Methoxychlor induces apoptosis via mitochondria- and FasL-mediated pathways in adult rat testis.

In the past few years, there has been much concern about the adverse health effects of environmental contaminants in general and organochlorine in particular. Studies have shown the repro-toxic effects of long-term exposure to methoxychlor, a member of the organochlorine family. However, the insight into the mechanisms of gonadal toxicity induced by methoxychlor is not well known. In the present study we sought to elucidate the mechanism(s) underpinning the gonadal effects within hours of exposure to methoxychlor. Experimental rats were divided into six groups of four each. Animals were orally administered with a single dose of methoxychlor (50mg/kg body weight) and killed at 0, 3, 6, 12, 24, and 72h post-treatment. The levels and time-course of induction of apoptosis-related proteins like cytochorome C, caspase 3 and procaspase 9, Fas-FasL and NF-kappaB were determined to assess sequential induction of apoptosis in the rat testis. DNA damage was assessed by TUNEL assay and flowcytometry. Administration of methoxychlor resulted in a significant increase in the levels of cytosolic cytochrome c and procaspase 9 as early as 6h following exposure. Time-dependent elevations in the levels of Fas, FasL, pro- and cleaved caspase 3 were observed. The DNA damage was measured and showed time-dependent increase in the TUNEL positive cells, and also by flowcytometry of testicular cells. The study demonstrates induction of testicular apoptosis in adult rats following exposure to a single dose of methoxychlor.

Methoxychlor-induced alteration in the levels of HSP70 and clusterin is accompanied with oxidative stress in adult rat testis.

Methoxychlor, an organochlorine pesticide, has been reported to induce abnormalities in male reproductive tract. However, the insight into the mechanisms of gonadal toxicity induced by methoxychlor is not well known. We investigated whether treatment with methoxychlor would alter the levels of stress proteins, heat shock proteins (HSP), and clusterin (CLU), and oxidative stress-related parameters in the testis of adult male rats. Animals were exposed to a single dose of methoxychlor (50 mg/kg body weight) orally and were terminated at various time points (0, 3, 6, 12, 24, and 72 h) using anesthetic ether. The levels of HSP70, CLU, and the activities of superoxide dismutase (SOD), catalase, and lipid peroxidation levels were evaluated in a 10% testis homogenate. A sequential reduction in the activities of catalase and SOD with concomitant increase in the levels of thiobarbituric acid reactive substance (TBARS) was observed. These changes elicited by methoxychlor were very significant between 6-12 h of posttreatment. Immunoblot analysis of HSP revealed the expression of HSP72, an inducible form of HSP, at certain time points (3-24 h) following exposure to methoxychlor. Similarly, the levels of secretory CLU (sCLU) were also found to be elevated between 3-24 h of treatment. The present data demonstrate methoxychlor-elicited increase in the levels of inducible HSP72 and sCLU, which could be a part of protective mechanism mounted to reduce cellular oxidative damage.

Lindane induces testicular apoptosis in adult Wistar rats through the involvement of Fas-FasL and mitochondria-dependent pathways.

Lindane, an organochlorine pesticide, is known to impair testicular functions and fertility. To elucidate the mechanism(s) underpinning the gonadal effects of lindane, we sought to investigate the levels of apoptosis-related proteins, namely cytochrome c, caspase-3 and-9, Fas and FasL in the testis of adult rats. Furthermore, the study aims to delineate whether nuclear factor kappa B (NF-kappaB) is involved in meditating the testicular effects of lindane. Animals were administered with a single dose of lindane (5mg/kg body weight) and sacrificed at specific post-treatment intervals (0, 3, 6, 12, 24 and 72h). Significant elevations in the levels of cytosolic cytochrome c with a parallel increase in pro-caspase-9 were observed as early as 6h following exposure. Time-dependent elevations in the levels of Fas, FasL and caspase-3 were observed. Immunofluorescence studies revealed increased colocalization of Fas and caspase-3 in peritubular germ cells. FasL levels were increased in Sertoli and peritubular germ cells. The cytoplasmic levels of NF-kappaB p65 decreased from 3h following exposure with a maximal decline at 12 and 24h. Changes in the localization of NF-kappaB were observed with maximal nuclear translocation in germ cells at 12 and 24h. Terminal deoxynucleotidyl transferase-mediated dUTP nickend-labeling (TUNEL) assay revealed a time-dependent increase in the number of apoptotic cells. Taken together, the data illustrate induction of testicular apoptosis in adult rats following exposure to a single dose of lindane. Early activation of NF-kappaB in contrast to late increase in Fas expression suggests a pro-apoptotic role of NF-kappaB in testicular response to lindane.

