Biophysical and structural characterization of tetramethrin serum protein complex and its toxicological implications

Tetramethrin (TMT) is a commonly used insecticide and has a carcinogenic and neurodegenerative effect on humans. The binding mechanism and toxicological implications of TMT to human serum albumin (HSA) were examined in this study employing a combination of biophysical and computational methods indicating moderate binding affinity and potential hepato and renal toxicity. Fluorescence quenching experiments showed that TMT binds to HSA with a moderate affinity, and the binding process was spontaneous and predominantly enthalpy-driven. Circular dichroism spectroscopy revealed that TMT binding did not induce any significant conformational changes in HSA, resulting in no changes in its alpha-helix content. The binding site and modalities of TMT interactions with HSA as computed by molecular docking and molecular dynamics simulations revealed that it binds to Sudlow site II of HSA via hydrophobic interactions through its dimethylcyclopropane carboxylate methyl propanyl group. The structural dynamics of TMT induce proper fit into the binding site creating increased and stabilizing interactions. Additionally, molecular mechanics-Poisson Boltzmann surface area calculations also indicated that non-polar and van der Waals were found to be the major contributors to the high binding free energy of the complex. Quantum mechanics (QM) revealed the conformational energies of the binding confirmation and the degree of deviation from the global minimum energy conformation of TMT. The results of this study provide a comprehensive understanding of the binding mechanism of TMT with HSA, which is important for evaluating the toxicity of this insecticide in humans.

Morphometric Evaluation of the Recurrent Laryngeal Nerve of Wistar Rats Exposed to Pesticides

The literature has been shown that exposition by inhalation to chemical compounds can cause vocal disorders and dysphagia in humans, in addition to other symptoms that are manifested according to the type, concentration and duration of exposure to the substance. Cypermethrin and dichlorvos are pesticides widely used in agriculture, public health, veterinary, and home environments. Despite the scientific evidence that cypermethrin and dichlorvos can cause neurodegenerative damage and motor alterations, there are no studies evaluating the toxic effects of these pesticides on the morphology of structures responsible for vocal mobility, especially to the Recurrent Laryngeal Nerve (RLN). Considering the association between vocal disorders in humans and variations in RLN and morphometry, the aim of this study was to evaluate the possible alterations in the microstructure of RLN secondary to subchronic exposure to cypermethrin (pyrethroid) and dichlorvos (organophosphate) in Wistar rats. The experimental protocol (approved by CEUA-UFCSPA: 321/15 and 323/15) consisted of 15 male Wistar rats, allocated in 3 groups: Control (n = 5, exposed to water), Cypermethrin (n = 5, exposed to cypermethrin - 1/10 of the inhalation median lethal concentration [LC50] - 0.25 mg/L) and dichlorvos (n = 5, exposed to dichlorvos - 1/10 of the LC50 - 1.5 mg/L). Inhalation exposure was performed for 4 hours, 5 times per week, for 6 weeks. The nerves were collected, histologically processed and analyzed using morphometric parameters measured using ZEN 2.6 (Zeiss - Germany). The cypermethrin and dichlorvos groups showed significant changes (P < 0.001, ANOVA) in the g-ratio and in the thickness of the myelin sheath of the RLN when compared to the control animals, however, none of the other parameters evaluated showed statistically significant differences. These findings indicate that repeated inhalation exposure to commercial products of cypermethrin and dichlorvos is able to modify the structure of the RLN and possibly generating vocal changes and / or dysphagia.

Neuroprotective Effect of White Nelumbo nucifera Gaertn. Petal Tea in Rats Poisoned with Mancozeb

Nelumbo nucifera Gaertn. (N. nucifera) tea is used as food and folk medicine to reduce toxicity in Southeast Asia. Mancozeb (Mz) is used for controlling fungi in agriculture and contains heavy metals. This study aimed to examine the effect of white N. nucifera petal tea on cognitive behavior, hippocampus histology, oxidative stress, and amino acid metabolism in rats poisoned with mancozeb. Seventy-two male Wistar rats were divided into nine groups (n = 8 in each). Y-maze spontaneous alternation test was used to assess cognitive behavior, and amino acid metabolism was investigated by nuclear magnetic resonance spectroscopy (1H-NMR) from blood. There was a significant increase in relative brain weight in the Mz co-administered with the highest dose (2.20 mg/kg bw) of white N. nucifera group. The levels of tryptophan, kynurenine, picolinic acid, and serotonin in blood showed a significant decrease in the Mz group and a significant increase in the Mz co-administered with low dose (0.55 mg/kg bw) of white N. nucifera group. However, there was no significant difference in cognitive behavior, hippocampus histology, oxidative stress, and corticosterone. This study demonstrated that a low dose of white N. nucifera petal tea has a neuroprotective effect against mancozeb.

