Dose-Dependent Oxidative Damage in Erythrocytes and Hepatic Tissue of Wistar Rats Concurrently Exposed with Arsenic and Quinalphos: a Subacute Study

Concurrent exposure to a multitude of environmental toxicants pose serious health hazard to humans and animals. The present investigation was conceptualized to determine deleterious effects of concomitant subacute arsenic and quinalphos exposure on antioxidant responses of liver and erythrocytes of Wistar rats. Fifty-four Wistar rats were divided into nine groups with six animals in each. Animals were exposed to either quinalphos (1/100th and 1/10th of LD50) through oral gavage daily or arsenic (50 and 100 ppb) in drinking water alone and in combination for 28 days. While treatment with different toxicants alone also significantly reduced hemoglobin concentration, hepatic biomarkers and levels of antioxidant parameters as compared with control values, concomitant exposure significantly (P < 0.05) elevated levels of hepatic transaminases and alkaline phosphatase. Moreover, along with significant depletion in activities of SOD, CAT, TTH, AChE, and enzymes of glutathione complex, a significant enhancement of lipid peroxidation was also recorded in liver and erythrocytes in co-exposed animals in a dose-dependent manner when compared with exposure to individual toxicant. More severe alterations occurred in hepatic histo-architecture of rats receiving combined treatment as compared with those treated with either toxicant. Results indicated that oxidative damage in erythrocytes was more than that of the liver of rats on concomitant exposure of arsenic and quinalphos in a dose-dependent manner. In nutshell, our results revealed that combined treatment of quinalphos with arsenic potentiated toxic effects of either toxicant on antioxidant machinery of liver and erythrocytes and hepatic histomorphology of exposed Wistar rats.

Ameliorative effect of N-acetylcysteine on the testicular tissue of adult male albino rats after glyphosate-based herbicide exposure

Glyphosate (GLP) is a broad-spectrum herbicide that is frequently used in crop production, but its residues remain in foodstuffs. This, in turn, has led to potential adverse effects on both human and animal health. Recent studies emphasized that GLP induces teratogenic effects and reproductive disorders, but its mechanism of toxicity is highly debated. N-acetylcysteine (NAC) is well known for its potent antioxidant capacity in addition to anti-inflammatory and cytoprotective properties. Therefore, our study aimed to investigate the reproductive toxicity of GLP in mature rats and evaluate the possible ameliorative effect of NAC against this toxicity. To this end, 30 adult male rats were assigned into three groups (10 rats per group) as follows: Group I, negative control; group II, GLP-exposed; 375 mg/kg GLP, orally; group III, NAC-cotreated, 160 mg/kg NAC 1 h before GLP, plus GLP, 375 mg/kg orally for 6 weeks. At the end of the experiment, the testicles were collected for semen analysis and biochemical, histopathological, and immunohistochemical studies. GLP-exposed rats exhibited disturbances in seminal parameters and a significant increase in malondialdehyde levels and expression of apoptotic markers. Several histopathological changes were observed, including strong immunoreactions for caspase-3 and proliferating cell nuclear antigen. Conversely, the administration of NAC before GLP was able to improve seminal parameters, attenuate the induced oxidative stress and apoptosis in addition to the regeneration of testicular damage. In conclusion, NAC can ameliorate the reproductive toxicity induced by GLP to an acceptable degree.

Potential Protective Effect of Vitamin C on Qunalphos-Induced Cardiac Toxicity: Histological and Tissue Biomarker Assay

Insecticides and toxicants abound in nature, posing a health risk to humans. Concurrent exposure to many environmental contaminants has been demonstrated to harm myocardial performance and reduce cardiac oxidative stress. The purpose of this research was to study the protective effect of vitamin C (Vit C) on quinalphos (QP)-induced cardiac tissue damage in rats. Eighteen albino male rats were randomly categorised into three groups (n = 6). Control, QP group: rats received distilled water. QP insecticide treatment: an oral administration of QP incorporated in drinking water. QP + Vit C group: rats received QP and Vit C. All the experiments were conducted for ten days. Decline of cardiac antioxidant biomarkers catalase (CAT) and reduced glutathione (GPx) along with increased proinflammatory markers tumour necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) indicated oxidative and inflammatory damage to the heart following administration of QP when compared to control rats. The light microscopic and ultrastructure appearance of QP-treated cardiomyocytes exhibited cardiac damage. Administration of Vit C showed decreased oxidative and inflammatory biomarkers, confirmed with histological and electron microscopic examination. In conclusion, Vit C protected the heart from QP-induced cardiac damage due to decreased inflammation and oxidative stress.

