A Study on Prostate Inammation in SD Rats After Castration Under the Effect of Estrogen/androgen at Different Concentrations

Background: To clarify the expression of histological inammation and major inammatory factors in prostate of castrated rats induced by different concentrations estrogen/ androgen. Methods: Male Sprague-Dawley (SD) rats aged 3-4 months were randomly divided into the blank group (sham operation group, bilateral testicular specimens were retained), and the castration group (surgical removal of bilateral testes) and different concentrations of estrogen/androgen treatment after castration. Dihydrotestosterone (DHT) and estradiol (E) were administered daily by subcutaneous injection for one month, and the rats in each group were sacriced by neck-broken method after one month. Obtained prostate specimens by surgery, and performed routine paran embedding and sectioning of prostate tissue. Observed the changes of prostate tissue structure and prostate inammation under light microscope after Hematoxylin-eosin (HE) staining. Immunohistochemical method was used to detect the expression of TGF-β1, IL-6 and IL-8 in the rats prostate tissues. Results: After castration, when the exogenous E concentration was constant, the exogenous DHT(0-0.15mg/kg) concentration of SD rats in each group increased gradually, and the anatomical position score of inammatory cell inltration in each group of rats gradually increased. Further, even if the DHT concentration increased again after the exogenous DHT concentration reached at 0.5mg/kg, the score did not increase but decreased insteadly. From the area of tissues involved in inammatory cell inltration and the density of typical inammatory cells, the inammation score of each group of rats increased gradually with the increase of DHT concentration. When the exogenous DHT concentration was constant, from the anatomical location and the area of tissues involved in inammatory cell inltration in each group of SD rats, the inammation score of each group of rats increased gradually with the increase of exogenous E concentration. The results of the immunohistochemical reaction showed that the positive rates of TGF-β1, IL-6 and IL-8 in SD rats after castration were higher than those in the blank group, and the positive oral soy isoavones SD oral prostatitis, further the signicance of hormone level changes in the occurrence of prostatitis. However, for middle-aged and elderly patients low androgen levels, the effects of changes in different levels of estrogen/ androgen on BPH and inammation were still unclear. In this study, we supplemented the castrated rats with a constant concentration of exogenous DHT(0.15 mg/kg) lower than the physiological dose, and used the different concentrations of exogenous E to stimulate SD rats. Establishing a rat model in which androgen levels were relatively low and estrogen was sequentially increased (that was also in line with the performance of hormone levels in middle-aged and elderly men). We found that when the concentration of exogenous DHT was constant and the concentration of exogenous E increased gradually. SD rats in each groups either from the perspective of the anatomical location of inammatory cells inltration involvement ratings, or from the perspective of the regional scale of inammatory cells inltration involvement. With the increase of exogenous E concentration, and the inammatory score in each group showed a gradual increase trend. To a certain extent, the results of this study also reected from the perspective of animal experiments why BPH and chronic prostatitis rarely occured in young patients with high androgen levels and relatively low estrogen levels. However, it usually occured in middle-aged and elderly patients with relatively low androgen levels and relatively high estrogen levels.

After crossing this in ection point, the in ammation of the prostate did not further deepen even if the concentration of exogenous androgens increased again. Of course, it needs to be con rmed by more systematic and comprehensive experiments in vivo and vitro.

