Study On The Post-injury Regenerating Ability Of Temporomandibular Joint, Masticatory Muscles, Heart, Liver And Kidney Of Rats Exposed To The Repeated+Gz Forces

OBJECTIVES The study was conducted to observe the Post-injury Regenerating Ability of temporomandibular Joint, masticatory muscles, heart, liver and kidney of rats exposed to the repeated +Gz forces. METHODS A hundred and eight male rats were randomly assigned to 9 groups with 12 rats in each group. Group A was normally fed as the blank control group. Group B was only fixed with rat-kept devices for 5 minutes as the fixed control group. Group C was borne +lGz for 5 minutes. In the same position as group C, group D, E, F, G, H and I were repeatedly exposed to +10Gz for 30 seconds each time with 5 times a day and +lGz for 1 minutes as a interval; the 6 groups were treated in the condition above for 4 days a week and 4 weeks in total. The rats in group A, B, C and D were killed on the next day after the centrifuge. The others in group E, F, G, H and I were killed at the week 1, 2, 4, 8 and 12 after the centrifuge, respectively. Before the rats were killed, blood was drawn to determine the serum concentrations of cell factors such as tumor necrosis factor- (TNF- ), interleukin-1 (IL-1 ), interleukin-6 (IL-6) and interleukin-8 (IL-8), the serum concentrations of endothelin (ET) and free radicals such as superoxide dismutase (SOD), malondiabdehy-de (MDA) and nitric trioxide (NO3), and the biochemical indexes such as CK, CK-MB, LDH, GPT, GOT, UN and Cr. After the rats were killed, temporomandibularjoint, masticatory muscles, heart, liver and kidney were taken for observe under optical microscope, scanning electron-microscope (SEM) and transmission electron-microscope (TEM).RESULTS All rats survived before killed. There was no significant difference observed in every organ and tissue in group A, B and C. Heart, liver, temporomandibular joint and masticatory muscles showed pathological changes to different extent in the other groups, except kidney. As time going, the above injury weakened and regenerated gradually. The content of the tested serum cell factors increased, the level of SOD increased continuously, and the levels of MDA and NOs showed no significant changes. Only Cr increased significantly in the later period, and the other biochemical indexes showed no significant changes.CONCLUSIONS It was confirmed further that the repeated +Gz not only induced the injury of temporomandibular joint, masticatory muscles, heart and liver, but also induced some changes in certain cell factors, ET and free radicals. It was also confirmed that the injury of organs and tissues exposed to +Gz forces could be self-regenerated in different period after.