Thermal stress causes oxidative stress and physiological changes in female rabbits

The present study investigated the effects of heat stress on oxidative stress status and physiological changes using female New Zealand White rabbits. 24 sexually mature female rabbits weighing 1953.1-2375.4 g were divided into 4 groups of 6 animals each and subjected to ambient temperature (T0: 19-26 °C), 27-28 °C for T1, 31-32 °C for T2 and 35-36 °C for T3 using electrical heaters from 8:00 a.m. to 4:00 p.m. daily for 30 days. Feed intake and body weight gain were recorded daily. Behavioral alterations of anxiety, dizziness, aggression, withdrawal, impaired feed intake were observed. At the end of experimental period animals were sacrificed, blood samples and vital organs such as liver, kidney, heart, ovaries, uterus collected for appropriate analysis. Results revealed that animals of T2 and T3 had an 11% decrease in the final body weights and 62% body weight gain but increase in feed conversion ratio by 64.81%, 24.19% water intake, 3.64% in rectal and 2.42% in skin temperature compared to the control. Dizziness, withdrawal to a corner of the cage and reduced feed intake were observed. The live weight of lungs and kidneys increased by 37.71% and 33.78% while that of ovaries and uterus decreased in the same animals of T2 and T3. Animals from T2 and T3 showed significant decrease (p < 0.05) by 23.64% in hemoglobin concentration, 12.73% in red blood cells, 11.93% in packed cell volume, 12.02% in total protein while mean corpuscular volume, white blood cells, lymphocytes, creatinine, urea and aspartate transaminase increased respectively by 10.73%, 42.37%, 15.53%, 28.98%, 53.2% and 23.31% compared to the control. The kidney level of malondialdehyde was significantly increased in T2 and T3 animals by 74.29%, whereas protein, catalase, superoxide dismutase and glutathione peroxidase activity were significantly lower (p < 0.05) compared with control. It was concluded that long-term exposure of female rabbits to elevated ambient temperatures induces heat stress and accompanying oxidative stress that consequently impairs physiological function.

Maximum contaminant level of arsenic in drinking water potentiates quinalphos-induced renal damage on co-administration of both arsenic and quinalphos in Wistar rats

This study was designed to determine alterations in renal biomarkers, antioxidant profile, and histomorphology of renal tissue following subacute exposure to quinalphos alone or in conjunction with arsenic in rats. A total of 54 adult Wistar rats were randomly divided into nine groups of six rats each and were administered sub-lethal concentrations of quinalphos (1/100th and 1/10th of LD50) orally daily and arsenic (50 and 100 ppb) in drinking water for 28 days. Significantly (p < 0.05) decreased levels of antioxidant biomarkers in renal tissue, viz., total thiols, catalase, superoxide dismutase, glutathione peroxidase, glutathione-s-transferase, and glutathione reductase along with increased (p < 0.05) thiobarbituric acid reacting substance (TBRAS) levels indicated that significant oxidative damage to renal tissue occurred following repeated administrations of quinalphos at either dose levels or arsenic at the concentration of 100 ppb when compared with the control rats. The alterations in the antioxidant parameters were observed to be more pronounced in co-administered groups as compared with either toxicant administered group. Similarly, activity of renal acetylcholinesterase was decreased after repeated exposure to quinalphos or arsenic, but inhibition was higher (up to 48%) in rat renal tissue co-exposed with quinalphos and arsenic at the higher concentration. These findings corroborated with the histopathological alterations in renal tissue of toxicant exposed rats. The altered plasma and tissue antioxidant biomarkers along with histopathological changes in the kidney at higher dose level of either toxicant indicate that renal tissue is significantly impacted by these toxicants, and these effects become more pronounced after their co-administration.

Investigating the protective effect of aerobic exercise on oxidative stress and histological damages of testicular tissue associated with chlorpyrifos in male rats

The current study aimed to investigate the protective effects of moderate aerobic exercise against chlorpyrifos (CPF)-induced testes dysfunction. In excremental study, 48 adult male albino rats were randomly allocated into 16 groups of 3 rats each. Twelve experimental groups received intraperitoneal injection (5 days a week) of either 1.0 or 3.0 mg/kg body weight CPF in DMSO for 2, 4 or 6 consecutive weeks. Seven of these experimental groups were subjected to run at moderate exercise intensity for 5 days per week over 2 weeks, whereas the other groups were not. Two groups (sham groups) were administered to the equal volume of vehicle (DMSO) for 4 or 6 consecutive weeks. The remaining two groups comprised the control groups including a sedentary and an exercise-trained control group. Exercise training leads to a markedly increase in testicular superoxide dismutase (SOD) activity in CPF-exposed rats compared with corresponding sedentary animals (p < .05). Lipid peroxidation level was found to be significantly decreased in the testis of exercised animals that had been exposed to CPF (p < .05). Our results suggest that aerobic exercise can alleviate the oxidative stress induced by sub-acute CPF exposure in testis. Exercise training could barely mitigate CPF-induced testicular damages in rats.

