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Bonfanti L, La Rosa C, Ghibaudi M, Sherwood CC. Adult neurogenesis and "immature" neurons in mammals: an evolutionary trade-off in plasticity? Brain Struct Funct 2024; 229:1775-1793. [PMID: 37833544 DOI: 10.1007/s00429-023-02717-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023]
Abstract
Neuronal plasticity can vary remarkably in its form and degree across animal species. Adult neurogenesis, namely the capacity to produce new neurons from neural stem cells through adulthood, appears widespread in non-mammalian vertebrates, whereas it is reduced in mammals. A growing body of comparative studies also report variation in the occurrence and activity of neural stem cell niches between mammals, with a general trend of reduction from small-brained to large-brained species. Conversely, recent studies have shown that large-brained mammals host large amounts of neurons expressing typical markers of neurogenesis in the absence of cell division. In layer II of the cerebral cortex, populations of prenatally generated, non-dividing neurons continue to express molecules indicative of immaturity throughout life (cortical immature neurons; cINs). After remaining in a dormant state for a very long time, these cINs retain the potential of differentiating into mature neurons that integrate within the preexisting neural circuits. They are restricted to the paleocortex in small-brained rodents, while extending into the widely expanded neocortex of highly gyrencephalic, large-brained species. The current hypothesis is that these populations of non-newly generated "immature" neurons might represent a reservoir of developmentally plastic cells for mammalian species that are characterized by reduced stem cell-driven adult neurogenesis. This indicates that there may be a trade-off between various forms of plasticity that coexist during brain evolution. This balance may be necessary to maintain a "reservoir of plasticity" in brain regions that have distinct roles in species-specific socioecological adaptations, such as the neocortex and olfactory structures.
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Affiliation(s)
- Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy.
- Department of Veterinary Sciences, University of Turin, Largo Braccini 2, 10095, Turin, Grugliasco, Italy.
| | - Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy
| | - Marco Ghibaudi
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano, Italy
- Department of Veterinary Sciences, University of Turin, Largo Braccini 2, 10095, Turin, Grugliasco, Italy
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC, USA.
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2
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Gems D, Virk RS, de Magalhães JP. Epigenetic clocks and programmatic aging. Ageing Res Rev 2024:102546. [PMID: 39414120 DOI: 10.1016/j.arr.2024.102546] [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: 07/24/2024] [Revised: 09/23/2024] [Accepted: 10/09/2024] [Indexed: 10/18/2024]
Abstract
The last decade has seen remarkable progress in the characterization of methylation clocks that can serve as indicators of biological age in humans and many other mammalian species. While the biological processes of aging that underlie these clocks have remained unclear, several clues have pointed to a link to developmental mechanisms. These include the presence in the vicinity of clock CpG sites of genes that specify development, including those of the Hox (homeobox) and polycomb classes. Here we discuss how recent advances in programmatic theories of aging provide a framework within which methylation clocks can be understood as part of a developmental process of aging. This includes how such clocks evolve, how developmental mechanisms cause aging, and how they give rise to late-life disease. The combination of ideas from evolutionary biology, biogerontology and developmental biology open a path to a new discipline, that of developmental gerontology (devo-gero). Drawing on the properties of methylation clocks, we offer several new hypotheses that exemplify devo-gero thinking. We suggest that polycomb controls a trade-off between earlier developmental fidelity and later developmental plasticity. We also propose the existence of an evolutionarily-conserved developmental sequence spanning ontogenesis, adult development and aging, that both constrains and determines the evolution of aging.
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Affiliation(s)
- David Gems
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, United Kingdom
| | - Roop Singh Virk
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, United Kingdom
| | - João Pedro de Magalhães
- Genomics of Ageing and Rejuvenation Lab, Institute of Inflammation and Ageing, University of Birmingham, B15 2WB, United Kingdom
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3
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Buffenstein R, Amoroso VG. The Untapped Potential of Comparative Biology in Aging Research: Insights From the Extraordinary-Long-Lived Naked Mole-Rat. J Gerontol A Biol Sci Med Sci 2024; 79:glae110. [PMID: 38721823 DOI: 10.1093/gerona/glae110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Indexed: 06/27/2024] Open
Abstract
The search for solutions to the vagaries of aging has, historically, been akin to searching at night in the bright light under street lamps by utilizing the few preexisting and well-established animal model systems. Throughout my career as a comparative biologist, I have ventured into the darkness across 4 continents and studied over 150 different animal species, many of which have evolved remarkable adaptations to survive on the harsh and rugged fitness landscape that exists outside of the laboratory setting. In this Fellows Forum, I will discuss the main focus of my research for the last 25 years and dig deeply into the biology of the preternaturally long-lived naked mole-rat that makes it an ideal model system for the characterization of successful strategies to combat aging.
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Affiliation(s)
- Rochelle Buffenstein
- Department of Biological Sciences, University of Illinois, Chicago, Illinois, USA
| | - Vince G Amoroso
- Department of Biological Sciences, University of Illinois, Chicago, Illinois, USA
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4
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Transcription Factors as Important Regulators of Changes in Behavior through Domestication of Gray Rats: Quantitative Data from RNA Sequencing. Int J Mol Sci 2022; 23:ijms232012269. [PMID: 36293128 PMCID: PMC9603081 DOI: 10.3390/ijms232012269] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/28/2022] [Accepted: 10/12/2022] [Indexed: 11/16/2022] Open
Abstract
Studies on hereditary fixation of the tame-behavior phenotype during animal domestication remain relevant and important because they are of both basic research and applied significance. In model animals, gray rats Rattus norvegicus bred for either an enhancement or reduction in defensive response to humans, for the first time, we used high-throughput RNA sequencing to investigate differential expression of genes in tissue samples from the tegmental region of the midbrain in 2-month-old rats showing either tame or aggressive behavior. A total of 42 differentially expressed genes (DEGs; adjusted p-value < 0.01 and fold-change > 2) were identified, with 20 upregulated and 22 downregulated genes in the tissue samples from tame rats compared with aggressive rats. Among them, three genes encoding transcription factors (TFs) were detected: Ascl3 was upregulated, whereas Fos and Fosb were downregulated in tissue samples from the brains of tame rats brain. Other DEGs were annotated as associated with extracellular matrix components, transporter proteins, the neurotransmitter system, signaling molecules, and immune system proteins. We believe that these DEGs encode proteins that constitute a multifactorial system determining the behavior for which the rats have been artificially selected. We demonstrated that several structural subtypes of E-box motifs—known as binding sites for many developmental TFs of the bHLH class, including the ASCL subfamily of TFs—are enriched in the set of promoters of the DEGs downregulated in the tissue samples of tame rats’. Because ASCL3 may act as a repressor on target genes of other developmental TFs of the bHLH class, we hypothesize that the expression of TF gene Ascl3 in tame rats indicates longer neurogenesis (as compared to aggressive rats), which is a sign of neoteny and domestication. Thus, our domestication model shows a new function of TF ASCL3: it may play the most important role in behavioral changes in animals.
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5
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Faykoo-Martinez M, Collins T, Peragine D, Malik M, Javed F, Kolisnyk M, Ziolkowski J, Jeewa I, Cheng AH, Lowden C, Mascarenhas B, Cheng HYM, Holmes MM. Protracted neuronal maturation in a long-lived, highly social rodent. PLoS One 2022; 17:e0273098. [PMID: 36107951 PMCID: PMC9477366 DOI: 10.1371/journal.pone.0273098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 08/02/2022] [Indexed: 11/19/2022] Open
Abstract
Naked mole-rats are a long-lived rodent species (current lifespan >37 years) and an increasingly popular biomedical model. Naked mole-rats exhibit neuroplasticity across their long lifespan. Previous studies have begun to investigate their neurogenic patterns. Here, we test the hypothesis that neuronal maturation is extended in this long-lived rodent. We characterize cell proliferation and neuronal maturation in established rodent neurogenic regions over 12 months following seven days of consecutive BrdU injection. Given that naked mole-rats are eusocial (high reproductive skew where only a few socially-dominant individuals reproduce), we also looked at proliferation in brain regions relevant to the social-decision making network. Finally, we measured co-expression of EdU (newly-born cells), DCX (immature neuron marker), and NeuN (mature neuron marker) to assess the timeline of neuronal maturation in adult naked mole-rats. This work reaffirms the subventricular zone as the main source of adult cell proliferation and suggests conservation of the rostral migratory stream in this species. Our profiling of socially-relevant brain regions suggests that future work which manipulates environmental context can unveil how newly-born cells integrate into circuitry and facilitate adult neuroplasticity. We also find naked mole-rat neuronal maturation sits at the intersection of rodents and long-lived, non-rodent species: while neurons can mature by 3 weeks (rodent-like), most neurons mature at 5 months and hippocampal neurogenic levels are low (like long-lived species). These data establish a timeline for future investigations of longevity- and socially-related manipulations of naked mole-rat adult neurogenesis.
