1
|
Theotokis P, Manthou ME, Deftereou TE, Miliaras D, Meditskou S. Addressing Spaceflight Biology through the Lens of a Histologist-Embryologist. Life (Basel) 2023; 13:life13020588. [PMID: 36836946 PMCID: PMC9965490 DOI: 10.3390/life13020588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 02/09/2023] [Accepted: 02/14/2023] [Indexed: 02/23/2023] Open
Abstract
Embryogenesis and fetal development are highly delicate and error-prone processes in their core physiology, let alone if stress-associated factors and conditions are involved. Space radiation and altered gravity are factors that could radically affect fertility and pregnancy and compromise a physiological organogenesis. Unfortunately, there is a dearth of information examining the effects of cosmic exposures on reproductive and proliferating outcomes with regard to mammalian embryonic development. However, explicit attention has been given to investigations exploring discrete structures and neural networks such as the vestibular system, an entity that is viewed as the sixth sense and organically controls gravity beginning with the prenatal period. The role of the gut microbiome, a newly acknowledged field of research in the space community, is also being challenged to be added in forthcoming experimental protocols. This review discusses the data that have surfaced from simulations or actual space expeditions and addresses developmental adaptations at the histological level induced by an extraterrestrial milieu.
Collapse
Affiliation(s)
- Paschalis Theotokis
- Laboratory of Histology and Embryology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Maria Eleni Manthou
- Laboratory of Histology and Embryology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | | | - Dimosthenis Miliaras
- Laboratory of Histology and Embryology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Soultana Meditskou
- Laboratory of Histology and Embryology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Correspondence:
| |
Collapse
|
2
|
Najrana T, Sanchez-Esteban J. Mechanotransduction as an Adaptation to Gravity. Front Pediatr 2016; 4:140. [PMID: 28083527 PMCID: PMC5183626 DOI: 10.3389/fped.2016.00140] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 12/12/2016] [Indexed: 12/22/2022] Open
Abstract
Gravity has played a critical role in the development of terrestrial life. A key event in evolution has been the development of mechanisms to sense and transduce gravitational force into biological signals. The objective of this manuscript is to review how living organisms on Earth use mechanotransduction as an adaptation to gravity. Certain cells have evolved specialized structures, such as otoliths in hair cells of the inner ear and statoliths in plants, to respond directly to the force of gravity. By conducting studies in the reduced gravity of spaceflight (microgravity) or simulating microgravity in the laboratory, we have gained insights into how gravity might have changed life on Earth. We review how microgravity affects prokaryotic and eukaryotic cells at the cellular and molecular levels. Genomic studies in yeast have identified changes in genes involved in budding, cell polarity, and cell separation regulated by Ras, PI3K, and TOR signaling pathways. Moreover, transcriptomic analysis of late pregnant rats have revealed that microgravity affects genes that regulate circadian clocks, activate mechanotransduction pathways, and induce changes in immune response, metabolism, and cells proliferation. Importantly, these studies identified genes that modify chromatin structure and methylation, suggesting that long-term adaptation to gravity may be mediated by epigenetic modifications. Given that gravity represents a modification in mechanical stresses encounter by the cells, the tensegrity model of cytoskeletal architecture provides an excellent paradigm to explain how changes in the balance of forces, which are transmitted across transmembrane receptors and cytoskeleton, can influence intracellular signaling pathways and gene expression.
