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Cerbantez-Bueno V, Viñuela-Berni V, Muñoz-Mayorga DE, Morales T, Corona R. Prolactin promotes the recruitment of main olfactory bulb cells and enhances the behavioral exploration toward a socio-sexual stimulus in female mice. Horm Behav 2024; 162:105527. [PMID: 38492348 DOI: 10.1016/j.yhbeh.2024.105527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/30/2023] [Accepted: 03/05/2024] [Indexed: 03/18/2024]
Abstract
Olfactory communication is triggered by pheromones that profoundly influence neuroendocrine responses to drive social interactions. Two principal olfactory systems process pheromones: the main and the vomeronasal or accessory system. Prolactin receptors are expressed in both systems suggesting a participation in the processing of olfactory information. We previously reported that prolactin participates in the sexual and olfactory bulb maturation of females. Therefore, we explored the expression of prolactin receptors within the olfactory bulb during sexual maturation and the direct responses of prolactin upon pheromonal exposure. Additionally, we assessed the behavioral response of adult females exposed to male sawdust after prolactin administration and the consequent activation of main and accessory olfactory bulb and their first central relays, the piriform cortex and the medial amygdala. Last, we investigated the intracellular pathway activated by prolactin within the olfactory bulb. Here, prolactin receptor expression remained constant during all maturation stages within the main olfactory bulb but decreased in adulthood in the accessory olfactory bulb. Behaviorally, females that received prolactin actively explored the male stimulus. An increased cFos activation in the amygdala and in the glomerular cells of the whole olfactory bulb was observed, but an augmented response in the mitral cells was only found within the main olfactory bulb after prolactin administration and the exposure to male stimulus. Interestingly, the ERK pathway was upregulated in the main olfactory bulb after exposure to a male stimulus. Overall, our results suggest that, in female mice, prolactin participates in the processing of chemosignals and behavioral responses by activating the main olfactory system and diminishing the classical vomeronasal response to pheromones.
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Affiliation(s)
- Viridiana Cerbantez-Bueno
- Laboratorio de Neuroanatomía Funcional y Neuroendocrinología, Instituto de Neurobiología (INB), Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro, Mexico
| | - Verónica Viñuela-Berni
- Laboratorio de Neuroanatomía Funcional y Neuroendocrinología, Instituto de Neurobiología (INB), Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro, Mexico
| | - Daniel Eduardo Muñoz-Mayorga
- Laboratorio de Neuroanatomía Funcional y Neuroendocrinología, Instituto de Neurobiología (INB), Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro, Mexico
| | - Teresa Morales
- Laboratorio de Neuroanatomía Funcional y Neuroendocrinología, Instituto de Neurobiología (INB), Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro, Mexico
| | - Rebeca Corona
- Laboratorio de Neuroanatomía Funcional y Neuroendocrinología, Instituto de Neurobiología (INB), Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro, Mexico.
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Dimonte S, Sikora V, Bove M, Morgese MG, Tucci P, Schiavone S, Trabace L. Social isolation from early life induces anxiety-like behaviors in adult rats: Relation to neuroendocrine and neurochemical dysfunctions. Biomed Pharmacother 2023; 158:114181. [PMID: 36592494 DOI: 10.1016/j.biopha.2022.114181] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/21/2022] [Accepted: 12/28/2022] [Indexed: 01/01/2023] Open
Abstract
Subjects suffering from psychosis frequently experience anxiety. However, mechanisms underlying this comorbidity remain still unclear. We investigated whether neurochemical and neuroendocrine dysfunctions were involved in the development of anxiety-like behavior in a rodent model of psychotic-like symptoms, obtained by exposing male rats to social isolation rearing from postnatal day 21 to postnatal day 70. In the elevated zero maze test, isolated rats showed a significant reduction in the time spent in the open arms, as well as an increase in the time spent in the closed arms, compared to controls. An increased grooming time in the open field test was also observed in isolated animals. Isolation-induced anxiety-like behavior was accompanied by a decrease of plasmatic oxytocin, prolactin, ghrelin and melatonin levels, whereas plasmatic amount of Neuropeptide S was not altered. Social isolation also caused a reduction of noradrenaline, serotonin and GABA levels, together with an increase of serotonin turnover and glutamate levels in the amygdala of isolated animals. No significant differences were found in noradrenaline and serotonin levels, as well as in serotonin turnover in hippocampus, while glutamate amount was increased and GABA levels were reduced in isolated rats. Furthermore, there was a reduction in plasmatic serotonin content, and an increase in plasmatic kynurenine levels following social isolation, while no significant changes in serotonin turnover were observed. Taken together, our data provide novel insights in the neurobiological alterations underlying the comorbidity between psychosis and anxiety, and open new perspectives for multi-target therapies acting on both neurochemical and neuroendocrine pathways. DATA AVAILABILITY STATEMENT: The data presented in this study are available on request from the corresponding author.