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Affiliation(s)
| | - Troy Collins
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Diana Peragine
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Manahil Malik
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Fiza Javed
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Matthew Kolisnyk
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Justine Ziolkowski
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Imaan Jeewa
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Arthur H. Cheng
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Christopher Lowden
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Brittany Mascarenhas
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Hai-Ying Mary Cheng
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Melissa M. Holmes
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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McCullagh EA, Peacock J, Lucas A, Poleg S, Greene NT, Gaut A, Lagestee S, Zhang Y, Kaczmarek LK, Park TJ, Tollin DJ, Klug A. Auditory brainstem development of naked mole-rats ( Heterocephalus glaber). Proc Biol Sci 2022; 289:20220878. [PMID: 35946148 PMCID: PMC9363996 DOI: 10.1098/rspb.2022.0878] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 07/15/2022] [Indexed: 01/12/2023] Open
Abstract
Life underground often leads to animals having specialized auditory systems to accommodate the constraints of acoustic transmission in tunnels. Despite living underground, naked mole-rats use a highly vocal communication system, implying that they rely on central auditory processing. However, little is known about these animals' central auditory system, and whether it follows a similar developmental time course as other rodents. Naked mole-rats show slowed development in the hippocampus suggesting they have altered brain development compared to other rodents. Here, we measured morphological characteristics and voltage-gated potassium channel Kv3.3 expression and protein levels at different key developmental time points (postnatal days 9, 14, 21 and adulthood) to determine whether the auditory brainstem (lateral superior olive and medial nucleus of the trapezoid body) develops similarly to two common auditory rodent model species: gerbils and mice. Additionally, we measured the hearing onset of naked mole-rats using auditory brainstem response recordings at the same developmental timepoints. In contrast with other work in naked mole-rats showing that they are highly divergent in many aspects of their physiology, we show that naked mole-rats have a similar hearing onset, between postnatal day (P) 9 and P14, to many other rodents. On the other hand, we show some developmental differences, such as a unique morphology and Kv3.3 protein levels in the brainstem.
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Affiliation(s)
| | - John Peacock
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Alexandra Lucas
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Shani Poleg
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Nathaniel T. Greene
- Department of Otolaryngology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Addison Gaut
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA
| | - Samantha Lagestee
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL USA
| | - Yalan Zhang
- Department of Pharmacology, Yale University, New Haven, CT, USA
| | - Leonard K. Kaczmarek
- Department of Pharmacology, Yale University, New Haven, CT, USA
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
| | - Thomas J. Park
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL USA
| | - Daniel J. Tollin
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Department of Otolaryngology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Achim Klug
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Department of Otolaryngology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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7
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Abstract
ABSTRACT
Hypoxia is one of the strongest environmental drivers of cellular and physiological adaptation. Although most mammals are largely intolerant of hypoxia, some specialized species have evolved mitigative strategies to tolerate hypoxic niches. Among the most hypoxia-tolerant mammals are naked mole-rats (Heterocephalus glaber), a eusocial species of subterranean rodent native to eastern Africa. In hypoxia, naked mole-rats maintain consciousness and remain active despite a robust and rapid suppression of metabolic rate, which is mediated by numerous behavioural, physiological and cellular strategies. Conversely, hypoxia-intolerant mammals and most other hypoxia-tolerant mammals cannot achieve the same degree of metabolic savings while staying active in hypoxia and must also increase oxygen supply to tissues, and/or enter torpor. Intriguingly, recent studies suggest that naked mole-rats share many cellular strategies with non-mammalian vertebrate champions of anoxia tolerance, including the use of alternative metabolic end-products and potent pH buffering mechanisms to mitigate cellular acidification due to upregulation of anaerobic metabolic pathways, rapid mitochondrial remodelling to favour increased respiratory efficiency, and systemic shifts in energy prioritization to maintain brain function over that of other tissues. Herein, I discuss what is known regarding adaptations of naked mole-rats to a hypoxic lifestyle, and contrast strategies employed by this species to those of hypoxia-intolerant mammals, closely related African mole-rats, other well-studied hypoxia-tolerant mammals, and non-mammalian vertebrate champions of anoxia tolerance. I also discuss the neotenic theory of hypoxia tolerance – a leading theory that may explain the evolutionary origins of hypoxia tolerance in mammals – and highlight promising but underexplored avenues of hypoxia-related research in this fascinating model organism.
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Affiliation(s)
- Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 9A7. University of Ottawa, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada, K1H 8M5
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8
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Kluever V, Fornasiero EF. Principles of brain aging: Status and challenges of modeling human molecular changes in mice. Ageing Res Rev 2021; 72:101465. [PMID: 34555542 DOI: 10.1016/j.arr.2021.101465] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 01/22/2023]
Abstract
Due to the extension of human life expectancy, the prevalence of cognitive impairment is rising in the older portion of society. Developing new strategies to delay or attenuate cognitive decline is vital. For this purpose, it is imperative to understand the cellular and molecular events at the basis of brain aging. While several organs are directly accessible to molecular analysis through biopsies, the brain constitutes a notable exception. Most of the molecular studies are performed on postmortem tissues, where cell death and tissue damage have already occurred. Hence, the study of the molecular aspects of cognitive decline largely relies on animal models and in particular on small mammals such as mice. What have we learned from these models? Do these animals recapitulate the changes observed in humans? What should we expect from future mouse studies? In this review we answer these questions by summarizing the state of the research that has addressed cognitive decline in mice from several perspectives, including genetic manipulation and omics strategies. We conclude that, while extremely valuable, mouse models have limitations that can be addressed by the optimal design of future studies and by ensuring that results are cross-validated in the human context.
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9
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Yamamura Y, Kawamura Y, Oiwa Y, Oka K, Onishi N, Saya H, Miura K. Isolation and characterization of neural stem/progenitor cells in the subventricular zone of the naked mole-rat brain. Inflamm Regen 2021; 41:31. [PMID: 34719407 PMCID: PMC8559411 DOI: 10.1186/s41232-021-00182-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/18/2021] [Indexed: 12/11/2022] Open
Abstract
Background The naked mole-rat (NMR) is the longest-lived rodent with a maximum lifespan of more than 37 years and shows a negligible senescence phenotype, suggesting that tissue stem cells of NMRs are highly capable of maintaining homeostasis. However, the properties of NMR tissue stem cells, including neural stem cells (NSCs), are largely unclear. Methods Neural stem/progenitor cells (NS/PCs) were isolated from the subventricular zone of the neonate NMR brain (NMR-NS/PCs) and cultured in neurosphere and adherent culture conditions. Expression of NSC markers and markers of neurons, astrocytes, and oligodendrocytes was analyzed by immunocytochemistry. In adherent culture conditions, the proliferation rate and cell cycle of NMR-NS/PCs were assessed and compared with those of NS/PCs from mice (mouse-NS/PCs). The DNA damage response to γ-irradiation was analyzed by immunocytochemistry and reverse transcription-quantitative PCR. Results NMR-NS/PCs expressed several NSC markers and differentiated into neurons, astrocytes, and oligodendrocytes. NMR-NS/PCs proliferated markedly slower than mouse-NS/PCs, and a higher percentage of NMR-NS/PCs than mouse-NS/PCs was in G0/G1 phase. Notably, upon γ-irradiation, NMR-NS/PCs exhibited a faster initiation of the DNA damage response and were less prone to dying than mouse-NS/PCs. Conclusions NMR-NS/PCs were successfully isolated and cultured. The slow proliferation of NMR-NS/PCs and their resistance to DNA damage may help to prevent stem cell exhaustion in the brain during the long lifespan of NMRs. Our findings provide novel insights into the mechanism underlying delayed aging of NMRs. Further analysis of NMR tissue stem cells may lead to the development of new strategies that can prevent aging in humans. Supplementary Information The online version contains supplementary material available at 10.1186/s41232-021-00182-7.
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Affiliation(s)
- Yuki Yamamura
- Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-0811, Japan
| | - Yoshimi Kawamura
- Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-0811, Japan
| | - Yuki Oiwa
- Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-0811, Japan
| | - Kaori Oka
- Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-0811, Japan
| | - Nobuyuki Onishi
- Division of Gene Regulation, Institute for Advanced Medical Research, Keio University School of Medicine, Tokyo, 160-0016, Japan
| | - Hideyuki Saya
- Division of Gene Regulation, Institute for Advanced Medical Research, Keio University School of Medicine, Tokyo, 160-0016, Japan
| | - Kyoko Miura
- Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-0811, Japan. .,Center for Metabolic Regulation of Healthy Aging, Kumamoto University, Kumamoto, 860-8556, Japan.
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10
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The Idiosyncratic Physiological Traits of the Naked Mole-Rat; a Resilient Animal Model of Aging, Longevity, and Healthspan. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1319:221-254. [PMID: 34424518 DOI: 10.1007/978-3-030-65943-1_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The subterranean-dwelling naked mole-rat (Heterocephalus glaber) is an extremophilic rodent, able to thrive in the harsh underground conditions of sub-Saharan Northeast Africa. This pelage-free mammal exhibits numerous unusual ecophysiological features including pronounced tolerance of thermolability, hypoxia, hypercapnia and noxious substances. As a mammal, the naked mole-rat provides a proof-of-concept that age-related changes in physiology are avoidable. At ages far beyond their expected lifespans given both their body size and/or the timing of early developmental milestones, naked mole-rats fail to exhibit meaningful changes in physiological health or demographic mortality. Lack of physiological deterioration with age is also evident in lean and fat mass, bone quality, and reproductive capacity. Rather, regardless of age, under basal conditions naked mole-rats appear to "idle on low" with their "shields up" as is manifested by low body temperature, metabolic rate, cardiac output and kidney concentrating ability, enabling better protection of organs and cellular function. When needed, they can nevertheless ramp up these functions, increasing cardiac output and metabolism 2-5 fold. Here we review many unusual aspects of their physiology and examine how these attributes facilitate both tolerance of the diverse suite of hostile conditions encountered in their natural milieu as well as contribute to their extraordinary longevity and resistance to common, age-related chronic diseases.
