Combined exposure to agriculture pesticides, paraquat and maneb, induces alterations in the N/OFQ-NOPr and PDYN/KOPr systems in rats: Relevance to sporadic Parkinson's disease

Ferulic acid grafted into β-cyclodextrin nanosponges ameliorates Paraquat-induced human MRC-5 fibroblast injury

Paraquat (PQ) is a commercially important and effective herbicide in the world. Nevertheless, it has higher toxicity causing acute organ damage and different complications, mainly in the lungs and kidneys. Ferulic acid (FA), 4-hydroxy-3-methoxycinnamic acid imposes multiple pharmacological impacts. No protective effect of FA on PQ poisoning-caused human embryonic lung fibroblast damage has not been reported. Despite their many beneficial effects, FA is characterized by poor water solubility, low bioavailability, and phytochemical instability. To solve the problem, β-cyclodextrin nanosponge (β-CD NSs) was utilized to increase the solubility of FA so that it was grafted into β-CD NSs to establish β-CD@FA NSs. The purpose of this work was to examine for the first time the protective effect of β-CD@FA NS on MRC-5 human lung cells damages induced by PQ poisoning. MTS assay was performed to investigate the viability of MRC-5 cells at different concentrations of FA/β-CD@FA NSs when cells were co-cultured with 0.2 μg/mL PQ. The flow cytometry study was carried out to determine apoptosis. Malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) levels were detected using appropriate biochemistry kits. Compared with the PQ group, the cell activity, CAT, and SOD levels were significantly increased in the FA and chiefly in β-CD@FA NSs intervention groups, whereas apoptosis and MDA levels were markedly decreased. The inflammatory factors tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and interleukin 22 (IL-22) were detected. The results demonstrate that β-CD@FA NSs can inhibit PQ-induced cell damage by enhancing antioxidant stress capacity and regulation of inflammatory responses.

Frequency of urinary pesticides in children: a scoping review

Pesticides are any mix of ingredients and substances used to eliminate or control unwanted vegetable or animal species recognized as plagues. Its use has been discussed in research due to the scarcity of strong scientific evidence about its health effects. International literature is still insufficient to establish a global recommendation through public policy. This study aims to explore international evidence of the presence of pesticides in urine samples from children and their effects on health through a scoping review based on the methodology described by Arksey and O'Malley. The number of articles resulting from the keyword combination was 454, and a total of 93 manuscripts were included in the results and 22 were complementary. Keywords included in the search were: urinary, pesticide, children, and childhood. Children are exposed to pesticide residues through a fruit and vegetable intake environment and household insecticide use. Behavioral effects of neural damage, diabetes, obesity, and pulmonary function are health outcomes for children that are commonly studied. Gas and liquid chromatography-tandem mass spectrometry methods are used predominantly for metabolite-pesticide detection in urine samples. Dialkylphosphates (DAP) are common in organophosphate (OP) metabolite studies. First-morning spot samples are recommended to most accurately characterize OP dose in children. International evidence in PubMed supports that organic diets in children are successful interventions that decrease the urinary levels of pesticides. Several urinary pesticide studies were found throughout the world's population. However, there is a knowledge gap that is important to address (public policy), due to farming activities that are predominant in these territories.

Parkinson's Disease: Exploring Different Animal Model Systems

Disease modeling in non-human subjects is an essential part of any clinical research. To gain proper understanding of the etiology and pathophysiology of any disease, experimental models are required to replicate the disease process. Due to the huge diversity in pathophysiology and prognosis in different diseases, animal modeling is customized and specific accordingly. As in other neurodegenerative diseases, Parkinson's disease is a progressive disorder coupled with varying forms of physical and mental disabilities. The pathological hallmarks of Parkinson's disease are associated with the accumulation of misfolded protein called α-synuclein as Lewy body, and degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc) area affecting the patient's motor activity. Extensive research has already been conducted regarding animal modeling of Parkinson's diseases. These include animal systems with induction of Parkinson's, either pharmacologically or via genetic manipulation. In this review, we will be summarizing and discussing some of the commonly employed Parkinson's disease animal model systems and their applications and limitations.

