| Objective: Whether the metabolism of the body can be influenced by local functional orthopedic treatments? The author investigates the circadian rhythm of the levels of prostaglandin(PGE2) in growing rats'blood and the changes after functional mandibular protrusion in daytime (8:00~20:00) or wholeday (24hour), with the method of chronobiology, inorder to determine the relationship between the proliferation and translation of condyle and the metabolism of the body.Methods: 54 4-week-old male Wistar rats were divided equally and randomly into three groups-- control group, daytime group and whole-day group. The functional appliances were self-made. Rats in daytime group were put on the functional appliances in daytime (8:00~20:00);rats in whloe-day group were put on the functional appliances for whole-day long(24hours);rats in control group didn't wear any appliances.The rats wearing functional appliances kept functional mandibular protrution for about 3mm. In case the rats flouncing away the appliance, we add neck rings on the neck of rats in experimental groups. Artificial light was between 8:00-20 : 00.The appliances were cleaned and soaked in glutaraldehyde solution after they were removed. The rats were fed for 7 days, free drinking and timing eating. After 7 days, all rats were sacrificed at 0:00, 4:00, 8:00, 12:00, 16:00, 20:00 in a day.Every 3 of them were sacrificed at each time points to collect blood . Competitive Enzyme Immunoassay were used to detect the levels of PGE2 in growing rats'blood in every four hours of a day. Date was processed using macroscopic and microscopic analysis in chronobiology, with statistical software of cosine fitting and spss11.5.Results:1 Biological Rhythm Analysis1.1 Macroscopic approachThe means of levels of prostaglandin ( PGE2 ) in rats'blood:1) Control groupLevels of prostaglandin(PGE2) in control-group rats'blood at 0:00 is 85.63 IU/ml on average;68.33 IU/ml at 04:00 on average; 59.99 IU/ml at 08:00 on average; 103.13 IU/ml at 12:00 on average; 100.07 IU/ml at 16:00 on average; 70.00 IU/ml at 20:00 on average.2) Daytime groupLevels of prostaglandin(PGE2) in control-group rats'blood at 0:00 is 75.40 IU/ml on average;84.33 IU/ml at 04:00 on average; 180.63 IU/ml at 08:00 on average; 150.23 IU/ml at 12:00 on average; 80.47 IU/ml at 16:00 on average; 192.87 IU/ml at 20:00 on average. 3)Whole-day groupLevels of prostaglandin(PGE2) in control-group rats'blood at 0:00 is 81.10 IU/ml on average;185.60 IU/ml at 04:00 on average; 83.50 IU/ml at 08:00 on average; 195.93 IU/ml at 12:00 on average; 83.30 IU/ml at 16:00 on average; 146.67 IU/ml at 20:00 on average.According to the Macroscopic approach there was a diel rhythm in the concentration of PGE2 in rats'blood. The normal diel rhythm of PGE2 in rats'blood disappeared in both daytime group and whole-day group.1.2 Microscopic approachWith the methods for cosinor-rhythmometry, the fitting equation of plasma levels of PEG2 are as follows:1) The fitting equation of levels of PEG2 in control-group rats'blood is Yi=81.4+15.1cos(15ti+229). The mesor is 81.4±7.31 IU/ml. The amplitude is 15.1±5.44 IU/ml.The acrophase is 229°(15:18). P<0.052) The fitting equation of levels of PEG2 in daytime-group rats'blood is Yi=127.3+22.3cos(15ti+186). The mesor is 127.3±24.83 IU/ml. The amplitude is 22.3±12.55 IU/ml. The acrophase is 186°(12:24). P>0.053) The fitting equation of levels of PEG2 in whole-day-group rats'blood is Yi=131.6+20.7cos(15ti+134). The mesor is 131.6±8.61 IU/ml. The amplitude is 20.7±8.62 IU/ml. The acrophase is 134°(8:58). P>0.05 There was a diel rhythm in the concentration of PGE2 in rats'Blood. The acrophase was about 15:18. After functional mandibular protrusion, the normal diel rhythm of PGE2 in blood disappeared.2 Difference analysis among groupsCompared control group with daytime group: the difference had statistical significance. (P<0.05).Compared control group with whole-day group: the difference had statistical significance. (P<0.05).Compared daytime group with whole-day group: the difference had no statistical significance. (P>0.05).The levels of plasma levels of PEG2 in daytime group and whole-day group are significantly higher than control group.Conclusions:1 In natural state, there was a diel rhythm in the concentration of PGE2in rats'blood.2 After functional mandibular protrusion, the normal diel rhythm of PGE2 in blood disappeared and the levels of plasma levels of PEG2 increased significantly.3 Wearing functional appliance for longer time, the change of rhythm of PGE2 in blood will be more obviously.
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