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11
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Pergande MR, Amoroso VG, Nguyen TTA, Li W, Vice E, Park TJ, Cologna SM. PPARα and PPARγ Signaling Is Enhanced in the Brain of the Naked Mole-Rat, a Mammal that Shows Intrinsic Neuroprotection from Oxygen Deprivation. J Proteome Res 2021; 20:4258-4271. [PMID: 34351155 DOI: 10.1021/acs.jproteome.1c00131] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Naked mole-rats (NMRs) are a long-lived animal that do not develop age-related diseases including neurodegeneration and cancer. Additionally, NMRs have a profound ability to consume reactive oxygen species (ROS) and survive long periods of oxygen deprivation. Here, we evaluated the unique proteome across selected brain regions of NMRs at different ages. Compared to mice, we observed numerous differentially expressed proteins related to altered mitochondrial function in all brain regions, suggesting that the mitochondria in NMRs may have adapted to compensate for energy demands associated with living in a harsh, underground environment. Keeping in mind that ROS can induce polyunsaturated fatty acid peroxidation under periods of neuronal stress, we investigated docosahexaenoic acid (DHA) and arachidonic acid (AA) peroxidation under oxygen-deprived conditions and observed that NMRs undergo DHA and AA peroxidation to a far less extent compared to mice. Further, our proteomic analysis also suggested enhanced peroxisome proliferator-activated receptor (PPAR)-retinoid X receptor (RXR) activation in NMRs via the PPARα-RXR and PPARγ-RXR complexes. Correspondingly, we present several lines of evidence supporting PPAR activation, including increased eicosapetenoic and omega-3 docosapentaenoic acid, as well as an upregulation of fatty acid-binding protein 3 and 4, known transporters of omega-3 fatty acids and PPAR activators. These results suggest enhanced PPARα and PPARγ signaling as a potential, innate neuroprotective mechanism in NMRs.
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Affiliation(s)
- Melissa R Pergande
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Vince G Amoroso
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Thu T A Nguyen
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Wenping Li
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Emily Vice
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Thomas J Park
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, United States.,Laboratory for Integrative Neuroscience, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Stephanie M Cologna
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States.,Laboratory for Integrative Neuroscience, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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12
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Adult Neural Plasticity in Naked Mole-Rats: Implications of Fossoriality, Longevity and Sociality on the Brain's Capacity for Change. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1319:105-135. [PMID: 34424514 DOI: 10.1007/978-3-030-65943-1_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Naked mole-rats (Heterocephalus glaber) are small African rodents that have many unique behavioral and physiological adaptations well-suited for testing hypotheses about mammalian neural plasticity. In this chapter, we focus on three features of naked mole-rat biology and how they impact neural plasticity in this species: (1) their fossorial lifestyle, (2) their extreme longevity with a lack of demonstrable senescence, and (3) their unusual social structure. Critically, each of these features requires some degree of biological flexibility. First, their fossorial habitat situates them in an environment with characteristics to which the central nervous system is particularly sensitive (e.g., oxygen content, photoperiod, spatial complexity). Second, their long lifespan requires adaptations to combat senescence and declines in neural functioning. Finally, their extreme reproductive skew and sustained ability for release from reproductive suppression indicates remarkable neural sensitivity to the sociosexual environment that is distinct from chronological age. These three features of naked mole-rat life are not mutually exclusive, but they do each offer unique considerations for the possibilities, constraints, and mechanisms associated with adult neural plasticity.
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13
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Park TJ, Smith ESJ, Reznick J, Bennett NC, Applegate DT, Larson J, Lewin GR. African Naked Mole-Rats Demonstrate Extreme Tolerance to Hypoxia and Hypercapnia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1319:255-269. [PMID: 34424519 DOI: 10.1007/978-3-030-65943-1_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Naked mole-rats are extremely tolerant to low concentrations of oxygen (hypoxia) and high concentrations of carbon dioxide (hypercapnia), which is consistent with the environment that they inhabit. Naked mole-rats combine subterranean living with living in very densely populated colonies where oxygen becomes depleted and carbon dioxide accumulates. In the laboratory, naked mole-rats fully recover from 5 h exposure to 5% O2 and 5 h exposure to 80% CO2, whereas both conditions are rapidly lethal to similarly sized laboratory mice. During anoxia (0% O2) naked mole-rats enter a suspended animation-like state and switch from aerobic metabolism of glucose to anaerobic metabolism of fructose. Additional fascinating characteristics include that naked mole-rats show intrinsic brain tolerance to anoxia; a complete lack of hypoxia-induced and CO2-induced pulmonary edema; and reduced aversion to high concentrations of CO2 and acidic fumes. Here we outline a constellation of physiological and molecular adaptations that correlate with the naked mole-rat's hypoxic/hypercapnic tolerance and which offer potential targets for ameliorating pathological conditions in humans, such as the damage caused during cerebral ischemia.
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Affiliation(s)
- Thomas J Park
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA.
| | - Ewan St J Smith
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Jane Reznick
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - N C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Daniel T Applegate
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - John Larson
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA
| | - Gary R Lewin
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine, Berlin, Germany
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14
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Barker AJ, Koch U, Lewin GR, Pyott SJ. Hearing and Vocalizations in the Naked Mole-Rat. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1319:157-195. [PMID: 34424516 DOI: 10.1007/978-3-030-65943-1_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Since their discovery, naked mole-rats have been speaking to us. Early field studies noted their extensive vocalizations, and scientists who are fortunate enough to spend time with these creatures in the laboratory setting cannot help but notice their constant peeping, chirruping and grunting (Hill et al., Proc Zool Soc Lond 128:455-514, 1957). Yet, few dwell on the function of these chirps and peeps, being instead drawn to the many other extraordinary aspects of naked mole-rat physiology detailed throughout this book. Still, no biology is complete without a description of how an organism communicates. While the field of naked mole-rat bioacoustics and acoustic communication has been largely silent for many years, we highlight recent progress in understanding how and what Heterocephalus glaber hears and which vocalizations it uses. These efforts are essential for a complete understanding of naked mole-rat cooperation, society and even culture.
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Affiliation(s)
- Alison J Barker
- Max Planck Institute for Brain Research, Max-von-Laue-Straße 4, Frankfurt am Main, Germany
| | - Ursula Koch
- Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Gary R Lewin
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Sonja J Pyott
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
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15
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Ward JM, Cartoceti AN, Delaney MA. Brain Lesions in Aging Zoo-Housed Naked Mole-Rats ( Heterocephalus glaber). Vet Pathol 2020; 58:142-146. [PMID: 33205701 DOI: 10.1177/0300985820969982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Naked mole-rats (NMRs) are common in the managed care of zoos and valuable models for aging research. Limited information on NMR neuropathology is available despite many studies regarding their aging physiology. Histologic sections of brain from 27 adult (5-27 years old) NMRs from 2 zoos were reviewed to determine presence or absence of lesions associated with advanced age in humans and other mammals. A majority (23/27; 85%) of NMR brains had cerebral cortical neuronal changes with rounded or angular neurons, cytoplasmic vacuoles containing pale yellow pigment, periodic acid-Schiff (PAS)-positive granules and green autofluorescence, compatible with lipofuscinosis. Less severe lesions were present in cerebellar Purkinje cells, medulla, and hippocampal neurons. The hypothalamic neuropil of all NMRs had scattered variably sized PAS-positive granules and 10 (37%) had larger round bodies consistent with corpora amylacea. The youngest NMRs, 5 to 7 years old, generally had minimal or no cerebrocortical lesions. Further studies will help understand brain aging in this long-lived species.
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Affiliation(s)
| | - Andrew N Cartoceti
- National Zoological Park, 53587Smithsonian Institution, Washington, DC, USA
| | - Martha A Delaney
- Zoological Pathology Program, College of Veterinary Medicine, 14589University of Illinois, Brookfield, IL, USA
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16
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La Rosa C, Cavallo F, Pecora A, Chincarini M, Ala U, Faulkes CG, Nacher J, Cozzi B, Sherwood CC, Amrein I, Bonfanti L. Phylogenetic variation in cortical layer II immature neuron reservoir of mammals. eLife 2020; 9:55456. [PMID: 32690132 PMCID: PMC7373429 DOI: 10.7554/elife.55456] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 06/03/2020] [Indexed: 12/22/2022] Open
Abstract
The adult mammalian brain is mainly composed of mature neurons. A limited amount of stem cell-driven neurogenesis persists in postnatal life and is reduced in large-brained species. Another source of immature neurons in adult brains is cortical layer II. These cortical immature neurons (cINs) retain developmentally undifferentiated states in adulthood, though they are generated before birth. Here, the occurrence, distribution and cellular features of cINs were systematically studied in 12 diverse mammalian species spanning from small-lissencephalic to large-gyrencephalic brains. In spite of well-preserved morphological and molecular features, the distribution of cINs was highly heterogeneous, particularly in neocortex. While virtually absent in rodents, they are present in the entire neocortex of many other species and their linear density in cortical layer II generally increased with brain size. These findings suggest an evolutionary developmental mechanism for plasticity that varies among mammalian species, granting a reservoir of young cells for the cerebral cortex. To acquire new skills or recover after injuries, the mammalian brain relies on plasticity, the ability for the brain to change its architecture and its connections during the lifetime of an animal. Creating new nerve cells is one way to achieve plasticity, but this process is rarer in humans than it is in mammals with smaller brains. In particular, it is absent in the human cortex: this region is enlarged in species with large brains, where it carries out complex tasks such as learning and memory. Producing new cells in the cortex would threaten the stability of the structures that retain long-term memories. Another route to plasticity is to reshape the connections between existing, mature nerve cells. This process takes place in the human brain during childhood and adolescence, as some connections are strengthened and others pruned away. An alternative mechanism relies on keeping some nerve cells in an immature, ‘adolescent’ state. When needed, these nerve cells emerge from their state of arrested development and ‘grow up’, connecting with the appropriate brain circuits. This mechanism does not involve producing new nerve cells, and so it would be suitable to maintain plasticity in the cortex. Consistent with this idea, in mice some dormant nerve cells are present in a small, primitive part of the cortex. La Rosa et al. therefore wanted to determine if the location and number of immature cells in the cortex differed between mammals, and if so, whether these differences depended on brain size. The study spanned 12 mammal species, from small-brained species like mice to larger-brained animals including sheep and non-human primates. Microscopy imaging was used to identify immature nerve cells in brain samples, which revealed that the cortex in larger-brained species contained more adolescent cells than its mouse counterpart. The difference was greatest in a region called the neocortex, which has evolved most recently. This area is most pronounced in primates – especially humans – where it carries out high-level cognitive tasks. These results identify immature nerve cells as a potential mechanism for plasticity in the cortex. La Rosa et al. hope that the work will inspire searches for similar reservoirs of young cells in humans, which could perhaps lead to new treatments for brain disorders like dementia.
