| Part One Establishment of Aging Model[Background] The senescence society is coming. Establishment of aging animal model is an effective way to study the aging process of human being. The researches on aging and anti-aging agents become a hot point which require aging model. But natural aging animals are very rare because of the long period of feeding time and the large spending. So experimental aging model being copied by chemical method is used to research and provide higher efficiency compared with natural aging model. So far, many methods have been reported to copy aging animal model successfully. For example, ozone induced aging model, thymus removed aging model, aging SAMP model and D-galactose induced aging model, et al. D-galactose induced aging model has been widely used because of its easy accessibility, less cost and stable performance. And the model rats had some similar physiological and biological changes compared with natural aging rats, which led to an accelerated aging.[Objectives] The aim of this study was to establish the D-galactose induced aging rat model, and evaluate its aging indexes such as the variation of weight, the levels of serum SOD and MDA, the index of the thymus weight and spleen weight by compared with young rat. Meanwhile, the D-galactose aging model provides aged test animals to the subsequent study.[Methods] (1) Ten 3-month-old and ten 12-month-old SD rats were set as group A and group B individually. Ten 24-month-old model rats (group C) were established by D-galactose injection subcultaneously for 40 days with the dose of 0.125 g · kg-1 · d-1. All groups were given regular feeding and water for 40 days. Rats body weight were measured once every 10 days. The levels of serum SOD and MDA were detected after 40 days feeding, and the indexes of thymus weight and spleen weight were calculated.(2) The difference of body weight growth, serum SOD, MDA levels and indexes of thymus weight and spleen weight in three groups were compared.[Results] (1) After 40 days normal diet feeding,24-month-old rats (group C) and 12-month-old rats (group B) had significantly lower body weight growth compared with 3-month-old SD rats (group A) [(41.3± 11. 1)g, (85.6±10.9)g vs. (125.3±15.2)g, both P<0.05]. And group C had lower body weight growth than group B (P<0.05).(2) 24-month-old rats (group C) and 12-month-old rats (group B) had significantly lower activity of serum SOD compared with 3-month-old SD rats (group A) [(50.48 ± 10.12)U/ml, (58.40 ± 5.57)U/ml vs. (66.38 ± 5.39)U/ml, both P<0.05]. And group C had lower activity of serum SOD than group B (P<0.05).(3) 24-month-old rats (group C) and 12-month-old rats (group B) had significantly higher level of serum MDA compared with 3-month-old SD rats (group A) [(11.83 ± 3.13)nmol/ml, (8.41 ± 2.04)nmol/ml vs. (4.81± 1.37) nmol/ml, both P<0.05]. And group C had higher level of serum MDA than group B (P<0.05).(4) 24-month-old rats (group C) and 12-month-old rats (group B) had significantly lower indexes of thymus and spleen weight [thymus:(0.089 ±0.006)g/100g, (0.107±0.005)g/100g vs. (0.230±0. 011) g/100g; spleen: (0.147±0.011) g/100g, (0.138±0.007) g/100g vs. (0.305±0.017) g/100g, both P<0.05]. And group C had lower index of thymus weight than group B (P<0.05).[Conclusion] The establishment of D-galactose induced aging model is successful. Along with aging, rat body weight increase was slow, the index of thymus weight and serum level of SOD became lower, and content of MDA became higher.Part Two the Effect of Aging onIntestinal Mucosa Epithelial Barrier in Rats[Background] With the increase of age, a variety of degenerative changes will appear in the body structure and function. As one of the very important organs, the intestine also changes with age. But the effect of aging on intestinal mucosal barrier is lack of evidence.[Objectives] To study the changes of intestinal epithelial barrier function in rats with aging.[Methods] (1) Ten 3-month-old and ten 12-month-old SD rats were set as group A and group B individually. Ten 24-month-old model rats (group C) were established by D-galactose injection subcultaneously for 40 days with the dose of 0.125 g ·kg-1 · d-1. After 40 days feeding, the terminal ileum was removed to make hematoxylin and eosin (HE) section, and the morphology of small intestine mucosa, intestinal villus altitude and thickness were observed under light microscope. The expressions of Occludin and Z0-1 protein in terminal ileum mucous membrane were detected by immunohistochemistry. The expressions of Occludin and Z0-1 mRNA were determined by semi-quantitative reveals transcription polymerase chain reaction (RT-PCR). The liver, spleen, mesenteric lymph node tissue of rats in each group were taken for bacterial culture to calculate bacterial translocation rate.(2) The expressions of Occludin and ZO-1 protein in the small intestinal tissue were compared. Bacterial translocation rate in three groups were also compared.[Results] (1) After 40 days normal diet feeding, the small intestinal mucosa thickness and villus height were lower in group C and B than group A [thickness:(87.6±6.32) μ m, (131.8±5.22) um vs. (162.9 ±7.28)μm; villus height:(56.4±5.38)μm, (76.7±5.40)μm vs (108.1 ±6.42) μm; both P<0.05], and the small intestinal mucosa thickness and villus height in group C were lower than that in group B (P<0.05).(2) Occludin and Z0-1 protein expressions in the small intestine tissue were reduced in group C and B as compared with group A [Occludin protein:(2.23±0.60)%, (4.21±0.61)% vs. (12.31±0.94)%; Z0-1 protein:(2.03±0.54)%, (4.02±0.65)% vs. (12.21±0.81)%; both P<0.05], and Occludin and Z0-1 protein expressions were less in group C than that in group B (P<0.05).(3) The levels of Occludin and ZO-1 mRNA in small intestine tissue were reduced in group C and B as compared with group A[Occludin:(0.20 ±0.03), (0.38±0.02) vs. (0.66±0.03); Z0-1:(0.18±0.03), (0.37±0.022) vs. (0.63±0.03); both P<0.05], and Occludin and ZO-1 mRNA expressions were less in group C than that in group B (P<0.05)(4) The bacterial translocation rate had no significant difference in 3 groups.[Conclusion] Our study indicated that age-related intestinal mucosa epithelial barrier changes may be associated with mucosal atrophy, less expressions of tight junction molecular (Occludin and ZO-1) mRNA and protein, but the difference of bacterial translocation rate is insignificant. |
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