Abstract
Background:
PGF2α hormone administration can improve semen quality through increased contractility of smooth muscle cells in testicular tissue and increased testosterone hormone. Immunohistochemically, the increase in contractility of smooth muscle cells and testosterone hormone can be measured by an increase in the expression of alpha-smooth muscle actin (α-SMA) and androgen receptor (AR).

Aim:
This study aims to determine the distribution and increased α-SMA expression and AR in the testis of Wistar rats after administration of PGF2α which detected using the immunohistochemistry (IHC) method.

Methods:
A total of 15 male Wistar rats (Rattus norvegicus) with body weight 200-250 g and 8-10 weeks old were used in this study. All rats were acclimated for two weeks. The rats were divided into 5 treatment groups (n=3). The rat in the control group (P0), testicular collection was carried out 30 minutes after injection of 0.5 ml NaCl. In group P1, P2, P3, and P4, the rats were intraperitoneal injected with 2.5 mg/kg BW of PGF2α (Lutalyze, Zoetis, USA), and the testis collection was performed 30 minutes, 60 minutes , 90 minutes , and 120 minutes after PGF2α injection, respectively. were processed into histology preparations and stained with immunohistochemistry staining using avidin-biotin complex peroxidase method (ABC method). The distribution of α-SMA and AR was analyzed descriptively, while the score difference of α-SMA and AR expression was analyzed using the Kruskal-Wallis test and the Mann-Whitney U Test.

Results:
The results showed that α-SMA was positively detected in peritubular myoid cells on the basal membrane of seminiferous tubules, blood vessel walls, and connective tissue. Statistical analysis showed that α-SMA expression in peritubular myoid cells and testicular connective tissue in P2 (60-minute interval) was significantly different than other treatment groups (P0, P1, P3, and P4) (P<0.05), while no significant difference was found in the blood vessel walls in all treatment groups (P>0.05). AR was positively detected in connective tissue, peritubular myoid cells, Leydig cells, Sertoli cells, and blood vessels. Statistical analysis showed significant differences in AR expression in peritubular myoid cells and Sertoli cells (P<0.05) between P0 and P2, P1 and P2, and P2 and P3 or P4.

Conclusion:
It can be concluded that the administration of PGF2α increase the expression of -SMA and AR, with the optimal administration interval is 60 minutes for peritubular myoid cells and Sertoli cells in Wistar rats testis.

Key words: Androgen receptor, Immunohistochemistry, PGF2α, Wistar rats, α-SMA