Paint thinner exposure inhibits testosterone synthesis and secretion in a reversible manner in the rat

Intracerebroventricular BDNF infusion may reduce cerebral ischemia/reperfusion injury by promoting autophagy and suppressing apoptosis

Here, it was aimed to investigate the effects of intracerebroventricular (ICV) Brain Derived Neurotrophic Factor (BDNF) infusion for 7 days following cerebral ischemia (CI) on autophagy in neurons in the penumbra. Focal CI was created by the occlusion of the right middle cerebral artery. A total of 60 rats were used and divided into 4 groups as Control, Sham CI, CI and CI + BDNF. During the 7-day reperfusion period, aCSF (vehicle) was infused to Sham CI and CI groups, and BDNF infusion was administered to the CI + BDNF group via an osmotic minipump. By the end of the 7th day of reperfusion, Beclin-1, LC3, p62 and cleaved caspase-3 protein levels in the penumbra area were evaluated using Western blot and immunofluorescence. BDNF treatment for 7 days reduced the infarct area after CI, induced the autophagic proteins Beclin-1, LC3 and p62 and suppressed the apoptotic protein cleaved caspase-3. Furthermore, rotarod and adhesive removal test times of BDNF treatment started to improve from the 4th day, and the neurological deficit score from the 5th day. ICV BDNF treatment following CI reduced the infarct area by inducing autophagic proteins Beclin-1, LC3 and p62 and inhibiting the apoptotic caspase-3 protein while its beneficial effects were apparent in neurological tests from the 4th day.

Effect of Methylphenidate on the onset of puberty and reproductive organ development in rats

Methylphenidate (MPH) is the first-line therapy for attention deficit hyperactivity disorder (ADHD) in children and adolescents. The aim of this study was to investigate the effects chronic MPH administration on reproductive parameters in both male and female pre-pubertal rats and reversibility of these effects. Sprague-Dawley rats were administered with 5 mg/kg MPH or saline orally from postnatal day (PND) 21 to PND60 and from PND21 to PND90. In addition, recovery groups from both sexes, in which MPH administration was stopped from PND60 to PND90 were included. Puberty onset, serum luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone and estradiol levels were determined. Histopathology of male and female reproductive organs was examined. Puberty onset was significantly early in the males (p<0.01), but late in females (p<0.05). In males, serum LH and FSH levels were similar. Testosterone levels tended to decrease in MPH-treated animals. Morphology of testes, epididymis and vas deferens was disrupted in MPH-treated animals, while it was improved in the recovery group. In females, estradiol levels decreased in MPH-treated group compared to controls, and elevated LH levels were detected in recovery group. Similar to the males, disruption in the reproductive organ histology was seen with morphological deterioration in basement membrane of the ovaries of MPH-treated groups. These adverse effects of MPH were recovered after drug cessation for 30 days. The present results demonstrate that MPH could affect the reproductive functions in both male and female rats. However, our findings also suggest that those effects are transient.

Endocrine disrupting chemicals: exposure, effects on human health, mechanism of action, models for testing and strategies for prevention

Endocrine Disrupting Chemicals (EDCs) are a global problem for environmental and human health. They are defined as "an exogenous chemical, or mixture of chemicals, that can interfere with any aspect of hormone action". It is estimated that there are about 1000 chemicals with endocrine-acting properties. EDCs comprise pesticides, fungicides, industrial chemicals, plasticizers, nonylphenols, metals, pharmaceutical agents and phytoestrogens. Human exposure to EDCs mainly occurs by ingestion and to some extent by inhalation and dermal uptake. Most EDCs are lipophilic and bioaccumulate in the adipose tissue, thus they have a very long half-life in the body. It is difficult to assess the full impact of human exposure to EDCs because adverse effects develop latently and manifest at later ages, and in some people do not present. Timing of exposure is of importance. Developing fetus and neonates are the most vulnerable to endocrine disruption. EDCs may interfere with synthesis, action and metabolism of sex steroid hormones that in turn cause developmental and fertility problems, infertility and hormone-sensitive cancers in women and men. Some EDCs exert obesogenic effects that result in disturbance in energy homeostasis. Interference with hypothalamo-pituitary-thyroid and adrenal axes has also been reported. In this review, potential EDCs, their effects and mechanisms of action, epidemiological studies to analyze their effects on human health, bio-detection and chemical identification methods, difficulties in extrapolating experimental findings and studying endocrine disruptors in humans and recommendations for endocrinologists, individuals and policy makers will be discussed in view of the relevant literature.