Collapse
Affiliation(s)
- Tanbir Najrana
- Department of Pediatrics, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island , Providence, RI , USA
| | - Juan Sanchez-Esteban
- Department of Pediatrics, Alpert Medical School of Brown University, Women & Infants Hospital of Rhode Island , Providence, RI , USA
| |
Collapse
|
3
|
Branoner F, Chagnaud BP, Straka H. Ontogenetic Development of Vestibulo-Ocular Reflexes in Amphibians. Front Neural Circuits 2016; 10:91. [PMID: 27877114 PMCID: PMC5099239 DOI: 10.3389/fncir.2016.00091] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 10/24/2016] [Indexed: 12/23/2022] Open
Abstract
Vestibulo-ocular reflexes (VOR) ensure gaze stability during locomotion and passively induced head/body movements. In precocial vertebrates such as amphibians, vestibular reflexes are required very early at the onset of locomotor activity. While the formation of inner ears and the assembly of sensory-motor pathways is largely completed soon after hatching, angular and translational/tilt VOR display differential functional onsets and mature with different time courses. Otolith-derived eye movements appear immediately after hatching, whereas the appearance and progressive amelioration of semicircular canal-evoked eye movements is delayed and dependent on the acquisition of sufficiently large semicircular canal diameters. Moreover, semicircular canal functionality is also required to tune the initially omnidirectional otolith-derived VOR. The tuning is due to a reinforcement of those vestibulo-ocular connections that are co-activated by semicircular canal and otolith inputs during natural head/body motion. This suggests that molecular mechanisms initially guide the basic ontogenetic wiring, whereas semicircular canal-dependent activity is required to establish the spatio-temporal specificity of the reflex. While a robust VOR is activated during passive head/body movements, locomotor efference copies provide the major source for compensatory eye movements during tail- and limb-based swimming of larval and adult frogs. The integration of active/passive motion-related signals for gaze stabilization occurs in central vestibular neurons that are arranged as segmentally iterated functional groups along rhombomere 1–8. However, at variance with the topographic maps of most other sensory systems, the sensory-motor transformation of motion-related signals occurs in segmentally specific neuronal groups defined by the extraocular motor output targets.
Collapse
Affiliation(s)
- Francisco Branoner
- Department Biology II, Ludwig-Maximilians-University Munich Munich, Germany
| | - Boris P Chagnaud
- Department Biology II, Ludwig-Maximilians-University Munich Munich, Germany
| | - Hans Straka
- Department Biology II, Ludwig-Maximilians-University Munich Munich, Germany
| |
Collapse
|
4
|
Branoner F, Straka H. Semicircular canal-dependent developmental tuning of translational vestibulo-ocular reflexes in Xenopus laevis. Dev Neurobiol 2014; 75:1051-67. [PMID: 25266079 DOI: 10.1002/dneu.22234] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 09/04/2014] [Accepted: 09/25/2014] [Indexed: 02/03/2023]
Abstract
Gaze stabilization during head/body movements is achieved to a large extent by vestibular-evoked compensatory eye movements. These reflexes derive from semicircular canal and otolith organs and depend on the transformation of the respective sensory signals into extraocular motor commands. To elicit directionally and dynamically appropriate compensatory eye movements, extraocular motoneurons require spatiotemporally specific inputs from semicircular canals and regions of the utricular epithelium with matching directional sensitivity. The ontogenetic establishment and maturation of the directional tuning of otolith inputs in extraocular motoneurons was studied in Xenopus laevis tadpoles. In young larvae at stage 46-48, superior oblique (SO) extraocular motoneurons receive omnidirectional utricular signals during horizontal translational motion, indicating an absence of spatial tuning. In contrast, in older larvae beyond stage 49 these motoneurons were activated by directionally more restricted otolith inputs with an increasingly enhanced spatial tuning until stage 53. This developmental process limited the origin of otolith signals to a utricular epithelial sector with a hair cell sensitivity that is coaligned with the pulling direction of the SO eye muscle. The maturation of the otolith response vector was abolished by enzymatic prevention of semicircular canal formation in postembryonic tadpoles at stage 44, suggesting that functionally intact semicircular canals are causally responsible for the observed directional tuning of utricular responses. A likely mechanism by which semicircular canals might influence the tuning of the otolith responses includes stabilization of coactivated and centrally converging sensory signals from semicircular canal and spatially aligned epithelial utricular regions during natural head/body motion.
