| The main function of the vestibular system is feeling the change of gravity and variablemotion, under integration of the central nervous system, reflectively adjust the body posture,keep balance and the vision stability during moving. In addition, the the vestibular systemparticipate in regulation of visceral function during moving and the process of spatial learningand memory. The embryonic development of vestibular sensory is the priority developmentalsense behind the sense of touch. And its deficiency or developmental disorders not only affectthe vestibular function, but also suppress the development of visual and auditory sense, andlead to the disorder of balance, motor coordination, and even reduce the learning and memoryability. The gravity and the variable motion are the two main external stimulation factors fordevelopment of the vestibular system. Previous animal study showed that hypergravity andmicrogravity inhibited the normal development of the vestibular system with varying degree,and could reduce or change the vestibular function after birth. However, there was nosystematic study based on the animal or human, under the1G gravity environment on theearth’s surface, whether the development of the vestibular system was affected by variablemotion or not. The existing data on the investigation showed that a certain amount of aerobicexercise for pregnant women during pregnancy, such as dancing, swimming, can not onlyreduce the incidence of sensory integration dysfunction, improve motor coordination andlearning and memory of the offspring, but also conducive to weight control and maternalpostpartum recovery, reduce the morbidity of gestational hypertension and gestationaldiabetes and other pregnancy complications. Following the progress of science andtechnology, human’s life-style has changed dramatically. The exercise time of modern peoplebecomes shorter, especially in pregnant women. Some people thought that this was the mainreason for increasing the incidence of children sensory integration disorder, attention deficitand hyperactivity disorder. Exercising for short periods of time in pregnancy period was oneof the main factors for vestibular dysfunction of the offspring. The above mentioned resultssuggested that the exercise of pregnant women may affect the development of vestibularsystem of the fetal, while how much exercise is effective (i.e., whether there is an optimal interventions intensity and duration of exercise)? Whether there is a key period that theexercise affects the development of the structure and function in vestibular system (the mostsensitive period)? These subjects need to be investigeated by qualitative and quantitativeresearch.Our previous studies showed that pregnant Kunming mice were given daily40minvariable speed rotary motion stimulation, during the embryos development of4-19days(E4-E19), could significantly improve the pups ability of surface righting reflex and aerialrighting reflex, the best intervention period was E10-E15, but the ultrastructure of thevestibular organ had no significant change.These preliminary results only confirmed that the variable rotation stimulation couldobviously improve the vestibular function of mice, and there was a sensitive period, but didnot reveal the most effective intensity and duration of the variable rotation stimulation, andwhether the exercise could affect the development of vestibular nucleus. Therefore, thepresent study based on the previous studies, Kunming pregnant mice were given a duration of3h,6h,12h variable speed rotary stimuli, respectively, from embryos4day to one daybefore birthday(E4-E19). Behavior methods were used to examine the effect of exercise onthe function of vestibular system, and immunohistochemistry method was used to detect theFos neurons in vestibular nucleus induce by natural vestibular stimuli, in order to detect theeffect of the exercise on the development of the vestibular neucleus. We want to determine thebest duration of variable rotation stimuli that facilitate vestibular function in mice, andwhether the exercise could affect the development of vestibular neucleus.The results of the study are as follows:1. There was no significant effect on body weight in each group of pregnant mice whichwere given variable speed rotary stimulation during E4-E19. However, there was a reducedtendency of the body weight in6h and12h rotary groups compared with blank control group,and the postpartum weight of6h rotation group was always at the low level.2. There was no significant difference of the average weight of pups in each group duringperioed of P0-P15, while the pups weight in6h rotation group was increased faster comparedwith the blank control group. 3. There was no significant difference in the average litter size, and survival rate, and thedays of open eyes and open ears in each group pups4. The Pups (on P0), which mother were given12h rotation during pregnant E4-E19,surface righting reflex success rate was significantly higher than the other groups, but therewas no significant difference in the period of P1-P7among the groups.5. The water righting reflex time of pups in control group and6h group was significantlyshorter than12h group on the P3and the P6. The water righting reflex time of pups in6hgroup was significantly shorter than12h group on the P5.6. The aerial righting reflex scores of the3h rotation group during E4-E19wassignificantly higher than the other three groups. There were no significant differences in theaerial righting reflex scores among groups on other days.7. The swimming scores of the pups in3h group were lower than12h group on the P12,and lower than6h group on the P13. There were no significant differences of swimmingscores among groups on other days.8. There was no significant difference in the number of Fos positive neurons induced byOVAR(natural stimulation) among the groups on the P7and the P14. There were only a smallnumber of Fos positive neurons distributed in brainstem nuclei related with vestibularfunction on the P7, while there were a lot of Fos positive neurons distributed inabove-mentioned nuclei and also appeared in the nucleus of IO on the P14.From above results, the conclusion can be inferred as follows:1. The long time variable speed rotary stimuli every day (12h) made the pregnant miceto generate anxiety, to increase the food-intake, and also made the postpartum mother to eatnewborn pups, to abandoned pups, and made postpartum weight gain of the mother to bemore. However, the variable speed rotary stimuli of6h per day had no significant impact, andit seems to be benefit to keep the weight of pregnant and the recovery of postpartum weight inthe overall trend.2. The variable speed rotary stimulation from3h to12h per day had no significant effecton the fetal mice’s overall development, while the rotary stimulation of6h per day may havethe role in increasing the weight of the pups after birth. 3. The stimulation of variable speed rotation12h per day can significantly improve thepups ability of surface righting reflex, but then the other functions are less than6h group. Onthe whole, daily6h rotary stimulation during E4-E19can improve the vestibular function ofthe pups.4. The variable speed rotary stimulation,3-12h daily from E4-E19, have no significanteffect on the postnatal development of the pups’ vestibular system.The results of this study provide some basic research data about sports and pregnancy,fetal development theory, and have some theoretical significance. |
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