Systematic Toxicity of Cypermethrin and Alterations in Behavior of Albino Rats

The present study aimed to evaluate the effect of repeatedly orally administering cypermethrin (CYP) at different doses on the behavior, hematology, and histology of adult male and female albino rats for 1 month. For this, animals have divided into four different groups and each group contained 10 animals (5 males and 5 females). Group I served as a control group and groups II, III, and IV were represented as experimental groups and treated with CYP at doses of 25, 50, and 75 mg/kg body weight/day/rat, respectively. Through the behavioral results of this study, it was observed that cypermethrin intoxication causes dose-dependent moderate to high toxicity symptoms like vomiting, decreased food consumption, thick eye discharge, rolling, tremors, loss of coordination, tilted neck, and convulsion attacks. A significant reduction in body weight of high-dose (75 mg)-treated animals, especially in females, was noticed. Similarly, hematological data also revealed that CYP exposure caused a reduction in the level of Hb, RBC, WBC, neutrophil, and other blood indices such as PCV and MCV and an increase in the lymphocyte percentage in both male and female experimental groups. Microscopic observation stated that CYP produced infiltration of cells near the central vein, hepatocyte degeneration, congestion of the central and portal veins, hemorrhage, and necrosis in liver tissue. Shrinkage of the glomerulus, necrosis in the glomerulus and renal tubules, congestion of blood cells, and hemorrhage were seen in kidney tissue. The current study suggests that hepatotoxicity and nephrotoxicity due to cypermethrin exposure were more prominent in female rats.

Pirimicarb Induction of Behavioral Disorders and of Neurological and Reproductive Toxicities in Male Rats: Euphoric and Preventive Effects of Ephedra alata Monjauzeana

Carbamate pesticides are a risk to human well-being, and pirimicarb is the most widely employed carbamate insecticide. This ongoing investigation aimed to reveal its toxicity on neurobehavioral and reproductive function. The study was carried out on male Wistar rats by assessment of behavioral changes via experiments, such as the forced swim test and the elevated plus maze; determination of oxidative stress (checking parameters such as catalase activity, etc.); measurement of cortisol and testosterone serum titers, and IL-1β levels in the plasma and brain; and evaluation of histopathological lesions that induced pirimicarb after 28 days of gavage, specifically in the brain and testis. Traces of pirimicarb were analyzed in tissue extracts using LCMS/MS. At the same time, the beneficial and protective effect of EamCE (Ephedra alata monjauzeana Crude Extract) were tested. The outcomes showed considerable anxiety and depressive status, with an evident increase in cortisol and IL-1β titers and an important decrease in oxidative enzymes and testosterone. Significant histological lesions were also recorded. In addition, the LCMS/MS analysis affirmed the accumulation of pirimicarb in organ tissue from rats force-fed with pirimicarb. Conversely, EamCE demonstrated outstanding potential as a preventive treatment, restoring cognitive and physical performance, boosting fertility, enhancing antioxidant and anti-inflammatory activities and preserving tissue integrity. We concluded that pirimicarb has critical deleterious impacts on health, affecting the neuroimmune-endocrine axis, and EamCE has a general euphoric and preventive effect.

Effect of cypermethrin on the postnatal development of the medulla oblongata and the possible protective role of melatonin in albino rats

Previous studies have shown that cypermethrin (CYP), a broad spectrum pesticide has a teratogenic effect on rat offspring born to an exposed dam with no information on its effect on the development of the brain. To the best of our knowledge, this research is the first attempt to study the postnatal development medulla oblongata of rat offspring exposed to CYP during the perinatal period and the possible neuroprotective role of melatonin. The offspring of treated female rats were organized into control, melatonin (1 mg/kg/day orally); CYP (12 mg/kg/day orally); and CYP/melatonin groups. The mothers received treatments from day 6 of gestation until day 21 after birth. At Postnatal days 7 and 21, the animals were sacrificed and their medulla oblongata was removed and subjected to histological, immunohistochemical, and electron microscopic studies. CYP induced neuronal degeneration by chromatolysis and pyknosis. Nuclear changes, cytoplasmic vacuolation, damage mitochondria, and breakdown of RER were also detected. Reduction of microtubule-associated protein-2 (MAP-2), myelin basic protein (MBP), and oligodendrocyte transcription factor expressions and increment of glial fibrillary acidic protein expression in the medulla oblongata of the developing rats were observed. On the other hand, melatonin led to an obvious improvement of the injured medulla oblongata tissues and ameliorating the damaging effects of CYP. In conclusion, melatonin has protected rats against CYP-induced histopathological and immunohistochemical changes. This may be due to the protection of MAP-2, conservation of MBP, an increment of oligodendrocytes, and alleviation of astrogliosis.