Collapse
Affiliation(s)
- Francisco Branoner
- Department Biology II, Ludwig-Maximilians-University Munich, Großhaderner Str. 2, 82152, Planegg, Germany
| | - Hans Straka
- Department Biology II, Ludwig-Maximilians-University Munich, Großhaderner Str. 2, 82152, Planegg, Germany
| |
Collapse
|
5
|
Jamon M. The development of vestibular system and related functions in mammals: impact of gravity. Front Integr Neurosci 2014; 8:11. [PMID: 24570658 PMCID: PMC3916785 DOI: 10.3389/fnint.2014.00011] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 01/20/2014] [Indexed: 12/12/2022] Open
Abstract
This chapter reviews the knowledge about the adaptation to Earth gravity during the development of mammals. The impact of early exposure to altered gravity is evaluated at the level of the functions related to the vestibular system, including postural control, homeostatic regulation, and spatial memory. The hypothesis of critical periods in the adaptation to gravity is discussed. Demonstrating a critical period requires removing the gravity stimulus during delimited time windows, what is impossible to do on Earth surface. The surgical destruction of the vestibular apparatus, and the use of mice strains with defective graviceptors have provided useful information on the consequences of missing gravity perception, and the possible compensatory mechanisms, but transitory suppression of the stimulus can only be operated during spatial flight. The rare studies on rat pups housed on board of space shuttle significantly contributed to this problem, but the use of hypergravity environment, produced by means of chronic centrifugation, is the only available tool when repeated experiments must be carried out on Earth. Even though hypergravity is sometimes considered as a mirror situation to microgravity, the two situations cannot be confused because a gravitational force is still present. The theoretical considerations that validate the paradigm of hypergravity to evaluate critical periods are discussed. The question of adaption of graviceptor is questioned from an evolutionary point of view. It is possible that graviception is hardwired, because life on Earth has evolved under the constant pressure of gravity. The rapid acquisition of motor programming by precocial mammals in minutes after birth is consistent with this hypothesis, but the slow development of motor skills in altricial species and the plasticity of vestibular perception in adults suggest that gravity experience is required for the tuning of graviceptors. The possible reasons for this dichotomy are discussed.
Collapse
Affiliation(s)
- Marc Jamon
- Faculté de Médecine de la Timone, Institut National de la Santé et de la Recherche Médicale U 1106, Aix-Marseille University Marseille, France
| |
Collapse
|
6
|
Kim WY. NeuroD regulates neuronal migration. Mol Cells 2013; 35:444-9. [PMID: 23652629 PMCID: PMC3887861 DOI: 10.1007/s10059-013-0065-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 03/13/2013] [Accepted: 03/18/2013] [Indexed: 01/24/2023] Open
Abstract
NeuroD is required for the survival of many subtypes of developing neurons in the vertebrate central nervous system. Because NeuroD-deficient neurons in the hippocampus, cerebellum, and inner ear die prematurely in the early stage of neurogenesis, the role of NeuroD during the later stages of neurogenesis of these cell subtypes is not well understood. In addition, the mechanism of NeuroDdeficient neuronal death has not been investigated. It was hypothesized that NeuroD-dependent neuronal death occurs through a Bax-dependent apoptotic pathway. Based on this hypothesis, this study attempted to rescue neuronal cell death by deleting the Bax gene in NeuroD null mice to investigate the role of NeuroD in surviving neurons. The NeuroD and Bax double null mice displayed a decrease in the number of apoptotic cells in the hippocampus and the cerebellum and the rescue of vestibulocochlear ganglion (VCG) neurons that failed to migrate and innervate. In addition, at E13.5, the NeuroD(-/-)Bax(-/-) VCG neurons failed to express TrkB and TrkC, which are known to be essential for the survival of those neurons. These data suggest that neuronal death in NeuroD null mice is mediated by Bax-dependent apoptosis and that NeuroD is required for the migration of VCG neurons. Finally, these data show that TrkB and TrkC expression in E13.5 VCG neurons requires NeuroD and that TrkB and TrkC expression may be necessary for the normal migration and innervations of those neurons.
Collapse
Affiliation(s)
- Woo-Young Kim
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Aurora, CO, 80309, USA.