Prenatal organophosphate pesticide exposure and reproductive hormones in cord blood in Shandong, China

BACKGROUND

Organophosphate pesticides (OPs) have been found to be associated with endocrine disorders, but limited research has been conducted to evaluate the relationship between maternal OP exposure and fetal reproductive hormone levels. In this study, we investigated the association between prenatal OP exposure and fetal reproductive hormones.

METHODS

A total of 306 healthy pregnant women were enrolled between September 2010 and February 2012. Pesticide exposure was assessed via the analysis of maternal urinary nonspecific metabolites of OPs (dialkylphosphate, DAP), and four reproductive hormones were measured in cord blood. Linear regression models and generalized linear models were used to estimate the associations between DAP metabolites and reproductive hormones, and further stratified by infant sex.

RESULTS

We found that concentrations of diethylphosphate (DEP) (β = -0.03; 95% CI: -0.07, -0.00) were inversely associated with estradiol (E2). Dimethylphosphate (DMP) (β = -0.08; 95% CI: -0.13, -0.03), diethylthiophosphate (DETP) (β = -0.08; 95% CI: -0.14, -0.01), and DAPs (β = -0.10; 95% CI: -0.17, -0.03) were inversely associated with testosterone (T) levels. DMP was inversely associated with follicle-stimulating hormone (FSH) levels (β = -0.03; 95% CI: -0.05, -0.01). DMP (β = -0.06; 95% CI: -0.10, -0.01) and DETP (β = -0.07; 95% CI: -0.13, -0.01) showed inverse associations with the testosterone/estradiol (T/E2) ratio. Moreover, the magnitude of associations notably increased in higher quartiles of concentrations in a dose-response manner. After stratification by sex, these effects were mainly observed among female infants.

CONCLUSION

Our findings suggest the potential impacts of prenatal OP exposure on fetal reproductive hormones, and that sex-related differences may exist.

A Systematic Review on Organophosphate Pesticide and Type II Diabetes Mellitus

Organophosphate (OP) pesticides are extremely poisonous and they affect the glucose breakdown in numerous and mechanism. There are higher evidence of stimulating diabetes mellitus through OP pesticides especially the type II diabetes. The upsurge in the level of glucose (hyperglycemia), and insulin resistance along with their related outcomes are discussed in this review. The data related to investigational and clinical techniques endorse a connection amid such molecular mechanism and compounds of OPs. Numerous studies conducted till March 2018 have reported OP' exposures and diabetes-related outcomes. The acute and chronic exposure in case of these insecticides and diabetesrelated outcomes are defined in this study. Initially, it was declared that OPs prompt to hyperglycemia. Then, a high association of glucose in blood beside insulin was found out. The affirmation from some clinical as well as investigational studies supported a connection amid exposure to OP and diabetes, yet in maximum number of instances, non-specific diabetes occurs.

Gonad pathology and intersex severity in pelagic (Tilapia zilli) and benthic (Neochanna diversus and Clarias gariepinus) species from a pesticide-impacted agrarian catchment, south-south Nigeria

Pesticides are distributed to different degrees in surface water and sediment, thus, risks of toxicity and adverse impacts to physiology of resident species could be determined by their microhabitat (sub-habitat) associations, either water column or sediment. River Owan receives pesticide input from diffuse sources from adjacent farmlands. Surface water, sediment and fish samples [(Pelagic: Tilapia zilli (n = 92) and benthic: Neochanna diversus (n = 59), Clarias gariepinus (n = 68) were collected within the catchment area across seasons for 18-months (August 2016-January 2018) and measured for pesticide levels. Testicular and Ovarian tissue samples across the three species were also examined for pathological alterations. Individual pesticide concentrations in surface water and sediment exceeded international allowable limits, while concentration of pesticide residues in tissues of benthic species was higher compared to pelagic fish. Histopathological assessment revealed a higher incidence of ovarian disruption including atretic follicles, intersex and disorganization of ovarian structure in benthic (bottom-dwelling) fish (C. gariepinus and N. diversus) compared to pelagic (water-column) fish (T. zilli). Males benthic fish species also recorded more severe anomalies, compared to pelagic fish. The damages and anomalies observed in ovarian and testicular tissue indicate chronic responses to pollutant exposure, and implicates the elevation of pesticide concentrations in surface water and sediment above permissible limits. The higher incidence of anomalies recorded for benthic species compared to pelagic species, indicates greater risks of reproductive disruption and could be associated with the microhabitat preferences (water-column or sediment).