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Affiliation(s)
- Stefania Dimonte
- Departement of Clinical and Experimental Medicine, University of Foggia, Via Napoli, 20, 71122, Foggia, Italy.
| | - Vladyslav Sikora
- Departement of Clinical and Experimental Medicine, University of Foggia, Via Napoli, 20, 71122, Foggia, Italy; Department of Pathology, Sumy State University, 2, Rymskogo-Korsakova st., Sumy 40007, Ukraine.
| | - Maria Bove
- Departement of Clinical and Experimental Medicine, University of Foggia, Via Napoli, 20, 71122, Foggia, Italy.
| | - Maria Grazia Morgese
- Departement of Clinical and Experimental Medicine, University of Foggia, Via Napoli, 20, 71122, Foggia, Italy.
| | - Paolo Tucci
- Departement of Clinical and Experimental Medicine, University of Foggia, Via Napoli, 20, 71122, Foggia, Italy.
| | - Stefania Schiavone
- Departement of Clinical and Experimental Medicine, University of Foggia, Via Napoli, 20, 71122, Foggia, Italy.
| | - Luigia Trabace
- Departement of Clinical and Experimental Medicine, University of Foggia, Via Napoli, 20, 71122, Foggia, Italy.
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Gilbert JD, Rossiter SJ, Bennett NC, Faulkes CG. The elusive role of prolactin in the sociality of the naked mole-rat. Horm Behav 2022; 143:105196. [PMID: 35597054 DOI: 10.1016/j.yhbeh.2022.105196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 04/13/2022] [Accepted: 05/05/2022] [Indexed: 12/01/2022]
Abstract
Despite decades of research into the evolutionary drivers of sociality, we know relatively little about the underlying proximate mechanisms. Here we investigate the potential role of prolactin in the highly social naked mole-rat. Naked mole-rats live in large social groups but, only a small number of individuals reproduce. The remaining non-breeders are reproductively suppressed and contribute to burrow maintenance, foraging, and allo-parental care. Prolactin has well-documented links with reproductive timing and parental behaviour, and the discovery that non-breeding naked mole-rats have unusually high prolactin levels has led to the suggestion that prolactin may help maintain naked mole-rat sociality. To test this idea, we investigated whether urinary prolactin was correlated with cooperative behaviour and aggression. We then administered the prolactin-suppressing drug Cabergoline to eight female non-breeders for eight weeks and assessed the physiology and behaviour of the animals relative to controls. Contrary to the mammalian norm, and supporting previous findings for plasma, we found non-breeders had elevated urinary prolactin concentrations that were similar to breeding females. Further, prolactin levels were higher in heavier, socially dominant non-breeders. Urinary prolactin concentrations did not explain variation in working behaviour or patterns of aggression. Furthermore, females receiving Cabergoline did not show any behavioural or hormonal (progesterone) differences, and urinary prolactin did not appear to be suppressed in individuals receiving Cabergoline. While the results add to the relatively limited literature experimentally manipulating prolactin to investigate its role in reproduction and behaviour, they fail to explain why prolactin levels are high in non-breeding naked mole-rats, or how female non-breeding phenotypes are maintained.
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Affiliation(s)
- James D Gilbert
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom of Great Britain and Northern Ireland.
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom of Great Britain and Northern Ireland
| | - Nigel C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Christopher G Faulkes
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom of Great Britain and Northern Ireland.
