Biomed Res- India 2014 Volume 25 Issue 3 391 Biomedical Research 2014; 25 (3): 391-400 ISSN 0970-938X http://www.biomedres.info Effects of genistein on male sprague dawley rats reproductive development. Nurul Iftitah Musameh, Siti Rosmani Md Zin, Normadiah M. Kassim Department of Anatomy, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia Abstract Genistein (Gen), is commonly consumed phytoestrogen among Asian and known to exert weak estrogenic effects. To account for potential reproductive effects in male rats, Control, Gen1, Gen10, Gen100 mg/kg body weight and Estradiol were administered to gestational day 10 (GD10) female Sprague Dawley for 5 weeks. At postnatal day, P50, the rats were sacrificed. Blood was taken and reproductive tissues were processed. At birth, body weight (BW) and anogenital distance (AGD) in Gen10 and Gen100 decreased significantly from Control. Throughout experiment, BW and AGD of Gen10 decreased significantly. Preputial separation (PPS) was significantly longer in Gen100 and one rat from Gen10 exhibited unilateral testis descent at P50. Testicular weight and serum testosterone level were reduced in a dose-dependent manner. Histopathological analysis of the seminiferous tubules in Gen1 group is comparable to the Control group. However, the seminiferous tubules of the Gen10 and Gen100 groups showed evidence of overstimulated spermatogenesis. From the immunohistochemical (IHC) analysis, there was higher staining intensity indicating increased expression of 3β-hydroxysteroid dehydrogenase (3β-HSD) and Connexin43 (Cx43) in Gen10 and Gen100 groups compared to Control. Thus, administration of genistein during the critical period of early development could cause antiestrogenic or/and estrogenic influence on the development and functions of the male reproductive system. Keywords: Soy, testis, estrogens , testosterone, nutrition Accepted May 08 2014 Introduction Genistein is a plant isoflavone with polyphenolic compounds derived from a common class of phytoestrogens. Phytoestrogens are classified into groups according to their chemical structures. The greatest estrogenic activity is found in flavones, flavonols, flavonones, lignans, chalcones and isoflavones [1]. These compounds share structural similarities to steroidal estrogens, hence, its binding to estrogen receptors therefore capable of exerting weak anti- and/or estrogenic effects mediated by ER-α and also ER-β through alternative signaling pathways [2-6]. Thus, it is known as an endocrine disrupting chemical (EDC) [4-6]. The relative affinity of phytoestrogens to the ER- β is higher than ER- α [7-9]. Isoflavone was first found to increase plasma concentrations of endogenous estrogens associated with infertility in ewes [10]. Genistein and daidzein form the most predominant isoflavones in soybean which contribute to the most important dietary source of phytoestrogens for mammals [11]. In human, exposure to genistein is mainly from consumption of soy-based food products such as soymilk, tempeh, tofu, miso, soy flour and soy sauce [12]. It was reported that Asian people consumed 1.5 mg genistein or other isoflavones daily higher than most Europeans and North Americans [13, 14]. Many EDCs in the environment are identified as environmental estrogens. These environmental estrogens may endanger fetuses as they are at the stage of highly susceptible to minor endocrine disturbances that may give rise to developmental abnormalities including testicular dysfunction [15] and thus lead to infertility. The morphological alteration is associated with lack of gap junction protein, Connexin43 (Cx43) which controls cell growth and differentiation of the germ cells [16-20]. Thus, Cx43 expression can be used as an indicator for the well-being of the intercellular communication in the seminiferous epithelium where it was normally expressed in rat testis [21], and was down-regulated in mice testis with disrupted spermatogenesis [22-24]. Failure of spermatogenesis is also associated with low testosterone levels due to disturbance in testicular steroidogenesis which depends on 3β-hydroxysteroid dehydrogenase (3β- HSD) enzyme for the synthesis and secretions of testosterone [25]. This is in agreement with analysis of contralateral testis of men with testis anomaly due to