Background
Benign Prostatic Hyperplasia(BPH) is one of the most common diseases in middle-aged and elderly males. Although the pathogenesis of BPH was not very clear at present, the role of sex hormone was a broad consensus in the academic community. While the breaking of the balance of estrogen/ androgen ratio was considered to be a key link in the pathogenesis of BPH. In addition, more and more scholars believed that BPH was essentially an immune in ammatory disease. It has been found that prostatic stromal cells were the main targets of in ammatory factors, and can also secrete a variety of in ammatory factors and increase the occurrence of in ammation. Under certain conditions, it can express and secrete in ammatory factors such as TGF-β, IL-6, IL-8, EGF, bFGF and IGF-1 [1] . Moreover, those in ammatory cytokines can also react on prostate stromal cells and other cells to secrete a large amount of in ammatory cytokines and recruit in ammatory cells to invade prostate tissues, thus, inducing in ammatory response [2,3] . Therefore, when the in ammation of the prostate tissues developed to a certain degree, the cells of the prostate tissues, the in ammatory cells and pro-in ammatory factors will promote each other to make the in ammatory response cycle enlarged continuously. A large number of in ammatory cells and in ammatory factors constituted the in ammatory microenvironment in the prostate tissues, and induced the dysfunction of prostate cells proliferation and apoptosis, which lead to the remodel of various cells and extracellular components in the prostate and initiated the occurrence of BPH.
At present, the relationship between sex hormones and in ammation of the prostate was still very subtle.
However, there was no systematically research on the relationship between sex hormone levels and prostate in ammation. Castration combined with estrogen-induced rats prostatitis was a commonly used animal model of chronic non-bacterial prostatitis. In this method, castration combined with estrogen caused imbalance of hormone levels in animals, and the balance of estrogen/ androgen was destroyed, which made the prostate producing a non-bacterial in ammatory response [4] . In the previous studies, we found that estrogen can signi cantly promote the expression of in ammatory factors and collagen of prostate epithelial cells. In addition, we used the 2 µm thulium laser to resect part of the prostate of male beagle dogs [5] : 1. After castration, the in ammation of the beagle dogs' prostate wounds were relatively mild. 2. The in ammatory response of beagle dogs' prostate wounds increased signi cantly after the androgen treatment. The purpose of this study was to clarify the expression of histological in ammation and major in ammatory factors in prostate of castrated rats induced by different concentrations estrogen/ androgen. And it provided a new theoretical basis and method for systematically to reveal the relationship among sex hormone levels, prostate in ammation and the pathogenesis of BPH.

Experimental Animals
Fifty-three male SD rats, aged from 3 to 4 months and weighing 250 g-350 g, were provided by the Experimental Animal Center of Guizhou Medical University. License number: SCXK (Guizhou) 2012-0001.
The disposal process of animals conformed with the "Opinions under the Guidance of Treating Experimental Animals". All animals (two rats in each cage) were kept in the light cycle from 08.00 to 20.00 at room temperature of 20 ~ 26℃and relative humidity of 40-70%. During the feeding period, the animals can freely take in water and food. This experiment was approved by the Ethics Committee of Guizhou Provincial People's Hospital (No. 2018025).

Castration of male rats
Male SD rats aged 3-4 months were anesthetized by intraperitoneal injection of 0.2 ml/100 g sodium pentobarbital. After satisfactory anesthesia, the rats were xed supine on the anatomical table, and the surgical eld of the scrotum was disinfected with iodophor. The scrotal incision was about 1-2cm long, and the skin and esh membrane were cut open layer by layer to the testicular sheath, one testicle was squeezed out from the incision, and the spermatic cord was ligated and then broken. The contralateral testis was removed in the same way, and each layer was closed in turn. Penicillin was injected intramuscularly at 50,000U/(kg/d) on the day of surgery and two consecutive days after surgery, and the wounds healed well one week after surgery.
1.3 The rats after castration were randomly divided into: 1.3.1 Four rats in the blank group (sham operation group, bilateral testis were kept) were injected with corn oil every day for one month. 1.3.2 In the castration group (surgical removal of bilateral testis), four rats were injected with corn oil every day for one month. 1.3.3 After castration (surgical removal of both testes), and there were four rats in different concentrations estrogen/androgen treatment groups, including: DHT0.15 + E(0-0.5) group and E0.05 + DHT(0-1.5) group. 1.4 In ammatory response in prostate tissues of rats in each group HE staining light microscopy was used to observe the morphology of prostate tissue in rats(Supplement Fig. 1 and Fig. 2), and the evaluation of histopathological in ammation of the prostate refers to the International Prostatitis Diagnosis and Grading Standard [6] , including the anatomical location of in ammatory cell in ltration(Anatomical location), the tissue area involved by in ammatory cell in ltration (Extent) and the density of typical in ammatory cell in ltration (Morphological description).
1.5 Expression of TGF-1, IL-6 and IL-8 in prostate tissue The image analysis system of image-J software was used to detect and analyze the prostate tissue in each group. Five randomly selected elds in the 40×10 eld of view were used for quantitative analysis of the positive rate of in ammatory factors in rats in each group.

Statistical Methods
The experimental data were statistically processed by SPSS24.0 software. The Kruskal Wallis Test was used to analysis the in ammation score of prostate histology, and one-way analysis of variance was used to analysis the positive rates expression of in ammatory factors. A value of p < 0.05 was considered signi cant.