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Paré P, Reales G, Paixão-Côrtes VR, Vargas-Pinilla P, Viscardi LH, Fam B, Pissinatti A, Santos FR, Bortolini MC. Molecular evolutionary insights from PRLR in mammals. Gen Comp Endocrinol 2021; 309:113791. [PMID: 33872604 DOI: 10.1016/j.ygcen.2021.113791] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/02/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022]
Abstract
Prolactin (PRL) is a pleiotropic neurohormone secreted by the mammalian pituitary gland into the blood, thus reaching many tissues and organs beyond the brain. PRL binds to its receptor, PRLR, eliciting a molecular signaling cascade. This system modulates essential mammalian behaviors and promotes notable modifications in the reproductive female tissues and organs. Here, we explore how the intracellular domain of PRLR (PRLR-ICD) modulates the expression of the PRLR gene. Despite differences in the reproductive strategies between eutherian and metatherian mammals, there is no clear distinction between PRLR-ICD functional motifs. However, we found selection signatures that showed differences between groups, with many conserved functional elements strongly maintained through purifying selection across the class Mammalia. We observed a few residues under relaxed selection, the levels of which were more pronounced in Eutheria and particularly striking in primates (Simiiformes), which could represent a pre-adaptive genetic element protected from purifying selection. Alternative, new motifs, such as YLDP (318-321) and others with residues Y283 and Y290, may already be functional. These motifs would have been co-opted in primates as part of a complex genetic repertoire related to some derived adaptive phenotypes, but these changes would have no impact on the primordial functions that characterize the mammals as a whole and that are related to the PRL-PRLR system.
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Affiliation(s)
- Pamela Paré
- Laboratório de Evolução Humana e Molecular, Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Guillermo Reales
- Laboratório de Evolução Humana e Molecular, Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus, University of Cambridge, Puddicombe Way, Cambridge CB2 0AW, UK; Department of Medicine, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge CB2 0QQ, UK
| | - Vanessa R Paixão-Côrtes
- Laboratório de Biologia Evolutiva e Genômica (LABEG), Programa de Pós-Graduação em Biodiversidade e Evolução, Instituto de Biologia, Universidade Federal da Bahia (UFBA), Salvador, BA, Brazil
| | - Pedro Vargas-Pinilla
- Laboratório de Evolução Humana e Molecular, Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil; Faculdade de Medicina de Ribeirão Preto, Departamento de Bioquímica e Imunologia, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Lucas Henriques Viscardi
- Laboratório de Evolução Humana e Molecular, Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Bibiana Fam
- Laboratório de Evolução Humana e Molecular, Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | | | - Fabrício R Santos
- Laboratório de Biodiversidade e Evolução Molecular, Departamento de Genética, Ecologia e Evolução da Universidade Federal de Minas Gerais (UFMG), Belo-Horizonte, MG, Brazil.
| | - Maria Cátira Bortolini
- Laboratório de Evolução Humana e Molecular, Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
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Kuwagata M, Muneoka K, Honda K, Miyazaki A. Hypothalamic Monoaminergic Pathology in a Neurodevelopmental Rat Model Showing Prenatal 5-Bromo-2'-Deoxyuridine Treatment-Induced Hyperactivity and Hyporeproductivity. Neuropsychobiology 2020; 79:161-169. [PMID: 31822012 DOI: 10.1159/000504552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 11/03/2019] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Prenatal treatment of rats with 5-bromo-2'-deoxyuridine (BrdU) is a neurodevelopmental model showing hyperactivity and impaired sexual activity. Human neurodevelopmental disorders, such as autism, exhibit sex-related pathology, but sex-related neurodevelopment has not been fully investigated in this model. We conducted this study to facilitate the understanding of the pathophysiology of neurodevelopmental disorders. METHODS Pregnant rats received 50 mg/kg BrdU on gestational days 9-15. The tissue content of dopamine (DA), serotonin (5-HT), and their metabolites dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid were measured in male and female offspring at 3 weeks (juveniles) and 10 weeks (adults) of age. RESULTS Prenatally BrdU-treated rats had reduced DA metabolism or DA content in the hypothalamus from the juvenile through the adult period without sex differences, but sex-specific striatal DA abnormalities emerged after maturation. A reduction in 5-HT metabolism was measured in the hypothalamus without sex differences throughout development. Developmental alterations in the striatal 5-HT states were sex-dependent. Temporal changes in DA or 5-HT metabolism were found in the frontal cortex and midbrain. CONCLUSION The sex-specific influence of a genotoxic factor on the development of the DA and 5-HT systems was clarified in the hypothalamus and striatum. The results suggest that the observed sex dependence and region specificity are related to the pathology of social dysfunction in neurodevelopmental disorders.