Safety assessment of cefuroxime on male reproductive system: Subacute toxicity and potential reversibility after a complete cycle of spermatogenesis and epididymal maturation in Wistar rats

The effects of cefuroxime on reproductive system were investigated in male rats. Doses of 0, 30, 60 or 120 mg/kg of cefuroxime were intraperitoneally injected daily, for 7 days. Half of the rats were euthanized 24 h after the last dose and other half were induced to death 70 days after the last treatment. After 8 days of the experiment, results showed that cefuroxime induced a significant reduction in the weights of testes, epididymis and accessory sex organs. In addition, it decreased sperm quality, plasma testosterone level, and antioxidant enzyme activities while increasing the level of malondialdehyde. After a complete cycle of spermatogenesis and epididymal maturation, the results indicated complete reversibility of the adverse effects previously mentioned. In conclusion, cefuroxime induced reversible dose-dependent adverse effects on testicular and epididymal functions of rats.

Mechanisms of diazinon effects on impaired spermatogenesis and male infertility

Diazinon (DZN) is an organophosphate insecticide that has cytotoxic and pathological effects on the reproductive system. It causes a wide variety of pathological effects on the reproductive system such as testicular atrophy, disturbance in sex hormones, impaired spermatogenesis, low quality of sperm, and fertility problems. However, molecular and cellular mechanisms of its adverse effects are not well understood. General events such as testicular damage, inflammation, mitochondrial deficiency, DNA fragmentation, disintegration of sperm plasma membrane, apoptosis, and cell death are observed in DZN-exposed animals. Oxidative stress (OS) induced by reactive oxygen species may be a main mechanism, which can be associated with sperm DNA fragmentation, reduced integrity of sperm cell membrane, apoptosis, depletion of antioxidants, and subsequently poor sperm quality and male infertility. Therefore, identification of these pathways may provide valuable information regarding the mechanisms of DZN action on the male reproductive system. In this review, we aim to discuss the proposed cellular and molecular mechanisms of DZN action on male reproductive system, the importance of OS and mechanisms by which DZN induces OS and depletion of other antioxidants.

Tracing of zinc and iron in experimentally induced varicocele: correlation with oxidative, nitrosative and carbonyl stress

This study was designed to evaluate how varicocele (VCL) can time dependently induce zinc (Zn) and iron (Fe) toxicity in testicular tissue and to analyse the relation between heavy metals toxicity and lipid peroxidation, sperm DNA damage, nitrosative and carbonyl stresses. Twenty-four mature male Wistar rats were divided into control-sham and test groups, which were then submitted to experimentally induced VCL. Non-VCL-induced rats were considered as control-sham. The test groups were subdivided into three groups based on the sample collecting date (2, 6 and 8 months after VCL induction). Zn and Fe distribution in testicles, DNA ladder for sperm DNA fragmentation, testicular total antioxidant capacity (TAC), malondialdehyde (MDA), nitrite oxide (NO) and carbonyl groups (CG) were analysed. A significant (p < .05) enhancement in the percentage of tubules with negative tubular repopulation, differentiation and spermiogenesis indices was revealed. The VCL increased Zn and Fe distribution in testicles. The VCL, time dependently, reduced sperm count, motility and enhanced sperm DNA damage (p < .05). The VCL downregulated the testicular TAC and enhanced the MDA, NO and CG contents. Our data showed that the VCL results in intensive Fe and Zn toxicities. Produced Zn- and Fe-mediated-oxidative stress increases sperm DNA damage associated with NO and CG-induced stresses.

Alleviating effects of melatonin on oxidative changes in the testes and pituitary glands evoked by subacute chlorpyrifos administration in Wistar rats

OBJECTIVE

To evaluate the alleviating effects of melatonin on oxidative changes in the testes and pituitary gland induced by subacute chlopyrifos (CPF) exposure in rats.