Garcinol protects SH-SY5Y cells against MPP+-induced cell death by activating DJ-1/SIRT1 and PGC-1α mediated antioxidant pathway in sequential stimulation of p-AMPK mediated autophagy

Parkinson's disease (PD), a chronic and progressive neurodegenerative disease, can reduce the population of dopaminergic neurons in the substantia nigra. The cause of this neuronal death remains unclear. 1-Methyl-4-phenylpyridinium ion (MPP+) is a potent neurotoxin that can destroy dopaminergic (DA) neurons and promote PD. Garcinol, a polyisoprenylated benzophenone derivative, was extracted from Garcinia indica and is an important active compound it has been used as an anticancer, antioxidant, and anti-inflammatory, agent and it can suppress reactive oxygen species (ROS) mediated cell death in a PD model. Human neuroblastoma (SH-SY5Y) cells (1 × 10⁵  cells) were treated with MPP+ (1 mM) for 24 h to induce cellular ROS production. The formation of ROS was suppressed by pretreatment with different concentrations of garcinol (0.5 and 1.0 μM) for 3 h in SH-SY5Y cells. The present study found that MPP+ treatment increased the formation of reactive oxygen species (ROS), and the increased ROS began to promote cell death in SH-SY5Y cells. However, our natural compound garcinol effectively blocked MPP+-mediated ROS formation by activating the DJ-1/SIRT1 and PGC-1α mediated antioxidant pathway. Further findings indicate that the activated SIRT1 can also regulate p-AMPK-mediated autophagy to protect the neurons from the damage it concludes that garcinol sub-sequential regulates intracellular autophagy in this model, and the productive efficacy of garcinol was confirmed by western blot analysis and MitoSOX DCFDA and MTT assays. The results showed garcinol increased protection due to the prevention of MPP+-induced ROS and the promotion of cell survival.

Cryptotanshinone protects against oxidative stress in the paraquat-induced Parkinson's disease model

Parkinson's disease (PD) is a common neurodegenerative disorder associated with striatal dopaminergic neuronal loss in the Substantia nigra. Oxidative stress plays a significant role in several neurodegenerative diseases. Paraquat (PQ) is considered a potential neurotoxin that affects the brain leading to the death of dopaminergic neurons mimicking the PD phenotype. Various scientific reports have proven that cryptotanshinone possesses antioxidant and anti-inflammatory properties. We hypothesized that cryptotanshinone could extend its neuroprotective activity by exerting antioxidant effects. This study was designed to evaluate the effects of cryptotanshinone in both cellular and animal models of PQ-induced PD. Annexin V-PI double staining and immunoblotting were used to detect apoptosis and oxidative stress proteins, respectively. Reactive oxygen species kits were used to evaluate oxidative stress in cells. For in vivo studies, 18 B6 mice were divided into three groups. The rotarod data revealed the motor function and immunostaining showed the survival of TH+ neurons in SNpc region. Our study showed that cryptotanshinone attenuated paraquat-induced oxidative stress by upregulating anti-oxidant markers in vitro, and restored behavioral deficits and survival of dopaminergic neurons in vivo, demonstrating its therapeutic potential.

Exposure to dithiocarbamate fungicide maneb in vitro and in vivo: Neuronal apoptosis and underlying mechanisms

Maneb, a widely-used dithiocarbamate fungicide, remains in the environment and exerts adverse health effects. Epidemiological evidence shows that maneb exposure is associated with a higher risk of Parkinson's disease (PD), one of the most common neurodegenerative diseases. However, the molecular mechanisms underlying maneb-induced neurotoxicity remain unclear. Here we investigated the toxic effects and the underlying mechanisms of maneb on the degeneration of dopaminergic cells and α-synuclein in A53T transgenic mice. In SH-SY5Y cells, exposure to maneb reduces cell viability, triggers neuronal apoptosis, induces mitochondrial dysfunction, and generates reactive oxidative species (ROS) in a dose-dependent manner. Furthermore, Western blot analysis found that the mitochondrial apoptosis pathway (Bcl-2, Bax, cytochrome c, activated caspase-3) and the PKA/CREB signaling pathway (PKA, PDE10A, CREB, p-CREB) were changed by maneb both in vitro and in vivo. In addition, the activation of the mitochondrial apoptosis pathway induced by maneb was attenuated by activating PKA. Therefore, these results suggest that the PKA/CREB signaling pathway is involved in maneb-induced apoptosis. This study provides novel insights into maneb-induced neurotoxicity and the underlying mechanisms, which may serve as a guide for further toxicological assessment and standard application of maneb.