Piperine activates testicular apoptosis in adult rats.

Piperine, an alkaloid present in the fruits of commonly used spice pepper, is known to impair reproductive functions. In the present study, piperine was administered to adult male rats at the dose levels of 1, 10, and 100 mg/kg body weight for 30 days to evaluate its effects on the testis. A significant decrease in the activities of antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase in the testis was observed at 10 and 100 mg of piperine administration when compared with the controls. A dose-dependent increase in lipid peroxidation and hydrogen peroxide generation was also observed. Sialic acid levels in the testis were also found to be decreased when piperine was administered at 10 and 100 mg dose levels. Immunofluorescence studies demonstrated a dose-dependent increase in caspase 3 and Fas protein in testicular germ cells after piperine treatment. These observations indicate that piperine induces oxidative stress and thereby triggers apoptosis in the testis, contributing to hampered reproductive functions.

Transient inhibitory effect of methoxychlor on testicular steroidogenesis in rat: an in vivo study.

Methoxychlor, an organochlorine pesticide, has been reported to induce reproductive abnormalities in male reproductive tract. To get more insight into the mechanism(s) of gonadal toxicity provoked by methoxychlor, we investigated whether treatment with methoxychlor at low observed adverse effect level (LOAEL) would alter the activities of steroidogenic enzymes such as Delta(5)3beta-hydroxysteroid dehydrogenase (3beta-HSD) and Delta(5)17beta-hydroxysteroid dehydrogenase (17beta-HSD), the expression levels of steroidogenic acute regulatory (StAR) protein and androgen binding protein (ABP) in the testis of adult male rats. The experimental rats were exposed to a single dose of methoxychlor (50 mg/kg body weight) orally. The rats were killed at 0, 3, 6, 12, 24 and 72 h following treatment using anesthetic ether and testes were collected, processed and used to measure the activities of 3beta-HSD, 17beta-HSD, levels of hydrogen peroxide produced and the expression levels of StAR protein, and ABP. Methoxychlor administration resulted in a sequential reduction in the expression of StAR protein and activities of 3beta-HSD, 17beta-HSD with concomitant increase in the levels of hydrogen peroxide in the testis. These changes were significant between 6-12 h following treatment. The levels of ABP declined at 6-12 h following exposure to methoxychlor. The present study demonstrates transient effect of methoxychlor at LOAEL on testicular steroidogenesis and the possible role of hydrogen peroxide in mediating these effects.

Single exposure to low dose of lindane causes transient decrease in testicular steroidogenesis in adult male Wistar rats.

Substantial evidence has piled up portending the adverse effects of environmental toxicants on male reproduction. Lindane, an organochlorine pesticide, has been reported to perturb testicular functions and hence fertility. To get more insight into the mechanism(s) involved in gonadal effect(s) of lindane, we sought to investigate whether treatment with lindane at a low dose would alter the levels of steroidogenic acute regulatory protein (StAR), androgen binding protein (ABP) and activities of steroidogenic enzymes (3beta-hydroxysteroid dehydrogenase and 17beta-hydroxysteroid dehydrogenase) in adult rat. Furthermore, the levels of H2O2 were monitored to delineate the possible role of H2O2 in mediating the testicular effects of lindane. Animals used for experimentation were divided into six groups and four animals were maintained in each group. Animals were administered with a single dose of lindane (5mg/kg body weight) and terminated at specific post-treatment intervals (0h, 3h, 6h, 12h, 24h and 72h) to analyze the early testicular response. Administration of lindane resulted in a sequential reduction in the levels of StAR and the activities of steroidogenic enzymes with a parallel increase in the levels of H2O2. These changes elicited by lindane were significant at 12h and 24h post-treatment. In case of ABP, a significant decline in the level was found at 12h after treatment. These findings demonstrate transient inhibitory effects of lindane on testicular steroidogenesis and the possible role of H2O2 in mediating these effects.

Lindane alters the levels of HSP70 and clusterin in adult rat testis.