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Affiliation(s)
- Makiko Kuwagata
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan.,Laboratory of Safety Evaluation, Division of Safety, Hatano Research Institute, Food and Drug Safety Center, Hadano, Japan.,Division of Cellular and Molecular Toxicology, Center for Biological Safety and Research, National Institute of Health Science, Kawasaki, Japan
| | - Katsumasa Muneoka
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan, .,Department of Biochemistry, Showa University School of Medicine, Tokyo, Japan,
| | - Kazuho Honda
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
| | - Akira Miyazaki
- Department of Biochemistry, Showa University School of Medicine, Tokyo, Japan
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6
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Prado NA, Keady M, Oestmann A, Steinbeiser CM, Brown JL. Hyperprolactinemic African elephant (Loxodonta africana) females exhibit elevated dopamine, oxytocin and serotonin concentrations compared to normal cycling and noncycling, low prolactin elephants†. Biol Reprod 2020; 100:1549-1560. [PMID: 30848798 DOI: 10.1093/biolre/ioz036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/26/2019] [Accepted: 03/06/2019] [Indexed: 01/09/2023] Open
Abstract
Many zoo elephants do not cycle normally, and for African elephants, it is often associated with hyperprolactinemia. Dopamine agonists successfully treat hyperprolactinemia-induced ovarian dysfunction in women, but not elephants. The objective of this study was to determine how longitudinal dopamine, serotonin, and oxytocin patterns in African elephants are related to ovarian cycle function. We hypothesized that dopamine concentrations are decreased, while oxytocin and serotonin are increased in non-cycling, hyperprolactinemic African elephants. Weekly urine and serum samples were collected for eight consecutive months from 28 female African elephants. Females were categorized as follows: (1) non-cycling with average prolactin concentrations of 15 ng/ml or greater (HIGH; n = 7); (2) non-cycling with average prolactin concentrations below 15 ng/ml (LOW; n = 13); and (3) cycling with normal progestagen and prolactin patterns (CYCLING; n = 8). Both oxytocin and serotonin were elevated in hyperprolactinemic elephants. Thus, we propose that stimulatory factors may play a role in the observed hyperprolactinemia in this species. Interestingly, rather than being reduced as hypothesized, urinary dopamine was elevated in hyperprolactinemic elephants compared to CYCLING and LOW prolactin groups. Despite its apparent lack of regulatory control over prolactin, this new evidence suggests that dopamine synthesis and secretion are not impaired in these elephants, and perhaps are augmented.
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Affiliation(s)
- Natalia A Prado
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA
| | - Mia Keady
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA.,School of Systems Biology, George Mason University, Fairfax, Virginia, USA
| | - Alexa Oestmann
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA
| | - Cathleen M Steinbeiser
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA.,Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Janine L Brown
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA
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Lopes PC, König B. Wild mice with different social network sizes vary in brain gene expression. BMC Genomics 2020; 21:506. [PMID: 32698762 PMCID: PMC7374831 DOI: 10.1186/s12864-020-06911-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/13/2020] [Indexed: 12/14/2022] Open
Abstract
Background Appropriate social interactions influence animal fitness by impacting several processes, such as mating, territory defense, and offspring care. Many studies shedding light on the neurobiological underpinnings of social behavior have focused on nonapeptides (vasopressin, oxytocin, and homologues) and on sexual or parent-offspring interactions. Furthermore, animals have been studied under artificial laboratory conditions, where the consequences of behavioral responses may not be as critical as when expressed under natural environments, therefore obscuring certain physiological responses. We used automated recording of social interactions of wild house mice outside of the breeding season to detect individuals at both tails of a distribution of egocentric network sizes (characterized by number of different partners encountered per day). We then used RNA-seq to perform an unbiased assessment of neural differences in gene expression in the prefrontal cortex, the hippocampus and the hypothalamus between these mice with naturally occurring extreme differences in social network size. Results We found that the neurogenomic pathways associated with having extreme social network sizes differed between the sexes. In females, hundreds of genes were differentially expressed between animals with small and large social network sizes, whereas in males very few were. In males, X-chromosome inactivation pathways in the prefrontal cortex were the ones that better differentiated animals with small from those with large social network sizes animals. In females, animals with small network size showed up-regulation of dopaminergic production and transport pathways in the hypothalamus. Additionally, in females, extracellular matrix deposition on hippocampal neurons was higher in individuals with small relative to large social network size. Conclusions Studying neural substrates of natural variation in social behavior in traditional model organisms in their habitat can open new targets of research for understanding variation in social behavior in other taxa.