Application of neurotoxin- and pesticide-induced animal models of Parkinson's disease in the evaluation of new drug delivery systems

Parkinson's disease (PD) is the second most prevalent neuro-degenerative disease after Alzheimer´s disease. It is characterized by motor symptoms such as akinesia, bradykinesia, tremor, rigidity, and postural abnormalities, due to the loss of nigral dopaminergic neurons and a decrease in the dopa-mine contents of the caudate-putamen structures. To this date, there is no cure for the disease and available treatments are aimed at controlling the symptoms. Therefore, there is an unmet need for new treatments for PD. In the past decades, animal models of PD have been proven to be valuable tools in elucidating the nature of the pathogenic processes involved in the disease, and in designing new pharmacological approaches. Here, we review the use of neurotoxin-induced and pesticide-induced animal models of PD, specifically those induced by rotenone, paraquat, maneb, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and 6-OHDA (6-hydroxydopamine), and their application in the development of new drug delivery systems for PD.

Paraquat herbicide diminishes chemoreflex sensitivity, induces cardiac autonomic imbalance and impair cardiac function in rats

Paraquat (PQT) herbicide is widely used in agricultural practices despite being highly toxic to humans. It has been proposed that PQT exposure may promote cardiorespiratory impairment. However, the physiological mechanisms involved in cardiorespiratory dysfunction following PQT exposure are poorly known. We aimed to determine the effects of PQT on ventilatory chemoreflex control, cardiac autonomic control, and cardiac function in rats. Male Sprague-Dawley rats received two injections/week of PQT (5 mg·kg-1 ip) for 4 wk. Cardiac function was assessed through echocardiography and pressure-volume loops. Ventilatory function was evaluated using whole body plethysmography. Autonomic control was indirectly evaluated by heart rate variability (HRV). Cardiac electrophysiology (EKG) and exercise capacity were also measured. Four weeks of PQT administration markedly enlarged the heart as evidenced by increases in ventricular volumes and induced cardiac diastolic dysfunction. Indeed, end-diastolic pressure was significantly higher in PQT rats compared with control (2.42 ± 0.90 vs. 4.01 ± 0.92 mmHg, PQT vs. control, P < 0.05). In addition, PQT significantly reduced both the hypercapnic and hypoxic ventilatory chemoreflex response and induced irregular breathing. Also, PQT induced autonomic imbalance and reductions in the amplitude of EKG waves. Finally, PQT administration impaired exercise capacity in rats as evidenced by a ∼2-fold decrease in times-to-fatigue compared with control rats. Our results showed that 4 wk of PQT treatment induces cardiorespiratory dysfunction in rats and suggests that repetitive exposure to PQT may induce harmful mid/long-term cardiovascular, respiratory, and cardiac consequences.NEW & NOREWORTHY Paraquat herbicide is still employed in agricultural practices in several countries. Here, we showed for the first time that 1 mo paraquat administration results in cardiac adverse remodeling, blunts ventilatory chemoreflex drive, and promotes irregular breathing at rest in previously healthy rats. In addition, paraquat exposure induced cardiac autonomic imbalance and cardiac electrophysiology alterations. Lastly, cardiac diastolic dysfunction was overt in rats following 1 mo of paraquat treatment.

Back and to the Future: From Neurotoxin-Induced to Human Parkinson's Disease Models

Parkinson's disease (PD) is an age-related neurodegenerative disorder characterized by motor symptoms such as tremor, slowness of movement, rigidity, and postural instability, as well as non-motor features like sleep disturbances, loss of ability to smell, depression, constipation, and pain. Motor symptoms are caused by depletion of dopamine in the striatum due to the progressive loss of dopamine neurons in the substantia nigra pars compacta. Approximately 10% of PD cases are familial arising from genetic mutations in α-synuclein, LRRK2, DJ-1, PINK1, parkin, and several other proteins. The majority of PD cases are, however, idiopathic, i.e., having no clear etiology. PD is characterized by progressive accumulation of insoluble inclusions, known as Lewy bodies, mostly composed of α-synuclein and membrane components. The cause of PD is currently attributed to cellular proteostasis deregulation and mitochondrial dysfunction, which are likely interdependent. In addition, neuroinflammation is present in brains of PD patients, but whether it is the cause or consequence of neurodegeneration remains to be studied. Rodents do not develop PD or PD-like motor symptoms spontaneously; however, neurotoxins, genetic mutations, viral vector-mediated transgene expression and, recently, injections of misfolded α-synuclein have been successfully utilized to model certain aspects of the disease. Here, we critically review the advantages and drawbacks of rodent PD models and discuss approaches to advance pre-clinical PD research towards successful disease-modifying therapy. © 2020 The Authors.