METHODS

Forty adult male Wistar rats divided into 4 groups of 10 animals were used for the study. Group I received soya oil (2 mL/kg) while group II was administered with melatonin (0.5 mg/kg). Group III was administered CPF only (8.5 mg/kg ∼ 1/10th of the LD50) while group IV was pretreated with melatonin (0.5 mg/kg) and then exposed to CPF (8.5 mg/kg), 10 min later. The regimens were administered by gavage once daily for a period of 28 d. At the end of the exposure period, the rats were sacrificed and the testicular tissues and pituitary glands were evaluated for the malonaldehyde (MDA) concentration and activities of superoxide dismutase (SOD) and catalase (CAT).

RESULTS

CPF increased MDA concentrations and reduced the activities of SOD and CAT in the testes and pituitary gland. Melatonin pretreatment reduced the testicular and pituitary MDA concentrations and improves the SOD and CAT activities.

CONCLUSIONS

the study showed that subacute CPF-induced oxidative stress in the testes and pituitary glands were alleviated by melatonin due to its antioxidant property.

Effects of subchronic exposure to cadmium and diazinon on testis and epididymis in rats

The present study aimed to elucidate the structural changes in testis and epididymis of adult rats following subchronic peroral administration of cadmium at 30 mg/L, diazinon at 40 mg/L, cadmium at 30 mg/L, and diazinon at 40 mg/L, respectively. At the end of 90-day experiment, the samples of the testes and epididymis were assayed by qualitative and quantitative histological methods. The testis and epididymis weights increased following exposure to cadmium and simultaneous exposure to cadmium and diazinon. Testicular damage following cadmium and diazinon coexposure was significantly less expressive than in groups with individual administration of these compounds. Cadmium caused a significant thickening of seminiferous epithelium, cellular degeneration, and necrosis. Desquamation of immature germ cells resulted in a significant increase of intraepithelial spaces and reduced tubule volume in all experimental groups. Vascular dilation and congestion were detected in the interstitial tissue. The changes in epididymal histology in the group exposed to cadmium and group exposed simultaneously included a reduction of epithelium, necrotic epithelial cells, vasoconstriction, and interstitial edema together with mononuclear cell infiltration. Results did not indicate a synergistic or any additional effect from the simultaneous administration of both toxicants. Further research is needed to determine the significance and the mechanism of the adverse effects.

Protective role of Nigella sativa oil against reproductive toxicity, hormonal alterations, and oxidative damage induced by chlorpyrifos in male rats

This study is aimed at elucidating the possible protective effects of Nigella sativa oil (NSO) in alleviating the toxicity of chlorpyrifos (CPF) on reproductive performance in male rats. Animals were orally administered with NSO (1 ml/kg/day), CPF (20 mg/kg/day), and NSO + CPF every day for 4 weeks. Results showed that CPF decreased spermatid number, sperm count, daily sperm production, and sperm motility while increased dead sperm and abnormal sperm compared with the control. Also the levels of testosterone, thyroxine levels, steroidogenic enzyme 17-ketosteroid reductase, body weight, food intake, and relative weight of reproductive organs were decreased. Thiobarbituric acid reactive substances were increased, while glutathione (GSH) and antioxidant enzymes were decreased in plasma and testes of rats treated with CPF. Histopathological examination of testes showed a decrease in the number of seminiferous tubules, form shrinkage, enlargement of the connective tissue and gametogenic changes in germ cells of rats treated with CPF. NSO alone increased testosterone, semen characteristics, GSH, and antioxidant enzymes and decreased the levels of free radicals. Furthermore, the presence of NSO with CPF alleviates its toxic effects. Our results indicated that NSO can improve semen picture and moderate CPF-induced reproductive toxicity.

Antioxidant mediated ameliorative steroidogenesis by Commelina benghalensis L. and Cissus quadrangularis L. against quinalphos induced male reproductive toxicity

Quinalphos (QP) is speculated to cause endocrine disruption through the generation of reactive oxygen species (ROS) by oxidative stress (OS). Exposure of QP decreased testosterone level considerably which resulted in reduced viable sperms in mice. The QP induced toxicity is initiated by the formation of free radicals as it is evidenced from the increased Lipid peroxidation (LPO) and diminution of antioxidant enzymes in testicular tissue. Increased serum cholesterol and reduced testicular cholesterol indicated the inhibition of cholesterol transport and biosynthesis in testicular tissues. Lack of cholesterol in testicular tissue impaired the steroidogenesis by down-regulating the expression of StAR protein, Cytochrome P450, 3β-HSD and 17β-HSD leading to reduced testosterone level. Treatment of Commelina benganlensis (CBE) and Cissus quadrangularis (CQE) significantly recovered the alterations in antioxidant profiles as well as increased LPO, thereby recovering the decreased mRNA expression levels of intermediate enzymes. However, CQE effectively protected the OS and prevented the inhibition of steroidogenesis thereby preventing male infertility.

