| Normally,sensory information accepted by different sensory systems iscompatible and complementary.Sensory conflict would induce varying degreesof physiology or psychological reactions,even incapacitation.Visual system andvestibular system are two very important sensory systems in maintaining normalphysical and mental activities.80%-90% of enviromental information isaccepted through the visual system,and the vestibular system plays animportment role in the body balance,sensing sports state and spatial orientation.Therefore,the match of visual system information and vestibular systeminformation is essential to maintain normal psychological and physiologicalactivities.Motion sickness and spatial disorientation has been two problems impedingaviation and aerospace activities.Due to their unclear pathogenesis,it is difficultto prevent and treat them effectivly.The conflict of visual system informationand vestibular system information is one of the main reasons which inducemotion sickness and spatial disorientation.It become hot issue to explore integration and impact mechanism of visual information and vestibularinformation in aerospace medicine.However,for lacking animal model withvisual defect,the role of visual system information in mechanisms of spatialdisorientation and motion sickness is rarely reported.A kind of mouse with dysopia named rdf (retinal degeneration fast)mousehas been detected and nurtured in our laboratory.In this study,we may initiallyclarify the integration mechanism of visual information and vestibularinformation in the central nervous system using animal model with visual defect—rdf mouse under motion sickness,and provide basic theory for the preventionand treatment of spatial disorientation and motion sickness.Materials and Methods1.Electrophysiological characteristics of rdf mice and normal wild-typeKunming mice were investigated using international standardization schedule ofelectroretinogram test,and organizational structures were observed by HEstaining.2.Rdf mice and normal wild-type Kunming mice were subjected to rotarystimulation (turning radius:0.6 m;angular volicity:180°/s;3 min per cycle;clockwise rotation alternated with the anticlockwise rotation)for 30 minutes toinduce motion sickness.The conditions taste anorexia (CTA)to saccharinsolution was used to observe the differences in the sensitivity of motion sicknessof the two kinds of mice.3.The critical regions of sensory integration of visual information andvestibular information in the central nervous system were determined throughobserving the differences in the expressions of Fos in the vestibular-relatedregions (vestibular nucleus,prepositus hypoglossal nucleus,Kooy cap of inferior olive medial nucleus,βsubnucleus of olive inferior,flocculus andparaflocculus)of rdf mice and normal wild-type Kunming mice after rotatorystimulation (turning radius:0.6 m;angular volicity:180°/s;3 min per cycle;clockwise rotation alternated with the anticlockwise rotation)30 min.4.The differences in the expressions of calcitonin gene-related peptide(CGRP)and choline acetyl transferase (ChAT)in the vestibular-related regionsof rdf mice and normal wild-type Kunming mice after rotatory stimulation(turning radius:0.6 m;angular volicity:180°/s;3 min per cycle;clockwiserotation alternated with the anticlockwise rotation;30 min every time;interval:24 h)3 times were used to determine whether the calcitonin gene-related peptideand diacetyl-choline play the roles in the sensory integration of visualinformation and vestibular information in the central nervous system of mice.Results1.The results of electroretinogram tests indicted that ScotERG,Ops,MaxERG,PhotERG and Flicker ERG induced normal waves in the normal wild-typeKunming mice,But under the same conditions,the five tests failed to inducenormal waves in the rdf mice.The HE staining of retina displayed that all layersexisted clearly in normal wild-type Kunming mice.The photoreceptor layer,outer nuclear layer and outer plexiform layer of retina were invisible,and theinner nuclear layer became thining in the rdf