General situation of rats in each group
SD rats were generally in good condition during feeding in each group. There was no obvious abnormality in appearance, physical signs and behavioral activities. Food intake, drinking water, and bowel movements were normal. After the operation, the 4 rats in the sham operation group were generally in good condition. A total of 49 cases underwent castration operation, among which one rat died after operation. The autopsy revealed that the vascular ligature was loose during the operation and the postoperative hemorrhagic shock died. Except for that, there was no death or postoperative wound infection during the experiment.

Evaluation of histological in ammation of the prostate of rats in each group
With reference to the international prostatitis histological diagnosis and grading standards, and evaluated the anatomical location of the in ltration of prostatitis cells in each group of rats (Anatomical location Table 1). The in ltration scope of in ammatory cells in the blank group, the castration group, the E0.05 + DHT0 group and the DHT0.15 + E0 group were relatively limited, which mainly located in the duct/ glandular epithelium and/ or lumen. In ammatory cells in ltration in the E0.05 + DHT0.015 group, the E0.05 + DHT0.05 group, the E0.05 + DHT1.5 group and the DHT0.15 + E0.015 group were mainly located in the matrix, with ducts/glands as the center, and close to duct/gland within 50 µm. In ammatory cells were mainly located in the prostate stroma in the E0.05 + DHT0.5 group, the DHT0.15 + E0.05 group, the DHT0.15 + E0.15 group and the DHT0.15 + E0.5 group, while not in the prostate/catheter and the distance from them were ≥ 50 µm. After the rats were castrated, when the exogenous E concentration remained constant, the in ammation score of the rats in each group increased gradually with the increase of exogenous DHT concentration (0-0.15 mg/kg). However, even if the DHT concentration was increased again after the exogenous DHT concentration reached at 0.5 mg/kg, the score did not increase further but decreased. In addition, when the concentration of exogenous DHT was constant and the concentration of exogenous E increased accordingly, the in ammation scores of rats in each group increased gradually with the increase of E concentration. Among them, compared with blank group and castration group, the DHT0.15 + E0.05 group, the DHT0.15 + E0.15 group and the DHT0.15 + E0.5 group were statistically signi cant (P < 0.05).
With reference to the international prostatitis histological diagnosis and grading standards, the tissue area involved by the in ltration of prostatitis cells in each group of rats were evaluated(Extent, Table 2). The tissue areas affected by in ammatory cells in ltration were less than 10% in the blank group, the castration group and the E0.05 + DHT0 group. In the E0.05 + DHT0.015 group, the E0.05 + DHT0.05 group, the DHT0.15 + E0.005 group, the DHT0.15 + E0.015 group and the DHT0.15 + E0.15 group, the tissue area affected by in ammatory cells in ltration were mainly between 10%-50%. The tissue areas affected by in ammatory cells in ltration were mainly > 50% in the E0.05 + DHT0.15 group, the E0.05 + DHT0.5 group, the E0.05 + DHT1.5 group, the DHT0.15 + E0.05 group and the DHT0.15 + E0.5 group. After the rats were castrated, when the exogenous E concentration remained constant (E 0.05), the in ammation score in each group of rats increased gradually with the increase of exogenous DHT concentration. Among them, compared with the blank group and the castration group, the tissue areas involving in ammatory cell in ltration were signi cantly increased in the E0.05 + DHT0.05 group, the E0.05 + DHT0.15 group, the E0.05 + DHT0.5 group and the E0.05 + DHT1.5 group(P < 0.05). When the exogenous DHT concentration was constant (DHT 0.15), the tissue areas involved in in ammatory cell in ltration were signi cantly greater in the DHT0.15 + E0.05 group, the DHT0.15 + E0.15 group and the DHT0.15 + E0.5 group than the blank group and the castration group(P < 0.05).