Transition from oxidative stress to nitrosative stress in rostral ventrolateral medulla underlies fatal intoxication induced by organophosphate mevinphos

As the most widely used pesticides in the world, fatal incidence of suicidal poisoning by organophosphate compounds is high and is often associated with cardiovascular toxicity. Using the pesticide mevinphos as our tool, we investigated the roles of oxidative stress and nitrosative stress at the rostral ventrolateral medulla (RVLM), the brain stem site that maintains arterial pressure (AP) and sympathetic vasomotor tone, in the cardiovascular depressive effects of organophosphate poisons. Microinjection of mevinphos (10 nmol) into the RVLM of anesthetized Sprague-Dawley rats induced progressive hypotension that was accompanied by an increase (phase I), followed by a decrease (phase II) of an experimental index of baroreflex-mediated sympathetic vasomotor tone, with a fatality rate of 35%. During phase I, there was a preferential upregulation of angiotensin type I receptor (AT1R) messenger RNA (mRNA) and protein that leads to activation of NADPH oxidase (Nox) and increase in superoxide at the RVLM. Pharmacological antagonism of these signals exacerbated fatality and shorted survival time by eliminating baroreflex-mediated sympathetic vasomotor tone, AP, and heart rate. During phase II, there was a progressive upregulation of angiotensin type II receptor (AT2R) mRNA and protein that leads to increase in peroxynitrite in the RVLM, blockade of both sustained brain stem cardiovascular regulation and improved survival. We further found that AT1R and AT2R cross-interacted at transcriptional and signaling levels in the RVLM. We conclude that a transition from AT1R-mediated oxidative stress to AT2R-mediated nitrosative stress in the RVLM underlies the shift from sustained to impaired brain stem cardiovascular regulation that underpins cardiovascular fatality during mevinphos intoxication.

Pesticide-induced decrease in rat testicular steroidogenesis is differentially prevented by lipoate and tocopherol

We have previously demonstrated that the sub-chronic administration of low doses of Toc or α-Toc, glyphosate and zineb to rats (i.p. 1/250 LD50, three times a week for 5 weeks) provoked severe oxidative stress (OS) in testicles. These effects were also reflected in plasma. Lipoic acid (LA) and α-tocopherol are considered as antioxidants due to their ability to neutralize reactive oxygenated species (ROS) and reset endogenous antioxidant levels. To investigate the possible protective effect on reproductive function, LA and Toc (i.p. 25, 50 and 100mg/kg) were administered simultaneously with the pesticide mixture (PM) for 5 weeks. Both drugs prevented OS and the damage to proteins and lipids caused by PM in a dose-dependent manner. The PM-induced increase levels of prostaglandins E2 and F2α was completely restored by LA but not by Toc. Similarly, only LA was able to restore the inhibition of testosterone production, the decrease of 3β- and 17β-hydroxysteroid dehydrogenases activities, and the elevation of gonatropins (FSH and LH) levels produced by PM. Furthermore, LA was more efficient than Toc in normalizing the histological alterations produced by PM administration, suggesting that pesticides act though other mechanisms that generate oxidative stress. In our experimental model LA displayed a higher protective role against pesticide-induced damage than that observed by Toc administration. Our results suggest that LA administration is a promising therapeutic strategy for coping with disorders suspected to be caused by OS generators - such as pesticides - in male reproductive system.

Correlation of testicular toxicity and oxidative stress induced by chlorpyrifos in rats

Effect of chlorpyrifos pesticide on testicular oxidative damage was studied in Sprague-Dawley rats at varying doses. At lower doses (5 and 10 mg/kg body weight/30 days), reduction in plasma levels of testosterone and follicular stimulating hormone (FSH) and luteinizing hormone (LH) along with significant shrinkage of seminiferous tubules and drastic changes in germ cells were seen. But these adverse changes of testes were restored with the revival of serum testosterone and FSH and LH at higher doses (20 and 30 mg/kg body weight/30 days). Similarly, levels of testicular lipid peroxidation and diene conjugates were elevated whereas activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), steroidogenic (Δ5, 3β-HSD and Δ5, 17β-HSD) enzymes and angiotensinogen-converting enzyme and glutathione content including lipid–protein content of testes were decreased at low doses. But at higher doses, reductions in level of lipid peroxidation (as revealed by malondialdehyde [MDA] value) and conjugated dienes were found and on the contrary, revivals of testicular antiperoxidative/antioxidant enzymes defense systems, angiotensinogen-converting enzyme (ACE), steroidogenic enzymes, lipid–protein and antioxidant glutathione content were observed. Therefore, the present study indicated from the results that chlorpyrifos had a dual effect at both doses on oxidative stress changes, but at higher doses, the cells were triggering its natural defense mechanism to combat the insult of lower doses of chlorpyrifos and became operative possibly through corrective measure of antioxidant enzymes defense system and pituitary gonadotropins hormones feedback mechanisms on testes.