Orchidectomy enhances the expression of endothelin-1 and ETB receptors in rat portal vein

Functional studies have shown that orchidectomy increases the effects of phenylephrine on rat portal veins, but that it is completely prevented in the presence of both ETA and ETB receptor antagonists. Although it suggests the involvement of endothelin-1 (ET-1), the local production of this vasoactive peptide has not been directly quantified in portal veins. Therefore, the aim of the present study was to verify if orchidectomy increases the local expression of ET-1 as well as ETA and ETB receptors in the rat portal vein. Indeed, the genic expression of ET-1, ETA and ETB receptors in rat portal veins taken from control (CONT), orchidectomized (ORX) and ORX plus testosterone-replacement therapy (ORX + T) animals were determined by Real Time RT-PCR. The results showed that orchidectomy induced a significant increment in genic expression of ET-1 and ETB receptors in the rat portal veins, which was completely reversed by testosterone replacement treatment. In conclusion, the results suggest that orchidectomy increases the production of ET-1 in the rat portal vein and that, at least partially, it may be related to the previously reported elevation of responses to phenylephrine.

A study on neurobehavioral performance of workers occupationally exposed to solvent in synthetic resin manufacturing

Background:

One major effect of occupational solvent exposure is central nervous system (CNS) impairment, ranging from depression to encephalopathy with cognitive, behavioral changes. Exposures in industries being varied, classification of health outcomes for different exposures is important.

Objectives:

This study assessed neurobehavioral performance of synthetic resin manufacturing workers exposed to organic solvent, mainly formalin.

Materials and Methods:

This cross-sectional study selected subjects by random selection from all such workers of an Indian city. Questionnaire survey and assessment by a neurobehavioral test battery (NBT) was undertaken.

Results:

Comparison between actual and allied workers observed significant difference in tweezer dexterity, card sorting and backward memory scores. Significant effect of exposure was observed on tweezer dexterity, card sorting, and hand dynamometer scores.

Conclusion:

Changes of neurobehavioral performance might occur following solvent exposure and these changes might have a relationship with the quantum of exposure. Periodic examination of workers with NBT is needed for detection of early neurotoxic effects.

Volatile aromatic hydrocarbons (VAHs) in residential indoor air in Brisbane, Australia

Volatile aromatic hydrocarbons (VAHs: benzene, toluene, ethylbenzene, mp-xylene, o-xylene, styrene, naphthalene) in residential indoor air in Brisbane, Australia were measured in 32 houses. The total VAHs (TVAHs) levels ranged between 2 and 137μg/m(3) and were lower than the most of the houses in the literature data. The VAHs were believed to originate from heat insulation systems, building material products as well motor vehicles but naphthalene and styrene originated from other sources. Internal garages had concentrations which are higher than the indoor air by 25-50% due to the presence of motor vehicles and may be a major source of indoor VAHs. However indoor concentrations are higher than that in the outdoor ambient air. The age of the house was found to be negatively related to VAHs concentrations in the houses with the half-life of TVAH at approximately 13years. The concentration levels of benzene, toluene, ethylbenzene and styrene are well below the guideline values set by agencies from Hong Kong, Japan, Germany and the WHO while the concentration level of naphthalene in one house exceeded the guideline value from Germany.

Toxicity of Methylcyclohexane and Its Effect on the Reproductive System in SD Rats

Objectives

There is limited data regarding the toxicity of methylcyclohexane, despite its wide use in rubber adhesives, paint diluents, and cleansing agents. This study aimed to verify the toxicity and influence on the reproductive system of methylcyclohexane after its repeated injection in Sprague Dawley (SD) rats.

Methods

Methylcyclohexane was injected subcutaneously into male and female SD rats once a day, five times a week, for 13 weeks at different doses (0, 10, 100, and 1,000 mg/kg/day) for each group. The toxicity of testing material was verified by observing the change in body and organ weight, hematological change, pathological findings, and effect on the reproductive system at each different concentration.

Results

In the 1,000 mg/kg/day group, there were cases of animal deaths. In animals that survived, hematological changes, including a decrease in the red blood cell count, were observed. A considerable weight gain or loss and pathological abnormalities in the liver, kidney, and other organs were found. However, the 10 and 100 mg/kg/day groups did not cause deaths or other specific abnormalities. In terms of reproductive toxicity, there were changes in hormone levels, including a significant decrease in hormones such as estradiol and progesterone (p < 0.001) in male animals. Menstrual cycle change for female animals did not show concentration dependency.

Conclusion

When injected repeatedly for 13 weeks, methylcyclohexane proved to be toxic for the liver, heart, and kidney at a high dose. The absolute toxic dose was 1,000 mg/kg/day, while the no observed adverse effect level was less than 100 mg/kg/day. The substance exerted little influence on the reproductive system.