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Affiliation(s)
- Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy.,Department of Veterinary Sciences, University of Turin, Torino, Italy
| | - Francesca Cavallo
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Alessandra Pecora
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Matteo Chincarini
- Università degli Studi di Teramo, Facoltà di Medicina Veterinaria, Teramo, Italy
| | - Ugo Ala
- Department of Veterinary Sciences, University of Turin, Torino, Italy
| | - Chris G Faulkes
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Juan Nacher
- Neurobiology Unit, BIOTECMED, Universitat de València, and Spanish Network for Mental Health Research CIBERSAM, València, Spain
| | - Bruno Cozzi
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, Italy
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington DC, United States
| | - Irmgard Amrein
- D-HEST, ETH, Zurich, Switzerland.,Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy.,Department of Veterinary Sciences, University of Turin, Torino, Italy
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17
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Zions M, Meehan EF, Kress ME, Thevalingam D, Jenkins EC, Kaila K, Puskarjov M, McCloskey DP. Nest Carbon Dioxide Masks GABA-Dependent Seizure Susceptibility in the Naked Mole-Rat. Curr Biol 2020; 30:2068-2077.e4. [PMID: 32359429 DOI: 10.1016/j.cub.2020.03.071] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 11/27/2019] [Accepted: 03/30/2020] [Indexed: 01/29/2023]
Abstract
African naked mole-rats were likely the first mammals to evolve eusociality, and thus required adaptations to conserve energy and tolerate the low oxygen (O2) and high carbon dioxide (CO2) of a densely populated fossorial nest. As hypercapnia is known to suppress neuronal activity, we studied whether naked mole-rats might demonstrate energy savings in GABAergic inhibition. Using whole-colony behavioral monitoring of captive naked mole-rats, we found a durable nest, characterized by high CO2 levels, where all colony members spent the majority of their time. Analysis of the naked mole-rat genome revealed, uniquely among mammals, a histidine point variation in the neuronal potassium-chloride cotransporter 2 (KCC2). A histidine missense substitution mutation at this locus in the human ortholog of KCC2, found previously in patients with febrile seizures and epilepsy, has been demonstrated to diminish neuronal Cl- extrusion capacity, and thus impairs GABAergic inhibition. Seizures were observed, without pharmacological intervention, in adult naked mole-rats exposed to a simulated hyperthermic surface environment, causing systemic hypocapnic alkalosis. Consistent with the diminished function of KCC2, adult naked mole-rats demonstrate a reduced efficacy of inhibition that manifests as triggering of seizures at room temperature by the GABAA receptor (GABAAR) positive allosteric modulator diazepam. These seizures are blocked in the presence of nest-like levels of CO2 and likely to be mediated through GABAAR activity, based on in vitro recordings. Thus, altered GABAergic inhibition adds to a growing list of adaptations in the naked mole-rat and provides a plausible proximate mechanism for nesting behavior, where a return to the colony nest restores GABA-mediated inhibition.
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Affiliation(s)
- Michael Zions
- PhD Program in Neuroscience, Graduate Center of The City University of New York, New York, NY 10016, USA; Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA
| | - Edward F Meehan
- Department of Psychology, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA; Department of Computer Science, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA
| | - Michael E Kress
- Department of Computer Science, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA; PhD Program in Computer Science, Graduate Center of the City University of New York, New York, NY 10016, USA
| | - Donald Thevalingam
- PhD Program in Neuroscience, Graduate Center of The City University of New York, New York, NY 10016, USA; Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA
| | - Edmund C Jenkins
- Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA
| | - Kai Kaila
- Neuroscience Center (HiLIFE), University of Helsinki, Helsinki, Finland; Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Martin Puskarjov
- Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA; Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
| | - Dan P McCloskey
- PhD Program in Neuroscience, Graduate Center of The City University of New York, New York, NY 10016, USA; Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA; Department of Psychology, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA.
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18
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Skulachev VP, Shilovsky GA, Putyatina TS, Popov NA, Markov AV, Skulachev MV, Sadovnichii VA. Perspectives of Homo sapiens lifespan extension: focus on external or internal resources? Aging (Albany NY) 2020; 12:5566-5584. [PMID: 32229707 PMCID: PMC7138562 DOI: 10.18632/aging.102981] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 03/24/2020] [Indexed: 01/01/2023]
Abstract
Homo sapiens and naked mole rats (Heterocephalus glaber) are vivid examples of social mammals that differ from their relatives in particular by an increased lifespan and a large number of neotenic features. An important fact for biogerontology is that the mortality rate of H. glaber (a maximal lifespan of more than 32 years, which is very large for such a small rodent) negligibly grows with age. The same is true for modern people in developed countries below the age of 60. It is important that the juvenilization of traits that separate humans from chimpanzees evolved over thousands of generations and millions of years. Rapid advances in technology resulted in a sharp increase in the life expectancy of human beings during the past 100 years. Currently, the human life expectancy has exceeded 80 years in developed countries. It cannot be excluded that the potential for increasing life expectancy by an improvement in living conditions will be exhausted after a certain period of time. New types of geroprotectors should be developed that protect not only from chronic phenoptosis gradual poisoning of the body with reactive oxygen species (ROS) but also from acute phenoptosis, where strong increase in the level of ROS immediately kills an already aged individual. Geroprotectors might be another anti-aging strategy along with neoteny (a natural physiological phenomenon) and technical progress.
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Affiliation(s)
- Vladimir P Skulachev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Gregory A Shilovsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia.,Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow 127051, Russia.,Faculty of Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Tatyana S Putyatina
- Faculty of Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Nikita A Popov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Alexander V Markov
- Faculty of Biology, Lomonosov Moscow State University, Moscow 119991, Russia.,Paleontological Institute, Russian Academy of Sciences, Moscow 117997, Russia
| | - Maxim V Skulachev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Victor A Sadovnichii
- Faculty of Mechanics and Mathematics, Lomonosov Moscow State University, Moscow 119991, Russia
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19
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Mild depolarization of the inner mitochondrial membrane is a crucial component of an anti-aging program. Proc Natl Acad Sci U S A 2020; 117:6491-6501. [PMID: 32152094 PMCID: PMC7104298 DOI: 10.1073/pnas.1916414117] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The mitochondria, organelles that produce the largest amounts of ATP and reactive oxygen species (mROS) in living cells, are equipped with a universal mechanism that can completely prevent mROS production. This mechanism consists of mild depolarization of the inner mitochondrial membrane to decrease the membrane potential to a level sufficient to form ATP but insufficient to generate mROS. In short-lived mice, aging is accompanied by inactivation of the mild depolarization mechanism, resulting in chronic poisoning of the organism with mROS. However, mild depolarization still functions for many years in long-lived naked mole rats and bats. The mitochondria of various tissues from mice, naked mole rats (NMRs), and bats possess two mechanistically similar systems to prevent the generation of mitochondrial reactive oxygen species (mROS): hexokinases I and II and creatine kinase bound to mitochondrial membranes. Both systems operate in a manner such that one of the kinase substrates (mitochondrial ATP) is electrophoretically transported by the ATP/ADP antiporter to the catalytic site of bound hexokinase or bound creatine kinase without ATP dilution in the cytosol. One of the kinase reaction products, ADP, is transported back to the mitochondrial matrix via the antiporter, again through an electrophoretic process without cytosol dilution. The system in question continuously supports H+-ATP synthase with ADP until glucose or creatine is available. Under these conditions, the membrane potential, ∆ψ, is maintained at a lower than maximal level (i.e., mild depolarization of mitochondria). This ∆ψ decrease is sufficient to completely inhibit mROS generation. In 2.5-y-old mice, mild depolarization disappears in the skeletal muscles, diaphragm, heart, spleen, and brain and partially in the lung and kidney. This age-dependent decrease in the levels of bound kinases is not observed in NMRs and bats for many years. As a result, ROS-mediated protein damage, which is substantial during the aging of short-lived mice, is stabilized at low levels during the aging of long-lived NMRs and bats. It is suggested that this mitochondrial mild depolarization is a crucial component of the mitochondrial anti-aging system.
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20
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Buffenstein R, Lewis KN, Gibney PA, Narayan V, Grimes KM, Smith M, Lin TD, Brown-Borg HM. Probing Pedomorphy and Prolonged Lifespan in Naked Mole-Rats and Dwarf Mice. Physiology (Bethesda) 2020; 35:96-111. [DOI: 10.1152/physiol.00032.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Pedomorphy, maintenance of juvenile traits throughout life, is most pronounced in extraordinarily long-lived naked mole-rats. Many of these traits (e.g., slow growth rates, low hormone levels, and delayed sexual maturity) are shared with spontaneously mutated, long-lived dwarf mice. Although some youthful traits likely evolved as adaptations to subterranean habitats (e.g., thermolability), the nature of these intrinsic pedomorphic features may also contribute to their prolonged youthfulness, longevity, and healthspan.