| |
Collapse
|
7
|
Neto FL, Borges G, Torres-Sanchez S, Mico JA, Berrocoso E. Neurotrophins role in depression neurobiology: a review of basic and clinical evidence. Curr Neuropharmacol 2012; 9:530-52. [PMID: 22654714 PMCID: PMC3263450 DOI: 10.2174/157015911798376262] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Revised: 08/18/2010] [Accepted: 08/09/2010] [Indexed: 01/02/2023] Open
Abstract
Depression is a neuropsychiatric disorder affecting a huge percentage of the active population especially in developed countries. Research has devoted much of its attention to this problematic and many drugs have been developed and are currently prescribed to treat this pathology. Yet, many patients are refractory to the available therapeutic drugs, which mainly act by increasing the levels of the monoamines serotonin and noradrenaline in the synaptic cleft. Even in the cases antidepressants are effective, it is usually observed a delay of a few weeks between the onset of treatment and remission of the clinical symptoms. Additionally, many of these patients who show remission with antidepressant therapy present a relapse of depression upon treatment cessation. Thus research has focused on other possible molecular targets, besides monoamines, underlying depression. Both basic and clinical evidence indicates that depression is associated with
several structural and neurochemical changes where the levels of neurotrophins, particularly of brain-derived neurotrophic factor (BDNF), are altered. Antidepressants, as well as other therapeutic strategies, seem to restore these levels. Neuronal atrophy, mostly detected in limbic structures that regulate mood and cognition, like the hippocampus, is observed in depressed patients and in animal behavioural paradigms for depression. Moreover, chronic antidepressant treatment enhances adult hippocampal neurogenesis, supporting the notion that this event underlies antidepressants effects. Here we review some of the preclinical and clinical studies, aimed at disclosing the role of neurotrophins in the pathophysiological
mechanisms of depression and the mode of action of antidepressants, which favour the neurotrophic/neurogenic hypothesis.
Collapse
Affiliation(s)
- Fani L Neto
- Instituto de Histologia e Embriologia, Faculdade de Medicina e IBMC, Universidade do Porto, 4200-319, Porto, Portugal
| | | | | | | | | |
Collapse
|
8
|
Beraneck M, Bojados M, Le Séac'h A, Jamon M, Vidal PP. Ontogeny of mouse vestibulo-ocular reflex following genetic or environmental alteration of gravity sensing. PLoS One 2012; 7:e40414. [PMID: 22808156 PMCID: PMC3393735 DOI: 10.1371/journal.pone.0040414] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 06/07/2012] [Indexed: 11/28/2022] Open
Abstract
The vestibular organs consist of complementary sensors: the semicircular canals detect rotations while the otoliths detect linear accelerations, including the constant pull of gravity. Several fundamental questions remain on how the vestibular system would develop and/or adapt to prolonged changes in gravity such as during long-term space journey. How do vestibular reflexes develop if the appropriate assembly of otoliths and semi-circular canals is perturbed? The aim of present work was to evaluate the role of gravity sensing during ontogeny of the vestibular system. In otoconia-deficient mice (ied), gravity cannot be sensed and therefore maculo-ocular reflexes (MOR) were absent. While canals-related reflexes were present, the ied deficit also led to the abnormal spatial tuning of the horizontal angular canal-related VOR. To identify putative otolith-related critical periods, normal C57Bl/6J mice were subjected to 2G hypergravity by chronic centrifugation during different periods of development or adulthood (Adult-HG) and compared to non-centrifuged (control) C57Bl/6J mice. Mice exposed to hypergravity during development had completely normal vestibulo-ocular reflexes 6 months after end of centrifugation. Adult-HG mice all displayed major abnormalities in maculo-ocular reflexe one month after return to normal gravity. During the next 5 months, adaptation to normal gravity occurred in half of the individuals. In summary, genetic suppression of gravity sensing indicated that otolith-related signals might be necessary to ensure proper functioning of canal-related vestibular reflexes. On the other hand, exposure to hypergravity during development was not sufficient to modify durably motor behaviour. Hence, 2G centrifugation during development revealed no otolith-specific critical period.
Collapse
Affiliation(s)
- Mathieu Beraneck
- CNRS UMR 8194, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
| | | | | | | | | |
Collapse
|
9
|
Sajdel-Sulkowska EM. Brain development, environment and sex: what can we learn from studying graviperception, gravitransduction and the gravireaction of the developing CNS to altered gravity? THE CEREBELLUM 2009; 7:223-39. [PMID: 18418693 DOI: 10.1007/s12311-008-0001-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
As man embarks on space exploration and contemplates space habitation, there is a critical need for basic understanding of the impact of the environmental factors of space, and in particular gravity, on human survival, health, reproduction and development. This review summarizes our present knowledge on the effect of altered gravity on the developing CNS with respect to the response of the developing CNS to altered gravity (gravireaction), the physiological changes associated with altered gravity that could contribute to this effect (gravitransduction), and the possible mechanisms involved in the detection of altered gravity (graviperception). Some of these findings transcend gravitational research and are relevant to our understanding of the impact of environmental factors on CNS development on Earth.
Collapse
|