| Objective: China have made important strides in manned-space in recent years.Meanwhile, the subject of space medico-engineering played an important role in China’s manned space project. As a significant branch of space medico-engineering,oral aerospace medicine received more and more attention.Previous research has shown that, weightlessness and simulated weightlessness environment would reduce tolerance to high + Gx exposure. It would cause symptoms that simple high + Gx exposure would not cause. The comfort and function of oral environment is closely related to the secretion of saliva and protein composition. As the largest of the salivary glands in mouth, the nornally secretion ability of the parotid gland is affect the secretion of saliva and composition directly. Stress, disease, spirit,etc will affect the secretion function of parotid gland. The various functional proteins in saliva produced by parotid gland. To investigate whether weightlessness and hypergravity environment are stressors for rhesus monkey, the specimens were detected the expression of HSP70. In order to discuss whether weightlessness and hypergravity environment would affect the ability secreting functionary proteins, the specimens were detected the expression of saliva alpha-amylase(s AA) and parotid secretory protein(PSP).Methods: According to the literature review and the actual situation of spaceflight,twenty-three healthy male rhesus macaques were randomly divided into four groups:(1) control group(n=3);(2) 30 days’ simulated weightlessness group(n=3);(3) +13 Gx/230 s group(n=3);(4)high +Gx after 30 d simulated weightlessness exposure group(n=14). Group D was further divided into four subgroups according to the + Gx load: +11 Gx/270 s(group D1, n=3), + 13 Gx/230 s(group D2, n=4), + 15 Gx/200 s(group D3, n=4), + 13 Gx/230 s and 9 d’s recovery(group D4, n=3). Salivary glands were collected in anesthesia at the second day of experimental operation except that of group D4 were collected at the ninth day. The morphologic changes of the parotid specimens were observed by HE staining. The expression of HSP70 on protein level was detected by Immunohistochemistry(IHC) analysis and Western blot. The specimens were detected the expression of s AA and PSP by q RT-PCR and Western blot. To further determine the mechanism of the expression changes of s AA and PSP,the specimens were detected by Elisa for determining the content of cyclic adenosine monophosphate(c AMP) in parotid gland cells.Results:1. Histological analysis showed that, structure of parotid in control group was normal.In group B, distention of ducts and infiltrated lymphocytes can be seen. In group C,ducts distented mildly. In group D, it showed focal lymphocytic infiltration heavier,where acinar cells atrophied partly. Meanwhile, dilatating and congesting vessels were aggravated. in group D4, small number of acinar cells were myxoid change.2. IHC analysis showed that, compared with control group, HSP70 was positive expressed in both experimental groups. Western blot analysis revealed that except for group D4, other groups in experimental group showed significantly higher expression levels than that of control group(P < 0.05). In addition, the expression of HSP70 increased as the value of overload increasing.3. Compared with control group, the content of s AA and PSP in experimental groups on m RNA level and protein level were consistently decreased. Among those, group D2 and D3 decreased significantly(P<0.01). Compared with group C, content of s AA in group D2 decreased significantly(P<0.01). Compared with group D2, s AA and PSP increased significantly(P < 0.01). Expression of c AMP showed a similar variation trend with s AA and PSP.Conclusion:1. 30-days simulated weightlessness and different hypergravity exposure injured parotid and the histological structure altered.2. Under 30-days simulated weightlessness, hypergravity and both conditions,expression of HSP70 increased, which indicates such special conditions will cause stress reaction in parotid. Decrease of s AA and PSP indicates that secretory function of parotid has been affected. Decrease of c AMP reflect that the alteration of s AA and PSP may be associated with c AMP signaling pathways.3. Compared with hypergravity exposure group, under the double donditions of 30 d simulated weightlessness and hypergravity, parotid gland of rhesus monkey pathological injured heavier, HSP70 increased more, s AA and PSP decreased more,which show that simulated weightlessness will aggravate the reaction to hypergravity.4. After 9 d recovery, both histological structure of parotid and expression of funtional proteins are recovered, which indicates that injuries caused by such conditions are reversible. |
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