively referred to as neural plasticity. We will concentrate on work in teleost fishes, while also elucidating conserved aspects. In fishes, environmental and physiological control of brain cell proliferation and neurogenesis has received recent attention. This work has revealed that the expression of genes involved in CNS plasticity is affected by heritable variation in stress coping style, and is also differentially affected by short- and long-term stress. Chronic stress experienced by subordinate fish in social hierarchies leads to a marked suppression of brain cell proliferation. Interestingly, typically routine dependent and inflexible behaviour in proactive individuals is also associated with low transcription of neurogenesis related genes. The potential for these findings to illuminate stress-related neurobiological disorders in other vertebrates is also discussed.
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Affiliation(s)
- Christina Sørensen
- Department of Molecular Biosciences, University of Oslo, PO Box 1041, N-0316 Oslo, Norway
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25
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Ebbesson LOE, Braithwaite VA. Environmental effects on fish neural plasticity and cognition. JOURNAL OF FISH BIOLOGY 2012; 81:2151-2174. [PMID: 23252732 DOI: 10.1111/j.1095-8649.2012.03486.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Most fishes experiencing challenging environments are able to adjust and adapt their physiology and behaviour to help them cope more effectively. Much of this flexibility is supported and influenced by cognition and neural plasticity. The understanding of fish cognition and the role played by different regions of the brain has improved significantly in recent years. Techniques such as lesioning, tract tracing and quantifying changes in gene expression help in mapping specialized brain areas. It is now recognized that the fish brain remains plastic throughout a fish's life and that it continues to be sensitive to environmental challenges. The early development of fish brains is shaped by experiences with the environment and this can promote positive and negative effects on both neural plasticity and cognitive ability. This review focuses on what is known about the interactions between the environment, the telencephalon and cognition. Examples are used from a diverse array of fish species, but there could be a lot to be gained by focusing research on neural plasticity and cognition in fishes for which there is already a wealth of knowledge relating to their physiology, behaviour and natural history, e.g. the Salmonidae.
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Affiliation(s)
- L O E Ebbesson
- Uni Research AS, Thormøhlensgate 49B, 5006 Bergen, Norway.
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26
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Dunlap KD, Chung M. Social novelty enhances brain cell proliferation, cell survival, and chirp production in an electric fish, Apteronotus leptorhynchus. Dev Neurobiol 2012; 73:324-32. [PMID: 23076841 DOI: 10.1002/dneu.22063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 10/10/2012] [Accepted: 10/11/2012] [Indexed: 12/12/2022]
Abstract
For many animals, enriched environments and social interaction promote adult neurogenesis. However, in some cases, the effect is transient, and long-term environmental stimuli have little benefit for neurogenesis. In electric fish, Apteronotus leptorhynchus, fish housed in pairs for 7 days show higher density of newborn brain cells (cell addition) than isolated fish, but fish paired for 14 days have rates of cell addition similar to isolated controls. We examined whether introduction of social novelty can sustain elevated levels of cell addition and prevent long-term habituation to social interaction. We also monitored electrocommunication signals ("chirps") as a measure of the behavioral response to social novelty. We paired fish for 14 days with one continuous partner (no social novelty), two sequential partners changed after 7 days (low novelty) or seven sequential partners changed every 2 days (high novelty). On Day 11, we injected fish with BrdU, sacrificed fish 3 days later and quantified BrdU labeling in the diencephalic periventricular zone. Fish exposed to no novelty had BrdU labeling similar to isolated fish. Fish with low novelty showed small increases in BrdU labeling and those with high novelty had much greater BrdU labeling. Similarly, chirp rates were greater in fish with low novelty than with no novelty and greatest yet in fish with high novelty. By varying the timing of novelty relative to BrdU injection, we showed that social novelty promoted both proliferation and survival of newborn cells. These results indicated that brain cell proliferation and survival is influenced more by social change than simply the presence of social stimuli.
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Affiliation(s)
- Kent D Dunlap
- Department of Biology, Trinity College, Hartford, Connecticut 06106, USA.
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27
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Zupanc GKH, Sîrbulescu RF. Adult neurogenesis and neuronal regeneration in the central nervous system of teleost fish. Eur J Neurosci 2011; 34:917-29. [DOI: 10.1111/j.1460-9568.2011.07854.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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