Effects of Sustained Acceleration on the Morphological Properties of Otoconia in Hamsters

Sondag, H.N.P.M.; Jong, H.A.A. de; Marle, J. van; Oosterveld, W. J.

doi:10.3109/00016489509139297

Cited by 27 publications

(13 citation statements)

References 9 publications

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“…This process was observed in different species including snails (Wiederhold et al, 2003a), aplysia (Pedrozo et al, 1996), fish (Wiederhold et al, 1997; Anken et al, 2001, 2002a,b; Wiederhold et al, 2003a,b), Xenopus (Lychakov and Lavrova, 1985), chicken (Hara et al, 1995), hamsters (Sondag et al, 1996), rats (Lim et al, 1974; Krasnov, 1991). At variance the otoconia of animals exposed to altered gravity at maturity did not show any change (Lim et al, 1974; Ross et al, 1985; Hara et al, 1995; Sondag et al, 1995). Some of these results supported the existence of a critical period during the development of otoliths (Wiederhold et al, 2003a,b).…”

Section: Effects Of Altered Gravity On the Development Of Gravity Senmentioning

confidence: 99%

The development of vestibular system and related functions in mammals: impact of gravity

Jamon

2014

Front. Integr. Neurosci.

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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.

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Section: Effects Of Altered Gravity On the Development Of Gravity Senmentioning

confidence: 99%

The development of vestibular system and related functions in mammals: impact of gravity

Jamon

2014

Front. Integr. Neurosci.

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“…The following complementary tests are commonly used to detect balance deficits manifested in postural control, spatial orientation, and sensorimotor function and coordination (Trune and Lim 1983;Sondag et al 1995Sondag et al , 1996Sondag et al , 1998Sondag et al , 1999Ying et al 1999;Jones et al 2004;Walton et al 2005;Rampello and Drago 1999;Hamm 2001;Sajdel-Sulkowska et al 2005). Severe abnormalities in the gravity receptor organ often lead to abnormal air-righting reflexes, irregular and wider gaits, compromised ability to swim, or shortened stay on the rotorod (Trune and Lim 1983;Ying et al 1999;Rampello and Drago 1999;Hamm 2001;Jones et al 2004).…”

Section: Tests For Imbalance Behaviorsmentioning

confidence: 99%

Osteopontin is not Critical for Otoconia Formation or Balance Function

Zhao

Jones

Thoreson

et al. 2008

JARO

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Unlike the structural and mechanical role of bone crystals, the inertial mass of otoconia crystals provides a shearing force to stimulate the mechanoreceptors of the utricle and saccule (the gravity receptor organ) under the stimuli of linear motion. It is not clear whether otoconia, composed primarily of CaCO 3 and glycoproteins, go through similar calcification processes as bone. We have recently shown that otoconin-90 (Oc90) regulates the growth of otoconia crystals as osteopontin does bone crystals. Here, we analyzed the role of this non-collagenous bone matrix protein, osteopontin, in otoconia formation and balance function utilizing its knockout mice, whose inner ear phenotype has not been examined. Despite the presence of the protein in wild-type otoconia and vestibular hair cells, morphological, ultrastructural, and protein and calcium composition analyses of osteopontin null otoconia show that the protein is not needed for crystal formation, and no evidence of compensatory protein deposition is found. Employment of a wide spectrum of balance behavioral tests demonstrates that the protein is not critical for balance function either, which is confirmed by the normal function of the gravity receptor organ directly measured with linear vestibular-evoked potentials (VsEPs). When compared with findings on other otoconins, the data manifest a hierarchy of importance of proteins in crystallization and indicate mechanistic similarities and differences between bone and otoconia calcification.

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“…The following complementary tests are commonly used to detect balance deficits manifested in postural control, spatial orientation and sensorimotor functions and coordination (Trune and Lim, 1983;Sondag et al, 1995Sondag et al, , 1996Sondag et al, , 1998Sondag et al, , 1999Ying et al, 1999;Rampello and Drago, 1999;Hamm, 2001;de Caprona et al, 2004;Jones et al, 2004;Besson et al, 2005;Walton et al, 2005;Sajdel-Sulkowska et al, 2005). These tests can involve multiple systems (i.e.…”

Section: Tests For Imbalance Behaviorsmentioning

confidence: 99%

Otoconin-90 deletion leads to imbalance but normal hearing: A comparison with other otoconia mutants

et al. 2008

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Our sense of gravitation and linear acceleration is mediated by stimulation of vestibular hair cells through displacement of otoconia in the utricle and saccule (the gravity receptor organ). We recently showed that otoconin-90 (Oc90) deletion led to formation of giant otoconia. In the present study, we determined the extent to which the giant otoconia affected balance and gravity receptor sensory input and compared the findings with other otoconia mutants. We employed a wide spectrum of balance behavioral tests, including reaching and air-righting reflexes, gait, swimming, beam-crossing, rotorod latencies, and a direct measure of gravity receptor input, vestibular evoked potentials (VsEPs). All tests on homozygous adult mutants consistently ranked the order of imbalance as (from worst to best) Nox3 het

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Effects of Sustained Acceleration on the Morphological Properties of Otoconia in Hamsters

Cited by 27 publications

References 9 publications

The development of vestibular system and related functions in mammals: impact of gravity

The development of vestibular system and related functions in mammals: impact of gravity

Osteopontin is not Critical for Otoconia Formation or Balance Function

Otoconin-90 deletion leads to imbalance but normal hearing: A comparison with other otoconia mutants

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