The Sensitivity of an Immature Vestibular System to Altered Gravity

Abstract

Stimulus deprivation or stimulus augmentation can induce long-lasting modifications to sensory and motor systems. If deprivation is effective only during a limited period of life this phase is called "critical period." A critical period was described for the development of the roll-induced vestibuloocular reflex (rVOR) of Xenopus laevis using spaceflights. Spaceflight durations and basic conditions of Xenopus' development did not make it possible to answer the question whether exposure of the immature vestibular organ to weightlessness affects rVOR development. The embryonic development of Pleurodeles waltl is slow enough to solve this problem because the rVOR cannot be induced before 15 dpf. Stage 20-21 embryos (4 dpf) were exposed to microgravity during a 10-day spaceflight, or to 3g hypergravity following the same time schedule. After termination of altered gravity, the rVOR was recorded twice in most animals. The main observations were as follows: (1) after the first rVOR appearance at stage 37 (16 dpf), both rVOR gain and amplitude increased steadily up to saturation levels of 0.22 and 20°, respectively. (2) Three days after termination of microgravity, flight and ground larvae showed no rVOR; 1 day later, the rVOR could be induced only in ground larvae. Differences disappeared after 3 weeks. (3) For 10 days after 3g exposure, rVOR development was similar to that of 1g-controls but 3 weeks later, 3g-larvae showed a larger rVOR than 1g-controls. These observations indicate that the immature vestibular system is transiently sensitive to microgravity exposure and that exposure of the immature vestibular system to hypergravity leads to a slowly growing vestibular sensitization.

Gravity changes during animal development affect IgM heavy‐chain transcription and probably lymphopoiesis

“…3). Horn and colleagues (13) studied the roll‐induced vestibuloocular reflex (rVOR) of Amphibody larvae and noticed that the median rVOR amplitude and gain of the F 0 g , F 1 g , and G 1 g groups were similar at landing. We also quantified transcript coding for HSPs because these molecules are involved in animal development (25, 26).…”

“…The ESA Botany Experiment (BOTEX) incubator (13) was used to expose embryos at stage 19‐20 of development to 3‐g hypergravity for 10 d. The temperature, time schedule, and handling of embryos were similar to those of the space experiment. Ten miniaquariums containing 32 embryos were placed in the BOTEX centrifuge, and 10 control miniaquariums were kept at 1 g in the BOTEX static racks.…”

Gravity changes during animal development affect IgM heavy‐chain transcription and probably lymphopoiesis

“…3). Horn and colleagues (13) studied the roll‐induced vestibuloocular reflex (rVOR) of Amphibody larvae and noticed that the median rVOR amplitude and gain of the F 0 g , F 1 g , and G 1 g groups were similar at landing. We also quantified transcript coding for HSPs because these molecules are involved in animal development (25, 26).…”

“…The ESA Botany Experiment (BOTEX) incubator (13) was used to expose embryos at stage 19‐20 of development to 3‐g hypergravity for 10 d. The temperature, time schedule, and handling of embryos were similar to those of the space experiment. Ten miniaquariums containing 32 embryos were placed in the BOTEX centrifuge, and 10 control miniaquariums were kept at 1 g in the BOTEX static racks.…”

Development of Vestibular Systems in Altered Gravity

“…In both species, rVOR development is retarded during early periods of life if the animals are reared for several days or permanently in complete darkness (Sebastian et al, 1996;2001). In Pleurodeles, the rVOR cannot be elicited until 15 days after fertilization (stage 37); thereafter, its amplitude and gain increase steadily and reach a saturation level of about α = 20° at stage 48 (Gabriel et al, 2012) (Fig. 16.1).…”

“…16.2) and young snails Biomphalaria glabrata the otolith (otoconia) mass was larger than in ground controls (Wiederhold et al, 2003). But hypergravity can also induce a higher sensitivity of the vestibular system, as shown in the augmentation of the rVOR in Pleurodeles four weeks after 3g termination (Gabriel et al, 2012) and in the improved balancing capabilities of mice after long-lasting 2g exposure starting at gestation day 0 (Bojados and Jamon, 2011).…”

Gender-related sensitivity of development and growth to real microgravity inXenopus laevis

“…Due to our experience from the experiment AMPHIBODY about temperature profiles during Soyuz flights (cf. Gabriel et al, ), the temperature of this incubator was set to 24°C immediately after integration of the 1g‐ground control and then stepwise reduced to 21°C until the launch time. At the nominal transfer time of the flight sample from KUBIK to Soyuz TMA12 before landing, the temperature in the 1g‐ground control container was stepwise increased to 24°C until the time of nominal Soyuz landing.…”