Managing Parkinson's disease: moving ON with NOP

The opioid-like neuropeptide nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP receptor) contribute to Parkinson's disease (PD) and motor complications associated with levodopa therapy. The N/OFQ-NOP receptor system is expressed in cortical and subcortical motor areas and, notably, in dopaminergic neurons of the substantia nigra compacta. Dopamine depletion, as in rodent models of PD results in up-regulation of N/OFQ transmission in the substantia nigra and down-regulation of N/OFQ transmission in the striatum. Consistent with this, NOP receptor antagonists relieve motor deficits in PD models by reinstating the physiological balance between excitatory and inhibitory inputs impinging on nigro-thalamic GABAergic neurons. NOP receptor antagonists also counteract the degeneration of nigrostriatal dopaminergic neurons, possibly by attenuating the excitotoxicity or modulating the immune response. Conversely, NOP receptor agonists attenuate levodopa-induced dyskinesia by attenuating the hyperactivation of striatal D1 receptor signalling in neurons of the direct striatonigral pathway. The N/OFQ-NOP receptor system might represent a novel target in the therapy of PD.

Wnt1 silencing enhances neurotoxicity induced by paraquat and maneb in SH-SY5Y cells

Wingless (Wnt) signaling regulates the proliferation and differentiation of midbrain dopamine (DA) neurons. Paraquat (PQ) and maneb (MB) are environmental pollutants that can be used to model Parkinson's disease (PD) in rodents. A previous study demonstrated that developmental exposure to PQ and MB affects the expression of Wnt1, Wnt5a, nuclear receptor-related factor 1 (NURR1) and tyrosine hydroxylase (TH). However, how Wnt signaling regulates these developmental factors in vitro is yet to be determined. To explore this, SH-SY5Y cells were exposed to PQ and MB. The results of the current study indicated that exposure to PQ and MB decreased Wnt1, β-catenin, NURR1 and TH levels and increased Wnt5a levels. Furthermore, Wnt1 silencing has the same effect as exposure to PQ and MB. Additionally, the neurotoxicity induced by PQ and MB is more severe in siWnt1-SH-SY5Y cells compared with normal SH-SY5Y cells. Therefore, Wnt1 may serve an important role in regulating developmental DA factors, and may be a candidate gene for PD diagnosis or gene therapy.

NOP Receptor Ligands and Parkinson's Disease

Nociceptin/Orphanin FQ (N/OFQ) and its NOP receptor are highly expressed in motor areas of the rodent, nonhuman, and human primate brain, such as primary motor cortex, thalamus, globus pallidus, striatum, and substantia nigra. Endogenous N/OFQ negatively regulates motor behavior and dopamine transmission through NOP receptors expressed by dopaminergic neurons of the substantia nigra compacta. Consistent with the existence of an N/OFQ tone over dopaminergic transmission, blockade of NOP receptor antagonists increases striatal dopamine release. In this chapter, we will review the evidence linking the N/OFQ-NOP receptor system to Parkinson's disease (PD). We will first discuss data showing that the central N/OFQ-NOP receptor system undergoes plastic changes in different basal ganglia nuclei following dopamine depletion. Then we will show that NOP receptor antagonists relieve motor deficits in different rodent and nonhuman primate models of PD. Mechanistically, NOP receptor blockade in substantia nigra reticulata results in rebalancing of the inhibitory GABAergic and excitatory glutamatergic inputs impinging on nigro-thalamic GABAergic neurons, leading to thalamic disinhibition. We will also present data showing that, in addition to motor symptoms, N/OFQ also plays a role in the parkinsonian neurodegeneration. In fact, NOP receptor antagonists possess neuroprotective/neurorescue properties in in vitro and in vivo models of PD.

Regulation of the Genes Encoding the ppN/OFQ and NOP Receptor

Over the years, the ability of N/OFQ-NOP receptor system in modulating several physiological functions, including the release of neurotransmitters, anxiety-like behavior responses, modulation of the reward circuitry, inflammatory signaling, nociception, and motor function, has been examined in several brain regions and at spinal level. This chapter collects information related to the genes encoding the ppN/OFQ and NOP receptor, their regulation, and relative transcriptional control mechanisms. Furthermore, genetic manipulations, polymorphisms, and epigenetic alterations associated with different pathological conditions are discussed. The evidence here collected indicates that the study of ppN/OFQ and NOP receptor gene expression may offer novel opportunities in the field of personalized therapies and highlights this system as a good "druggable target" for different pathological conditions.

