Background: Inorganic arsenic is a major water pollutant and a known human carcinogen that has a suppressive influence on spermatogenesis and androgenesis in male reproductive system. However, the actual molecular events resulting in male reproductive dysfunctions from exposure to arsenic remain unclear. In this context, we evaluated the mode of action of chronic oral exposure of sodium arsenite on hypothalamo-pituitary- testicular activities in mature male albino rats.Methods: The effect of chronic oral exposure to sodium arsenite (5 mg/kg body weight/day) via drinking water without or with hCG (5 I.U./kg body weight/day) and oestradiol (25 micrograms oestradiol 3-benzoate suspended in 0.25 ml olive oil/rat/day) co-treatments for 6 days a week for 4 weeks (about the duration of two spermatogenic cycle) was evaluated in adult male rats. Changes in paired testicular weights, quantitative study of different varieties of germ cells at stage VII of spermatogenic cycle, epididymal sperm count, circulatory concentrations of hormones (LH, FSH, testosterone and corticosterone), testicular activities of delta 5, 3beta-hydroxysteroid dehydrogenase (delta 5, 3beta-HSD), 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD), sorbitol dehydrogenase (SDH), acid phosphatase (ACP), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH), as well as the levels of biogenic amines (dopamine, noradrenaline and 5-hydroxytryptamine (5-HT)) in the hypothalamus and pituitary were monitored in this study. Hormones were assayed by radioimmuno- assay or enzyme- linked immunosorbent assay and the enzymes were estimated after spectrophotometry as well as the biogenic amines by HPLC electrochemistry.Results: Sodium arsenite treatment resulted in: decreased paired testicular weights; epididymal sperm count; plasma LH, FSH, testosterone and testicular testosterone concentrations; and increased plasma concentration of corticosterone. Testicular enzymes such as delta 5, 3 beta-HSD, 17 beta-HSD, and sorbitol dehydrogenase (SDH) were significantly decreased, but those of acid phosphatase (ACP), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were significantly increased. A decrease in dopamine or an increase in noradrenaline and 5-HT in hypothalamus and pituitary were also noted after arsenic exposure. Histological evaluation revealed extensive degeneration of different varieties of germ cells at stage VII of spermatogenic cycle in arsenic exposed rats. Administration of human chorionic gonadotrophin (hCG) along with sodium arsenite partially prevented the degeneration of germ cells and enhanced paired testicular weights, epididymal sperm count, plasma and intratesticular testosterone concentrations, activities of delta 5, 3beta-HSD, 17 beta-HSD and sorbitol dehydrogenase along with diminution in the activities of ACP, ALP and LDH. Since many of the observed arsenic effects could be enhanced by oestradiol, it is suggested that arsenic might somehow acts through an estrogenic mode of action.Conclusion: The results indicate that arsenic causes testicular toxicity by germ cell degeneration and inhibits androgen production in adult male rats probably by affecting pituitary gonadotrophins. Estradiol treatment has been associated with similar effects on pituitary testicular axis supporting the hypothesis that arsenite might somehow act through an estrogenic mode of action.

B(a)P (Benzo(a)pyrene) is an environmental toxicant that induces male germ cell apoptosis. Curcumin and resveratrol are phytochemicals with cytoprotective and anti-oxidative properties. At the same time resveratrol is also a natural Aryl hydrocarbon Receptor (AhR) antagonist. Our present study in isolated testicular germ cell population from adult male Wistar rats, highlighted the synergistic protective effect of curcumin and resveratrol against B(a)P induced p53 mediated germ cell apoptosis. Curcumin-resveratrol significantly prevented B(a)P induced decrease in sperm cell count and motility, as well as increased serum testosterone level. Curcumin-resveratrol co-treatment actively protected B(a)P induced testicular germ cell apoptosis. Curcumin-resveratrol co-treatment decreased the expression of pro-apoptotic proteins like cleaved caspase 3, 8 and 9, cleaved PARP, Apaf1, FasL, tBid. Curcumin-resveratrol co-treatment decreased Bax/Bcl2 ratio, mitochondria to cytosolic translocation of cytochrome c and activated the survival protein Akt. Curcumin-resveratrol decreased the expression of p53 dependent apoptotic genes like Fas, FasL, Bax, Bcl2 and Apaf1. B(a)P induced testicular ROS (Reactive Oxygen Species) generation and oxidative stress were significantly ameliorated with curcumin and resveratrol. Curcumin-resveratrol co-treatment prevented B(a)P induced nuclear translocation of AhR and CYP1A1(Cytochrome P4501A1) expression. The combinatorial treatment significantly inhibited B(a)P induced ERK 1/2, p38 MAPK and JNK 1/2 activation. B(a)P treatment increased the expression of p53 and its phosphorylation (p53 ser 15). Curcumin-resveratrol co-treatment significantly decreased p53 level and its phosphorylation (p53 ser 15). The study concludes that curcumin-resveratrol synergistically modulated MAPKs and p53, prevented oxidative stress, regulated the expression of pro and anti-apoptotic proteins as well as the proteins involved in B(a)P metabolism thus protected germ cells from B(a)P induced apoptosis.

Resveratrol, a trans-stilbene polyphenolic compound and its synthetic analogs are widely used bioactive molecules due to their remarkable chemo-preventive potential. Here, we have identified a novel synthetic trans-stilbene compound, Z-DAN-11 ((Z)-3-(3, 4-dimethoxyphenyl)-2-(3, 4, 5-trimethoxyphenyl) acrylonitrile) which shows remarkable efficacy in blocking tumor growth and progression both in vitro and in vivo. Z-DAN-11 inhibits proliferation of cancer cells in vitro through microtubule depolymerization that induced G2/M arrest and consequently leads to apoptotic cell death. More importantly, Z-DAN-11 shows limited cytotoxicity to normal cells as compared to cancer cells. Quite interestingly, we have found that Z-DAN-11-mediated ROS production helps in dramatic alteration in the mitochondrial redox status which critically contributes to the apoptosis. Mechanistic studies reveal that Z-DAN-11 induces the expression of pro-apoptotic proteins and decreases anti-apoptotic protein expression that decisively helps in the activation of caspase 8, caspase 9, and caspase 3, leading to cleavage of PARP1 and cell death via intrinsic and extrinsic pathways of apoptosis. Moreover, Z-DAN-11-mediated apoptosis of cancer cells is through a partial p53-dependent pathway, since both HCT116 p53^−/− cells as well as p53-silenced cells (siRNA) were able to block apoptosis partially but significantly. Importantly, Z-DAN-11 also imparts its anti-tumorigenic effect by inhibiting clonogenic property and anchorage-independent growth potential of cancer cells at concentrations at least 10 times lower than that required for inducing apoptosis. Finally, in vivo study with immuno-competent syngeneic mice shows Z-DAN-11 to be able to impede tumor progression without any adverse side-effects. Hence, we identified a novel, synthetic trans-stilbene derivative with anti-tumorigenic potential which might tremendously help in devising potential therapeutic strategy against cancer.