Lindane, an organochlorine pesticide, has been reported to induce reproductive abnormalities in male rats and induction of stress is considered to play an important role in the toxicity of lindane. To get more insight into the mechanism(s) involved in gonadal effect(s) of lindane, we sought to investigate whether treatment with lindane would alter the levels of stress proteins (heat shock proteins and clusterin) and change oxidative stress-related parameters (antioxidant enzymes and lipid peroxidation) in the testis of adult male rats. Animals used for experimentation were divided into six groups and four animals were maintained in each group. Animals were administered with a single dose of lindane (5mg/kg body weight) and terminated at specific post-treatment intervals (0, 3, 6, 12, 24 and 72 h) to analyze the early stress response. Administration of lindane resulted in a sequential reduction in the activities of catalase and superoxide dismutase (SOD) with concomitant increase in the levels of lipid peroxidation. These changes elicited by lindane were significant between 6 and 24 h post-treatment. In case of heat shock protein, the level of the constitutive HSP70 remained constant at all post-treatment intervals. However, a significant induction in the level of inducible HSP70 was observed between 6 and 24 h post-treatment. Similarly, the levels of secretory clusterin (sCLU) was found be significantly elevated at 12 and 24 h after treatment. These findings indicate a transitory state of stress induced by lindane in rat testis accompanied by an alteration in the levels of stress proteins, which could be a part of protective mechanism mounted to reduce cellular damage.

Effect of environmental contaminants on male reproduction.

A substantial body of evidence has accumulated in recent years that consistently indicate various adverse effects of environmental contaminants on human health. Decreasing trend of male fertility in terms of sperm counts and sperm quality, along with other changes in male reproductive health, including congenital malformations and testicular cancer in humans, and similar problems in wildlife has been correlated to the exposure to environmental contaminants. Many environmental chemicals have been reported to cause these reproductive abnormalities by eliciting changes in endocrine control of reproduction; however the specific underlying mechanisms are poorly understood. The present review summarizes recent studies on environmental contaminants and associated possible mechanism leading to adverse effects on male reproduction. Numerous studies demonstrate the interaction of environmental toxicants with steroid receptors and thereby causing interference with developmental and functional aspects of testis, epididymis and accessory sex organs. Induction of reactive oxygen species (ROS) by environmental contaminants and associated oxidative stress also have role in defective sperm function and male infertility.

Induction of oxidative stress by lindane in epididymis of adult male rats.

Lindane, an organochlorine pesticide, has been reported to induce reproductive abnormalities in male rats. The mechanism of action of lindane on male reproductive system remains unclear. In the present study we have sought to investigate the effect of lindane on antioxidant parameters and sialic acid levels of caput, corpus and cauda epididymis of adult male rats. Lindane (1, 5, and 50mg/kg per day) was administered orally to adult male rats for 45 days. The animals were killed using anaesthic ether on the day following the last treatment. The body weight of the animals did not show significant change. However, the weights of caput, corpus and cauda epididymis decreased in lindane treated animals. Administration of lindane caused decrease in epididymal sperm count and motility. Sialic acid levels in the epididymis decreased significantly at 5 and 50mg/kg dosage of lindane treatment. Significant decline in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase along with increase in hydrogen peroxide generation and lipid peroxidation were observed in lindane treated animals. In conclusion, lindane induces oxidative stress by decreasing the activities of antioxidant enzymes and sialic acid levels in the epididymis thereby causing impaired sperm function.

Oxidative stress and protein glycation in patients with chronic obstructive pulmonary disease.

Several studies have indicated the presence of increased oxidative stress as a critical feature in the pathogenesis of chronic obstructive pulmonary disease (COPD). Another biochemical complication leading to pathogenesis is protein glycation. The nexus between oxidative stress and protein glycation in various pathological conditions is being unraveled. Increased oxidative stress can lead to enhanced protein glycation by a process of auto-oxidative glycation. No information is available in the literature regarding protein glycation among COPD patients. Eleven non-diabetic COPD patients were included in the study and equal number of age and sex-matched healthy individuals were enrolled as controls. The whole-blood reduced glutathione was found to be less among the patients while lipid peroxides and fructosamine were elevated in comparison to control. The present study confirmed oxidative stress and enhanced protein glycation among the COPD patients. Antioxidant therapy may be considered as part of the treatment regimen for COPD patients.