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Affiliation(s)
| | | | - Patrick A. Gibney
- Calico Life Sciences LLC, South San Francisco, California
- Department of Food Science, College of Agriculture and Life Sciences, Stocking Hall, Cornell University, Ithaca, New York
| | - Vikram Narayan
- Calico Life Sciences LLC, South San Francisco, California
| | - Kelly M. Grimes
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Megan Smith
- Calico Life Sciences LLC, South San Francisco, California
| | - Tzuhua D. Lin
- Calico Life Sciences LLC, South San Francisco, California
| | - Holly M. Brown-Borg
- Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota
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21
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Popov NA, Skulachev VP. Neotenic Traits in Heterocephalus glaber and Homo sapiens. BIOCHEMISTRY (MOSCOW) 2019; 84:1484-1489. [DOI: 10.1134/s0006297919120071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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22
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Schulze-Makuch D. The Naked Mole-Rat: An Unusual Organism with an Unexpected Latent Potential for Increased Intelligence? Life (Basel) 2019; 9:life9030076. [PMID: 31527499 PMCID: PMC6789728 DOI: 10.3390/life9030076] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/13/2019] [Accepted: 08/28/2019] [Indexed: 11/24/2022] Open
Abstract
Naked mole-rats are eusocial, hairless mammals that are uniquely adapted to their harsh, low-oxygen subsurface habitat. Although their encephalization quotient, a controversial marker of intelligence, is low, they exhibit many features considered tell-tale signs of highly intelligent species on our planet including longevity, plasticity, social cohesion and interaction, rudimentary language, sustainable farming abilities, and maintaining sanitary conditions in their self-built complex housing structures. It is difficult to envision how naked mole-rats would reach even higher levels of intelligence in their natural sensory-challenged habitat, but such an evolutionary path cannot be excluded if they would expand their range onto the earth’s surface.
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Affiliation(s)
- Dirk Schulze-Makuch
- Astrobiology Group, Center for Astronomy and Astrophysics (ZAA), Technical University Berlin, 10623 Berlin, Germany.
- School of the Environment, Washington State University, Pullman, WA 99163, USA.
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23
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La Rosa C, Ghibaudi M, Bonfanti L. Newly Generated and Non-Newly Generated "Immature" Neurons in the Mammalian Brain: A Possible Reservoir of Young Cells to Prevent Brain Aging and Disease? J Clin Med 2019; 8:jcm8050685. [PMID: 31096632 PMCID: PMC6571946 DOI: 10.3390/jcm8050685] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 01/21/2023] Open
Abstract
Brain plasticity is important for translational purposes since most neurological disorders and brain aging problems remain substantially incurable. In the mammalian nervous system, neurons are mostly not renewed throughout life and cannot be replaced. In humans, the increasing life expectancy explains the increase in brain health problems, also producing heavy social and economic burden. An exception to the “static” brain is represented by stem cell niches leading to the production of new neurons. Such adult neurogenesis is dramatically reduced from fish to mammals, and in large-brained mammals with respect to rodents. Some examples of neurogenesis occurring outside the neurogenic niches have been reported, yet these new neurons actually do not integrate in the mature nervous tissue. Non-newly generated, “immature” neurons (nng-INs) are also present: Prenatally generated cells continuing to express molecules of immaturity (mostly shared with the newly born neurons). Of interest, nng-INs seem to show an inverse phylogenetic trend across mammals, being abundant in higher-order brain regions not served by neurogenesis and providing structural plasticity in rather stable areas. Both newly generated and nng-INs represent a potential reservoir of young cells (a “brain reserve”) that might be exploited for preventing the damage of aging and/or delay the onset/reduce the impact of neurological disorders.
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Affiliation(s)
- Chiara La Rosa
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy.
- Department of Veterinary Sciences, University of Turin, 10095 Torino, Italy.
| | - Marco Ghibaudi
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy.
| | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi (NICO), 10043 Orbassano, Italy.
- Department of Veterinary Sciences, University of Turin, 10095 Torino, Italy.
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24
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Oppenheim RW. Adult Hippocampal Neurogenesis in Mammals (and Humans): The Death of a Central Dogma in Neuroscience and its Replacement by a New Dogma. Dev Neurobiol 2019; 79:268-280. [DOI: 10.1002/dneu.22674] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 01/31/2023]
Affiliation(s)
- Ronald W. Oppenheim
- Department of Neurobiology and Anatomy, The Neuroscience Program Wake Forest School of Medicine Medical Center Blvd. Winston‐Salem NC 27157‐1010
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25
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Barone CM, Douma S, Reijntjes DOJ, Browe BM, Köppl C, Klump G, Park TJ, Pyott SJ. Altered cochlear innervation in developing and mature naked and Damaraland mole rats. J Comp Neurol 2019; 527:2302-2316. [PMID: 30861124 PMCID: PMC6767702 DOI: 10.1002/cne.24682] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 01/04/2023]
Abstract
Compared to many other rodent species, naked mole rats (Heterocephalus glaber) have elevated auditory thresholds, poor frequency selectivity, and limited ability to localize sound. Because the cochlea is responsible for encoding and relaying auditory signals to the brain, we used immunofluorescence and quantitative image analysis to examine cochlear innervation in mature and developing naked mole rats compared to mice (Mus musculus), gerbils (Meriones unguiculatus), and Damaraland mole rats (Fukomys damarensis), another subterranean rodent. In comparison to mice and gerbils, we observed alterations in afferent and efferent innervation as well as their patterns of developmental refinement in naked and Damaraland mole rats. These alterations were, however, not always shared similarly between naked and Damaraland mole rats. Most conspicuously, in both naked and Damaraland mole rats, inner hair cell (IHC) afferent ribbon density was reduced, whereas outer hair cell afferent ribbon density was increased. Naked and Damaraland mole rats also showed reduced lateral and medial efferent terminal density. Developmentally, naked mole rats showed reduced and prolonged postnatal reorganization of afferent and efferent innervation. Damaraland mole rats showed no evidence of postnatal reorganization. Differences in cochlear innervation specifically between the two subterranean rodents and more broadly among rodents provides insight into the cochlear mechanisms that enhance frequency sensitivity and sound localization, maturation of the auditory system, and the evolutionary adaptations occurring in response to subterranean environments.
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Affiliation(s)
- Catherine M Barone
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Sytse Douma
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Daniël O J Reijntjes
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Brigitte M Browe
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Christine Köppl
- Cluster of Excellence "Hearing4All", Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Georg Klump
- Cluster of Excellence "Hearing4All", Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Thomas J Park
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Sonja J Pyott
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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26
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Dzal YA, Seow A, Borecky LG, Chung D, Gill SKG, Milsom WK, Pamenter ME. Glutamatergic Receptors Modulate Normoxic but Not Hypoxic Ventilation and Metabolism in Naked Mole Rats. Front Physiol 2019; 10:106. [PMID: 30833905 PMCID: PMC6387965 DOI: 10.3389/fphys.2019.00106] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/28/2019] [Indexed: 11/28/2022] Open
Abstract
Naked mole rats (Heterocephalus glaber) are among the most hypoxia-tolerant mammals, but their physiological responses to acute and chronic sustained hypoxia (CSH), and the molecular underpinnings of these responses, are poorly understood. In the present study we evaluated the acute hypoxic ventilatory response and the occurrence of ventilatory acclimatization to hypoxia following CSH exposure (8–10 days in 8% O2) of naked mole rats. We also investigated the role of excitatory glutamatergic signaling in the control of ventilation and metabolism in these conditions. Animals acclimated to normoxia (control) or CSH and then exposed to acute hypoxia (7% O2 for 1 h) exhibited elevated tidal volume (VT), but decreased breathing frequency (fR). As a result, total ventilation (V.E) remained unchanged. Conversely, VT was lower in CSH animals relative to controls, suggesting that there is ventilatory plasticity following acclimatization to chronic hypoxia. Both control and CSH-acclimated naked mole rats exhibited similar 60–65% decreases in O2 consumption rate during acute hypoxia, and as a result their air convection requirement (ACR) increased ∼2.4 to 3-fold. Glutamatergic receptor inhibition decreased fR, V.E, and the rate of O2 consumption in normoxia but did not alter these ventilatory or metabolic responses to acute hypoxia in either the control or CSH groups. Taken together, these findings indicate that ventilatory acclimatization to hypoxia is atypical in naked mole rats, and glutamatergic signaling is not involved in their hypoxic ventilatory or metabolic responses to acute or chronic hypoxia.
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Affiliation(s)
- Yvonne A Dzal
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada.,Department of Biology, Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, MB, Canada
| | - Allison Seow
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Lisa G Borecky
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Danielle Chung
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Sharn K G Gill
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Matthew E Pamenter
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada.,Department of Biology, University of Ottawa, Ottawa, ON, Canada.,University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
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27
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Delayed Onset of Age-Dependent Changes in Ultrastructure of Myocardial Mitochondria as One of the Neotenic Features in Naked Mole Rats ( Heterocephalus glaber). Int J Mol Sci 2019; 20:ijms20030566. [PMID: 30699925 PMCID: PMC6387357 DOI: 10.3390/ijms20030566] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 11/17/2022] Open
Abstract
In this study, the ultrastructure of mitochondria in cardiomyocytes of naked mole rats (Heterocephalus glaber) aged from 6 months to 11 years was examined. Mitochondria in cardiomyocytes of naked mole rats have a specific ultrastructure that is different from those in cardiomyocytes of other mammalian species studied to date. In contrast to mitochondria of other mammalian cardiomyocytes, where the internal space is completely filled by tightly packed parallel rows of cristae, mitochondria in cardiomyocytes of naked mole rats have a chaotic pattern of cristae organization with wave-like contours. Gradual formation of mitochondrial ultrastructure occurs in naked mole rats for many years. Two mitochondrial populations are developed to the age of 5 years. In addition to the main population, there are some large organelles which exceed normal sizes by two to three times. Most cristae in these mitochondria are assembled into small groups, which form the curved and ring-like structures. The appearance of some specific structural changes (i.e. bundles of parallel cristae) is observed in the mitochondrial population of naked mole rat after 11 years of age. However, these bundles are very rare and of sporadic nature. Morphometric analysis has shown that the superficial density of the inner mitochondrial membrane is similar in all examined age groups of naked mole rats: 21.1 at 6 months; 23.21 at 3 years; 23.55 at 5 years; and 20.8 at 11 years. This level is almost two times lower than in other animals studied (mice and rats). The data demonstrate that pathological changes in mitochondrial apparatus are not present in naked mole rats at least until the age of 11 years. The mitochondrial apparatus corresponds to the phenotype in young animals, thus being another neotenic feature in naked mole rats.