With reference to the international prostatitis histological diagnosis and grading standards, the density of typical in ammatory cells in ltration in the prostate of each group of rats were evaluated (Morphological description, Table 3). The blank group, the castration group and the E0.05 + DHT0 group were mainly showed low density(single in ammatory cells), most of which were separated by different interventional spaces (< 100). The DHT0.15 + E0 group was mainly showed moderate density(fusion of in ammatory cell sheets), and no tissue destruction or lymph node/ follicle formation (100-500). The E0.05 + DHT0.15 group, the E0.05 + DHT1.5 group, the DHT0.15 + E0.05 group and the DHT0.15 + E0.5 group were mainly showed high density, and the fused in ammatory cell sheet has organization destruction or nodule/hair follicle formation (> 500). The E0.05 + DHT0.015 group and the E0.05 + DHT0.05 group were mainly in low and medium density. And the E0.05 + DHT0.5 group and the DHT0.15 + E0.005 group were mainly in medium and high density. In addition, after the rats were castrated, when the concentration of exogenous E was constant (E 0.05), the density of typical in ammatory cells in ltration in the E0.05 + DHT0.15, the E0.05 + DHT0.5 and the E0.05 + DHT1.5 groups were signi cantly higher than in the blank group and the castration group(P < 0.05). When the concentration of exogenous DHT was constant (DHT0.15), the density of typical in ammatory cells in ltration in theDHT0.15 + E0 group, the DHT0.15 + E0.005 group, the DHT0.15 + E0.05 group and the DHT0.15 + E0.5 group were signi cantly higher than the blank group and the castration group(P < 0.05).
The positive rates of in ammatory factors in each group of SD rats were quantitatively analyzed, and the results were shown in Fig. 3 and Fig. 4. The positive rates of TGF-β1, IL-6, and IL-8 in SD rats after castration were higher than those in the blank group, and the positive rates of TGF-β1 were statistically signi cant compared with the blank group (P < 0.05). After castration of SD rats, when only exogenous E (0.05 mg/kg) was given, the positive rates of TGF-β1 in the E0.05 + DHT0 group were lower than the castration group (P < 0.05). However, the positive rate of IL-6 and IL-8 were slightly higher than the castration group (P > 0.05). In addition, when SD rats were castrated with only exogenous DHT (0.15 mg/kg) stimulation and no exogenous E supplementation, the positive rates of TGF-β1, IL-6 and IL-8 in the DHT0.15 E0 group decreased compared with the castrated group, and the positive rate of TGF-β1 was statistically signi cant compared with the castrated group (P < 0.05). When the concentration of exogenous E was constant, the positive rates of TGF-β1 and IL-8 in E0.05 + DHT0.015 group, the E0.05 + DHT0.05 group, the E0.05 + DHT0.15 group and the E0.05 + DHT0.5 group increased with the increase of exogenous DHT concentration. But when the exogenous DHT concentration exceeded 0.5 mg/kg, even if the exogenous DHT concentration increased again, and the positive rate of TGF-β1 and IL-8 in E0.05 + DHT1.5 group did not increase with the further increase of exogenous DHT. On the contrary, compared with the E0.05 + DHT0.5 group, the positive rates of TGF-β1 and IL-8 in the E0.05 + DHT1.5 group decreased to a certain extent. In addition, when the concentration of exogenous DHT was constant, the positive rates of TGF-β1, IL-6 and IL-8 in each group of SD rats increased to a certain extent with the increase of exogenous E concentration. Among them, the positive rates of TGF-β1, IL-6, and IL-8 in the DHT0.15 + E0.05 group and the DHT0.15 + E0.5 group were statistically signi cant compared with the blank group and the castration group (P < 0.05). In addition, the positive rates of TGF-β1 in the DHT0.15 + E0.15 group were statistically signi cant compared with the blank group and the castration group (P < 0.05), and the positive rates of IL-6 and IL-8 were statistically signi cant compared with the blank group ( P < 0.05), but there was no statistical signi cance compared with the castration group (P > 0.05).