Nano selenium ameliorates oxidative stress and inflammatory response associated with cypermethrin-induced neurotoxicity in rats

Cypermethrin (CYP), a class II synthetic pyrethroid, is used to control household insects. CYP can cross the blood-brain barrier to exert neurotoxicity through changes in sodium ion channels. Selenium is an essential component of glutathione peroxidise enzyme; in addition, it shows a potential anti-inflammatory property. The present study aimed to investigate the neuroprotective role of Nano-Se on CYP-induced neurotoxicity. Twenty-four adult male Wister rats were randomly divided into three groups: a) control, b) CYP (1mg/kg) administered orally for 21 days, c) CYP (1mg/kg) administered orally for 21 days and Nano-Se (2.5 mg/kg) given once a day three times a week for three weeks). Locomotor activity was assessed using open field test then rats were sacrificed under anaesthesia, and their brains were dissected out and processed for biochemical and histopathological studies. Histological examination of CYP-treated rats demonstrated some degenerative changes; besides, CYP affected rat locomotor activity. CYP-treated rats showed increased levels of malondialdehyde (MDA), TNF-α and IL-1β in addition to the reduction of glutathione (GSH) levels and gamma-Aminobutyric acid (GABA). Nano-Se restored normal behavioural function and significantly attenuated CYP-evoked degenerative changes. Nano-Se increased levels of GABA and glutathione; on the other hand, it significantly prevented the rise in the levels of MDA, TNF-α and IL-1β. Therefore, Nano-Se demonstrated both anti-oxidant and anti-inflammatory potential. Nano-Se may be suggested to be a prospective candidate to ameliorate CYP-induced neurotoxicity.

Ototoxicity of cypermethrin in Wistar rats

Introduction

This study presents the effect of cypermethrin on the cochlear function in Wistar rats post-subchronic inhalation exposure. Worldwide several pesticides are described as causing health disorders. Cypermethrin is currently one of the most commonly used, however, little is known about its harmful effects, especially related to hearing. Human studies have associated pesticides with hearing disorders, but they present limited conclusions due to the multiple factors to which the population is exposed, such as noise.

Objective

Mimic human exposure to cypermethrin and to verify the effects on cochlear function.

Methods

It is a subchronic inhalation animal study (6 weeks, 4 hours/day), using 36 male Wistar aged 60 day. Rats were randomly assigned into three groups: Control (12 rats exposed to inhalation of water); Positive Control for auditory lesion (12 rats administrated with 24 mg/kg intraperitoneal cisplatin); Experimental (12 rats exposed to inhalation of cypermethrin – 0.25 mg/L). Animals were evaluated by distortion product otoacoustic emissions pre- and post-exposure.

Results

The frequencies of 8, 10 and 12 kHz in both ears (right p = 0.003; 0.004; 0.008 and left 0.003; 0.016; 0.005 respectively) and at frequencies 4 and 6 in the right ear (p = 0.007 and 0.015, respectively) in the animals exposed to cypermethrin resulted in reduction.

Conclusion

Subchronic inhalation exposure to cypermethrin provided ototoxicity in rats.

Long term biochemical changes in offspring of rats fed diet containing alpha-cypermethrin

To investigate the possible developmental programming, we analyzed the effects of maternal and postnatal low dose alpha-cypermethrin exposure on metabolic and redox parameters in the offspring. Postnatal changes in plasma biochemical parameters and plasma and tissue oxidative stress markers were determined in offspring of dams fed standard chow or diet containing alpha cypermethrin at 1.50mg/kg/day during gestation and lactation, weaned on to standard chow or on treated diet until adulthood (5months). Our results showed that exposure to alpha cypermethrin induced a significant reduction in body weight, food intake and metabolic alterations such as an increase in plasma glucose, triglyceride, urea, creatinine and AST levels in both postnatal and prenatal/postnatal treated female and male rats. This increase was more pronounced in prenatal/postnatal exposed rats. Alpha-cypermethrin exposure resulted in an imbalance of oxidant/antioxidant status, marked by high levels of carbonyl proteins and MDA, and low levels of antioxidants in erythrocytes, liver and kidney of both male and female offspring. Offspring of exposed dams have pre-existing oxidative stress that was accentuated with postnatal pesticide exposure. In conclusion, maternal alpha-cypermethrin exposure affected metabolism leading to permanent changes in biochemical parameters, enzyme activities and redox markers in the offspring. These abnormalities in offspring were worsened under postnatal pesticide exposure from weaning to adulthood.

