Neuroinflammatory implication of Schistosoma mansoni infection in the mouse

Alternate-day fasting, a high-sucrose/caloric diet and praziquantel treatment influence biochemical and behavioral parameters during Schistosoma mansoni infection in male BALB/c mice

Schistosoma mansoni-induced granulomas result in severe damage to the host's liver, as well as neurological and metabolic disorders. We evaluated the biochemical and behavioral changes during schistosomiasis under three diet protocols: ad libitum (AL), alternate-day fasting (ADF) and a high-sucrose/caloric diet (HSD). Healthy male BALB/c mice were divided into noninfected, matched infected and infected/treated [praziquantel (PZQ)] groups. Caloric intake and energy efficiency coefficients associated with diets were measured. Behavioral (exploratory and locomotor) and biochemical (glucose, triglycerides, total cholesterol, AST, ALT, ALP, and γ-GT) tests and histological analysis were performed. Fifteen weeks postinfection, HSD and PZQ promoted weight gain, with higher caloric consumption than ADF (p < 0.05), reflecting serum glucose levels and lipid profiles. HSD and PZQ prevented liver dysfunction (AST and ALT) and significantly prevented increases in granuloma area (p < 0.05). HSD and PZQ also significantly improved mouse physical performance in exploratory and locomotor behavior (p < 0.05), reversing the impaired motivation caused by infection. These findings showed that ADF worsened the course of S. mansoni infection, while HSD and PZQ, even with synergistic effects, prevented and/or attenuated biochemical and behavioral impairment from infection.

Nerve Growth Factor, Stress and Diseases

Stress is a constant threat for homeostasis and is represented by different extrinsic and intrinsic stimuli (stressors, Hans Selye's "noxious agents"), such as aggressive behavior, fear, diseases, physical activity, drugs, surgical injury, and environmental and physiological changes. Our organisms respond to stress by activating the adaptive stress system to activate compensatory responses for restoring homeostasis. Nerve Growth Factor (NGF) was discovered as a signaling molecule involved in survival, protection, differentiation, and proliferation of sympathetic and peripheral sensory neurons. NGF mediates stress with an important role in translating environmental stimuli into physiological and pathological feedbacks since NGF levels undergo important variations after exposure to stressful events. Psychological stress, lifestyle stress, and oxidative stress are well known to increase the risk of mental disorders such as schizophrenia, major depressive disorders, bipolar disorder, alcohol use disorders and metabolic disorders such as metabolic syndrome. This review reports recent works describing the activity of NGF in mental and metabolic disorders related to stress.

Nerve Growth Factor in Alcohol Use Disorders

The nerve growth factor (NGF) belongs to the family of neurotrophic factors. Initially discovered as a signaling molecule involved in the survival, protection, differentiation, and proliferation of sympathetic and peripheral sensory neurons, it also participates in the regulation of the immune system and endocrine system. NGF biological activity is due to the binding of two classes of receptors: the tropomyosin-related kinase A (TrkA) and the low-affinity NGF pan-neurotrophin receptor p75. Alcohol Use Disorders (AUD) are one of the most frequent mental disorders in developed countries, characterized by heavy drinking, despite the negative effects of alcohol on brain development and cognitive functions that cause individual’s work, medical, legal, educational, and social life problems. In addition, alcohol consumption during pregnancy disrupts the development of the fetal brain causing a wide range of neurobehavioral outcomes collectively known as fetal alcohol spectrum disorders (FASD). The rationale of this review is to describe crucial findings on the role of NGF in humans and animals, when exposed to prenatal, chronic alcohol consumption, and on binge drinking.

Does physical exercise influence in the development of neuroeschistosomiasis?

Neuroschistosomiasis is a severe form of presentation of schistosomiasis in which Schistosoma spp. affects the central nervous system. This is the first study performed to analyze whether there is any relationship between physical effort and the appearance of neuroschistosomiasis, through clinical, molecular and immunological evaluations. An experimental controlled study using 64 male Balb/c inbred mice divided into four groups according to presence or absence of S. mansoni infection and submitted to physical effort or resting was conducted. Thirteen weeks after exercise training, S. mansoni DNA was detected in the brain or spinal cord in about 30% of the infected animals moreover, only S. mansoni-positive samples showed positive labeling for S. mansoni antigens in the brain or spinal cord, with a striking reaction inside the microglia. However, the behavioral tests did not show any clinical symptoms of neuroschistosomiasis in animals submitted to physical effort or in resting. In animals with S. mansoni-positive DNA, immunohistochemical data revealed astrogliosis and microgliosis, elevated IL-10 levels and decreased TNF-α expression. This study demonstrated that isometric exercise does not promote neuroschistosomiasis, furthermore, ectopic forms of schistosomiasis in the central nervous system were largely asymptomatic and exhibited a Th2 immune response profile. More experimental studies are necessary in order to characterize the pathological process of experimental neuroschistosomiasis.