Discussion
BPH was a ubiquitous chronic progressive disease [7] . Aging and the presence of androgen are considered as essential links for the development of BPH, but the exact pathogenesis of BPH was still unclear [8,9] . In recent years, the role of sex hormone level has been paid more and more attention to scholars. In particular, the synergy between estrogen and androgen played a prominent role in the pathogenesis of BPH. In vitro studies, King et al. [10] found that increasing the ratio of estrogen to androgen could promote the proliferation of prostate stromal cells and epithelial cells. Current research found that there was a balance mechanism between estrogen and androgen in the body. Maintaining a dynamic balance between estrogen and androgen levels contributes to the normal growth and development of the prostate and the maintenance of physiological functions, while breaking the original balance may be the cause of changes in prostate proliferation and apoptosis, leading to BPH [11] .
In ammation was an important defense response for the body to resist pathogen invasion and repair tissue damage. However, excessive or uncontrolled in ammatory response could also cause tissue damage, becoming the basic pathological mechanism for the occurrence and development of diseases. In ammation also played a very central role in the development of various prostate diseases including BPH [12] . Compared with normal prostate, almost all prostate biopsy and surgical tissues had a large number of in ammatory factors in ltrated [13] . The IPSS, the prostate volume and the serum PSA were relatively higher in patients with more severe in ammation [14] , and the degree of chronic in ammation was also inseparable from the clinical progress of BPH [15] . It has been suggested that elevated levels of lymphocyte-derived cytokines, such as IL-2, IL-4, and IFN-γ, could be found in the resected BPH tissues.
These in ammatory factors seem to be involved in the stimulation of prostate bromuscular growth [16] . In addition, BPH and chronic prostatitis could mutually induce, promote, and aggravate disease progression, and formed a vicious circle [17] .
The interaction between androgens and in ammation played an important role in the pathogenesis of many tumors. In animal models, androgens could decrease the concentration of circulating proin ammatory factors and increase the levels of cytokines with anti-in ammatory effects [18] . Preclinical studies have shown that the in ammation and tissue structure reconstruction in the prostate of males with hypogonadism were more serious, but this phenomenon disappeard with the addition of androgen [19] . In addition, compared with people with normal gonadal function, patients with hypogonadism were ve times more likely to have in ammation in the prostate gland, and the degree of in ammation was often more severe. Naslund et al. [20] found that oral estrogen signi cantly increased the degree of non-bacterial in ammation of the prostate in rats. Therefore, the academic community gradually realized that some in ammatory response genes in the body were regulated by sex hormones, but how the level of sex hormones in the body affects the expression of these in ammatory response genes was still poorly understood.
In this study, we used castration combined with different ratios of estrogen/ androgen to successfully induce the in ammatory response in SD rats. At the same time, the in ammatory response in the prostate tissue of each group of SD rats were systematically evaluated according to the international prostatitis histological diagnosis and grading standards. We found that only part of the glands showed a little in ammatory cell in ltration in the blank group. By contrast, the number of in ammatory cells in the glands of the castrated group relatively increased. However, according to the international prostatitis histological diagnosis and grading standards, the blank group and the castration group were scored 1 point in three aspects: the anatomical location of in ammatory cell in ltration, the tissue area of in ammatory cell in ltration and the density of typical in ammatory cells. After the rats were castrated, when the concentration of exogenous E was constant (E0.05 mg/kg), increased the concentration of exogenous DHT (0-0.15 mg/kg) of SD rats in each group. From the perspective of the anatomical location involved in in ammatory cells in ltration, the in ammation scores of rats in each group increased gradually as well. However, when the exogenous DHT concentration reached at 0.5 mg/kg, even if the DHT concentration increased again, the in ammation score did not increase further but decreased. In addition, judging from the tissue area affected by in ammatory cells in ltration and the density of typical in ammatory cells, After the rats were castrated, the source of androgen was blocked.
When a constant dose of exogenous E was given to stimulate, and the exogenous DHT concentration increased gradually, we found that the in ammation score in each group of rats increased gradually with the increase of DHT concentration. Therefore, we believed that when SD rats were given a certain dose of exogenous E concentration stimulation after castration, and increased gradually the exogenous DHT concentration. When DHT was within a certain concentration range, whether it was viewed from the anatomical location of in ammatory cells in ltration, tissue areas affected by in ammatory cells in ltration and typical in ammatory cells density, which could induce the in ammation response in SD rats. However, judging from the performance of the E0.05 + DHT0.5 group and the E0.05 + DHT1.5 group in the anatomical locations involved in in ammatory cell in ltration, there may be an in ection point between the ratio of estrogen/ androgen and the in ammation of the prostate. After crossing this in ection point, the in ammation of the prostate did not deepen even if the concentration of exogenous androgen increased again. Of course, it needs to be con rmed by more systematic and comprehensive experiments in vivo and vitro.