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28
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Recalibrating the Relevance of Adult Neurogenesis. Trends Neurosci 2019; 42:164-178. [PMID: 30686490 DOI: 10.1016/j.tins.2018.12.001] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/28/2018] [Accepted: 12/10/2018] [Indexed: 10/27/2022]
Abstract
Conflicting reports about whether adult hippocampal neurogenesis occurs in humans raise questions about its significance for human health and the relevance of animal models. Drawing upon published data, I review species' neurogenesis rates across the lifespan and propose that accelerated neurodevelopmental timing is consistent with lower rates of neurogenesis in adult primates and humans. Nonetheless, protracted neurogenesis may produce populations of neurons that retain plastic properties for long intervals, and have distinct functions depending on when in the lifespan they were born. With some conceptual recalibration we may therefore be able to reconcile seemingly disparate findings and continue to ask how adult neurogenesis, as studied in animals, is relevant for human health.
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29
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Browe BM, Vice EN, Park TJ. Naked Mole‐Rats: Blind, Naked, and Feeling No Pain. Anat Rec (Hoboken) 2018; 303:77-88. [PMID: 30365235 DOI: 10.1002/ar.23996] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 01/15/2018] [Accepted: 01/24/2018] [Indexed: 01/05/2023]
Affiliation(s)
- Brigitte M. Browe
- Department of Biological Sciences University of Illinois at Chicago, Laboratory of Integrative Neuroscience 840 West Taylor St, Chicago Illinois
| | - Emily N. Vice
- Department of Biological Sciences University of Illinois at Chicago, Laboratory of Integrative Neuroscience 840 West Taylor St, Chicago Illinois
| | - Thomas J. Park
- Department of Biological Sciences University of Illinois at Chicago, Laboratory of Integrative Neuroscience 840 West Taylor St, Chicago Illinois
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30
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Parolisi R, Cozzi B, Bonfanti L. Humans and Dolphins: Decline and Fall of Adult Neurogenesis. Front Neurosci 2018; 12:497. [PMID: 30079011 PMCID: PMC6062615 DOI: 10.3389/fnins.2018.00497] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/02/2018] [Indexed: 02/06/2023] Open
Abstract
Pre-clinical research is carried out on animal models, mostly laboratory rodents, with the ultimate aim of translating the acquired knowledge to humans. In the last decades, adult neurogenesis (AN) has been intensively studied since it is viewed as a tool for fostering brain plasticity, possibly repair. Yet, occurrence, location, and rate of AN vary among mammals: the capability for constitutive neuronal production is substantially reduced when comparing small-brained, short living (laboratory rodents) and large-brained, long-living species (humans, dolphins). Several difficulties concerning scarce availability of fresh tissues, technical limits and ethical concerns did contribute in delaying and diverting the achievement of the picture of neurogenic plasticity in large-brained mammals. Some reports appeared in the last few years, starting to shed more light on this issue. Despite technical limits, data from recent studies mostly converge to indicate that neurogenesis is vestigial, or possibly absent, in regions of the adult human brain where in rodents neuronal addition continues into adult life. Analyses carried out in dolphins, mammals devoid of olfaction, but descendant of ancestors provided with olfaction, has shown disappearance of neurogenesis in both neonatal and adult individuals. Heterogeneity in mammalian structural plasticity remains largely underestimated by scientists focusing their research in rodents. Comparative studies are the key to understand the function of AN and the possible translational significance of neuronal replacement in humans. Here, we summarize comparative studies on AN and discuss the evolutionary implications of variations on the recruitment of new neurons in different regions and different species.
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Affiliation(s)
- Roberta Parolisi
- NICO - Neuroscience Institute Cavalieri Ottolenghi, Turin, Italy
| | - Bruno Cozzi
- Department of Comparative Biomedicine and Food Science, University of Padua, Padua, Italy
| | - Luca Bonfanti
- NICO - Neuroscience Institute Cavalieri Ottolenghi, Turin, Italy.,Department of Veterinary Sciences, University of Turin, Turin, Italy
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31
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Husson Z, Smith ESJ. Naked mole-rat cortical neurons are resistant to acid-induced cell death. Mol Brain 2018; 11:26. [PMID: 29739425 PMCID: PMC5941639 DOI: 10.1186/s13041-018-0369-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 04/27/2018] [Indexed: 01/02/2023] Open
Abstract
Regulation of brain pH is a critical homeostatic process and changes in brain pH modulate various ion channels and receptors and thus neuronal excitability. Tissue acidosis, resulting from hypoxia or hypercapnia, can activate various proteins and ion channels, among which acid-sensing ion channels (ASICs) a family of primarily Na+ permeable ion channels, which alongside classical excitotoxicity causes neuronal death. Naked mole-rats (NMRs, Heterocephalus glaber) are long-lived, fossorial, eusocial rodents that display remarkable behavioral/cellular hypoxia and hypercapnia resistance. In the central nervous system, ASIC subunit expression is similar between mouse and NMR with the exception of much lower expression of ASIC4 throughout the NMR brain. However, ASIC function and neuronal sensitivity to sustained acidosis has not been examined in the NMR brain. Here, we show with whole-cell patch-clamp electrophysiology of cultured NMR and mouse cortical and hippocampal neurons that NMR neurons have smaller voltage-gated Na+ channel currents and more hyperpolarized resting membrane potentials. We further demonstrate that acid-mediated currents in NMR neurons are of smaller magnitude than in mouse, and that all currents in both species are reversibly blocked by the ASIC antagonist benzamil. We further demonstrate that NMR neurons show greater resistance to acid-induced cell death than mouse neurons. In summary, NMR neurons show significant cellular resistance to acidotoxicity compared to mouse neurons, contributing factors likely to be smaller ASIC-mediated currents and reduced NaV activity.
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Affiliation(s)
- Zoé Husson
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Ewan St John Smith
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK.
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32
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Manskikh VN, Averina OA, Nikiforova AI. Spontaneous and Experimentally Induced Pathologies in the Naked Mole Rat (Heterocephalus glaber). BIOCHEMISTRY (MOSCOW) 2018; 82:1504-1512. [PMID: 29486700 PMCID: PMC7088389 DOI: 10.1134/s0006297917120094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The naked mole rat (Heterocephalus glaber, Rüppell, 1842) is a unique eusocial rodent with unusually long lifespan. Therefore, the study of spontaneous and experimentally induced pathologies in these animals is one of the most important tasks of gerontology. Various infections, noninfectious pathologies (including age-dependent changes), and tumors have been described in the naked mole rat. The most frequent pathologies are traumas (bite wounds), purulent and septic complications of traumatic injuries, renal tubular calcinosis, chronic progressive nephropathy, hepatic hemosiderosis, testicular interstitial cell hyperplasia, calcinosis cutis, cardiomyopathy, and dysbiosis-related infectious lesions of the digestive system. However, the summarized data on pathology (including tumor incidence) and on the causes of mortality are insufficient. There are only few publications about the results of experiments where pathologies were induced in the naked mole rat. All these problems could be subjects for promising future studies without which adequate studies on mechanisms providing the long lifespan of the naked mole rat are impossible, as well as the elucidation of causes of tumor resistance of this species.
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Affiliation(s)
- V N Manskikh
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, 119991, Russia.
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33
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Pamenter ME, Dzal YA, Thompson WA, Milsom WK. Do naked mole rats accumulate a metabolic acidosis or an oxygen debt in severe hypoxia? J Exp Biol 2018; 222:jeb.191197. [DOI: 10.1242/jeb.191197] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/18/2018] [Indexed: 01/02/2023]
Abstract
In severe hypoxia, most vertebrates increase anaerobic energy production, which results in the development of a metabolic acidosis and an O2 debt that must be repaid during reoxygenation. Naked mole rats (NMRs) are among the most hypoxia-tolerant mammals, capable of drastically reducing their metabolic rate in acute hypoxia; while staying active and alert. We hypothesized that a key component of remaining active is an increased reliance on anaerobic metabolism during severe hypoxia. To test this hypothesis, we exposed NMRs to progressive reductions in inspired O2 (9 to 3% O2) followed by reoxygenation (21% O2) and measured breathing frequency, heart rate, behavioural activity, body temperature, metabolic rate, and also metabolic substrates and pH in blood and tissues. We found that NMRs exhibit robust metabolic rate depression in acute hypoxia, accompanied by declines in all physiological and behavioural variables examined. However, blood and tissue pH were unchanged and tissue [ATP] and [phosphocreatine] were maintained. Naked mole rats increased their reliance on carbohydrates in hypoxia, and glucose was mobilized from the liver to the blood. Upon reoxygenation NMRs entered into a coma-like state for∼15-20 mins during which metabolic rate was negligible and body temperature remained suppressed. However, an imbalance in the rates at which V̇O2 and V̇CO2 returned to normoxic levels during reoxygenation hint at the possibility that NMRs do utilize anaerobic metabolism during hypoxia but have a tissue and/or blood buffering capacity that mask typical markers of metabolic acidosis, and prioritize the synthesis of glucose from lactate during recovery.