Testicular toxicity of chlorpyrifos (an organophosphate pesticide) in albino rat

Organophosphates are among the most widely used synthetic insect pesticides. The widespread use of organophosphates has stimulated research into the possible existence of effects related with their reproductive toxic activity. Present study was therefore, undertaken to assess the effects of chlorpyrifos on testes, the main organ of male reproduction. Chlorpyrifos at the dose levels of 7.5, 12.5 and 17.5 mg/kg b. wt./day was administered orally to male rats of Wistar strain for 30 days to evaluate the toxic alterations in testicular histology, biochemistry, sperm dynamics and testosterone levels. The body weight of animals did not show any significant change, however, a significant reduction was observed in testes. Chlorpyrifos also brought about marked reduction in epididymal and testicular sperm counts in exposed males and a decrease in serum testosterone concentration. Histopathological examination of testes showed mild to severe degenerative changes in seminiferous tubules at various dose levels. Fertility test showed 85% negative results. A significant reduction in the sialic acid content of testes and testicular glycogen was noticed, whereas the protein and cholesterol content was raised at significant levels. All these toxic effects are moderate at low doses and become severe at higher dose levels. From the results of the present study it is concluded that chlorpyrifos induces severe testicular damage and results in reduction in sperm count and thus affect fertility. Small changes in sperm counts are known to have adverse affects on human fertility. Therefore, application of such insecticide should be limited to a designed programme.

AN ORGANOPHOSPHATE INSECTICIDE METHYL PARATHION (O- O- DIMETHYL O-4-NITROPHENYL PHOSPHOROTHIOATE) INDUCES CYTOTOXIC DAMAGE AND TUBULAR ATROPHY IN THE TESTIS DESPITE ELEVATED TESTOSTERONE LEVEL IN THE RAT

Methyl parathion (MP) is an organophosphate pesticide used in agriculture, although quite often illegally used indoors to contain insects. The present study was planned to investigate the effects of MP on rat testis. Adult male Wistar rats (13-14 weeks) were treated with MP as follows. Experiment 1-0, 1.75, 3.5 or 7 mg/kg i.p. for 5 days and sacrificed on Day 14; experiment 2 and 3- 0, 0.5, or 1 mg/kg i.p. for 12 days, and sacrificed on Days 130 and 77, respectively; experiment 4- 0, 0.75, or 1.5 mg/kg i.p. for 25 days, and sacrificed on Day 17; experiment 5- 0 or 3.5 mg/kg po for 25 days, and sacrificed on Day 17, after the last exposure. MP decreased the body weight and the testis weight in experiments 4 and 5 (p<0.05-0.001) due to decreased food intake and tubular atrophy respectively. MP increased the intra-testicular testosterone level and decreased the LH level in experiments 4 and 5. The seminiferous epithelium showed sloughing of germ cells, vacuoles, focal necrosis, and formation of multinucleated giant cells, cellular degeneration (nuclear pyknosis, halo appearance and shrinkage of nuclei) and tubular atrophy, especially in experiment 4. The degree of testicular damage was higher in experiment 4>5>1>3>2 indicating more effect of prolonged i.p. treatment. Homogenization-resistant spermatid count was decreased in experiments 1, 4 and 5, and MP also decreased the tubular diameter, and epithelial height (p<0.05-0.001). Incidences of stage XIV tubules, number of meiotic figures and elongating spermatids were also decreased, whereas the incidence of tubules showing epithelial sloughing increased (p<0.05-0.001). We conclude that MP is a reproductive toxicant in male rats which causes significant testicular damage in the testis.