In our clinical work, we have found that BPH usually occured in middle-aged and elderly patients whose androgen levels have been reduced and estrogen levels were relatively high, while rarely occured in young patients with high androgen levels and relatively low estrogen levels. In addition, according to the epidemiological survey data, the incidence of chronic prostatitis was higher in people aged 40-49 and over 60 years old [21,22,23,24] . Therefore, we found that both BPH and chronic prostatitis were prone to occur in middle-aged and elderly patients whose androgen levels have decreased and estrogen levels were relatively increased. Seethalakshmi et al. [25] induced chronic non-bacterial prostatitis in rats by using 17--estradiol and found that the pathological manifestations of estradiol-induced non-bacterial prostatitis in rats were similar to those of clinical chronic non-bacterial prostatitis. In addition, Kwon et al. [26] successfully induced chronic non-bacterial prostatitis by giving oral soy iso avones to SD rats, which con rmed that oral estrogen could also cause prostatitis, and further proved that the signi cance of hormone level changes in the occurrence of prostatitis. However, for middle-aged and elderly patients with low androgen levels, the effects of changes in different levels of estrogen/ androgen on BPH and prostate in ammation were still unclear. In this study, we supplemented the castrated rats with a constant concentration of exogenous DHT(0.15 mg/kg) lower than the physiological dose, and used the different concentrations of exogenous E to stimulate SD rats. Establishing a rat model in which androgen levels were relatively low and estrogen was sequentially increased (that was also in line with the performance of hormone levels in middle-aged and elderly men). We found that when the concentration of exogenous DHT was constant and the concentration of exogenous E increased gradually. SD rats in each groups either from the perspective of the anatomical location of in ammatory cells in ltration involvement ratings, or from the perspective of the regional scale of in ammatory cells in ltration involvement. With the increase of exogenous E concentration, and the in ammatory score in each group showed a gradual increase trend. To a certain extent, the results of this study also re ected from the perspective of animal experiments why BPH and chronic prostatitis rarely occured in young patients with high androgen levels and relatively low estrogen levels. However, it usually occured in middle-aged and elderly patients with relatively low androgen levels and relatively high estrogen levels.
In addition, we used immunohistochemistry to detect the expression of TGF-β1, IL-6, and IL-8 in the prostate tissue of SD rats in each group. After quantitative analysis, we found that: Compared with the blank group, the positive rate of TGF-β1, IL-6, and IL-8 in the prostate tissue of SD rats increased after castration, which indicated that castration or decreased androgen levels could induce the in ammation response of the prostate tissue in SD rats and the expression of TGF-β1, IL-6 and IL-8 could increase to a certain extent. In addition, after the rats are castrated, when the exogenous E concentration was constant, the positive rates of TGF-β1 and IL-8 in the E0.05 + DHT0.015 group, the E0.05 + DHT0.05 group, the E0.05 + DHT0.15 group and the E0.05 + DHT0.5 group all increased with the increase of exogenous DHT concentration to a certain extent. However, when the concentration of exogenous DHT exceeded 0.5 mg/kg, even if the concentration of exogenous DHT increased again, the positive rates of TGF-β1 and IL-8 in the E0.05 + DHT1.5 group did not increase again with the increase of exogenous DHT. While the positive rates of TGF-β1 and IL-8 in the E0.05 + DHT1.5 group decreased to a certain extent compared with the E0.05 + DHT0.5 group. In addition, when the concentration of exogenous DHT was constant, the concentration of exogenous E increased gradually. The positive rates of TGF-β1, IL-6, and IL-8 in each group of SD rats increased to a certain extent with the concentration of exogenous E. Therefore, we believed that TGF-β1, IL-6, and IL-8 were involved in the regulation of prostate in ammation in SD rats, and their positive rate expression varied with the change in the levels of estrogen and androgen in SD rats, and the positive rates expression of TGF-β1, IL-6 and IL-8 could re ect the in ammation in the prostate tissues of SD rats to a certain extent.

Conclusions
In this study, we used castration combined with different ratios of estrogen/ androgen to successfully induce in ammation in SD rats. In addition, we systematically analyzed and evaluated the relationship between sex hormone levels and prostate in ammation and the expression of related in ammatory factors. It is con rmed that the changes of sex hormone levels are involved in the regulation of the in ammatory response in the prostate of SD rats. And TGF-β1, IL-6, and IL-8 were involved in the regulation of prostate in ammation in SD rats, and their positive rate expression varied with the change in the levels of estrogen and androgen in SD rats, and the positive rate expression of TGF-β1, IL-6 and IL-8 could re ect the in ammation in the prostate tissues of SD rats to a certain extent. In addition, there may be an in ection point between the ratio of estrogen and androgen and prostate in ammation. After crossing this in ection point, even increasing the concentration of exogenous androgens, the in ammation of the prostate did not further deepen. Of course, it needs to be con rmed by more systematic and comprehensive experiments in vivo and vitro.

Consent for publication
Written informed consent was obtained from all participants..