Revisiting the Paraquat-Induced Sporadic Parkinson's Disease-Like Model

Parkinson's disease (PD) is a major neurodegenerative disorder that affects 1-2% of the total global population. Despite its high prevalence and publication of several studies focused on understanding its pathology, an effective treatment that stops and/or reverses the damage to dopaminergic neurons is unavailable. Similar to other neurodegenerative disorders, PD etiology may be linked to several factors, including genetic susceptibility and environmental elements. Regarding environmental factors, several neurotoxic pollutants, including 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), have been identified. Moreover, some pesticides/herbicides, such as rotenone, paraquat (PQ), maneb (MB), and mancozeb (MZ), cause neurotoxicity and induce a PD-like pathology. Based on these findings, several in vitro and in vivo PD-like models have been developed to understand the pathophysiology of PD and evaluate different therapeutic strategies to fight dopaminergic neurodegeneration. 6-OHDA and MPTP are common models used in PD research, and pesticide-based approaches have become secondary models of study. However, some herbicides, such as PQ, are commonly used by farming laborers in developing countries. Thus, the present review summarizes the relevant scientific background regarding the use and effects of chronic exposure to PQ in the context of PD. Similarly, we discuss the relevance of PD-like models developed using this agrochemical compound.

Orexin receptor expression is increased during mancozeb-induced feeding impairments and neurodegenerative events in a marine fish

Food intake ensures energy resources sufficient for basic metabolism, immune system and reproductive investment. It is already known that food-seeking performances, which are crucially controlled by orexins (ORXs), may be under the influence of environmental factors including pollutants. Among these, mancozeb (mz) is becoming an environmental risk for neurodegenerative diseases. Due to few studies on marine fish exposed to mz, it was our intention to correlate feeding latency, food intake and feeding duration to potential neurodegenerative processes in key diencephalic sites and expression changes of the ORX neuroreceptor (ORXR) in the ornate wrasses (Thalassoma pavo). Hence, fish exposed for 4 days (d) to mz 0.2 mg/l (deriving from a 0.07, 0.14, 0.2, 0.3 mg/l screening test) displayed a significant reduction (p < 0.05) of food intake compared to controls as early as 1d that became more evident (p < 0.01) after 3d. Moreover, significant enhancements of feeding latency were reported after 1d up to 3d (p < 0.001) and even feeding duration was enhanced up to 3d (p < 0.001), which instead moderately increased after 4d (p < 0.05). A reduction (-120%; p < 0.001) of mean body weight was also detected at the end of exposure. Likewise, a notable (p < 0.001) activation of ORXR protein occurred together with mRNA up-regulations in diencephalic areas such as the diffuse nucleus of the inferior lobe (+48%) that also exhibited evident degenerative neuronal fields. Overall, these results highlight an ORX role as a vital component of the neuroprotective program under environmental conditions that interfere with feeding behaviors.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Parkinson's disease: animal models and dopaminergic cell vulnerability

Parkinson's disease (PD) is a neurodegenerative disorder that affects about 1.5% of the global population over 65 years of age. A hallmark feature of PD is the degeneration of the dopamine (DA) neurons in the substantia nigra pars compacta (SNc) and the consequent striatal DA deficiency. Yet, the pathogenesis of PD remains unclear. Despite tremendous growth in recent years in our knowledge of the molecular basis of PD and the molecular pathways of cell death, important questions remain, such as: (1) why are SNc cells especially vulnerable; (2) which mechanisms underlie progressive SNc cell loss; and (3) what do Lewy bodies or α-synuclein reveal about disease progression. Understanding the variable vulnerability of the dopaminergic neurons from the midbrain and the mechanisms whereby pathology becomes widespread are some of the primary objectives of research in PD. Animal models are the best tools to study the pathogenesis of PD. The identification of PD-related genes has led to the development of genetic PD models as an alternative to the classical toxin-based ones, but does the dopaminergic neuronal loss in actual animal models adequately recapitulate that of the human disease? The selection of a particular animal model is very important for the specific goals of the different experiments. In this review, we provide a summary of our current knowledge about the different in vivo models of PD that are used in relation to the vulnerability of the dopaminergic neurons in the midbrain in the pathogenesis of PD.