HSP70 immune reactivity and TUNEL positivity in the liver of toluene-inhaled and melatonin-treated rats

Toluene is a clear, colorless and volatile hydrocarbon that is metabolized in liver, produced free oxygen radicals and can mediate cellular damage. Melatonin which is a pineal gland hormone is a very potent antioxidant. It can make the cellular membrane more durable against oxidative attacks and protect nuclear DNA from oxidative damage. This study aimed to investigate heat shock protein (HSP)70 immune reactivity and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) positivity (apoptotic activity) in the liver of toluene-inhaled and melatonin-treated rats. A total of 21 adult male Wistar albino rats were divided at random into 3 equal groups. Animals in group I were designated as control. The rats in group II were exposed to toluene (3000 ppm/1 h/day) for 30 days, while the rats in group III were treated with melatonin (10 mg/kg/day, intraperitoneally) plus toluene inhalation. At the end of the 30-day experimental period, all rats were killed by decapitation. Then the liver tissues of rats were removed and tissue specimens were embedded in paraffin blocks. The specimens were stained with periodic acid-schiff (PAS) following routine histological procedures. Sections obtained from paraffin blocks were used for immune detection of TUNEL and HSP70. In light microscopic observations of tissues from toluene-inhaled rats, massive hepatocyte degeneration, ballooning degeneration and decreased PAS positivity were observed. Increased TUNEL positivity and HSP70 immune reactivity were determined in toluene-inhaled group and melatonin treatment decreased all these adverse effects.

Environmental chemical mediated male reproductive toxicity: Drosophila melanogaster as an alternate animal model

Industrialization and indiscriminate use of agrochemicals have increased the human health risk. Recent epidemiological studies raised a concern for male reproduction given their observations of reduced sperm counts and altered semen quality. Interestingly, environmental factors that include various metals, pesticides and their metabolites have been causally linked to such adversities by their presence in the semen at levels that correlate to infertility. The epidemiological observations were further supported by studies in animal models involving various chemicals. Therefore, in this review, we focused on male reproductive toxicity and the adverse effects of different environmental chemicals on male reproduction. However, it is beyond the scope of this review to provide a detailed appraisal of all of the environmental chemicals that have been associated with reproductive toxicity in animals. Here, we provided the evidence for reproductive adversities of some commonly encountered chemicals (pesticides/metals) in the environment. In view of the recent thrust for an alternate to animal models in research, we subsequently discussed the contributions of Drosophila melanogaster as an alternate animal model for quick screening of toxicants for their reproductive toxicity potential. Finally, we emphasized the genetic and molecular tools offered by Drosophila for understanding the mechanisms underlying the male reproductive toxicity.

Hepatotoxic activity of toluene inhalation and protective role of melatonin

This study was designed to investigate the harmful effects of toluene inhalation in the liver of rats and possible protective effects of melatonin on these detrimental effects. For this purpose, 21 adult male Wistar-albino rats were randomly divided into three equal groups. Animals in group I were used as control. The rats in group II were exposed to toluene (3000 ppm/1 hour/day) for 4 weeks, while the rats in group III were treated with melatonin (10 mg/kg/day, intraperitoneally [ip]) plus toluene inhalation. At the end of the experimental period, liver and blood samples were taken from the decapitated animals. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin and albumin levels were determined. Liver tissue sections were stained with routine histological methods and examined under the light microscope. In addition, the sections were immunohistochemically stained using avidin-biotin-peroxidase method for determination of apoptosis. The liver tissue activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and malondialdehyde (MDA) levels were also measured. Toluene inhalation significantly increased serum ALT, AST and tissue MDA, and decreased serum albumin, but did not affect serum ALP, total bilirubin levels and tissue SOD, GSH-Px and CAT activity when compared with controls. The increases in tissue MDA and serum ALT and AST levels induced by toluene inhalation were significantly inhibited by melatonin treatment. In light microscopic observations of tissues from toluene-inhaled rats, massive hepatocyte degeneration, ballooning degeneration and mild pericentral fibrosis were observed. Bax immune reactivity was also increased significantly. Melatonin treatment decreased the balloon degeneration, fibrosis and Bax immune reactivity in the liver of toluene-inhaled rats. In view of the present findings, it is suggested that melatonin has hepatoprotective effects against toluene toxicity via primarily antioxidative properties.

