2.2. Induction of BPH and Agent Administration

BPH was induced with testosterone propionate (TP) in male Wistar rats via intramuscular injection, and this epithelial hyperplastic model has been used in numerous studies [18,19]. Briefly, rats were divided into five groups (n = 8): Group 1—control animals (Con, castrated rats with vehicle: intramuscular injection of ethanol with corn oil); Group 2—rats with BPH induction (BPH); Group 3—rats with BPH orally administrated 5 mg/kg finasteride (Fina); Group 4,5—rats with BPH intraperitoneally administrated 0.5 or 1.0 mg/kg 6SL (6SL 0.5 and 1.0). Castration was performed by removing the testicles and epididymal fat in all rats. Rats were injected with 10 mg/kg testosterone propionate (TP; Wako Pure Chemicals, Tokyo, Japan) alone or along with finasteride or 6SL every day, except on weekends, for 4 weeks. All animals were sacrificed under anesthesis with Zoletil^® 50 (intraperitoneal, 20 mg/kg; Virbac, Carros, France) 28 days after the first testosterone injection. The ventral prostate (VP) and dorsolateral prostate (DLP) were excised, weighed, and stored at −80 °C.