mice.2.The intake of saccharin solution was significantly reduced in rdf mice[10.94±0.92 g (before stimulation)vs 6.87±0.79 g (first 24 h after stimulation),n=7,P＜0.01] and normal wild-type Kunming mice [11.16±0.96 g (beforestimulation)vs 9.37±0.86 g (first 24 h after stimulation),n=7,P＜0.01] afterrotary stimulation.The intake volumes first 24 h after stimualation of rdf mice and normal wild-type Kunming mice were 62.07% and 84.49% of intake beforestimulation respectively,the decrease of rdf mice was more greater than that ofnormal wild-type kunming mice [the intake volume in first 24 h afterstimulation/the intake volume before stimulation:63.07±8.35 (%,rdf mice)vs84.49±10.16(%,Kunming mice),n=7,P＜0.05]3.The numbers of Fos-positive neurons in prepositus hypoglossal nucleusand Kooy cap of inferior olive medial nucleus were significantly less in rdf micethan those in normal wild-type Kunming mice after rotary stimulation[PrH:35.33±2.19 (Kunming mice)vs 20.67±1.45 (rdf mice),n=6,P＜0.01;IOK:12.17±1.19 (Kunming mice)vs 6.67±0.42 (rdf mice),n=6,P＜0.01].In othervestibular-related regions,the differences in the numbers of Fos-positiveneurons between the two experimental groups were not significant.4.After rotatory stimulus 3 times at interval 24 h,the expressions of CGRP[PrH:87.33±1.96 (Kunming mice)vs 62.67±1.65 (rdfmice),n=6,P＜0.01;IOK:26.50±1.23 (Kunming mice)vs 17.00±0.89 (rdfmice),n=6,P＜0.01] and ChAT[PrH:78.33±1.78 (Kunming mice)vs 56.67±1.73 (rdfmice),n=6,P＜0.01;IOK:17.17±1.05 (Kunming mice)vs 10.33±0.92 (rdf mice),n=6,P＜0.01] inprepositus hypoglossal nucleus and Kooy cap of inferior olive were significantlyless in rdf mice than those in normal wild-type Kunming mice.There were somedifferences in expression of CGRP and ChAT in the other vestibular-regions inthe two kinds of mice after rotatory stimulus,but the differences were notsignificant except the differences of ChAT in the medial vestibularnucleus[62.67±3.84 (Kunming mice)vs 66.67±2.54 (rdfmice),n=6,P=0.03].ConclusionThe five electroretinogram tests of Scot ERG,Ops,Max ERG,Phot ERG and Flicker ERG failured to induce normal waves in the rdf mice,and the HEstaining of retina displayed that photoreceptor layer,outer nuclear layer andouter plexiform layer were not visible and the inner nuclear layer became thin inthe rdf mice.All those indicated that the rdf mouse is a kind of mouse withdysopia.After rotatory 30 min,the reduction of intake volune of saccharinsolution was greater in rdf mice compared to that of normal wild-type Kunmingmice.That indicated that anorexia in the rdf mice was more seriously than thatin the normal wild-type Kunming mice.It also manifested that the rdf mice weremore sensitivie to rotatory stimulation than normal wild-type Kunming mice.Sowe came to a conclusion that visual information plays a role in the mechanismof motion sickness.Visual information and vestibular information impact eachother through certain channels.After rotatory stimulation 30 min,the numbers of Fos-positive neurons inprepositus hypoglossal nucleus and Kooy cap of inferior olive were significantlyless in rdf mice than those in normal wild-type Kunming mice.The expressionof Fos protein reflects activation of neurons.The results indicated that visualinformation may affect the activation of neurons by rotatory stimulation in thosetwo regions.Therefore,the prepositus hypoglossal nucleus and Kooy cap ofinferior olive medial nucleus are key regions where the visual information andvestibular information integrate in the central nervous system in mice.Theexpression patterns of CGRP and ChAT were similar to that of Fos in thevestibular-related regions in the normal wild-type Kunming mice and rdf miceafter rotatory stimulus 3 times at interval 24 h.So we speculated that CGRP andAch generated and released by neurons in the hypoglossal nucleus and Kooy capof inferior olive may paly a role in the sensory integration of visual systeminformation and vestibular system information in the central nervous system in mice with motion sickness. |
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