eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2017-06-20 10 2 725 737 10.13005/bpj/1162 15028 article Yurnadi Hanafi Midoen 1 Dita Rany Anggraeni 2 Dwi Anita Suryandari 1 Hans-Joachim Freisleben 3 Department of Medical Biology, Faculty of Medicine, Universitas Indonesia. Master Program Biomedical Sciences, Faculty of Medicine, Universitas Indonesia. Medical Research Unit, Faculty of Medicine, Universitas Indonesia, Jalan Salemba Raya 6, Jakarta Pusat, 10430 Indonesia. To reduce population growth, the Indonesian government promotes a Family Planning Program for fertile couples. Depot-medroxyprogesterone acetate (DMPA) combined with testosterone or herbal androgens as testosterone substitute is intended for hormonal male contraception because it is expected that these combinations can suppress gonadotropin and inhibit spermatogenesis. Various medicinal herbs contain androgens, e.g., Javanese long pepper (JLP) (Piper retrofractum Vahl). Traditionally, JLP chili extract (JCE) is used to cure impotency and was proven to increase blood testosterone levels in hypogonad men. The aim of this study is to combine increasing amounts of JCE (0.94 – 3.76 mg) with DMPA (1.25 mg) and to study the effects on testicular parameters using male Sprague-Dawley rats: testis weight, seminiferous tubule diameter, the subpopulations of spermatogenic cells, and Leydig cells. Our randomized study design used six equally sized groups with 6 animals, each. Testis weight only decreased vs. controls in two groups, DMPA + placebo and DMPA + 3.76 mg JCE. Significant decrease occurred in the diameter of seminiferous tubules and at 3.76 mg JCE, in Leydig cell population. Within spermatogenic cell population spermatogonia A, spermatocyte-I preleptotene, spermatocyte-I pachiten, and spermatid population decreased. The combination of 1.25 mg DMPA and 3.76 mg JCE appears to be the minimal dose and a potent candidate for male contraception in our rat model. https://biomedpharmajournal.org/vol10no2/finding-the-minimal-effective-dose-of-a-combination-of-depot-medroxyprogesterone-acetate-and-javanese-long-pepper-for-male-contraception-on-testicular-fertility-parameters-in-male-sprague-dawley-rats/ DMPA  Leydig cells  Piper retrofractum Vahl seminiferous tubules spermatogenic cells