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Affiliation(s)
- Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Yvonne A. Dzal
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
- Department of Biology and Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, MB, Canada
| | - William A. Thompson
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
- Department of Biology, University of Calgary, Calgary, AB, Canada
| | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
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34
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Skulachev MV, Skulachev VP. Programmed aging of mammals: Proof of concept and prospects of biochemical approaches for anti-aging therapy. BIOCHEMISTRY (MOSCOW) 2017; 82:1403-1422. [DOI: 10.1134/s000629791712001x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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35
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Grimes KM, Barefield DY, Kumar M, McNamara JW, Weintraub ST, de Tombe PP, Sadayappan S, Buffenstein R. The naked mole-rat exhibits an unusual cardiac myofilament protein profile providing new insights into heart function of this naturally subterranean rodent. Pflugers Arch 2017; 469:1603-1613. [PMID: 28780592 PMCID: PMC5856255 DOI: 10.1007/s00424-017-2046-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 06/27/2017] [Accepted: 07/23/2017] [Indexed: 02/08/2023]
Abstract
The long-lived, hypoxic-tolerant naked mole-rat well-maintains cardiac function over its three-decade-long lifespan and exhibits many cardiac features atypical of similar-sized laboratory rodents. For example, they exhibit low heart rates and resting cardiac contractility, yet have a large cardiac reserve. These traits are considered ecophysiological adaptations to their dank subterranean atmosphere of low oxygen and high carbon dioxide levels and may also contribute to negligible declines in cardiac function during aging. We asked if naked mole-rats had a different myofilament protein signature to that of similar-sized mice that commonly show both high heart rates and high basal cardiac contractility. Adult mouse ventricles predominantly expressed α-myosin heavy chain (97.9 ± 0.4%). In contrast, and more in keeping with humans, β myosin heavy chain was the dominant isoform (79.0 ± 2.0%) in naked mole-rat ventricles. Naked mole-rat ventricles diverged from those of both humans and mice, as they expressed both cardiac and slow skeletal isoforms of troponin I. This myofilament protein profile is more commonly observed in mice in utero and during cardiomyopathies. There were no species differences in phosphorylation of cardiac myosin binding protein-C or troponin I. Phosphorylation of both ventricular myosin light chain 2 and cardiac troponin T in naked mole-rats was approximately half that observed in mice. Myofilament function was also compared between the two species using permeabilized cardiomyocytes. Together, these data suggest a cardiac myofilament protein signature that may contribute to the naked mole-rat's suite of adaptations to its natural subterranean habitat.
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Affiliation(s)
- Kelly M Grimes
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Sam and Ann Barshop Institute for Aging and Longevity Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - David Y Barefield
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL, USA
- Center for Genetic Medicine, Northwestern University, Chicago, IL, USA
| | - Mohit Kumar
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL, USA
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH, USA
| | - James W McNamara
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH, USA
| | - Susan T Weintraub
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Pieter P de Tombe
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL, USA
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL, USA
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH, USA
| | - Rochelle Buffenstein
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Sam and Ann Barshop Institute for Aging and Longevity Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Calico Life Sciences, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA.
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36
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Smith LK, White CW, Villeda SA. The systemic environment: at the interface of aging and adult neurogenesis. Cell Tissue Res 2017; 371:105-113. [PMID: 29124393 PMCID: PMC5748432 DOI: 10.1007/s00441-017-2715-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/09/2017] [Indexed: 02/06/2023]
Abstract
Aging results in impaired neurogenesis in the two neurogenic niches of the adult mammalian brain, the dentate gyrus of the hippocampus and the subventricular zone of the lateral ventricle. While significant work has characterized intrinsic cellular changes that contribute to this decline, it is increasingly apparent that the systemic environment also represents a critical driver of brain aging. Indeed, emerging studies utilizing the model of heterochronic parabiosis have revealed that immune-related molecular and cellular changes in the aging systemic environment negatively regulate adult neurogenesis. Interestingly, these studies have also demonstrated that age-related decline in neurogenesis can be ameliorated by exposure to the young systemic environment. While this burgeoning field of research is increasingly garnering interest, as yet, the precise mechanisms driving either the pro-aging effects of aged blood or the rejuvenating effects of young blood remain to be thoroughly defined. Here, we review how age-related changes in blood, blood-borne factors, and peripheral immune cells contribute to the age-related decline in adult neurogenesis in the mammalian brain, and posit both direct neural stem cell and indirect neurogenic niche-mediated mechanisms.
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Affiliation(s)
- Lucas K Smith
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, 94143, USA.,The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA, 94143, USA.,Biomedical Sciences Graduate Program, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Charles W White
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, 94143, USA.,The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA, 94143, USA.,Developmental and Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Saul A Villeda
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, 94143, USA. .,The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, San Francisco, CA, 94143, USA. .,Biomedical Sciences Graduate Program, University of California San Francisco, San Francisco, CA, 94143, USA. .,Developmental and Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, 94143, USA.
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37
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Oosthuizen MK. From Mice to Mole-Rats: Species-Specific Modulation of Adult Hippocampal Neurogenesis. Front Neurosci 2017; 11:602. [PMID: 29163007 PMCID: PMC5670158 DOI: 10.3389/fnins.2017.00602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 10/16/2017] [Indexed: 11/23/2022] Open
Abstract
Rodent populations living in their natural environments have very diverse ecological and life history profiles that may differ substantially from that of conventional laboratory rodents. Free-living rodents show species-specific neurogenesis that are dependent on their unique biology and ecology. This perspective aims to illustrate the benefit of studying wild rodent species in conjunction with laboratory rodents. African mole-rats are discussed in terms of habitat complexity, social structures, and longevity. African mole-rats are a group of subterranean rodents, endemic to Africa, that show major differences in both intrinsic and extrinsic traits compared to the classical rodent models. Mole-rats exhibit a spectrum of sociality within a single family, ranging from solitary to eusocial. This continuum of sociality provides a platform for comparative testing of hypotheses. Indeed, species differences are apparent both in learning ability and hippocampal neurogenesis. In addition, social mole-rat species display a reproductive division of labor that also results in differential hippocampal neurogenesis, independent of age, offering further scope for comparison. In conclusion, it is evident that neurogenesis studies on conventional laboratory rodents are not necessarily representative, specifically because of a lack of diversity in life histories, uniform habitats, and low genetic variability. The observed level of adult neurogenesis in the dentate gyrus is the result of an intricate balance between many contributing factors, which appear to be specific to distinct groups of animals. The ultimate understanding of the functional and adaptive role of adult neurogenesis will involve research on both laboratory animals and natural rodent populations.
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Affiliation(s)
- Maria K Oosthuizen
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
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38
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Lipp HP. Evolutionary Shaping of Adult Hippocampal Neurogenesis in Mammals-Cognitive Gain or Developmental Priming of Personality Traits? Front Neurosci 2017; 11:420. [PMID: 28785199 PMCID: PMC5519572 DOI: 10.3389/fnins.2017.00420] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 07/05/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Hans-Peter Lipp
- Institute of Evolutionary Medicine, University of ZurichZurich, Switzerland.,Institute of Anatomy, University of ZurichZurich, Switzerland.,Department of Physiology, School of Laboratory Medicine, University of Kwazulu-NatalDurban, South Africa
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39
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Skulachev VP, Holtze S, Vyssokikh MY, Bakeeva LE, Skulachev MV, Markov AV, Hildebrandt TB, Sadovnichii VA. Neoteny, Prolongation of Youth: From Naked Mole Rats to “Naked Apes” (Humans). Physiol Rev 2017; 97:699-720. [DOI: 10.1152/physrev.00040.2015] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
It has been suggested that highly social mammals, such as naked mole rats and humans, are long-lived due to neoteny (the prolongation of youth). In both species, aging cannot operate as a mechanism facilitating natural selection because the pressure of this selection is strongly reduced due to 1) a specific social structure where only the “queen” and her “husband(s)” are involved in reproduction (naked mole rats) or 2) substituting fast technological progress for slow biological evolution (humans). Lists of numerous traits of youth that do not disappear with age in naked mole rats and humans are presented and discussed. A high resistance of naked mole rats to cancer, diabetes, cardiovascular and brain diseases, and many infections explains why their mortality rate is very low and almost age-independent and why their lifespan is more than 30 years, versus 3 years in mice. In young humans, curves of mortality versus age start at extremely low values. However, in the elderly, human mortality strongly increases. High mortality rates in other primates are observed at much younger ages than in humans. The inhibition of the aging process in humans by specific drugs seems to be a promising approach to prolong our healthspan. This might be a way to retard aging, which is already partially accomplished via the natural physiological phenomenon neoteny.
