| Objective:In recent years, due to the effects of improvement of living standards, diet changes, the growing tension over the rhythm of life, as well as the lifestyle of less movement, and many other factors, the global incidence of diabetes increased rapidly. It has become another chronic and non-comminicable disease. After the heart and brain vascular diseases, cancer, which have seriously endangered public health. The dysfunction of reproductive system is one of the complications of diabetes, the incidence is 5 to 10 times more than that of non-diabetic patients. It has brought severe stress and distress to the patient's physical and mental health, so more and more attention has been paid. This study was designed to establish type 2 diabetes mellitus rat model to discuss two kinds of factors affecting the reproductive function and the effects PCNA and EGFR made on testicular function of normal and different duration of diabetes SD rats,and to observe the testicular morphology, which could provide some theoretical basis for pathogenesis and treatment of male reproductive dysfunction in T2DM.Methods:30 healthy male SD rats, daily free drinking water and eating feed, were randomly divided into three groups:normal control group (group N,10), given saline gavage; T2DM 4-week-group (group A,10) and T2DM 8-week-group (group B,10) rats, given fat emulsion gavage (high-suger and high-fat diet).At the 7th weekend, the level of plasma insulin was detected and compared. On the next morning, the weight of the rats were measured. The experimental group was given 30mg/kg body weight of streptozotocin (STZ, Sigma Company) by tail vein injection to induced model of type 2 diabetes mellitus; While normal control rats were given the equivalent sterile citron acid-sodium citrate buffer by tail vein injection. With FPG≥16.7mmol/L as standard for the diagnosis of diabetic rats, experimental rats suceeded modeling in the 8th week. After modeling group A and B rats maintained fat emulsion diet.Group A was killed after T2DM 4 weeks, B rats was killed after T2DM 8 weeks (the end of experiment). Tail blood glucose were measured using Roche blood glucose meter; Group N and group A were killed at the same time. After blood was collected from the abdominal aorta and centrifuged, serum was collected to be tested insulin, glycosylated serum protein, testosterone, lipids and so on. Serum insulin was tested by Radioimmunoassay; Glycosylated serum protein was tested by colorimetric assay; Serum testosterone was tested by Chemiluminescence Determination; EGFR, PCNA expression of testicular tissue was detected by immunohistochemistry SABC, and related factors were analyzed. The data was processed by using SPSS 11.5 statistical software.Results:The fasting blood glucose level and insulin resistance index in A and B group rats was statistically significant higher than that in N group rats (P<0.05,P< 0.05);Glycosylated serum protein increased with the course of DM and there was statistically significant difference among the three groups (P<0.05,P<0.05,P<0.05); Fasting insulin level of B group rats had a statistically significant increase compared with that of N group and A group rats (respectively P=0.001, P=0.036);The weight of A and B group rats had a statistically significant decrease compared with N group rats (P<0.05); The testicular weight and serum testosterone of A and B group rats had a statistically significant decrease compared with group N rats (P<0.05,P<0.05); Testis immunohistochemistry showed that PCNA-immunoreactive materials were brown paticles, mainly in spermatogonia and primary spermatocytes, there was also coloring in sertoli cells; EGFR was positive in the spermatocyte, sperm cells, mesenchymal cells and supporing cells. The positive rate of PCNA and EGFR in testis of A and B group rats was significantly lower than that in N group rats (P<0.05,P<0.05);PCNA> EGFR and blood glucose had a negative correlation and the correlation coefficient was r=-0.665 (P<0.05),-0.540 (P=0.002); PCNA and EGFR were positively correlated with testicular weight and the correlation coefficient was respectively r= 0.496 (P=0.009), r=0.454 (P=0.012); PCNA, EGFR and serum testosterone levels were positively correlated and the correlation coefficient was r=0.574 (P=0.001), r =0.428 (P=0.018).Conclusions:(1) After fat emulsion gavage(high-suger and high-fat diet) for 7 weeks plus a small dose of a tail vein injection of STZ, type 2 diabetes SD rats model could be successfully induced. The method was reliable and SD rats would be fully molded; (2) PCNA and EGFR expression in testis tissues of the SD diabetic male rats remarkably reduced compared with normal male SD rats;(3)Testis weight and serum testosterone levels in diabetic male SD rats remarkably reduced compared with normal male SD rats;(4) PCNA and EGFR expression in testis tissues of the SD male rats was negatively correlated with blood glucose; (5) The PCNA and EGFR expression in rat testis was positively correlated with testicular weight and serum testosterone levels. In short, PCNA and EGFR expression in the testis of diabetic male SD rats decreased, which could affect the spermatogenesis and testosterone secretion by any possible ways and led to the decline in testicular weight, and the condition may deteriorate with the course of diabetes. These above may become possible one of mechanisms of leading to dysfunction of reproductive system in T2DM male rats.
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