Effect of pyrethroids on female genital system. Review

Pyrethroids have been associated with a range of toxicological effects on various organs in animals.Recent animal studies suggest that neurodevelopmental, reproductive, and immunological effects may result following exposure to some pyrethroids at levels below those that induce overt signs of neurotoxicity. A variety of pyrethroids and their metabolites have the potential to affect the reproductive system. Dose-dependent effects on reproduction are associated with exposure across pyrethroid types. In mammals, permethrin and tetramethrin and cypermethrin have been found to be associated with adverse effects at high doses. Fenvalerate, deltamethrin, cypermethrin, caused morphometric and structural changes in the female genital organs. These pyrethroids affect ovulation, cause atresia of follicles, decrease the number of follicular cells, oocytes and corpora lutea and induce vesicular atrophy of the endometrial glands. The potential hormonal activity of pyrethroids showed that certain pyrethroids and their metabolites have multiple effects on the endocrine system. The level of steroid hormones, such as progesterone and estradiol, was inhibited. The pyrethorids may have the potential to mimic estrogens or to inhibit estrogen action. Some metabolites of pyrethroids, in particular permethrin and cypermethrin, are more likely to interact with the cellular estrogen receptors than the parent pyrethroids. Though several pyrethroids posses low toxicity, some pyrethroids, such as deltamethrin, cypermethrin, fenvalerate and bifenthrin have showed considerable toxicity.

Proliferation and TH1/TH2 cytokine production in human peripheral blood mononuclear cells after treatment with cypermethrin and mancozeb in vitro

In recent times, human cell-based assays are gaining attention in assessments of immunomodulatory effects of chemicals. In the study here, the possible effects of cypermethrin and mancozeb on lymphocyte proliferation and proinflammatory (tumor necrosis factor (TNF-) α) and immunoregulatory cytokine (interferon- (IFN-) γ, interleukins (IL) 2, 4, 6, and 10) formation in vitro were investigated. Human peripheral blood mononuclear cells (PBMC) were isolated and exposed for 6 hr to noncytotoxic doses (0.45–30 µM) of cypermethrin or mancozeb in the presence of activating rat S9 fraction. Cultures were then further incubated for 48 or 72 hr in fresh medium containing phytohemagglutinin (10 µg/mL) to assess, respectively, effects on cell proliferation (BrdU-ELISA method) and cytokine formation (flow cytometric bead immunoassays). Mancozeb induced dose-dependent increases in lymphocyte proliferation, inhibition of production of TNFα and the T_H2 cytokines IL-6 and IL-10, and an increase in IFNγ (T_H1 cytokine) production (at least 2-fold compared to control); mancozeb also induced inhibition of IL-4 (T_H2) and stimulated IL-2 (T_H1) production, albeit only in dose-related manners for each. In contrast, cypermethrin exposure did not cause significant effects on proliferation or cytokine profiles. Further studies are needed to better understand the functional significance of our in vitro findings.

Histomorphometric study of testis in deltamethrin treated albino rats

Deltamethrin, a type II synthetic pyrethroid, has lead to a widespread concern over the potential adverse effects on human health. Adult Wistar albino rats, weighing 150-200 g, were divided into two groups of ten animals each. The group II rats were injected with deltamethrin (1 mg/kg body weight) intraperitoneally, for five days/week for a month. The group I were controls. Animals were sacrificed within 24 h of the last injection by perfusion under anesthesia. Paraffin sections (8 μm) were cut, and stained with hematoxylin and eosin. Histomorphometry was done. There was a decrease in the body weight but increase in the weight of the testis of rat. The mean vertical, antero-posterior and transverse diameter of the testis is reduced. The basement membrane enclosing the seminiferous tubules appeared thickened at sites. The number of seminiferous tubules per unit area is statistically significantly reduced. There was a generalized significant decrease in the diameter and the epithelium thickness (height) of the seminiferous tubules, associated collapse and distortion at sites of the tubules predominantly in the central region. The data obtained in the present work suggest that gonadal (testis) changes could seriously affect the reproductive potential of the rat.