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Affiliation(s)
- Vladimir P. Skulachev
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, Russia; Lomonosov Moscow State University, Institute of Mitoengineering, Moscow, Russia; Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Lomonosov Moscow State University, Biological Faculty, Moscow, Russia; Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow, Russia
| | - Susanne Holtze
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, Russia; Lomonosov Moscow State University, Institute of Mitoengineering, Moscow, Russia; Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Lomonosov Moscow State University, Biological Faculty, Moscow, Russia; Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow, Russia
| | - Mikhail Y. Vyssokikh
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, Russia; Lomonosov Moscow State University, Institute of Mitoengineering, Moscow, Russia; Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Lomonosov Moscow State University, Biological Faculty, Moscow, Russia; Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow, Russia
| | - Lora E. Bakeeva
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, Russia; Lomonosov Moscow State University, Institute of Mitoengineering, Moscow, Russia; Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Lomonosov Moscow State University, Biological Faculty, Moscow, Russia; Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow, Russia
| | - Maxim V. Skulachev
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, Russia; Lomonosov Moscow State University, Institute of Mitoengineering, Moscow, Russia; Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Lomonosov Moscow State University, Biological Faculty, Moscow, Russia; Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow, Russia
| | - Alexander V. Markov
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, Russia; Lomonosov Moscow State University, Institute of Mitoengineering, Moscow, Russia; Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Lomonosov Moscow State University, Biological Faculty, Moscow, Russia; Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow, Russia
| | - Thomas B. Hildebrandt
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, Russia; Lomonosov Moscow State University, Institute of Mitoengineering, Moscow, Russia; Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Lomonosov Moscow State University, Biological Faculty, Moscow, Russia; Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow, Russia
| | - Viktor A. Sadovnichii
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, Russia; Lomonosov Moscow State University, Institute of Mitoengineering, Moscow, Russia; Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Lomonosov Moscow State University, Biological Faculty, Moscow, Russia; Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow, Russia
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Anisotropically organized three-dimensional culture platform for reconstruction of a hippocampal neural network. Nat Commun 2017; 8:14346. [PMID: 28146148 PMCID: PMC5296669 DOI: 10.1038/ncomms14346] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 12/19/2016] [Indexed: 01/06/2023] Open
Abstract
In native tissues, cellular and acellular components are anisotropically organized and often aligned in specific directions, providing structural and mechanical properties for actuating biological functions. Thus, engineering alignment not only allows for emulation of native tissue structures but might also enable implementation of specific functionalities. However, achieving desired alignment is challenging, especially in three-dimensional constructs. By exploiting the elastomeric property of polydimethylsiloxane and fibrillogenesis kinetics of collagen, here we introduce a simple yet effective method to assemble and align fibrous structures in a multi-modular three-dimensional conglomerate. Applying this method, we have reconstructed the CA3–CA1 hippocampal neural circuit three-dimensionally in a monolithic gel, in which CA3 neurons extend parallel axons to and synapse with CA1 neurons. Furthermore, we show that alignment of the fibrous scaffold facilitates the establishment of functional connectivity. This method can be applied for reconstructing other neural circuits or tissue units where anisotropic organization in a multi-modular structure is desired. Alignment or anisotropic organisation within and between cells enables biological function but is challenging to engineer. Here, the authors align collagen fibres in a pre-strained polydimethylsiloxane mould to generate a 3D scaffold that guides hippocampal neuron axon growth to form CA3–CA1 neural circuits.
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Chung D, Dzal YA, Seow A, Milsom WK, Pamenter ME. Naked mole rats exhibit metabolic but not ventilatory plasticity following chronic sustained hypoxia. Proc Biol Sci 2016; 283:20160216. [PMID: 27009224 DOI: 10.1098/rspb.2016.0216] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 02/25/2016] [Indexed: 02/03/2023] Open
Abstract
Naked mole rats are among the most hypoxia-tolerant mammals identified and live in chronic hypoxia throughout their lives. The physiological mechanisms underlying this tolerance, however, are poorly understood. Most vertebrates hyperventilate in acute hypoxia and exhibit an enhanced hyperventilation following acclimatization to chronic sustained hypoxia (CSH). Conversely, naked mole rats do not hyperventilate in acute hypoxia and their response to CSH has not been examined. In this study, we explored mechanisms of plasticity in the control of the hypoxic ventilatory response (HVR) and hypoxic metabolic response (HMR) of freely behaving naked mole rats following 8-10 days of chronic sustained normoxia (CSN) or CSH. Specifically, we investigated the role of the major inhibitory neurotransmitter γ-amino butyric acid (GABA) in mediating these responses. Our study yielded three important findings. First, naked mole rats did not exhibit ventilatory plasticity following CSH, which is unique among adult animals studied to date. Second, GABA receptor (GABAR) antagonism altered breathing patterns in CSN and CSH animals and modulated the acute HVR in CSN animals. Third, naked mole rats exhibited GABAR-dependent metabolic plasticity following long-term hypoxia, such that the basal metabolic rate was approximately 25% higher in normoxic CSH animals than CSN animals, and GABAR antagonists modulated this increase.
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Affiliation(s)
- Danielle Chung
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yvonne A Dzal
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Allison Seow
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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Orr ME, Garbarino VR, Salinas A, Buffenstein R. Extended Postnatal Brain Development in the Longest-Lived Rodent: Prolonged Maintenance of Neotenous Traits in the Naked Mole-Rat Brain. Front Neurosci 2016; 10:504. [PMID: 27877105 PMCID: PMC5099538 DOI: 10.3389/fnins.2016.00504] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/21/2016] [Indexed: 11/24/2022] Open
Abstract
The naked mole-rat (NMR) is the longest-lived rodent with a maximum lifespan >31 years. Intriguingly, fully-grown naked mole-rats (NMRs) exhibit many traits typical of neonatal rodents. However, little is known about NMR growth and maturation, and we question whether sustained neotenous features when compared to mice, reflect an extended developmental period, commensurate with their exceptionally long life. We tracked development from birth to 3 years of age in the slowest maturing organ, the brain, by measuring mass, neural stem cell proliferation, axonal, and dendritic maturation, synaptogenesis and myelination. NMR brain maturation was compared to data from similar sized rodents, mice, and to that of long-lived mammals, humans, and non-human primates. We found that at birth, NMR brains are significantly more developed than mice, and rather are more similar to those of newborn primates, with clearly laminated hippocampi and myelinated white matter tracts. Despite this more mature brain at birth than mice, postnatal NMR brain maturation occurs at a far slower rate than mice, taking four-times longer than required for mice to fully complete brain development. At 4 months of age, NMR brains reach 90% of adult size with stable neuronal cytostructural protein expression whereas myelin protein expression does not plateau until 9 months of age in NMRs, and synaptic protein expression continues to change throughout the first 3 years of life. Intriguingly, NMR axonal composition is more similar to humans than mice whereby NMRs maintain expression of three-repeat (3R) tau even after brain growth is complete; mice experience an abrupt downregulation of 3R tau by postnatal day 8 which continues to diminish through 6 weeks of age. We have identified key ages in NMR cerebral development and suggest that the long-lived NMR may provide neurobiologists an exceptional model to study brain developmental processes that are compressed in common short-lived laboratory animal models.
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Affiliation(s)
- Miranda E Orr
- Department of Physiology, University of Texas Health Science Center at San AntonioSan Antonio, TX, USA; The Barshop Institute for Longevity, Aging Studies, University of Texas Health Science Center at San AntonioSan Antonio, TX, USA
| | - Valentina R Garbarino
- Department of Physiology, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - Angelica Salinas
- Department of Physiology, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - Rochelle Buffenstein
- Department of Physiology, University of Texas Health Science Center at San AntonioSan Antonio, TX, USA; The Barshop Institute for Longevity, Aging Studies, University of Texas Health Science Center at San AntonioSan Antonio, TX, USA; Calico Life Sciences LLCSouth San Francisco, CA, USA
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Lipp HP, Bonfanti L. Adult Neurogenesis in Mammals: Variations and Confusions. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:205-221. [DOI: 10.1159/000446905] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mammalian adult neurogenesis has remained enigmatic. Two lines of research have emerged. One focuses on a potential repair mechanism in the human brain. The other aims at elucidating its functional role in the hippocampal formation, chiefly in cognitive processes; however, thus far it has been unsuccessful. Here, we try to recognize the sources of errors and conceptual confusion in comparative studies and neurobehavioral approaches with a focus on mice. Evolutionarily, mammalian adult neurogenesis appears as protracted juvenile neurogenesis originating from precursor cells in the secondary proliferation zones, from where newly formed cells migrate to target regions in the forebrain. This late developmental process is downregulated differentially in various brain structures depending on species and age. Adult neurogenesis declines substantially during early adulthood and persists at low levels into senescence. Short-lasting episodes in proliferation or reduction of adult neurogenesis may reflect a multitude of factors, and have been studied chiefly in mice and rats. Comparative studies face both species-specific variations in staining and technical abilities of laboratories, lacking quantification of important reference measures (e.g. granule cell number) and evaluation of maturational markers whose persistence might be functionally more relevant than proliferation rates. Likewise, the confusion about the functional role of variations in adult hippocampal neurogenesis has many causes. Prominent is an inferential statistical approach, usually with low statistical power. Interpretation is complicated by multiple theories about hippocampal function, often unrealistically extrapolating from humans to rodents. We believe that the field of mammalian adult neurogenesis needs more critical thinking, more sophisticated hypotheses, better statistical, technical and behavioral approaches, and a broader conceptual perspective incorporating comparative aspects rather than neglecting them.
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Trading new neurons for status: Adult hippocampal neurogenesis in eusocial Damaraland mole-rats. Neuroscience 2016; 324:227-37. [DOI: 10.1016/j.neuroscience.2016.03.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 02/19/2016] [Accepted: 03/07/2016] [Indexed: 11/21/2022]
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Triplett JC, Swomley AM, Kirk J, Grimes KM, Lewis KN, Orr ME, Rodriguez KA, Cai J, Klein JB, Buffenstein R, Butterfield DA. Reaching Out to Send a Message: Proteins Associated with Neurite Outgrowth and Neurotransmission are Altered with Age in the Long-Lived Naked Mole-Rat. Neurochem Res 2016; 41:1625-34. [DOI: 10.1007/s11064-016-1877-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Revised: 02/06/2016] [Accepted: 02/18/2016] [Indexed: 10/22/2022]
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