Thymoquinone reestablishes spermatogenesis after testicular injury caused by chronic toluene exposure in rats

The aim of this study was designed to evaluate the possible protective effects of thymoquinone (TQ) on the spermatogenesis after testicular injury caused by chronic toluene exposure in rats. The rats were randomly allotted into one of three experimental groups: control, toluene-treated and toluene treated with TQ; each group contained 10 animals. Control group received 1 mL serum physiologic and toluene treatment was performed by inhalation of 3000 ppm toluene, in an 8-hour/day and 6-day/week order for 12 weeks. The rats in TQ-treated group was given TQ (50 mg/kg body weight) once a day orally for 12 weeks starting just after toluene exposure. Tissue samples were obtained for histopathological investigation. To date, no histopathological changes of testis in rats after chronic toluene exposure by TQ treatment have been reported. Spermatogenesis and mean seminiferous tubule diameter (MSTD) were significantly decreased in toluene treated groups when compared to the control group. Furthermore, the TQ-treated animals showed an improved histological appearance in toluene-treated group. Our data indicate a significant reduction in the activity of in situ identification of apoptosis using terminal dUTP nick end-labeling (TUNEL), endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS) and there was a rise in the expression of proliferating cell nuclear antigen (PCNA) in testis tissues of the toluene-treated group with TQ therapy. Electron microscopy of the testes of the rats demonstrated that pretreatment with TQ was particularly effective in preventing the mitochondrial degeneration, dilatation of smooth endoplasmic reticulum (SER) and enlarged intercellular spaces in both Sertoli and spermatid cells in the toluene-treated animals. We believe that further preclinical research into the utility of TQ may indicate its usefulness as a potential treatment on the spermatogenesis after testicular injury caused by chronic toluene exposure in rats.

Orchidectomy enhances the effects of phenylephrine in rat isolated portal vein

1. Orchidectomy results in long-term testosterone deprivation similar to that observed in male clinical pathologies, such as hypogonadism and age-related reductions in plasma testosterone concentrations. Although the vascular effects of these sorts of hormone deprivations are known in arteries, they have not been studied to the same extent in veins. 2. The aim of the present study was to determine the effect of orchidectomy, with or without subsequent testosterone replacement (started 23 days after orchidectomy; 10 mg/kg, i.m., testosterone propionate once every 5 days for 3 weeks), on responses of rat isolated portal veins and vena cavae to exogenous phenylephrine (PE). Isolated vessels were mounted in an organ bath and concentration-response curves constructed to PE (10(-10)-10(-4) mol/L), endothelin (ET; 10(-10)-10(-5) mol/L) and KCl (10(-2)-1.2 x 10(-1) mol/L; as a control). 3. Orchidectomy had no effect on contractile responses of either the portal vein or vena cava to KCl. However, orchidectomy enhanced the maximum response (R(max)) of the portal vein, but not the vena cava, to PE. Testosterone replacement had no effect on these responses. The effects of orchidectomy on the R(max) to PE in portal veins were not altered by the nitric oxide synthase inhibitor N(G)-nitro-l-arginine methyl ester (10(-4) mol/L) alone or combined with 10(-5) mol/L indomethacin (a non-selective cyclo-oxygenase inhibitor), but they were abolished following treatment of isolated vessels with the ET(A) and ET(B) receptor antagonists BQ-123 and BQ-788 (both at 10(-6) mol/L). Orchidectomy did not alter portal vein responses to the application of exogenous ET. 4. The results of the present study indicate that orchidectomy-induced decreases in plasma testosterone can increase the venoconstrictor effects of PE on the portal vein and that this effect involves activation of both ET(A) and ET(B) receptors by locally produced ET.

Effects of maternal toluene exposure on testosterone levels in fetal rats

The goal of our study was to determine if toluene affected the synthesis and secretion of testosterone in fetal rats. Dams were exposed to atmospheres that contained 0.09 ppm, 0.9 ppm or 9 ppm of toluene for 90 min/day from gestational days (GDs) 14.5 to 18.5 via nasal inhalation. Fetal plasma testosterone concentrations determined by enzyme immunoassay were significantly reduced on GD 18.5 after exposure to 0.9 and 9 ppm, but not to 0.09 ppm, of toluene in male, but not in female, fetuses. We measured, using real-time PCR methods, mRNA levels in fetal testes for several steroidogenic enzymes involved in testosterone synthesis and insulin-like 3 (Insl3), a maker of Leydig cell differentiation. The mRNA levels of 3beta-hydroxysteroid dehydrogenase (3beta-HSD) were significantly reduced after exposure to 0.9-ppm toluene. However, the mRNA levels of cytochrome P450 cholesterol side-chain cleavage, cytochrome P450 17alpha-hydroxylase/c17-20 lyase, 17beta-hydroxysteroid dehydrogenase, and Insl3 were not significantly altered by exposure to 0.9-ppm toluene. In addition, immunohistochemical analysis showed reduced 3beta-HSD-immunoreactive areas in the interstitial region of fetal testes after exposure to 0.9 and 9 ppm, but not 0.09 ppm, toluene. These findings indicate that toluene reduced the synthesis and secretion of testosterone in fetal testes from rats possibly as a consequence of reduced 3beta-HSD expression.