Gravity changes during animal development affect IgM heavy‐chain transcription and probably lymphopoiesis

“…3). Horn and colleagues (13) studied the roll‐induced vestibuloocular reflex (rVOR) of Amphibody larvae and noticed that the median rVOR amplitude and gain of the F 0 g , F 1 g , and G 1 g groups were similar at landing. We also quantified transcript coding for HSPs because these molecules are involved in animal development (25, 26).…”

“…The ESA Botany Experiment (BOTEX) incubator (13) was used to expose embryos at stage 19‐20 of development to 3‐g hypergravity for 10 d. The temperature, time schedule, and handling of embryos were similar to those of the space experiment. Ten miniaquariums containing 32 embryos were placed in the BOTEX centrifuge, and 10 control miniaquariums were kept at 1 g in the BOTEX static racks.…”

Development of Vestibular Systems in Altered Gravity

“…In both species, rVOR development is retarded during early periods of life if the animals are reared for several days or permanently in complete darkness (Sebastian et al, 1996;2001). In Pleurodeles, the rVOR cannot be elicited until 15 days after fertilization (stage 37); thereafter, its amplitude and gain increase steadily and reach a saturation level of about α = 20° at stage 48 (Gabriel et al, 2012) (Fig. 16.1).…”

“…16.2) and young snails Biomphalaria glabrata the otolith (otoconia) mass was larger than in ground controls (Wiederhold et al, 2003). But hypergravity can also induce a higher sensitivity of the vestibular system, as shown in the augmentation of the rVOR in Pleurodeles four weeks after 3g termination (Gabriel et al, 2012) and in the improved balancing capabilities of mice after long-lasting 2g exposure starting at gestation day 0 (Bojados and Jamon, 2011).…”

Gender-related sensitivity of development and growth to real microgravity inXenopus laevis

“…Due to our experience from the experiment AMPHIBODY about temperature profiles during Soyuz flights (cf. Gabriel et al, ), the temperature of this incubator was set to 24°C immediately after integration of the 1g‐ground control and then stepwise reduced to 21°C until the launch time. At the nominal transfer time of the flight sample from KUBIK to Soyuz TMA12 before landing, the temperature in the 1g‐ground control container was stepwise increased to 24°C until the time of nominal Soyuz landing.…”

Gravity changes during animal development affect IgM heavy‐chain transcription and probably lymphopoiesis

“…3). Horn and colleagues (13) studied the roll‐induced vestibuloocular reflex (rVOR) of Amphibody larvae and noticed that the median rVOR amplitude and gain of the F 0 g , F 1 g , and G 1 g groups were similar at landing. We also quantified transcript coding for HSPs because these molecules are involved in animal development (25, 26).…”

“…The ESA Botany Experiment (BOTEX) incubator (13) was used to expose embryos at stage 19‐20 of development to 3‐g hypergravity for 10 d. The temperature, time schedule, and handling of embryos were similar to those of the space experiment. Ten miniaquariums containing 32 embryos were placed in the BOTEX centrifuge, and 10 control miniaquariums were kept at 1 g in the BOTEX static racks.…”

Development of Vestibular Systems in Altered Gravity

“…In both species, rVOR development is retarded during early periods of life if the animals are reared for several days or permanently in complete darkness (Sebastian et al, 1996;2001). In Pleurodeles, the rVOR cannot be elicited until 15 days after fertilization (stage 37); thereafter, its amplitude and gain increase steadily and reach a saturation level of about α = 20° at stage 48 (Gabriel et al, 2012) (Fig. 16.1).…”

“…16.2) and young snails Biomphalaria glabrata the otolith (otoconia) mass was larger than in ground controls (Wiederhold et al, 2003). But hypergravity can also induce a higher sensitivity of the vestibular system, as shown in the augmentation of the rVOR in Pleurodeles four weeks after 3g termination (Gabriel et al, 2012) and in the improved balancing capabilities of mice after long-lasting 2g exposure starting at gestation day 0 (Bojados and Jamon, 2011).…”

Gender-related sensitivity of development and growth to real microgravity inXenopus laevis

“…Due to our experience from the experiment AMPHIBODY about temperature profiles during Soyuz flights (cf. Gabriel et al, ), the temperature of this incubator was set to 24°C immediately after integration of the 1g‐ground control and then stepwise reduced to 21°C until the launch time. At the nominal transfer time of the flight sample from KUBIK to Soyuz TMA12 before landing, the temperature in the 1g‐ground control container was stepwise increased to 24°C until the time of nominal Soyuz landing.…”