Development of an experimental model of schistosomal myeloradiculopathy

Schistosomal myeloradiculopathy (SMR) is a severe form of presentation of schistosomiasis in which Schistosoma spp. affect the spinal cord. The aims of the present study were to develop an animal model of SMR caused by S. mansoni, to characterize both sensory and motor abnormalities in the infected animals, and to investigate the relationship of the sensory, motor and histological findings with the progression of the infection over time. Mechanical sensitivity and behavioral tests were performed followed by euthanasia in male Wistar rats divided into six groups of five animals each, on days 5, 10, 20 and 30 after infection of S. mansoni eggs. The controls were subjected to the same procedure but were administered phosphate-buffered saline (PBS). The spinal cord was removed and subjected to histological analysis. S. mansoni eggs were found in the spinal cord of 25% of the infected animals, which belonged to the groups that exhibited more significant reduction of the superficial mechanical sensitivity, thermal sensitivity and muscle strength. This model proved to be satisfactory to assess functional changes in Wistar rats and might be used in studies investigating the pathogenesis of SMR. To our knowledge, this is the first experimental model of SMR.

[Electromyografic patterns predictive of motor evolution in neuroschistosomiasis]

Neuroschistosomiasis in myeloradicular pattern is frequently observed in patients from Northeast of Brazil. Despite of this, the evolution of neurologic and electromyographic patterns is not well studied in this group of patients. The aims of this study were to describe and compare the clinic and electromyographic abnormalities of patients with neuroschistosomiasis and radicular involvement. We analyzed 21 electromyographic exams of the lower limbs carried out in the initial presentation of the disease. Electromyographic pattern of 95.2% of patients was compatible to axonal lumbosacral multirradiculopathy, with variable denervation extension, but predominantly from levels L2 to S2. There was variable degree of deficit in the lower limbs, and the follow-up of motor disturbances was better more frequently when the roots were involved in smaller number. Electromyography should permit to know the motor prognosis of patients with myeloradiculitis due schistosomiasis.

Aluminum disrupts the pro-inflammatory cytokine/neurotrophin balance in primary brain rotation-mediated aggregate cultures: possible role in neurodegeneration

The etiology of human neurodegenerative diseases including Alzheimer's disease (AD) is exceedingly complex and our understanding of the mechanisms involved is far from complete. The experimental neurotoxicology of aluminum has been shown to recapitulate many of the pathophysiological features of AD and therefore represents a useful model to study the mechanisms involved in neurodegeneration. The present study investigated the effects of aluminum maltolate (Al-maltol) on the delicate balance that exists between pro-inflammatory cytokines and neurotrophins using primary brain rotation-mediated aggregate cultures. Aggregates were treated with Al-maltol (5-150 microM) on day 15 in vitro for 72 h. Cell death increased in a time- and concentration-dependent manner reaching significance in aggregates treated with 150 microM Al-maltol in 48 h and 50 microM by 72 h. Analysis of gene expression at 72 h revealed a concentration-dependent increase in tumor necrosis factor alpha (TNFalpha) and macrophage inflammatory protein-1alpha (MIP-1alpha) suggestive of a state of inflammation. In contrast, a dramatic concentration-dependent decrease in the expression of nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) was observed. In fact, NGF expression could not be detected in aggregates treated with 50 and 150 microM Al-maltol. These changes in gene expression correlated with a decrease in aggregate size and an increase in neurodegeneration as indicated by Fluoro-Jade B staining. The results indicated a differential regulation of pro-inflammatory cytokines and neurotrophins in brain tissue following treatment with Al-maltol. Such findings provide insight into the possible involvement of deregulation of the cytokine/neurotrophin balance in the etiology of neurodegeneration.