Evidence for the involvement of central serotonergic mechanisms in cholinergic tremor induced by tacrine in Balb/c mice

Tacrine is a potent and reversible inhibitor of acetylcholinesterase (AChE) in the brain. It produces tremor in animals, which is believed to be due to an increase in the brain acetylcholine level following AChE inhibition. The present study was undertaken to investigate the involvement, if any, of biogenic amines in the genesis of this motor dysfunction. Administration of tacrine (10-20 mg/kg, i.p.) produced dose- and time-dependent tremor in Balb/c mice. While in vivo inhibition of striatal AChE activity was observed only for the highest dose of tacrine, a dose-dependent increase in striatal choline acetyltransferase activity was obtained. Serotonin (5-HT) levels, as assayed following a sensitive HPLC-electrochemical procedure, were significantly increased in nucleus caudatus putamen, nucleus accumbens, substantia nigra, nucleus raphe dorsalis, olivary nucleus and the cerebellum. However, dopamine or norepinephrine levels remained unaltered in these areas of the brain. In animals treated with p-chlorophenylalanine, a specific tryptophan hydroxylase inhibitor and 5-HT depletor, tacrine failed to elevate the levels of 5-HT in the brain regions, and significantly attenuated tremor response to the drug. Tacrine-induced tremor was also significantly (83%) attenuated by 5-HT(2A/2C) receptor antagonist mianserin (5 mg/kg, i.p.), but methysergide (5 mg/kg, i.v.) could block tacrine-induced tremor only by 20%. Atropine (5 mg/kg, i.p.) antagonized tacrine-induced tremor by about 53%, but a combination of atropine and mianserin completely blocked the tremor response. These results indicate that the cholinergic tremor produced by tacrine in Balb/c mice is mediated via central serotonergic mechanisms, and stimulation of 5-HT(2A/2C) receptors plays a pivotal role in this motor dysfunction.

Effect of maternal exposure to the environmental estrogen, octylphenol, during fetal and/or postnatal life on onset of puberty, endocrine status, and ovarian follicular dynamics in ewe lambs

Octylphenol (OP) is one of a number of compounds found in the environment that has estrogen-mimicking actions in vivo. Our objective was to determine if maternal exposure to octylphenol during fetal and/or postnatal life would affect the onset of puberty, endocrine status, and subsequent ovarian follicular dynamics of ewe lambs. Lambs were born in March to ewes that received twice weekly s.c. injections of octylphenol (1000 micro g/kg/day) from Day 70 of gestation to weaning (n = 6); Day 70 of gestation to birth (n = 3); birth to weaning (n = 5; gestation = 145 days); or corn oil from Day 70 of gestation to weaning (control; n = 5). Blood samples were collected twice weekly to determine progesterone and FSH concentrations from 20 wk of age throughout the first breeding season. Onset of puberty and interestrous intervals were determined from 20 wk of age by twice daily observation for estrus in the presence of a vasectomized ram. During January the ovaries of each lamb were examined using transrectal ultrasonography from the day of estrus for 15 days. Blood samples were collected every 8 h to examine FSH concentrations and every 2 h to detect the preovulatory gonadotropin surge throughout this estrous cycle. The onset of puberty and first progesterone rise was advanced and the FSH preovulatory surge was elevated for longer in the OP-treated lambs compared with the control lambs (P < 0.05). Interestrous intervals, FSH profiles, and ovarian follicular dynamics were not affected (P > 0.05) by exposure to octylphenol. In conclusion, octylphenol exposure advanced the onset of puberty but it did not disrupt FSH concentrations or the dynamics of ovarian follicular growth.

Effects of serotoninergic drugs on tremor induced by physostigmine in rats

We investigated the effects of various serotoninergic drugs and serotonin (5-HT) depletion on physostigmine-induced visible tremor in rats. Physostigmine (0.25-1.5 mg/kg) caused dose-dependent tremor, initiated at 3-5 min (latency decreases as dose increases) and lasted for 30-35 min. Serotonin agonists, 8-hydroxy-2-(di-n-propylamino) tetralin (2.5 mg/kg) and buspirone (5 mg/kg) augmented the tremor response caused by physostigmine. The 5-HT(1)/5-HT(2) receptor antagonist, metergoline (1 mg/kg), and 5-HT(2) blocker, cyproheptadine (10 mg/kg) significantly decreased the duration (40%) as well as intensity (45-50%) of physostigmine-tremor. The 5-HT(2a)/5-HT(2c) antagonist ritanserin (5 mg/kg) significantly reduced the duration (60%) without affecting the intensity of the tremor. In 5-HT depleted rats (p-chlorophenylalanine; 300 mg/kg, for 3 days), physostigmine failed to produce tremor. Interestingly, in these animals, administration of a non-specific 5-HT agonist, 5-methoxy-N,N-dimethyl tryptamine, caused high intensity tremor. These results suggest that presence of 5-HT at the pre-synaptic terminals is needed for the tremor response by physostigmine and the response is greatly mediated via post-synaptic 5-HT receptors. The overall data indicated a direct involvement of central 5-HT system in the cholinergic tremor induced by physostigmine.