Establishment and histopathological characteristics of rat model of chronic nonbacterial prostatitis / 中华泌尿外科杂志

ABSTRACT

Objective To establish a rat model of chronic nonbacterial prostatitis (CNP) and investigate the histopathological characteristics of CNP in rat. Methods The prostate tissues of 4 male SD rats were taken out under aseptic condition,and prostate tissue homogenate supernate (PTHS) was made.Another 20 male SD rats were randomly divided into control group and CNP group with 10 rats each.Each rat of group CNP was immunized with 1.0 ml PTHS (20 mg/ml) emulsified by isopyknic Freund's complete adjuvant (FCA) intradermally in the multiple points,and simultaneously immunized with 0.5 ml pertussisdiphtheria-tetanus (PDT) vaccine intraperitoneally on 0 and 30th day.Each rat of control group was injected with equivalent normal saline in the same way.Rats from each group were sacrificed 45 days after immunization,and the prostates were harvested under aseptic condition.Prostatic tissues were examined macropathologically and histologically for degree of inflammation.Another 80 CNP rats were established after confirming success of the modeling.They were divided into high-dose androgen group (H),medial-dose androgen group (M),low-dose androgen group (L) and control group (C) with 20 in each.Rats of group H,M and L were injected with different concentrations of testosterone propionate ( 1,2,4 mg/ml).Rats of group C were injected with sterilized peanut oil.O.5 ml was applied through subcutaneous injection every other day.Each group was equally divided into 4 subgroups,in which the durations of medication were 1,2,4 and 6 weeks,respectively.After the expiration of the injection,animals from each subgroup were sacrificed and the macropathological and histological features of the prostatic tissues were examined as above. Results Macroscopic features of prostate tissues of group CNP at the 45th day were serious congestion and edema,adhesion with surrounding tissues,aneretic prostate capsule and so on.Histologically,the prostatic tissues were characterized by lymphoid tissue proliferation and chronic inflammatory cell infiltration in the stromal connective tissue around the acini or ducts.The rats of control group showed no inflammatory manifestations as above.After injection of testosterone propionate,the inflammatory degree of the CNP rats was lessen in varying degrees.For example,the destructive glands and stroma appeared repair and regeneration,the lymphoid tissue proliferation was alleviated,and the locations,ranges and amount of chronic inflammatory cell infiltration were also decreased.Furthermore,the relief of inflammatory degree had a positive correlation with the concentration and duration of testosterone propionate.The degree of inflammation in group C scarcely changed. Finally,the histopathological characteristics of CNP in rat model were summarized according to the results of histopathology,including inflammation locations,ranges and grades.Inflammation locations:①inflammation in the glands referred to the inflammatory cell infiltration in the ductal epithelium,alveolar epithelial and (or)glandular cavity; ②inflammation in the periglandular tissues referred to the inflammatory cell infiltration in the stroma and around the glandulartube; ③inflammation in the stroma referred to the inflammatory cell infiltration in the stroma without the glandulartube.Inflammation-rangeg:①focal inflammation indicates that the area of inflammatory cell infiltration was less than 10％ ; ②multifocal inflammation indicates that the area of inflammatory cell infiltration ranged from 10％ to 50％ ; ③diffuse inflammation indicates that the area of inflammatory cell infiltration was more than 50％.Inflammation grades:①grade Ⅰ meant that scattered inflammatory cells were in the specific area,cell count 1 - 10/HP; ②grade Ⅱ meant that inflammatory cell assembled without glandular epithelial tissue destruction or lymphoid nodule/follicle formation,cell count l1 -20/HP; ③grade Ⅲ meant that inflammatory cell assembled with part of glandular epithelial tissue destruction or lymphoid nodule/follicle formation,cell count ＞ 20/HP; ④grade Ⅳ meant that inflammatory cell assembled with a mass of glandular epithelial tissue destruction or lymphoid nodule/follicle formation,cell count full field of vision/HP. Conclusions The CNP rat model can be established by immunized with syngeneic PTHS plus FCA and PDT.The histopathological characteristics of CNP in rat can be evaluated according to the locations,ranges and grades of inflammation,which serve for further research of pathogenesis and treatment of this disease.