Haematological alterations induced by oral subacute exposure to fenvalerate, nitrate and their combination in domestic buffalo, Bubalus bubalis

The present study investigated haematological alterations induced by oral subacute exposure to fenvalerate, nitrate and their combination in the domestic buffalo, Bubalus bubalis. Fenvalerate exposure produced significant declines in haemoglobin (Hb), total leukocyte count (TLC), total erythrocyte count (TEC) and mean corpuscular haemoglobin concentration (MCHC), and a corresponding elevation in mean corpuscular volume (MCV). Following oral exposure to sodium nitrate, significant declines in blood Hb, TLC, TEC, MCH and MCHC, and a significant elevation in MCV occurred. Combined exposure to fenvalerate and sodium nitrate produced severe effects with an appreciably more prominent decline in Hb, TLC, TEC and MCHC and a significant elevation in MCV. The percentage of methaemoglobin was observed to follow an elevating trend in animals exposed to sodium nitrate alone (0.69 %-13.8 %) and in combination with fenvalerate (0.75 %-13.7 %).

Comparison of the haemodynamic effects of pyrethroid insecticide and amodiaquine in rats

Malaria infection is a common cause of morbidity and mortality especially in the tropics and subtropics. This has led to the increased prophylactic use ofpyrethroid insecticides and/or Amodiaquine (Aq) to combat the parasitic protozoan infection. The aim of this study was to investigate the comparative haemodynamic effects of pyrethroid insecticide and amodiaquine in rats. Experimental rats were randomly allocated into seven groups of five rats in each. Groups 1, 2 and 3 were exposed to pyrethroid by inhalation for 1, 2 and 3 min, respectively, while groups 4, 5 and 6 were administered Aqper oral at 5, 10 and 15 mg kg(-1) b.wt., respectively. Control rats were neither exposed to pyrethroid nor administered Aq. Pyrethroid insecticide led to reduced systolic, diastolic and mean arterial pressures, but increased pulse pressure. Aq treatment did not cause any significant variation in haemodynamic variables. Heart rate was comparable in all groups. Results from the study provide extended safety/toxicity profile for pyrethroid use and Aq treatment. Aq showed no cardiotoxic potential, while pyrethroids have hypotensive effect. It is thus recommended that exposure to pyrethroids should be minimized.

Effects of pyrethroid insecticide exposure on haematological and haemostatic profiles in rats

High malaria burden has led to the increase use of insecticides in the tropics and subtropics. This study thus aimed at assessing the haematological effects and associated haemostatic alteration of pyrethroid insecticide exposure using experimental animal model. Rats of comparable ages and weights were randomized into four groups (A-D). Rats in groups B, C and D were exposed to pyrethroid insecticide by inhalation for 1, 2 and 3 min daily respectively for three weeks. Rats in group A (control) were not exposed. Haematological and haemostatic variables were comparable in all groups (< 0.05). Results from the study show that minimal exposure to pyrethroids is safe.

Toxicological studies on a standardized extract of Solanum indicum ssp. distichum

A standardized extract of the fruits of Solanum distichum has previously been shown to possess anti-hypertensive activity in rats (ED50 about 1 mg/kg). Earlier acute toxicity studies had shown that single doses up to 2g/kg orally or intraperitoneally failed to show any signs of morbidity. To study its potential long-term toxicity, rats of either sex were fed orally 1g/kg of the extract daily over a period of 4 weeks to 6 months. The extract did not affect food intake or rate of growth of the animals. Blood counts and other hematological parameters remained unaffected. Treatment for 4 weeks had no effect on plasma cholesterol or blood urea nitrogen in both sexes, but extended treatment to 6 months tended to lower both parameters. Plasma creatinine, liver enzymes and fasting blood sugar, plasma electrolytes, total protein and albumin were not altered. Gross necropsy showed a 20% increase in liver to body weight ratios after 6 months. None of the body organs tested showed any histopathological changes. Bearing in mind that the dose of the extract used in this study was several 100 times greater than its ED50, the present findings point to the wide safety margin of the extract.

Effect of oral administration of fenitrothion on biochemical and hematological parameters in rats

The aim of this study was to evaluate the effects of acute exposure to various doses of fenitrothion (FNT) on level of serum glucose, total protein, triglycerides (TG), total cholesterol (TC) and some hematological parameters. The study was conducted on 8-week-old male Wistar rats that divided into four groups (three experimental groups and one control group), were treated orally with different doses (25, 50 and 100 mg kg(-1)) of fenitrothion for 28 consecutive day. After treatment, blood samples were collected for biochemical and hematological studies. Present results demonstrated that exposed groups led to significant dose-dependent increase in serum glucose and cholesterol levels. Significant decrease was observed in some hematological parameters [Red Blood Cell (RBC) counts, Hemoglobin (Hb), Haematocrite (Ht) and Mean Corpuscular Hemoglobin (MCH) values]. Serum total protein and triglycerides were also decreased not significantly in exposed groups when compared with control. Generally, the degrees of observed variations were found to be dose dependent.