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Affiliation(s)
- Patricia C Lopes
- Schmid College of Science and Technology, Chapman University, Orange, CA, USA.
| | - Barbara König
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zürich, Switzerland
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Cunha AAP, Partridge CG, Knapp R, Neff BD. Androgen and prolactin manipulation induces changes in aggressive and nurturing behavior in a fish with male parental care. Horm Behav 2019; 116:104582. [PMID: 31445012 DOI: 10.1016/j.yhbeh.2019.104582] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/29/2019] [Accepted: 08/20/2019] [Indexed: 11/26/2022]
Abstract
Parental care can include two general types of behavior: (1) aggressive behavior, which is used to defend offspring from predators; and (2) nurturing behavior, which is used to provide offspring with environmental conditions or resources necessary for survival. Many studies have implicated androgens in promoting aggressive behavior and prolactin in promoting nurturing behavior. We experimentally manipulated these hormones to investigate their effects on parental care behavior in bluegill (Lepomis macrochirus). Parental males, which provide sole care to the developing eggs and larvae, received an implant with an androgen (11-ketotestosterone [11-KT]), an androgen antagonist (flutamide), prolactin, a prolactin-release inhibitor (bromocriptine), or castor oil (placebo). We found that 11-KT implants led to a significant increase in the frequency of aggressive behavior directed towards a simulated brood predator, and were associated with a nearly significant decrease in the frequency of nurturing behavior directed towards the developing eggs. In contrast, prolactin implants were associated with a significant increase in the frequency of nurturing behavior, but also reduced the frequency of aggressive behavior directed towards the simulated brood predator. These results suggest a hormone-mediated mechanistic trade-off between nurturing and aggressive behavior, whereby parental males are unable to be both highly nurturing and highly aggressive.
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Affiliation(s)
- Adriano A P Cunha
- Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada
| | - Charlyn G Partridge
- Annis Water Resources Institute, Grand Valley State University, Muskegon 49441, MI, USA
| | - Rosemary Knapp
- Department of Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Bryan D Neff
- Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada.
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Medger K, Bennett NC, Ganswindt SB, Ganswindt A, Hart DW. Changes in prolactin, cortisol and testosterone concentrations during queen succession in a colony of naked mole-rats (Heterocephalus glaber): a case study. Naturwissenschaften 2019; 106:26. [PMID: 31089819 DOI: 10.1007/s00114-019-1621-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 04/09/2019] [Accepted: 05/02/2019] [Indexed: 12/18/2022]
Abstract
Colonies of naked mole-rats (Heterocephalus glaber, NMRs) are characterised by an extreme skew in lifetime reproductive success with only one female and one to three male consorts in a colony. The rest of the individuals in a colony are reproductively suppressed and much research has been focussed on elucidating that mechanism. The dopamine system and prolactin have recently been implicated in the suppression of reproduction of subordinate NMRs. To investigate the changes in prolactin during the removal of an aged reproductive female (queen) and succession of a new queen, blood samples were collected during different stages of queen removal: before queen removal, after separation, but in olfactory contact with the queen and after the total removal of the queen. Further, plasma cortisol and testosterone concentrations were determined. The colony appeared unstable prior to queen removal as indicated by high concentrations of cortisol and testosterone and lack of successful breeding. A new queen succeeded the old queen whilst she was still in olfactory contact. The time preceding queen succession was characterised by high levels of aggression, the death of a number of individuals, high cortisol and testosterone and low prolactin concentrations. Once the older queen was removed entirely and the new queen had given birth, prolactin concentrations increased and cortisol and testosterone concentrations decreased in subordinate NMRs. The results suggest that low prolactin levels are associated with low reproductive suppression during times of colony instability due to the removal or death of a queen.
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Affiliation(s)
- Katarina Medger
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
| | - Nigel C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
- SARChI Chair of Mammal Behavioural Ecology and Physiology, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Stefanie B Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
- Department of Anatomy and Physiology, Faculty of Veterinary Science, Endocrine Research Laboratory, Private Bag X04, Onderstepoort, 0110, South Africa
| | - Andre Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
- Department of Anatomy and Physiology, Faculty of Veterinary Science, Endocrine Research Laboratory, Private Bag X04, Onderstepoort, 0110, South Africa
| | - Daniel W Hart
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
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