Expression of apoptosis-related genes Bcl-2 and Bax and the rate of cell apoptosis of the penis tissues of the experimental diabetic rats:A positional, qualitative and quantitative analysis / 中国组织工程研究

ABSTRACT

BACKGROUND: Recent studies have indicated that cellular apoptosis might be related with the pathological process of diabetic penis erection function disorder. OBJECTIVE: To observe the expression of apoptosis inhibiting gene Bcl 2 and apoptosis inducing gene Bax in the penis cavernosal tissue of diabet ic rats based on the diabetic rat model. DESIGN: A randomized controlled experimental study. SETTING: The Central Laboratory of Jiamusi University. MATERIALS: Fifty male adult Wistar rats were selected. The rats wererandomly divided into normal control group (n=10) and the model group(n=40). The rats in the model group were divided into subgroups according to whether they had diabetes mellitus, namely alloxan medicine control group (n=9) and diabetes mellitus group (n=12). METHODS: The experiment was conducted at the Central Laboratory of Jiamusi University. 20 g/L Alloxan was injected intravenously into the tails of the rats in the model group at a dose of 50 mg/kg. Urine and blood sugar were examined 48 hours after the injection. Diagnosis of diabetes was established when urine sugar was (+++)～ (++++) and blood sugar was above 16.67 mmol/L. The rats in the alloxan group (n=9) were not found to have diabetes mellitus. The rats in the diabetic group were found to have diabetes mellitus, and dead rats were excluded. The blood sugar and urine sugar were measured before experiment and 48 hours, 2, 4, 6and 8 weeks after the experiment. After 8 weeks, the penises were harvested and fixed in 10% neutral formaldehydum polymerisatum. The remaining structures were thoroughly embedded in paraffin, and sections were obtained. Then, apoptosis and the protein of Bcl-2 and Bax were detected in the erectile tissues. 0.5 cm of the middle-section of bulbocavernosus body was collected, and it was then fixed in 10 g/L neutral formaldehydum polymerisatum at 4 ℃ for 24 hours. Then, 5-7 μ m paraffin sections were obtained. The cellular apoptosis was detected with in situ end labeling method. Bcl-2 and Bax gene expressions were detected with histochemical staining. MAIN OUTCOME MEASURES: Cellular apoptosis in the erectile tissues of the rats and genes Bcl-2 and Bax expressions. RESULTS: Nineteen rats died after model establishment and 31 rats entered the stage of the result analysis. ①Cellular apoptosis of the erectile tissues of the rats: The apoptosis rate in the diabetic group was significantly higher than that in the normal control group and alloxan group (16.26±6.63)%,(0.38±0.02)%, (0.40±0.03)%,(q=4.45, P ＜ 0.01). ② Expression of Bcl-2gene of the erectile tissues of the rats: Bcl-2 gene expression of the diabetic group was significantly lower than that in the normal control group and alloxan group [(12.04±2.30)%,(20.88±3.02)%,(21.23±2.58)%,q=4.45,P＜0.01].③Expression of Bax gene in the erectile tissues of the rats: Bax gene expression of the diabetic group was significantly higher than that in the normal control group and alloxan group [(18.35±2.00)%, (9.33±0.56)%,(10.32±0.63)%, (q=4.45, P ＜ 0.01)]. ④ The ratio of Bcl-2 to Bax: The ratio of Bcl-2 to Bax of the diabetic group was significantly lower than that in the normal control group and alloxan group. CONCLUSION: That the cellular apoptosis of the erectile tissues in rats with diabetes mellitus increased suggests that cellular apoptosis is related with diabetic erectile dysfunction. Also, Bcl-2/Bax was down-regulated,and this indicates that Bcl-2 and Bax cooperates in the cellular apoptosis in the diabetic erectile tissues.